ORNL-TM-0729A.txt

 

Contract No. W-7405-eng-26

Instrum i
entation and Controls Division

MS
RE DESIGN AND OPERATIONS REPORT
Part IIA.

Je« R. Tallackson

" LEGA

as an account of

racy, completeness,
of any information,
privately owned rights; or

B. Assumes any 1iabilities
use of any information, apparatus,

As used in the above,
ployee oF contractor
guch employee or contractor of the
disseminates,
with the Commission,

with respect

or his employment with such

FEBRUARY 1968

OAK Ré[)l;l(iE IETATIONAL LABORATORY
R(l)dge » Tennessee
perated b
UNION CARBIDE CORPgRATION
.S, ATO for the
. MIC ENERGY COMMISSION

Government
acting on be
expres sed

to the use of,
method, OF process disclol
ting on behalf
or employee of 8¢
or employes
any information pursusnt
contractoT.

Nucl
ear and Process Instrumentatio
n

or for damages resulting from the
sed in this report.

of the Comm.\sslon" {ncludes any em~
ch contractor,

 

ORNL-TM-729, Fart tl A

 

to the extent that
of such contractor prepares,
o his employment of contract

-::V‘. T
B

\u

ry

 
 

 

 

 

 

 
 

CONTENTS

ACmOWIED(mNT..“.V..D.....l'...‘.........l...................l....

1. MSEE INSTRUMENTATION AND CONTROL SYSTEM — CGENERALeasececsecaens

1.1
1.2

1.3

Introductol‘y. RemarkS..IlC.........O‘.......0..............

Desigl ConsiderationSIIl.O......‘...O....’...l..‘...l.....

1.2.1
1.2.2

1.2.3

1.2.4

102.5

102.6-

1.2.7

1.2.8

Introduction....................‘.....ll....Ol..l.

Operational RequirementS.ceesccscesssssssccscsnes

10720201

o
d POV

-
»

. o & .
° ® ®
LW

o
o

W Ww
o

O FHEEHE
VOH DN

e3.3
0

Compatibility with Centralized Control

”Philosopl]y..‘.'....0...................

Fase of Operation..cssececsscececcceses
Flexibilityeeescesesosestsscccscssonsnae
Experimental DatB.seesecscosccsccssccsse
Remote MaintenancCe.c.ceecscescccscscceces
Maintainability.ceeeesessssccesossnnces

y Req_uirements.l..‘.l......l...'..l.......‘l.

Containmentlio_.......'..........‘....l.
Redundancy, Separation, and Identifi-

cation.ili.....'....Ol......'..........

Hazards to Operating Persomnel..cececes

erformance CharacteristicCSeeccesvecsssssecsscsnae

PHEPRREE PERY e
0]
ot

FRHHFY PR HPE
_ 3
0n
o
LN Wb E

O'V-era\ll Accwacy. LI B B B RN RN BN BN L BN NN B NN BN N BN
Reliabili‘ty. S &0 & 6O 0 020888 s SO E B eSO SSE eSS
Fai 1 uI‘e MOdeS LR BN R RE B BN RN BN B B B BN BN B BN AR B BN B BN A I

of Process ConditionNSeescesseseccsssccsse

Operating TemperaturCsiescoescsesessecscce
Operating PressurC.cceccsssssosesscscns
COrrosiON.isecssesessesssscncsccsanccnsns
Salt Plugging and Vapor Depositiones...
Electrical Resistivity of Molten Salts.

ntal Effectsl.l......'.I.l.l............

Anbient TemperatuUrCecsecsesscscessesass
Am.bient Pressure..........0.-..........
RadiationDamalge.l.....I.O.I.I.l.‘.....

Requlrements...'..-...‘..........'l.....
Weld.-sea.led COIlS'bI'LlCthIl.-.o..-...-....

RUuggednesSS.eeesescosccssssccecsssscscsnas
S1Z€eccesescnssscecsssscssncssscssccsne
Materials of ConstructioNe.esececscesss
CleanlineSSeecescssccacsssoncosssscassces

‘Cost.....-...l....'.....l..'......'......-.........

Plant Instrumentation Layoubl.ceeceevcescsceccsscosscccssnnss

1.3.1
1.3.2

%neral Description.ro...l..ll.'..;......OOOOOUOOO.

Main contI'Ol Area..l’..........l'..l............'.

iii

17
17
17

17
19
20
20
20

21

27
27

27
27
27
28

29
29
29
30
30
31

32
32
32
33

35
35
35
35
35
36

36
37
37
37

 
 

1l.4
1.5

1.3.3
1.3.4
1.3.5
1.3.6
1.3.7

iv

Auxiliary Control Are€f.ceccecccccccccssosccnscsss
Transmitter ROOMeceeceeoccesevecssseaseosssesncanne
Field PanelSceeeccccsscccossassscsesssascsnsnsncanse
InterconmnectionS..eececsssseesescessessssacncacns

Data- Room....o.o.l'olool...oooono.oc.ooo.oo.o-.oo

Plant contrOl System.....0.0.'.0...0..'l..l....l!l.l..l..

Safety Systemoot.0.0.0-.-.00........l..o..o.oc.bo.o.ooooo

1.5.1
1.5.2

105.3
1.5.4

1.5.5

1'5.6

Reactor Fi]—]- md Dralin System..........‘...Q.O..O
Helium Pressure Measurements in the Fuel Salt

LOOP.00......00...'..0....‘.00...0!..0......0....

Afterheat Removal Systelleeeececccecesccccesconsosnecs

Containment System Instrumentationecscececccceass
1.5.4.1 Helium Supply Block ValveSe.seeeecosecoss
1.5.4.2 Off-Gas System Monitoringe.ceeeescececees
1.5.4.3 1In-Cell Liquid Waste and Instrument
Air Block ValVeS.eeeeesssesssccssssccnce
1.5.4.4 In-Cell Cooling Water Block ValveS.....

Underpressure Protection for the Secondary Con-
tainment Cells..........I.....'ll'...OO'QDC.I'.'.

Fuel Salt Sampler-Enricher Containment Instru-
mentation'l..II.....l'..'...'..l.......'II'....'I

2. SAF'ETY mSTleTATIONANDmACTOR CONTROL......'.......'.‘...'

2.1
2.2

2.3

Nuclear Instrumentation: Installation and LocatioNeeeess

BF3 Instrmentation-oo....0...00..-...0oooooooc-lo.t..ooo

2.2.1
2.2.2
2.2.3
2.2.4
2.2.5
2.2.6
2.2.7
2.2.8

GeNeralescecessoccsssccscesccssssscsscocssnsssnsse
BF3 COUnberieceecesccncccocoscrscscscccccoscscacncsns
High-Voltage Power SUpPPlYescscesossccccsocsacases
Preamplifier, ORNL Model Q-1857.ccccceevsccccccss
Pulse Amplifier, ORNL Model Q-1875.cccesecscccecs
Scaler, ORNL Model Q=1743.ccescessecscoassesasnas
Logarithmic Count Rate Meter, ORNL Model Q-751...

ConfidenCe Trips..o.o...00..'..C..C...D0.00C..'.O

Wide-Ra.nge Comting Cha:nnels-ool'.tOcl.t....oo.o....'oono

2.3.1
2.3.2

Principle of OperatioN.ececsceccceseccccessacsnns

Fission Chamber and Preamplifier Assembly.sececececss
2:3.2.1 Introductioneceececcccccsceccescccccsee
2:3.2.2 Preamplifiercieseccecssssccscscscsccscosse
2.3.2.3 TFlexible CBbleSeveccsersccccocosssccncss

37
38
38
39
39

55
67

69
70

71
72
72

76
76

77

77

7

97
106
106
106
107
107
107
108
108
108

111

115
116
116
118
 

2.3.3

2.3.4

2.3.5

2.3.6

2.3.7

2.3.8

oA PO
* :

Electrical Shielding Layoub.eecseescees
Low Pickup-Noise Performasnce of the
Assembly.l..'...‘....I.l....ll..l....‘.

ifier Power SUDPPlY eececccscesssnscsssscsncs

GENEraleseeercesecsesssssssssssosassese
ConstructioNeeeessecscscscsscssscnscnne
Applicalionicesesecscesscsascacccensacee
SpecificabionS,scscacscscscesccssnsscnonse
Circuit Description of the —22-v
SUPDlY seseorssvsesscctncsssncnsccsacssnsns
Circuit Description of the +300-v and
+110-V SUPDlYceeoesosscssossnssssasccssse

Plllse A@llfler...-....‘.....‘..'..‘.I'...‘......

w»&}&k
MWL

- »
P)P)h)h)b)fi‘ LWLWLWLW

< DOV O DD

M

8 .

H ot
.

0n

-
-*
*

.
0\?\0\0\0\0\
.

B oD DD
LVWLWLL WVWW
Q LMLV HFG MWD E

o
P
o

™~ e

»
*
-

. |
WLWwWW UJb)th)h)h)g WWwWww
- L I
o0 '0101019101018"QFQ'Q'Q
B

HWoHI LMW H

o

DO

General.ceeccecscesnsccsnsscsncssnsnsoccs
ConstructioNseesseccessocvossscoccccnss
ApplicatioNeesssececcecsscossssscaccsnne
OpecificationSesececescsescccsocsnsnnse
Theory of Operation.cceescsccccessaces .

P Sel"VO AmplifiEI‘, ORNL MOdel Q,"2615. es s e v

Genersal.cssccsccosccscsosscscosnsansnancs
ConstructioNeesecsecssesscsceccnccconse
AppPlicalionessscscessesesorscscssensoces
SpecificationSeessceseescsosssscscessncee
Theory of OperatioNesescecccccesssosccsns

a...................................I....

GeNEr8l.cevscsssasassossssnsannssnssssse
ConstructioNeceecessscsssecncesssnesanes
Applicationeseecsesscescescescnscnscone
SpecificationSeecseccssssccscccscsccssee
Applicable DrawingSeescescescsscsscensce
Theory of OperatlONeiecesssessoscssassss

Amplifier..-.............................
T GENEYBLlessecessosnsessssssesssenssssasns
Specifications.eccececcenss sscecssscses
Amplifier BalanCingeeceseesesscscssccacs
Theory of Operation.cesceccccesscscenes

Chember DriVeeseesssssessosassssscssssnes
Description.sceececscscesscceccsosrecanase
Drive MOtOTesesessseescoossccsssnsssons
Lead SCreWeesssesesscosssescccsscssosses
Position-Sensing Potentiometer...eeees.
SYyNChYOesescossscssssnsssssessncscsscnes
Auxiliary Position-Sensing Potenti-
OMELEr e s eosensesssscosssesscosascasnses
Vernistat Interpolating Potentiometer,.
Gear RedUCerS.ccesscssctcoscscsscscccns
S1IP CLUBCH .t eeeeeeonncereasaosnncnnans
Limit SwitcheS.eeessececrsssscssnnasnnsns

119

119

120
120
120
120
120

121

122

123
123
123
123
124
125

135
135
135
135
135
136

138
138
138
139
139
139
139

140
140
141
141
141

146
146
147
147
147
147

148
148
148
148
148

 
 

2.4

2.5

2.6

vi

Linear Power ChannelSDOCC...l......‘..l....'l......‘..l..

2.4'1
2.4.2
24,3

2obrots

2.4.5

2.4.6

Description...................O.....-....'C......
Visual Readout Device, Series 360..cccesevccescse

Keithley Model 418-20 Picoammeter: Specifica-
tions mld- Description...l........................

Procedure for Field Testing and Compensating

Compensated Chamber Q-l045..ceececscccccccscsccasns
24441 Descriptionicesccccsssescsossscescessnnsns
2eietee2 TestiNgeeessvssesscacesscesscssecssonns

The Use of a Colloidsal Dispersion of Boron in
0il to Obtain a Uniform and Easily Applied
coating Of Boron..‘........'.I.....-.l.....l.'...

High Current Saturation Characteristics of the
ORNL Compensated Ionization Chamber (Q-1045).....

ROd. Scram. Safew System.........l...................l.l'.

2.5.1

2.5.2

2.5.3
2.5.4

2.5.5

2.5.6

2.5.7

2.5.8

Rod Scram Safety Channel — Input Instrumen-

tation.oo.o.o.oooo.oo.-cooooon.oon..ooooo-.ccooo--

Rod Scram Safety Channel — Output Instrumen-

tation..I.............................‘l‘.ll.l...
Safety C}lmbers.l...............'........Q.......

Period Safety Module, ORNL Model Q=2635.cccecssee
2eD.4.l  DescripbiONeececcesscscsscessssscnsocns
2.5.4.2 Theory of Operation.cesescesacscsscesss
2.5.4.3 Operating InstructionS..cceeeccsccessnns

Flux Amplifier and Ion Chamber High-Voltage

Supply, ORNL Model Q-2602..cccesssscccscsssssccsne
2.5.5.1 DescripbioNeecececceccssesscscesccscnnsns
5.2 Theory of OperatioN.ecscccescccscscsveses
5.3 Operating InstructionSeececsssccessosess
5.4 Maintenance InstructionS.cecscceccsseces

NIQN
Ux\n\.n
*

&
&

TeSt MOd-lfl.e, ORNII MOdel Q"2634..0000.0000.00
.1 DescriptionO............-‘..'........'.
.2 Theory of Operationesccesssecccossososs
3
r

Operating InstructionS.cecececcccecscss

NE\JN
Ut W\
*
NV Oy

Fast-Trip Comparator, ORNL Model Q-=2609..scevssse
2.5,7.1 DescriptioN.ecececescesescesscscescccons
2.5.7.2 Theory. Of Operation..fll..........l.'.'.
2.5.7.3 Operating InstructionS.eceescsssscsscns
Coincidence Matrix Monitor, ORNL Model Q-2624....
2.5‘8.1 Description..............'...‘..........
2.5.8.2 Theory of Operationecececcececessssccess
2.5.8.3 Operating InstructionS.cecececcccesenas

Shim and REglfl-ating ROd. contrOl System. * 0 60 9 8 6000 EN B

163
163
164

164

165
165
165

168

168
177

177

178
180

181
181
183
184

185
185
187
189
190

191
191
192
195

196
196
199
201

203
203
204
205

221
 

 

2.7

2.6.1
2.6.2
2.6.3

2.6.4

2.6.5

2.6.6

Control
2.7.1
2.7.2
2.7.3
2.7.4
2.7.5
2.7.6
2.7.7
2.7.8
2.7.9

DPVDVDDDN
N3 =1-2-~1-31-1-3

vii

Introduction..l..C....l.....l............ll.'...
Rod Control CircultSessiecccececessscosccscnsessns

The Automatic Rod Controller.ecceceecescssscscss .o
2.6.3,1 Basic Rod Control Circuitecsccscscscses
2.6.3.2 Temperature Control.csscssscssscssssss
3 TFlux Demand Limiting.ecesecscscsccecaes

ating Rod Limit Switch Assembly, Q-2586....
.l Range Switching...'.........‘........I
2 RaIlge Seal]-.............'.............‘
2

D -
% O
W

o O
>

nent Descriptions.'..-.......... oooooooo se oo
.l SerVO MO'EOI'................--...-....-

g

.
AR ON O
Ut Q

Aplifierececescecssscscesssssccsccacessne
3  Clubch-BraKe.seeeessscsscececssscsssss
4  Shim-Locating MotOreseeseesccssceacess
5 Mechanical Differentialecceccecceccveces
6 Size 15 Control TransformMerecsccecesse
.7 Size 31 Torque Transmitterececeececececsse

L ] L]
.

Operational Situations Involving the Regulating
Rod Limit Switch and the Regulating Rod Servo...

Rods and ROd DriveSeeesssssscsnsesccscesscscsses
General ArrangemenNt..cecssscscscssssncescscsscsse
Position IndicabioN.ececesecsscscsscscscocescncse
Shock ADSOIDEerececossovssssessssicssncssssccssccss
Cooling Air Flow and Temperature Mbnitoring.....
Limit SwitcheSeeeesecsossssocssessccccsscsocnnns
Control ROAS.sseeseasossssscsssosssoscscsssascass
Rod Drop Timerececeessecsssccsassascesrscscsnsssasns

Performance CharacteristicSessccccscscscccvens .

. Component Descriptions and SpecificationsS.ceevee

2.7.9.1 Rod Drive Motor Assembly.cceesccccccss
Electromechanical Clutcheececcssecccss
Overrunning Clutchessscccessssvasnases
Position-Indicating SynchroS.sseascses
' Position-Indicating Potenticmeter.....
Limit SwitcheSeeessessvsessscscecccscns
Electrical Wiringeeeceeessasosescssccssce
LubricatioNeesescccscsoccscsscscscnssne
Thermostatic SWwitCheS.ecesscsccoscsscne
2.7.9.10 GCBIS.evescossoscscssccsssoscasssansscs

0 00 ~1 0" Ut I

*

-~J

. o .
:0\0\0\0\0\0\0\0

2.8 'Load Control System........V............l".;.l.‘.........

2.8‘1
2.8.2

Blower Operation..'.;to.........O.......O..C0.0.

Door Operation........ll...'....l.l.........l....

221
221

228
228
229
230

231
234
235

236
236
236
237
237
237
237
238

238
263
263
264
265
265
266
267
268
268

269
269
269
270
270
271
271
271
271
272
272

301
302
302

 
 

2.9

2,10

2.11

2.12

2.13

viii

2.8.3 Automatic Load Programming..ceccecescccsccocsess
2.8.4 Manual Control.eeecssccsscsscscscsscoesassssssnass
2.8.5 INterloCKkS.eessecsssoscscsssscosasosssscnssoncas
2.8.6 Load SCrall...ecessseessccsssesssssossescsasasnsss
Health Physics Monitoring.ececesesccssssssccscscsscsscsscse
2.9.1 Introduction..ceccesscescsccecesssssscsccnsscoses

2.9.,2 Tacility Radiation and Contamination System.....
2.9.2.1 IntroductioNecesccecscescccccacanssese
2.9.2.2 System Descriptioneeeccecssacecssscccse

3 ComponentSecececcscssccscsasossscnsnsons

2.9.3 General SySteMeseecccccccasscessssccasescsscases
1 IntroductiONecesceescecsscsccocasnnnns
.2 Beta-Gamma Monitors, Q-2091...........
3 Hand-and-Foot Beta-Gamma Monitor,
Q=1939-Bicseesssssssscscocscsccssssssss
2.9.3.4 Beta and Alpha Sample CountersS.csseces

Process Radiation Monitors.secececscescccsscscccoscsssane
2.10.1 IntroductioNececsccscsscssossccscscsstssscsnscsasns
2.10,2 System DescripbioON.eccececececscscsccsccsssscosssvse
Stack Monitoring SystemM.eeseecccccasessecssscescsscsnacee
2.,11.1 IntroductioN.ceeececscsccscsscessscsccsscsnsscns

2.11.,2 System DescriptioN.scesscscesssscccsccsscscsscss
2.11.2,1 Flow Channel FT-Sleceeccoccsscsssscces
2.11.2.2 In-Stack Sampler.ccececssscescscssnsscs
2.11.2.3 Particulate MonitorS.ceeeceecsseccceces
2.11.2.4 Todine Monitor, RE~SlCecescesssocaccecs

2.11.3 ORNL Drawing List for the MSRE Stack Monitoring

SySteMeceeeceossosssecenvecscsssssssssscsnsssanne
Data Logger-Compulerececeecvecscesssscssccsscssesossnnsae
2.12.1 IntroductioONisscessscscssessscssosesssssscssssosssns
2.12.2 Basic System Equipment DescriptioNessecccescscse
2.12.3 Peripheral Equipment DescriptioNececcsecscesessecss

2.12.4 System Operation.cecececcccscescccesscsocsssesssse
2.12.4.1 Collection and Processing of Analog

and Digital Input SignalS.ceccecscecsss

2.12.4.2 Logging FunctionS.ccececccesacossccsacs

2.12.4.3 CalculationSeeeeesssosesscssasssansnns

2.12.4,4 Miscellaneous FunctionSeceeeceesccccss

2.12.5 References and ORNL DravwingSecceccccscscsssscase

MSRE BerlliUIIl Monitoring SyStemooooooooo-oooooooaoo.ooo

304
308
308
308
331
331

331
331
332
334

339
339
339

340
341
351
351
351
367
367

367
368
368
368
368

372
379
379
379
381
382

382

384
385
386

393
 

 

ACKNOWLEDGMENT

This report represents the collective efforts of many more persons
than the authors of record, who, in some areas, served as editors, not
writers. We gratefully acknowledge the contributions of the following.?!

H. R. Brashear for checking and final editing of the section on
Process Radiation Monitoring.

G. H. Burger2 for preparing the sections on Process Radiation Mon-
itoring, Health Physics Monitoring, Stack Monitoring, and the Data Log-
ger-Computer.

S, J. Ditto and E. N. Fray® for assistance in writing and checking
large portions of the sections on the nuclear and electronic instru-
mentation.

P. G. Herndon, C. E. Mathews, J. L. Redford, and R. W. Tucker for
continuous and invaluable assistance in gathering information and in
reviewing the drawings and text material.

D. J. Knowles and J. A. Russell for help with reviews of the Health
Physics and Stack Monitoring sections.

R. H. Guymon, Chief of MSRE Operations, and his staff for giving
generously of their time to review the sections on control and safety.

M. Richardson for help with the section discussing the control rod
and the drive unit.

 

lExcept as noted, those listed below are members of the ORNL In-
strumentation and Controls Division.

2Formerly with the Instrumentation and Controls Division, ORNL,
now with Union Carbide Corporation, Mining and Metals Division, Niagara
Falls, N.Y.

3Formerly with the Instrumentation and Controls Division, ORNL,
now with General Electric Co., San Jose, Calif.

ix

 
 

1. MSRE INSTRUMENTATION AND CONTROL SYSTEM — GENERAL
1.1 -INTRODUCTORY REMARKS

Instrumentation is required by the MSRE to provide information and
control for routine operations, to obtain experimental data, and to
protect against hazard or damage to persomnel or equipment resulting
from abnormel conditions.

Both nuclear and nonnuclear instrumentation are used for measure-
ment, for control, and for protection; however, because of the nature
of the system, nonnuclear instrumentation predominates. Vital oper-
ational instrumentation on the MSRE is that which measures and controls
levels, flows, and temperatures of molten salts, helium gas, cooling air,
and water and which is required for opersation and control of the auxil-
iary systems. -

Two grades of instrumentation, control grade and safety grade, are
found in the MSRE. Control-grade instrumentation is used where a fail-
ure of control or a loss of information or protective action (though
undesirable) can be tolerated. Safety-grade instrumentation is used
where such failures or losses cannot be accepted. The choice between
the two systems is based on considerations of cost vs consequences.
Safety-grade systems involve the use of redundant, reliable instruments
and interconnections and tend to be much more expensive than control-
grade systems. Hence safety-grade instruments are used only where nec-
essary; control-grade instrumentation predominates.

The experimental nature of the reactor has increased the instrumen-
tation requirements if compared to a power reactor. In some cases eX-
perimental data are obtained from instrumentation required for operation;
however, in many cases, additional instrumentation was installed pri-
marily for data. A second-generation, nonexperimental version of the
MSRE will require less instrumentation.

The MSRE system,’ the components comprising the system, and its
nuclear and operating characteristics have been fully described pre-
viously.2‘5 It is not inappropriate to introduce & description of the

 

1The MSRE has been operating since June 1, 1965, and as of May 9,
1967, had developed & total of 32,654 Mwhr.

?S. E. Beall et al., MSRE Design and Operations Report, Part V,
Reactor Safety Analysis, ORNL-TM-732 (August 1964).

3R. E. Wintenberg and J. L. Anderson, Trans. Am. Nucl. Soc. 3,
454~55 (1960).

4J. L. Anderson and R. E. Wintenberg, Instrumentation and Controls
Div. Ann. Progr. Rept. July 1, 1959, CORNL-2787, p. 145.

°P. N. Haubenreich, "Safety Aspects of the Molten-Salt Reactor Ex-
periment,"” Nucl. Safety 8(3), 226~-33 (Spring, 1967).

 
 

MSRE instrumentation and control system by repeating some of the essen-
tial features of the MSRE.

Figure l1.1.1 is a pictorial drawing of the reactor installation,
and Fig. 1l.1.2 is a schematic drawing of the primary and secondary
molten-salt loops in which nuclear power is generated and transferred.
The primary (fuel) salt is a mixture of fluorides of lithium, beryllium,
and zirconium with sufficient uranium fluoride to achieve criticality at
the desired temperature. Several compositions of salt are under con-
sideration for the MSRE,2 differing principally in the concentration of
UF§ as a consequence of the degree of enrichment in 235y, The use of
233y is also being studied. These variations or changes in composition
are not expected to affect the design of the instrumentation and con-
trols.

The coolant salt, containing no uranium, is similar to the fuel
salt in its nonnuclear characteristics. The use of sodium fluoroborate
coolant salt®:7 is under consideration, but this experiment is expected
to have little or no effect on the instrumentation.

Teble l.1l.1 gives the composition and characteristics of the fuel
and coolant salts currently (March 1966) being used in the MSRE.

 

®P. N. Haubenreich et al., Consideration of Substituting Uranium-233
in the MSRE Fuel, ORNI-CF-66-12-28.

 

7R. E. Brooksbank, P. N. Haubenreich, and J. H. Shaffer, "Study of
the Use of U?33 in MSRE," MSR-66-21 (internal memorandum).

Table l.1l.1.

 

 

Fuel Salt Coolant Salt

Composition (mole %)

IiF 65 66

BeF» 29.2 34

UF; (33% 23°U), approx 0.8
Physical properties (at 1200°F)

Density, 1b/ft?> 134 120

Viscosity, 1b ft~% hr~t 20 24

Heat capacity, Btu 1b~1 (°F)~% 0.47 0.53

Liquidus- temperature, °F 840 850

 
 

&'

Since these salts are frozen below 840°F, it is necessary to apply
heaters to the tanks and the piping throughout the salt systems.

Figure 1.1.3 shows the reactor core vessel after assembly. The re-
actor is graphite-moderated, with the graphite in the form of long
vertical bars, or stringers. These stringers are essentially square in
cross section with grooves cut into the four faces to channel the flow.
Figure l.1l.4 is a horizontal cross section through the axial center line
of the core, showing the shape of the graphite moderator bars and the
location of the control rods.

Whereas the fuel is a homogeneous salt, the core itself has many of
the nuclear characteristics of a heterogeneous reactor. Table 1l.1.2
lists some of the nuclear parameters of interest to the control and safety
system designer.z'

Table 1.1.2.

 

Core size 141 cm diam X 200 cm long
Neutron lifetime, £*% ' 240 Hsec
Temperature coefficient of reactivity

In fuel salt . 10> (8k/k)/°F

4.0 X
In graphite 3.3 x 10™° (8k/k)/°F
Total 7.3 x 10™° (8k/k)/°F

Effective delayed neutron fraction

Stationary fuel 0.0067

Circulating fuel 0.0045
Power density (fuel) at 7.5 Mw

Maximum 29.0 w/cm?

Average in core 13.3 w/cm?
Maximum slloweble rod drop time 1.35 sec

 

Control rods are employed for both safety and routine operational
control. Nuclear excursions are not incredible, but none have been
postulated that cannot be averted by well-established techniques using
a reliable protective system. '

Both the fuel and coolant salt loops are blanketed and purged with
flowing helium at a slight positive pressure, nominally 5 psig. This
is accomplished in the salt pumps, which are designed to provide &a gas
space for the helium; see Fig. 1l.1.5. The volute around the pump im-
peller is enclosed in a larger tank, the pump bowl. The pump bowl is

 

~ 8g, W. Allin and H. J. Stripling, Jr., Instrumentation and Controls
Div. Ann. Progr. Rept. Sept. 1, 1963, ORNL-3578, pp. 11l4-15.

 
 

kept about half filled with fresh circulating salt by means of a bypass ng
flow of 50 to 65 gpm (~5.0%) around the pump. The salt, at pump outlet

pressure, is delivered to the relatively quiescent volume in the pump

bowl through a toroidal spray ring which allows the escape of gaseous

materials from the salt. These released gases, composed mainly of

fission products and, perhaps, hydrocarbons, are carried to the off-gas

system by a continuous flow of helium which sweeps across the free salt

surface in the pump bowl. Hydrocarbons, if present, will originate with

small leaks in the lubricating oil seals in the pumps.

While MSRE fuel at 1200°F has & vapor pressure of only 4.47 X 1073
mm Hg, the 5-psig overpressure substantially reduces the amount of long-
term salt carry-over into the off-gas system; it also helps to prevent
large-scale contamination of the pump itself by salt deposition. The
gas spaces in the pump bowl and the overflow tank provide extra volume
for fuel expansion from excessive temperature should the need arise.

A second helium flow is used to purge the lubricating and cooling
0il passages in the pump to prevent the entry of contaminants from the
pump bowl.

Helium is used as a cover gas in the fuel and coolant salt drain
and storage tanks and, by increasing the pressure, becomes the driving
force used to fill the circulating loops.

The off-gas system conveys the helium from the tanks and the pump
bowls to particle traps, filters, charcoal beds, etc., and thence to
discharge via the off-gas stack.

In addition to the main nuclear heat rejection system, described in
Sect. 2.8, auxiliary cooling is required in the reactor and drain tank
cells. The ambient air temperature in these cells is maintained at 150°F kaj
or less by two air-to-water space coolers. Direct forced air cooling is
used on the freeze valves and on the control rods and their drives. This
forced air pumping system is also used to evacuate the reactor and drain
tank cells to their operating pressure of —2.0 psig. The in-cell cooling
water system is used to cool such in-cell components as the thermal
shield, salt pump motors, and space coolers.

Fuel additions and the removal of samples for analyses are made with
the sampler-enricher. This is a device connected with a pipe to the fuel
salt pump bowl and which, of necessity, penetrates all containment barriers.

Freeze valves are used in the interconnecting salt pipelines between
the various tanks and the reactor vessel. A length of flattened pipe
that can be cooled and heated is a conceptual and perhaps oversimplified
description of a freeze valve. Valve closure is obtained by freezing a
salt plug in the flattened portion of the pipe.

The complex of reliable instrumented subsystems used solely for pro-
tection forms the MSRE safety system. In the MSRE the protection may be
categorized as (1) protection against nuclear excursions, (2) protection
against loss of containment, and (3) protection of vital equipment.

From the standpoint of extent and quantity, & majority of the safety
system instrumentation is in category 2. These are process-type instru-
ments based on measurements of pressure and radiation level. Their out-
put actions are to close valves, shut down pumps, etc., in lines which
are possible escape routes for contamination.

The preceding paragraphs highlight those features of the MSRE that
are of particular interest to the instrumentation and controls designer. Qfifi
 

Two of the major problem areas created by the reactor system's design
are containment and temperature (its measurement, control, display, and
recording).

The first containment barrier, cladding, always present in a
heterogeneous reactor, is missing. This placed more stringent require-
ments on the instruments used to measure pressures and levels inside the
reactor loop. The problems were magnified by the higher than usual tem-
peratures encountered in this service. Obtaining high-grade satisfactory
measurements of important flows, pressures, levels, and temperatures is
complicated by the general requirement that the number of primary con-
tainment penetrations be minimum and, even more so, by the environments
of molten salt, fission products, and radiation inside the primary con-
tainment or in the coolant salt loop, where measurements involve either
molten fuel or coolant salt.

It is impossible to operate the MSRE and not breach the primary snd
secondary containment volumes with process lines for helium, air, and
water (Fig. 1.1.6). In many cases these containment penetrations violate
design criteria unless they are capable of being relisbly blocked with
instrumented systems when potential hazards are detected; hence the ex-
tent of the process-type instruments in the safety systems and the
extensive use of sensors and transducers designed to meet containment
requirements. In addition, wide variations of reactor and drain tank
cell temperatures and pressures complicated the containment aspects of
pressure-measuring instruments since this large and convenient contained
volume could not serve as a stable reference.

To a degree the apparent emphasis on problems of contalnment is &
result of the inherent characteristics of unclad, fluid-fueled reactor
systems. BHowever, the design of the MSRE was complicated by having to
shoehorn it into an existing facility with size and general configuration
less than ideal. This housing situation generated additional design
problems with both the reactor system and the instrumentation and con-
trols. Auxiliary systems for air, oil, water, helium, and emergency
power are of necessity spread out and remotely located, cable and piping
runs tend to be long and tortuous, power and signal cables could not be
properly separated, and it was not feasible to put all the controls in
one central area. Instead, some of the auxiliaries are provided with
local control panels that are periodically supervised by the operators.
These problems of interconnecting and integrating the various subsystems
into an operating entity would have been substantially reduced in a
facility engineered specifically for the MSRE. In particular, problems
of containment and the amount of instrumentation for containment could
have been substantially reduced.

Temperatures throughout the two salt systems are the most numerous
and possibly the most vital single type of measurement in the MSRE. Both
salt systems (freeze valves excepted) must be maintained above the freezing
temperature (850°F) and should not exceed 1300°F. This upper temperature
1imit® is based on stress and metallurgical considerations and, depending
on location, a reasonable and safe allowance for fuel expansion caused by

 

°R. B. Briggs, Effects of Irradiation on Service Life of MSRE,
ORNL-CF-66-5-16.

 

 
 

any unscheduled temperature excursion. Stress producing temperature o
gradients are to be avoided. If salt freezes, it may rupture the con- Q_,
taining pipe or vessel on remelting. The coolant salt radiator is par-

ticularly vulnerable in this respect. Accurate, reliasble temperature

information is essential to successful operation of the afterheat removal

system, to freeze valve operation, to heat balance calculations, to re-

activity balance calculations, to all operations involving criticality,

to routine operational controls, and as input information to the safety

system.

There are over 1050 thermocouples installed on the MSRE. A prepon-
derance of these are on the salt loops, on the storage and drain tanks,
and on associated piping. These salt systems are equipped with many
manually controlled heaters; safe and effective control is only possible
if the operators have a clear, relisble picture or profile of temperatures
in the system and if they are assisted by suitable off-limit interlocks
and alarms. For these reasons, high-speed temperature scanning and dis-
play and continuous data logging are extensively used. These logging and
displey systems also provide off-limit alarms. It is worth while to note
that these temperature instrumentation systems are most intensively used
when the salt loops are being heated prior to filling or before teking
the reactor to power. When the reactor is on line and generating power,
the loop temperatures become more uniform and certain; hence the control
and monitoring problem is sharply reduced.

Other areas which called for more than usual care in design or for
nonroutine solutions are:

1. measuring and controlling low flows of helium and off-gas to and .
from the cover-gas system, Lfi“

2. measuring helium cover-gas pressure in the fuel salt pump bowl,
3. measuring salt level in the pump bowls,

4. measuring coolant salt flow rate,

5. measuring and controlling salt levels in the drain tanks,

6. designing containment penetrations for instrument lines,

7. designing in-cell instrumentation end related disconnects, piping,
and wiring to accommodate remote maintenance requirements.

It was recognized at the onset of the MSRE design that suitable and
eminently satisfactory instrumentation for some of these measurements
was nonexistent. Therefore, in some cases the methods and components now
in use have developmental status.

Sections 1.2 to 1.5 are concerned with broad and quite general

—descriptions which are intended to convey design philosophy and criteria.

Detailed descriptions of MSRE instrumentation and control are contained
in Sects. 2 to 8. The outline which follows will give the reader an
idea as to the scope and the arrangement of this report.
 

REAGCTOR CONTROL
ROOM

/

 

      
 

REMOTE MAINTENANCE
CONTROL ROOM

ORNL-DWG 63-1209R

 

 

 

 

 

Fig. 1.1l.1.

 

. FREEZE FLANGE

. COOLANT PUMP

MSRE Iayout.

 

 

8
. REACTOR VESSEL 7. RADIATOR
. HEAT EXCHANGER 8. COOLANT DRAIN TANK
. FUEL PUMP 9. FANS

10. FUEL DRAIN TANKS

. THERMAL SHIELD 11, FLUSH TANK

12. CONTAINMENT VESSEL
13. FREEZE VALVE

 
 

ORNL-LR-DWG 59158AR

 
   
   
 
   
   
       

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

COOLANT "
PUMP !|
- |
PUMP I “
! |
HEAT |
EXCHANGER 4 !11012°F 820 gpm )
I I}
hcwz°r cooLant i
FREEZE OVERFLOW | CELL ||
FLANGE | I
REACTOR |
VESSEL Il |}
f H71°F 1200 gpm I ) Il
1 ) i - I ' l
CORE | '
o RADIATOR |
L) | |
REACTOR CELL H i
I | —_— —C “
AR i
220,000
b o ———=—=—=m7 o= ————-=—mm--=——====L ¢fnm il
I i 40 °F I
| ORAIN TANK i I
|V ceLL il TEMPERATURES AND 1
| 1 FLOWS ARE TYPICAL (|
1 FREEZE 1 FOR REACTOR AT I
i I I
1 I Il
I I il
(///,//J' GOOLANT
SPARE FILL FILL AND FLUSH TANK gy K
AND DRAIN DRAIN TANK (73#3) (a4n=
TANK (73t3) (73 t3)

Fig. 1.1.2. MSRE Primary and Secondary Molten-Salt Loops.

 

 
 

ORNL-LR-DWG 61097 R2

 

 

FLOW DISTRIBUTOR

             

 

~MODERATOR
SUPPORT GRID

 

ACCESS PORT COOLING JACKETS

REACTOR ACCESS PORT

 

JAYAYAVAYAYAYAYA

=t Y
Y2 24

  

.wll il - ’ \ EeTy
P T o
. - \Mll. _ _EQE?N D000

     

 

VESSEL DRAIN LINE:

  

»
w
+ ] :
W = »
.ulu = nE R %
o ¥ 5 S N V \ <
- o wl L S W -7
o L -l
w o - o 0
D x x 2 o 14
o W o W S w.ow 3
< xz o z
R OR OG w o 1
o =2 Q x -
- w ) - > o =
o Z = o O L o
o w ¥ - ,
2 b=
o [+

MSRE Reactor Core Vessel After Assembly.

Fig. 1.1.3.
 

10

 

RN G oh-eaa

 

 

 

 

 

 

TYPICAL FUEL PASSAGE

NOTE: STRINGERS NOS. 7, 60 AND 61 (FIVE) ARE
REMOVABLE.

 

 
 
 

|_—CONTROL ROD

=AWA7—6uipe Tuee
l - e LN

“-GUIDE BAR

= “
(¢}
REACTOR
/ CENTERLINE
9
e \

| THREE GRAPHITE AND
INOR-8 REMOVABLE
SAMPLE BASKETS

 

 

 

Fig. 1.1.4. Lattice Arrangement of MSRE Control Rods.
 

11

ORNL-LR-DWG-56043-BRi

   
  
 
  
  
  
  
  
 
 
  
 
 
  
   
   
  
 
  
  
  
  
  
  

SHAFT WATER
COUPLIN COOLED
MOTOR

SHAFT SEAL

LEAK
DETECTOR

LUBE OIL IN

UBE OIL BREATHER

BALL BEARINGS

(Face to Face) BEARING HOUSING

BALL BEARINGS
(Back to Back)

GAS PURGE IN

SHAFT SEAL

SHIELD COOLANT PASSAGES
(!n Parallel With Lube Oil)

SHIELD PLUG
GAS PURGE OUT

LUBE OIL OUT

SEAL OIL LEAKAGE
DRAIN

LEAK DETECTCR

SAMPLER ENRICHER GAS FILLED EXPANSION

(Out of Section) SPACE
N STRIPPER
HELIUM (Spray Ring)
SPRAY

OPERATING
LEVEL
ol
PUMP BOWL
HELIUM BUBBLER
CONFIGURATION

To Overflow Tank

Fig. 1.1.5. MSRE Fuel Pump.

 
 
    

 

TMEMBLZANE SEAL

   

  

'

 

 

7777

ORNL DWG. 67-2688

 

SHIELD BLOCKS

 

 

 

 

 

 

 

 

 

 

 

 

 
 

 

 

N RN
m <z N - AN 2 / //
@ | AR CONTROL
VALVE- L.;_,_f";’j.‘-
AlR
SAFETY VA, D\S&—gfi:fi 't )
varen o L VATER
;“"““—95 Z CORTEATED | VELDS
cvVv
ELECTRICAL
HELIUM  SUPPLY - WELIUM _ : A
SARETY VA, VELDS ;;‘:_" To -cERAM
SEALED CONTAINMENT
TO OCFGAS ENCLOSURE- -
SYSTEM METAL TO GLASS
SARETY VA. ! SEAL
o™ == ) : THERMOCOUPLES
WELILM v WELDS ;
SUPPLY coemeaTen | TANK e I
Cv W
\¢ S
TO_STACK 5) ou “
| == P - COMPONENT
COOLING
"“@— N OFF GAS
SAFETY VA, WVELDS
ENTILATED MAINTENANCE ™S
CON N NT
CHARCOAL - ENCLOGULRE- VENTILATION

 

 

 

 

 

 

 

 

 

 

 

   

$AR SuPPLY

 

SAFETY VA.

COMPRESSION
FITTINGS

SAFETY VA,

 

 

. TN c””";__,a:_:—‘___,
SEALING COMPOND SEAL

 

WTO STACK .

 

   
      

SAFETY VA, SAFETY VA,

CELL BVACUATION TO STACK

 

 

QLUPTURE
DSC

    
  

 

 

30" BUTTERELY VA.
QURBEDR SEALS

 
   

| <O VARPOR, CONDENSING
SYSTEM

 

Fig. 1.1.6. Schematic of MSRE Secondary Containment, Showing Typical Penetration Seals and Closures,

PRESSLRNZED \-\b’E%ox o
SOLOER Lcoppen\ {
SHEATH a N, SuPpLy

cl

 
 

13

OUTLINE OF CONTENTS OF TM-729

1. MSRE Instrumentation and Control System — General

1.2 Design Considerations

Discusses the considerations which influenced the design,
particularly those which are unique or are peculiar to
the MSRE.

1.3 Plant Instrumentation Iayout

Describes the physical layout of the instrumentation system.
Gives a general description of the overall layout (Sect.
1.3.1) and then describes each area separately. The instru-
ment systems are located by area, and the routing and in-
stallation of their interconnections are included.

1.4 Plant Control System

Gives a broad, all-inclusive picture of the entire MSRE
instrumentation and control system, including control of
auxiliary equipment and the instrument power system. The
"mode control" used to guide reactor operation is discussed
with diagrams which define (or give) the conditions for the
various modes (Prefill, Operate-Start, Operate-Run). The
intent of this section is to outline the main subsystems
and not to dig into fine structure. The reader is referred
to Sects. 2 to 7 for details.

1.5 BSafety System

Discusses the safety-grade instrumentation and controls
associated with the MSRE safety system. The discussion
includes general design criteria (designer's guidelines)
illustrated by & typical system. The entire safety system,
what it does, and why are tabulated and diagrammed. This
section replaces similar but obsolete material in ref. 2.

2. Safety Instrumentation and Reactor Control

2.1 Nuclear Instrumentation

Describes the instrumentation in the neutron channel up to,
but not including, the panel electronics. The neutron
penetration, including the guide tube assembly, is described,
and the interconnecting cabling, Jjunction boxes, etc.,
associated with transmission of signals to the control rooms
are diagrammed.

 
 

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

14

BF'3 Instrumentation

Describes briefly the instrumentation associated with the
sensitive BF3 channels used for low-level flux measurement
and control. The interlocks associated with the BF3; channels
are discussed in Sect. 2.6.

Wide-Range Counting Channels

The. wide-range counting channels are described with block
diagrams and an explanation of their operation. This is
followed by descriptions of the chamber assembly, of the
chamber and the associated electronic circuits, and of the
electromechanical drive. The interlock and control functions
associated with the wide-range counting channels are covered
in Sect. 2.6.

Linear Power Channels

Describes briefly the linear power channels and includes
block diagrams and descriptions of the compensated ion
chamber and of the picoammeter.

Rod Scram Safety System

Contains a thorough description of the rod scram safety sys-
tem. Block diagrams and circuit diagrams illustrate the
discussion. The associated electronics are discussed in
detail.

Shim and Regulating Rod Control System

Gives a thorough description of the shim and regulating rod
control system. Block diagrams and composite elementary
circuit diagrams for both the servo rod and the shim rods
are included. The "Confidence" interlocks originating in
the wide-range counting channels (see Sect. 2.3) are also
described.

Control Rods and Drives

Describes the control rods and the rod drive units. A
description of the pneumatic fiduciel zero position in-
dicator is included.

Load Control

Describes in considerable detail the control of the equipment
which determines the reactor load, namely: radiator, radi-
ator doors, blowers, and bypass damper.

Health Physics Monitoring

Describes the health physics instrumentation and includes a
general description of the individual types of instruments
used plus a description of their interconnections to form
an integrated salarm system.
 

15

2.10 Process Radiation Monitors

The components and electronics used to monitor process lines
carrying helium, water, off-gas, etc., are described. The
operation of interlocks and alarms i1s covered in Sect. 4.

2.]11 Stack Monitoring

Describes the radiation monitoring installed in the off-gas
stack. The components, how they function, and their purpose
are included in the discussion.

Process Instrumentation

Provides a general description of the instrumentation in the
various systems. Included are descriptions of major control loops
with drawings of individual control loops and their instrumentation.
The principles of operation of the various components as well as
control circuit operations are discussed in other sections. In
general, sufficient descriptive material, augmented by flowsheets
and diagrams, is included so that a reader with a reasonable
knowledge of instrumentation systems can determine the arrangement
and composition of the process instrumentation system.

Electrical Control and Alarm Circuits

4.1  General Description

Introduces in very general terms the types of circuits to

be found in the MSRE system and how they are related. This
text material provides the background for succeeding sections
(4.2 to 4.13).

4.2 to 4.10 Master Control Ciréuits, etc.

Describes the electrical control circuits with engineering
elementary schemetic circuits dlagrams and, where instructive,
includes the nonobvious interlock functions and explains why
they are required. The material presented enables a person
with a reasonsble knowledge of instrumentation and control
systems to understand the operation of the control circuits.

4.11 Jumper Board

Explains purpose and descfibes thé physical construction of
the Jjumper board. Iayout and wiring of a typical section
of the board are included. .

4.12 Annuncistors

The annunciator system is described. Considerations involved
in the location of annuncistors are outlined. Schematics of
the annunciators used and their sequence of operation are in-
cluded. Their operational use is also discussed.

 
 

16

4.13 Instrument Power Distribution

Outlines the system which provides the MSRE instrumentation,
control circuits, and annunciators with the necessary power.
Religbility considerations are included.

Standard Process Instrumentation

Provides a general description of the various types of standard
instruments used in the MSRE and includes basic principles of their
operation.

Special Process Instrumentation

Contains descriptions of the nonstandard instruments required by
the MSRE. Their unique or special features are outlined.

Data Logging and Computation

Gives a general, broad description of the data system. Describes
basic capabilities, operations, and purpose of the logger-computer.
Note: The reader is referred to manufacturers' literature and the
operations manual for detailed information.

Miscellaneous

8.1 Instrument Numbering System and Instrument Application Diagram
Coding System

Explains the system of flow plan symbols and numbering used
in preparation of instrument applications diagrams and
tabulations with typical examples.

8.2 Wiring Practices and Coding

Describes the system used in designing and identifying MSRE
instrumentation and control wiring with typical examples of
pranel and interconnection wiring.

8.3 Pneumatic Tubing Installation Practices and Coding

Describes the system used in designing and identifying MSRE
instrument tubing installations and includes a typical
pneumatic schematic circuit and & typical panel and inter-
connection tubing installation.

 

 
 

17

1.2 DESIGN CONSIDERATIONS

l.2.1 Introduction

The design of the MSRE instrumentation and controls system and the
selection, procurement, and/or development of components involved con-
sideration of & number of operational, safety, and physical reguire-
ments. Table 1.2.1 lists the more important considerations, together
with an indication of the design areas in which these considerations
apply. In many cases, these considerations are similar to those en-
countered in the design of industrial plants and research facilities,
such as high-temperature liquid-metals systems, chemical processing
plants, petroleum refineries, and other types of nuclear reactors.
Wherever possible, the design was based on existing technology, and
components were procured from commercial sources of supply; however, in
some cases, individual considerations (or combinations of considerations)
presented problems which required special design or the development of
special components. A discussion of the considerations listed in Table
1.2.1 is presented in the following paragraphs.

1.2.2 Operational Requirements
1.2.2.1 Compatibility with Centralized Control Philosophy

As discussed in Sect. 1.3.1, the MSRE instrumentation is centralized
in the main control area so that the information and controls needed for
routine operation of the reactor are immediately available to the oper-
ator. This philosophy of operation dictates that modular-type systems
with signal transmission from primary element to receivers and from con-
trollers to final control elements be used rather then integral field-
mounted systems. For example, in the MSRE pressure transmitters and
receiver indicators are sometimes used when & simple pressure gage would
have sufficed for a noncentralized system. This example, however,
should not imply that all the measured variables are transmitted to the
main control area. There are, in fact, many direct-reading field in-
struments, such as pressure gages, rotameters, thermometers, etc., in
use in the MSRE. This type of instrumentation is used mainly where the
instrument is located in an accessible area, usage is low, and quick
access to information is not required. Where frequent or fast access to
information is required; where containment, personnel safety, or basic
instrument installation requirements dictate that the primary sensing
elements be located in inaccessible areas; or where transmitted signals
are required for operation of controls or interlocks or for logging of
data, transmitters are used and the receiving equipment is located in
the central control area. or in other centralized locations such as the
transmitter room and various field panels (see Sect. 1.3.1).

Similar considerations apply to the selection of final control ele-
ments. Where the final control elements are located in inaccessible
areas or where control is either automatic or restricted by control

 
Table 1.2.1.

MSRE Instrumentation and Control Design Considerations

 

1 = Frimry Considerstion Safety or Contrel
2 = Seoondary Considerwtion Safety or
Control

Primry Considerstion - Safsty Ouly.

Primary Sensing Elements, Transmitters, & Final Control Elswents

Thermooouples, Flow Blements, Pressurs, Differential
Pressure, lavel and Flow Transmitters, Valves, Motors,

Interconnections Wirin

Wire, Tuling, Cables, Terminal Stripe,
t Junction Boxes, DI b

 

y @tce

Recels

strumentations

Reocorders, Indicators, Comtrollars,
Switohss, Signal Conditionsrs,

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3a
k- Considaration - Control Only. Heaters, sto. Telays, ete.
= Primary Considaration Safety. fneide Hological Shislding]  Cutelde Hlologioal
condary Consd Control. 1 Outside Blo: cal Inside Biological Shielding | Outside Biological Shislding
6 - Primry ma:w w_l and Secondary Coutalsment o 1ding, Ineide Shislding, m" Inside Secondery Contairment | Inside Secondary Containment
Secondary Considsretion Sefety. condary Contalnment Secondary Containment
T - Elther Primary or
Considerution Depending on Outside Biologlicsl
Applicaticn. With Frimary | No Prismary |With Primry| o Primry |With Secondary| wo With Secondary| Ne Secondary| witn Secondary | Wo Secomdery | Bmtelsing Pamel Piald
I - Not A ble Containment | Containment |Containment | Gontainment [ Containment Containment | Containment Containment | Containment Containment and Secondary Mowmnted Mounted
= pplicabls. Petetration | Penetrution [Penetmtion { Penetrstion [ Fenstration Penetration | Penetration Pengtration | Panatration Penatration Containment
Compatibility with
Centralised Control 1 1 1 1 1 1 1 1 1 1 1 1 2
orera ol Ease of Operation & 6 6 & é 6 X I X I I 6 6
Requizemsnts Nexibility 2 2 2 2 1 1 2 2 2 2 1 1 b |
Experimental Data 3 4 h b 4 L 1 X I X I b L
Remote Maintensnce 1 1 x x X I 1 1 X X I X X
Maintainatdlity 1 1 1 1 1 1 2 2 ? 2 2 1 1
Containment 1 1 1 1 1 X X 1 X X X X
Redundancy, Beparation,
s.m,yu eto. 3 3 3 3 3 3 3 3 3 3 3 3 3
Eazands to Operunting
Perscrnel 2 2 2 2 1 1 2 2 2 2 1 1 1
Overall Aceuracy 6 & 6 6 6 6 I I I 1 X 6 &
Characteristics | Reliatdlity 1 1 1 1 1
Failure Modes 5 S 5 5 5 s x X X I s 5
Salt Conductivity 1 X X X X X X X X X I X 1
Opsrating Pressure 1 1 1 1 1 1 I X X I X I I
Operating Tempsrature 1 1 1 1 1 1 T X X X X X I
Frocess Correaion 1 1 1 2 2 2 2 2 2 2 2 I X
Conditiona
Effects Salt Plugging and
Vapor Deposition 1 X 1 X X X X X X X X b 4 X
Electrical Resistivity
of Molten Salts 1 X 7 I x X X T I I X 1 1
Anbient Tempsratare 1 1 1 1 1 1 1 1 1 1 1 1 1
Effects Anbisnt Pressure 1 1 1 1 1 1 X 1
Fadiation Damege 1 1 X X X 1 1 X X I X I
Veld-Sealed Construction 1 2 1 2 2 2 I X X I X X X
Buggednese 1 1 3 1 1 1 1 1 1 1 1 2 1
Physical
Requirements Sise 7 7 1 7 7 7 7 7 T 7 T 1 2
Matertals of Construction 1 7 1 7 7 7 1 1 2 2 2 2 2
Cleanlingas 1 2 1 2 2 2 2 2 2 2 2 2 2
Cost & & & 6 & 6 6 6 6 6 & 6 6

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

81

 
 

 

19

interlocks, remotely controlled pneumatic or electric actuators are
used.

Where frequent control adjustments are required,where the operator
must have quick access to the control, or where it is desirable to pre-
vent operation of the control element by persons other than the reactor
operator, the control signal originates in control devices (automatic
controllers, control interlocks, manually operated switches, etc.)
located in the main control area.

Where centralized control is not required, the final control ele-
ments are operated either directly by hand or indirectly by means of
control devices mounted individually on local control stations or grouped
on field panels.

1.2.2.2 Ease of Operation

The layout of control areas, the placement of instruments and con-
trols within control areas, and the selection of receiving instruments,
control switches, etc., were strongly affected by considerations of
operator convenience and ease of operation. Insofar as possible, con-
trols and adjustments needed for routine operations of the reactor were
placed on the central control console, and the receiving instruments
which provide the information required for routine operation were lo-
cated on either the console or the main control board.

To reduce the need for frequent reference to flowsheets and to re-

" duce the chances of operational error, a graphic presentation was used

in the layout of the main control board and of the Jjumper board. This
graphic presentation is also a valuable aid in training of operators.
As nearly as possible and consistent with other considerations, the
prime space in the center of the main control board and console was re-
served for the most important instrumentation and controls components.
Components of lesser importance were located in auxiliary control areas
or in the field. Instrument components and control devices on the
graphic panel were placed so that they are visually associated with
specific components or portions of the reactor system. Attention was
also given to the vertical placement of components so that receiving
instruments could be easily read from various positions in the control
room and so that control switches would be within reach of an operator
of average height.

Where a given operation requires frequent simultaneous observations

-of a receiving instrument and operation of control switches or adjust-

ments, the controls and adjustments were located near the receiving in-
strument and were placed so that the receiving instrument would not be
obscured by the operator's arms. :

To implement the above design objectives and to minimize space re-
guirements in the control areas, attention was given to the physical
size of instrument components mounted in the control boards. In general,
preference was given to small-sized instrument components where the use
of such components was consistent with other considerations. Attention
was also given to readability in the selection of receiving devices such
as recorders and indicators.

 
 

20

Where possible and consistent with other considerations, systems Qifl‘
were automated to relieve the operator of the necessity of performing
numerous manual operations and thus free him to devote more time to the
more important aspects of reactor operation. For example, the freeze
valve circuits were designed to perform "freeze" and "thaw" operations
automatically. Also a number of other variables, such as helium inlet
purge flow, which might have been smenable to manual control are
automatically controlled.
Further simplification of operations was obtained by use of the
Computer-Data Iogger described in Sect. 2.12.

1.2.2.3 Flexibility

The experimental nature of the MSRE dictated that the design of the
instrumentation and control systems be flexible, that is, that it be
amenable to change. To accomplish this objective the use of point-to-
point wiring was avoided, and control circuit interconnections were made
at centralized locations in the relay cabinets. Similarly, most thermo-
couples were routed to a patch panel in the main control area, where
they were connected to readout instrumentation by patch cords. Further
flexibility was provided by the use of ORNL standard modular hardware
for fabrication of control panels and by selection of instrument compo-
nents which permits ranges to be changed and control switches to be reset
easily in the field. In addition to gaining the capability to change
the system design after startup of the reactor, the flexibility designed
into the system was of great value during the initial design since it QiJ
permitted portions of the system to be designed, fabricated, and in-
stalled before the final design criteria were established.

1.2.2.4 Experimental Data

The requirements for experimental data from the MSRE resulted in
more instrumentation than would be required for a nonexperimental
(second-generation) reactor of the same type. Also, in many cases, the
accuracy requirements imposed by the need for experimental data were
greater than would have been required by process control considerations
alone. Since the data inputs to the Computer-Data logger are electrical
(de) voltages, first preference was given to the use of electrical
transmission systems in these applications. However, in some applica-
tions, such as weigh cells, it was found that the use of pneumatic
transmitters offered significant advantages. In these cases strain-gage
pressure transducers were used to interface the pneumatic systems with
the Computer-Data Logger.

l1.2.2.5 Remote Maintenance

The requirement that all major components located within biological
shielding or containment be amenable to remote serviecing or removal and
replacement was a primary consideration in the design of instrumentation
 

 

21

systems and the selection of instruments in these areas. In general, the
design philosophy was to locate instrument components outside biological
shielding so that they could be maintained directly. Where this was not
possible, provisions were made for remote removal and replacement, or
adequate operating and installed spares were provided. The major problem
encountered in providing remote maintenance capabilities for in-cell
instruments was the development of disconnect devices and methods of
mounting instrument components. Disconnects were required for pneumatic
tubing, electrical power wiring, and for low-level electrical signals.
Because of the quantity involved, providing thermocouple disconnect
capability required the greatest effort. With the exception of the
weigh cell mountings, the design of in-cell instrument mountings did not
present any special problems. The design of the weigh cell mountings
required specisl attention because side loads must not be impressed on
the cell and because the cells must be aligned so that the direction of
force is parallel to the center line of the cell (see Sect. 6.6).

Remote maintenance requirements also imposed severe restrictions on
the design of in-cell instrumentation and control systems. To permit
unrestricted vertical access for tools and for component removal, in-
strument components were located and associated wiring and tubing were
routed in a manner that would not interfere with these operations.

1.2.2.6 Maintainability

Consideration was given to the maintainability of all instruments
whether located in-cell or not. Whenever a choice between instrument
component types existed and other considerations were equal, preference
was given to the type that was easiest to maintain. Plug-in instruments
were used extensively. The use of this type of instrument permits quick
replacement of faulty components with minimum disturbance of operations
and subsequent repair of the faulty components in field or central
shops. Attention was also given to the location of instrument compo-
nents to ensure that they would be physically accessible for maintenance.
Wherever possible, provisions were made so that components could be
tested, adjusted, or replaced without excessive disturbance of operations.

1.2.3 BSafety Requirements

1.2.3.1 Containment

Since many of the primary instrument elements associated with meas-
urement of variables in the reactor system are attached to, or require
penetrations of, the reactor primary or secondary containment, these
instruments and/or associated lines are, in themselves, s part of con-
tainment. ‘To avoid compromising the reactor containment, special pre-
cautions were required in the selectlon of these components and in the
design of associated systems.
| The MSRE contaimment criteria require the presence of two inde-
pendent barriers against the release of activity. DPreferably these

 
 

22

barriers would consist of fixed barriers such as a pipe or a vessel
wall; however, the need for piping connections to auxiliary systems and
for transmission of instrumentation and control information to and from
the in-cell reactor system dictated that containment barriers be pene-
trated.

In general, the measurement of variables within the secondary con-
tainment involves the penetration of at least one containment barrier.
However, in cases such as measurement of nuclear flux and process ra-
diation, the desired information is obtained without penetrating either
primery barrier. In other cases, such as measurement of primary system
temperatures, drain tank weight, and pump speed, only secondary contain-
ment penetrations are required.

Penetrations® may take the form of electrical penetrations, piping
penetrations, or special penetrations that are physically a part of the
containment vessel, with the type of penetration being determined by the
type of signal transmitted. Such penetrations were made in a manner
that did not seriously degrade the integrity of the containment barrier
or were provided with instrumented closures that will restore the in-
tegrity of the barrier if unsafe conditions occur (see Sect. 1.5).

The most difficult penetrations to close or protect were those
associated with piping penetrations of primary containment. Weld-sealed
(helium leak-tight) construction is used on all instrument components
associated with such penetrations; connections are made by means of
butt welds, leak-detected ring-joint flanges, or "autoclave" (or
equivalent) connectors; and valves are provided with welded bellows stem
seals.

In all cases where weld-sealed construction was required, the compo-
nents were designed and tested to ensure that leakage through the body
was less than 1078 em® of helium per second under conditions of 50 psig
internal pressurization. Also, those valves which form a part of the
primary blocking system were designed and tested to have very tight
shutoff characteristics (see Sects. 6.5 and 6.20).

Wherever possible, the instrument systems having primary system
penetrations are designed to dead-end the penetration in a sealed compo-
nent located inside the secondary containment. However, in some MSRE
instrument systems, the penetration extends through both primary and
secondary containment barriers. Examples of such penetrations are the
helium purge lines associated with measurement of level and pressure in
the fuel salt system and with the leak detection system used to deter-
mine whether sampler-enricher valves and ports are closed and sealed
(see Sects. 3.12 and 6.8). A similar type of penetration is found in
the lines connecting the drain-tank pressure transmitters to drain
tanks. This latter example differs from the preceding one in that the

 

1In some cases, such as the helium flow elements, the coolant salt
flow venturi, valves, and the helium flow restrictors, the instrument
components are an integral part of the system piping, and the required
penetrations may be made on the instrument component rather than on the
system piping. For the purpose of this discussion it will be considered
that the component itself is the penetration and the connections to the
component are extensions of the penetration.

‘:f
 

23

lines also serve as process lines which are used to pressurize the drain
tanks during filling and transfer operations. Similarly, the purge lines
that supply helium purge flow to the reactor as well as the flow elements
and differential pressure cells associated with measurement of flow in
these lines are part of the primary containment. 1In all the above cases,
reliance is placed on the flow of helium purge gas to prevent the back
diffusion of activity, with check valves and instrumented closures being
provided to prevent the escape of activity. In general, the rule was
used that two block valves or one block valve and one check valve were
equal to one barrier. In some cases, two series check valves were in-
stalled, but in the primary system the use of redundant check valves
alone was not considered to be adequate protection. Weld-sealed solenoid
and pneumatically operated valves of the type discussed in Sects. 6.5

and 6.20 were used to provide the instrumented closures of these lines.
Blocking action is initiated via the electrical control circuitry in the
event of occurrence of unsafe conditions such as high activity in process
lines, low helium supply pressure, high reactor cell pressure, etc.
Operation of these protective systems is discussed in more detail in
Sect. 1.5.

Other examples of instrument components that form a part of primary
containment are the pneumatic and hand-operated valves located in primary
system piping, the charcoal bed differential pressure cell, and the
conductivity-type drain-tank level probe (discussed in Sect. 6.10). The
drain-tank level probes are an example of an instrument penetration where
the instrument component is physically a part of the containment vessel.

The most numerous (and fortunately the easiest to seal) penetrations
of MSRE containment are those required for the 495 thermocouples attached
to pipes and vessels within the secondary containment. These penetrations
are closed by using ceramic (or glass) to metal feed-through seals inside
and epoxy seals outside of the reactor containment vessel and biological
shield (see Sect. 6.7). Similar techniques are used for sealing elec-
trical penetrations required for in-cell heater, motor, signal, and con-
trol wiring. Examples of devices requiring electrical signal penetration
of secondary containment are given below:

Primary system pressure and differential pressure transmitiers

Primary system solenoid valves '_

Fuel salt pump speed pickups |

Fuel salt pump microphbhes

In-cell valve pos1t10n sw1tches

Conduct1v1ty level probes

Primary system thermocouples

Rod Drives

At this point it should be noted that, with the possible exception
of the conductivity level probes, there are no electrical penetrations
of primary containment in the MSRE heated salt systems. This lack of

electrical penetration of salt system primary containment is due partly
to the lack of a suitable feed-through penetration seal and partly to

 

 

 
 

24

the fact that the high temperatures, high radiation, and low salt con-
ductivity associated with the primary system tended to discourage the
use of electrical techniques for measurement inside the primary system.

The next most numerous penetrations are the instrument piping
penetrations of the secondary containment required for operation of
valves, weigh systems, etc., within the secondary containment. With a
few exceptions, these lines connect to closed systems or lnstrument com-
ponents and are essentially inward extensions of secondary containment.
To protect against possible rupture of these lines in the event of the
maximum credible accident, a blocking system is provided which will
close these lines if the reactor cell pressure rises above atmospheric
(see Sect. 1.5). Some instrument penetrations of secondary containment
vent directly to the space inside secondary containment and connect to
components outside containment. These form an outward extension of
secondary containment. Where the lines are short and the construction
of the components satisfies the requirements for containment, as is the
case for the pressure switches used in the blocking system, no blocking
protection is provided. However, where the connecting lines are long
or where the components do not meet the containment requirement, block
valves operated by the systems discussed in Sect. 1.5 are provided.

Instrument components that form a part of secondary containment
are, for the most part, standard commercially available items; however,
consideration was given in their selection to maintenance of minimum
overall leakage of the secondary containment. While containment require-
ments for these components were much less stringent than for components
that formed a part of the primary containment system, more attention was
given to the leak-tightness of these components than was given to similar
components not associated with contaimment. Gasketed construction and
standard tubing and pipe fittings were considered acceptable in most
applications; however, the components were tested before installation,
and systems were tested after installation to ensure that leakage was
acceptably low. Although weld-sealed construction was not required for
secondary containment, many components of the helium, lube oil, sampler-
enricher, coolant salt, and chemical processing systems were weld-sealed
and tested for helium leak-tightness to conserve helium; to prevent re-
lease of activity from potentially dirty systems (such as the lube 0il,
chemical processing, and coolant salt systems); to minimize the possi-
bility of inleakage of oxygen to the heated salt systems during periods
of abnormal operation; and to maintain the performance characteristics
of the instrument system. In some cases, weld-sealed components were
used because they were commercially available at costs comparable with
similar components using standard construction.

Examples of instrument components of secondery containment using
standard construction are:

1. block valves in the cell penetration blocking system,?

 

2Wherever possible, valves were installed so that the pressure (or
reactor) side of the valve was under the seat. Also, "fail-closed"
(air-to-open) operator action was used so that loss of supply air pressure
would cause valves to close.

 

 
 

 

25

2. all components in the cooling water systems,
3. pressure regulators in the helium supply system,

4. pneumatically operated off-gas system valves downstream of the
charcoal beds?® (these valves were, however, ordered with weld
nipple connections and were welded into the system),

5. solenoid block valves in the chemical process system sampler,2

6. drain tank weigh cells and associated piping (special attention,
beyond that required for contaimment, was given to the leak-
tightness of this system to obtain maximum accuracy),

7. some components connecting to penetrations of the outer barrier of
the fuel sampler-enricher and chemical processing system sampler.

Examples of instrument components of secondary contaimment using
weld-sealed, helium leak-tight construction are:

1. All components of the helium supply system and associated purge and
supply lines, except regulators. Included in this category are
pressure switches; flow elements; differential pressure and pressure
transmitters; control valves; hand control valves in the bubbler
purge lines; and capillary flow restrictors in the sampler-enricher
purge lines, in the fuel and coolant system bubbler purge lines, and
in the main helium supply to the fuel salt system drain tanks.

2. Flow elements, capillary flow restrictors, and differential pressure
transmitters in upper ges letdown lines from the fuel and coolant
salt circulating pumps.

 

3. All fuel and coolant lube oil system instrument components except
the oil tank level transmitters. Included in this category are flow
elements, pressure and differential pressure transmitters, control
valves, and pressure switches. The level transmitters utilize
gasketed construction but were shop tested for leak-tightness before
installation.

 

4. Components of the chemical processing system associated with reactor
gsecondary containment and with containment of radiocactive salts and
gases during chemical processing operations. In addition to those
components covered in item 1 above, this category includes the ultra
sonic level probe, described in Sect. 6.11, and pressure and differ-
ential pressure transmitters, flow elements, and pressure switches
in the associated HF, ¥, N, Hp, and SOz gas supply systems. In
general, a quality level intermediate between the weld-sealed con-
struction required for reactor primary containment and the gasketed
construction allowed in secondary containment was used in the chemical
process system. For example, silver solder was accepted in lieu of
welding, and Hoke type S-26 fittings were accepted in lieu of auto-
clave-type connections. Gasketed construction and standard tubing
and piping fittings were not acceptable in this service because of
the relatively high activity that will be present in the system
during fuel processing operations.

 
 

26

2. Components of the chemical process sampler connecting to inner con-
tainment barriers. Although, for containment. purposes, the quality
of construction required in this system is the same as that for the
chemical processing system, many components in this category have a
higher quality of construction than required because of sampler
operational requirements and because the chemical process sampler
was originally the prototype for the fuel sampler-enricher. Instru-
mentation for this system is discussed in more detail in Sect. 3.12.

 

6. Components of the coolant salt system associated with reactor second-
ary containmment. In addition to those components covered by items
1l to 3 above, this category includes the ball float level transmitter
described in Sect. 6.9, the coolant salt venturi described in Sect.
6.13, the NaK-filled differential transmitter described in Sect. 6.12,
the coolant-salt drain-tank supply vent and bypass valves, the coolant
pump-bowl pressure transmitter, the coolant-salt drain-tank pressure
transmitter, and the coolant-salt pump bubbler-level system. Weld-
sealed construction was used in these applications because of the
consideration of conservation of helium and exclusion of oxygen
noted previously and because of the high operating temperature of
the venturi, NaK-filled differential pressure transmitter, and the
ball-float level transmitter. Because the coolant salt system is
considered secondary containment, less protection was provided on
the coolant-salt helium-supply purge and vent lines than was pro-
vided on similar lines in the fuel system.

 

From the gbove discussion, it should be noted that operational con-
siderations, in many cases, dictated a quality of construction greater
than that dictated by the containment considerations. Also, it should
be noted that no mention has been made of sealing or closure of penetra-
tions associated with signal and control wires or tubing for those in-
strument components that form a part of secondary containment. In almost
all such cases the components are installed so that the bodies of the
components form outward extensions of secondary containment and no
penetrations were required. In the case of the few exceptions (notably
the cell radiation monitors, cell ambient temperature thermocouples, and
some components of the sampler-enricher and chemical process sampler),
the signals are electrical, and the required seals are made by means of
feed-through penetration seals.

With the exception of the cell ambient temperature thermocouples
noted above, the measurement of temperature in the secondary containment
systems posed no containment problems since all such measurements were
made by means of thermocouples located on the outside of pipes and
vessels (or in wells), and no penetrations were required. Other possible
exceptions to the above are the thermocouples installed on the charcoal
beds and the off-gas sampler (see Sects. 3.5 and 6.7). Penetration seals
are provided where these thermocouples penetrate enclosures; however,
since the enclosures are vented to the stack, these seals should probsbly
be considered part of building containment rather than secondary contain-
ment.
 

27

1.2.3.2 Redundancy, Separation, and Identification

As discussed in subsequent sections of this report, the instrumenta-
tion and control systems associated with reactor safety are required to
be redundant. In the MSRE, this redundancy is in the form of one-out-of-
two or two-out-of-three logic. ORNL practices require that all compo-
nents, wiring, and tubing be installed so that redundant safety channels
are physically separated from each other and from control-grade compo-
nents, wiring, and tubing and that safety channels be identified as such.
Where possible, separation was accomplished by means of separate con-
duits, wireways, Jjunction boxes, cabinets, and metallic barriers. In
some cases, complete separation was not possible, and physical separa-
tion with appropriate identification (painted signs, labeling, and color
coding) was used.

1.2.3.3 Hazards to Operating Personnel

Attention was given to providing protection against hazards to oper-
ating personnel beyond that provided by the reactor safety system.
Wiring was installed in accordance with the National Electric Code and
with ORNL recommended practices. Instrument lines that presented possible
pressure or radiation hazards were either protected or confined to areas
not normally accessible to operating personnel.

1.2.4 Performance Characteristics

1.2.4.1 Overall Accuracy

Accuracy was a prime consideration in the selection of instrumenta-
tion associated with the acquisition of experimental data and with some
process and nuclear control systems. However, in reactor safety systems,
accuracy was considered to be secondary to reliability. Also, in many
process instrumentation applications, high accuracy was not required, and
accuracy was considered to be secondary to other considerations, particu-
larly cost. Since accuracy is & poorly understood and often misused
term, the performance requirements for those instruments associated with
the acquisition of high-accuracy data or information were specified in
terms of individual performance characteristics such as linearity, zero
drift, span shift, hysteresis, ambient temperature and pressure effects,
process temperature and pressure effects, etc. 1In general, an effort was
made to match accuracy specifications to the epplication; however, in
some applications, considerations of minimization of the number of instru-
ment types used and reduction in requirements for operating spares re-
sulted in the use of instruments having a higher accuracy than required.

1.2.4.2 Reliability
Reliability was a prime’cohsideration in the selection of all instru-

ment components and was of particular importance in the selection of re-
actor safety system components. However, since obtaining high reliability

 

 
 

 

28

can be very expensive, the degree of reliability needed for a particular
component was based, in general, on considerations of "cost vs conse-
quences." Where high reliasbility was needed, relisbility requirements
were incorporated in the specifications, and components were tested before
and after installation. Where moderate reliability was sufficient,
selection of component was based on experience and engineering Jjudgment,
and performance was proved during system shakedown testing and subsequent
operations. At this point the distinction between component relisbility
and system relisbility should be noted. As discussed in the following
section, overall reliability can be enhanced by the use of redundancy

in system design. Conversely, improper use of redundancy can reduce the
overall system reliability below that of the individual components.

1.2.4.3 Failure Modes

Insofar as possible, components of the safety system (and of most
control systems) were selected and installed in such a manner as to
"fail safe." That is, the components were selected and systems were
designed to produce the desired corrective or control action in the
event of component failure or loss of supply power. A fail-safe action
is sometimes referred to as a "failure toward danger,” since such an
action appears to the controlled system as a dangerous condition and is
therefore in the safe direction. A single "failure toward danger" in a
system using two-of-three logic converts it to one-of-two logic. The
fail-safe mode of failure is the direct opposite of the "unsafe failure"
mode, which results either in an unsafe or undesired action or in no
action at all. Examples of the latter would be an upscale failure of
an instrument channel having a downscale trip, an open-circuited coil in
a relay which must be energized to produce the desired action, a welded
contact which must open to produce the desired action, and an "in-place"
failure of an instrument resulting in the controlled system remaining in
the state that it was in when the failure occurred. In~place failures
are characteristic of motorized equipment and occur mainly in servo-
controlled equipment such as potentiometric recorder-controllers. This
type of failure can be caused by loss of supply power, by desensitization
of amplifiers by excessive noise on the signal, by dirty slide-wires, or
by component failures.

It should be recognized at this point that an "unsafe failure" of
one channel in a safety system utilizing redundancy can be very serious.
In the case of systems using one-of-two logic, an "unsafe failure" of
one channel will convert the system to & "single-tracked" system with
full dependence for safety being placed on each and every component of
the remeining chennel. The situation is even more critical in the case
of systems using two-of-three coincidence logic, since an "unsafe
failure" of one channel will convert the system to a two-of-two coinci-
dence logic system, with full dependence for safety being placed on each
and every component of both remaining channels. Routine testing is re-
quired to detect such conditions.

While fail-safe action is desirable, it is usually difficult or
impossible to obtain in practice. Few (if any) devices have only one
failure mode. For example, an otherwise fail-safe device or system in-
corporating a feedback loop will usually fail "unsafe" if the feedback
 

 

29

loop is opened. Most devices have two possible modes, and some have nore
(such as upscale, downscale, and in place). However, the devices will
usually have a "preferred" or "most probable" failure mode. Where one
mode is predominant the device is said to fall in this mode, and circuits
are designed accordingly. In some cases ambiguity of modes can be reduced
or eliminated by the use of "confidence" circuitry and monitoring devices
(such as "power-failure" relays), which produce a corrective action in
the safe direction in the event of the occurrence of a condition that
could result in an unsafe or unwarrented action. Although it is possible
to design around some undesirable failure modes, components and system
are, 1ln general, too complex and too unpredicteble to use this crutch
extensively. In the final analysis the use of fail-safe design tech-
niques must be recognized for what it is — a means for reducing the
probability of unsafe or unwarranted actions -~ and reliance must be
Placed on the use of the principles of redundancy and diversity together
with surveillance, testing, and monitoring to obtain a level of reli-
ability commensurate with the requirements for reactor safety and con-
tinuity of operations.

1.2.5 Effects of Process Conditions

l.2.5.1 Operating Temperature

Temperature effects were an important consideration in the selection
of all primary sensing elements and were a primary consideration for
those components which were attached to the heated salt systems. In
these systems the 1200°F operating temperature presented problems which
necessitated the development of special instrumentation. In other MSRE
systems the temperatures were within the range where satisfactory per-
formance was obtainable with commercially available instrument compo-
nents. The effects of variations of temperature on accuracy and other
performance characteristics are of interest at low temperatures (below
150°F) and become increasingly important as the temperature increases.
At higher temperatures (sbove 300°F), damage to materisls such as
plastics and elastomers becomes important; at elevated temperatures
(ebove 600°F) the general operability becomes a metter of concern. Also,
since corrosion is accelerated and structural strength of material is
degraded as the temperature is increased, the choice of materials be-
comes a prime consideration at elevated temperatures. The philosophy
adopted in the design of MSRE salt system instrumentation was to avoid
operation of instruments at high system temperatures wherever possible
and to obtain readings indirectly with instruments operated under more
favorable conditions. Where this was not possible or desirable, de-
velopment of special instrumentation was initiated (see Sect. 6).

1.2.5.2 Operating Pressure

As in the case of temperature the effects of process operating pres-
sure and of pressure variations on performance characteristics and
structural strength become increasingly important as the pressure in-
creases. These pressure effects are most important in applications

 
 

30

where the operating temperature is high. Fortunately, MSRE pressures
are low (below 50 psig) in those portions of the system where tempera-
tures are above 150°F; so the required structural strength was, in most
cases, obtainable with a minimum of effort. Close attention to effects
of pressure was required in the selection or development of components
which operate at temperatures sbove 600°F, and in cases such as the
molten-salt level probes, the requirements for structural strength and
containment imposed severe restrictions on the design. In other cases,
such as the NaK-filled differential pressure transmitters, the effects
of pressure variations were the boundary conditions which limited the
accuracy of the instrument.

1.2.5.3 Corrosion

Corrosion was a prime consideration in the selection or development
of all instrument components which were exposed to process fluid. How-
ever, in all reactor systems except the fuel processing system, the
requirements for corrosion resistance were easily satisfied by use of
standard materials available for commercial components or by use of
INOR-8 (Hastelloy N) materials for developmental instruments.,

In the fuel processing system the high corrosion rates expected
during fluorination precluded the use of the thin-walled conductivity
level probes for level detection in the fuel storage tank and forced a
redesign of the ultrasonic level probe to obtain adequate corrosion
allowance.

In some cases materials were used which gave corrosion resistance
beyond that dictated by the process conditions. This was done to permit
decontamination of components with acid rinses.

Exposure of components to corrosive conditions was avoided where
possible by obtaining readings indirectly with components operated under
more favorable conditions. For example, pressure in the fuel storage
tank was obtained by measurement of pressure in a purge line connecting
to the tank. This technique is similar to that used to avoid tempera-
ture problems (see Sect. 1l.2.5.1).

Since corrosive conditions did not exist in the MSRE operating
areas, no special precautions were required for the selection of compo-
nents and designh of systems located in these areas.

1.2.5.4 Salt Plugging and Vapor Deposition

Consideration was given to the possibility of plugging of instrument
lines with salt wherever these lines penetrasted lines or vessels containe
ing salt. Such plugs can occur as a result of expulsion of salt into
cold instrument lines or as a result of vapor deposition of salt in the
lines. ILines can also be plugged by formation of oxides where gas is
purged into the system below salt level.

The consequences of plugging range from minor to very serious,
since the resultant loss of information could further result in loss of
experimental data, loss of control, or loss of one or more channels of
safety protection.

During initial stages of MSRE design, it was believed that vapor
deposition and oxide formation might be very serious problems and might
preclude measurement of pressures, differential pressures, etc., with

C
 

31

instruments attached to purged ges lines. This belief was based on ex-
perience in earlier molten-salt systems in which considerable difficulty
with plugging was experienced. Further investigation revealed that the
vapor pressure of the MSRE salts and the expected oxygen content of the
MSRE cover gas would be much lower than those of previous systems. On
the basis of this information the indirect measurement approach was
adopted. |

To minimize the possibility of plugging, all instrument lines which
penetrated salt-containing lines and vessels were made as large as was
consistent with other considerations, and instrument taps were located
as far sbove salt level as possible. In almost all cases MSRE instrument
components are located on inlet gas lines, and a small purge flow is
maintained in the lines. This purge flow also serves to minimize back
diffusion of radiocactive gases. Some components, such as the fuel off-
gas letdown valve, the charcoal-bed differential-pressure transmitter,
and the fuel-pump gas-letdown flow transmitters, were located on lines
downstream of the reactor. In these cases the components were placed
as far downstream as possible and were protected by filters. In cases
such as the bubbler level indicator, where instrument lines are required
to extend below salt level, provisions were made to ensure that pressure
transients will not expel salt into cold lines (see Sect. 6.8).

Experience to date on the MSRE and on related engineering test
facilities indicates that the philosophy adopted was sound and that the
provisions made in the design to prevent plugging were adequate. Some
plugging has occurred in off-gas lines; however, this plugging was due
to hydrocarbon plugging and was not expected during the initial design.

While the MSRE instrumentation and controls system has been essen-
tially free of salt plugging problems, the need for purge flow, together
with other considerations (such as operating temperature and radiation
damage ), resulted in a complexity of instrumentation beyond that re-
guired for the basic measurement. This increased complexity resulted
from the additional instrumentation needed to prevent the escape of
activity through instrument lines which penetrated both containment
barriers. If radiation-resistant transmitters capable of operating in
direct contact with the salt had been available, this complexity of
instrumentation (and the probability of salt plugging) would have been
reduced. NaK-filled transmitters offer promise for use in future re-
actor systems, provided the possibility of release of NaK into the sys-
tem can be tolerated. Also the ball float level transmitter described
in Sect. 6.9 may be a satisfactory replacement for the bubbler-type
level system in some applications. :

1.2.5.5 Electrical Resistivity of Molten Salts

The electrical resistivity of the MSRE fuel and coolant salts was
determined to be approximately 1 ohm-cm at 1200°F and 1 kilohertz
(1000 cps). While this resistivity indicates that the MSRE salt is
a fair conductor, it is high in comparison with the 120-microhm-cm
resistivity of Hastelloy N and Inconel and even higher in comparison
with the 35-microhm-cm resistivity of sodium and 80-microhm-cm re-
sistivity of NaK at 1200°F. Conversely, the resistivities of NaK and

 
 

 

32

sodium are low in comparison with Hastelloy N and Inconel. Therefore,
while Inconel can be considered as a poor insulator in comparison with
NaK end sodium, Hastelloy N is a good conductor in comparison with the
MSRE salt. For this reason, devices such as magnetic flowmeters and

"J" probe type level indicators, which are used extensively in liquid-
metal systems, are not suitable for use in the MSRE molten-salt systems.
However, the conductivity properties of the MSRE salt were utilized to
obtain single-point indications of level in the MSRE drain tanks (see
Sect. 6.10).

1.2.6 Environmental Effects

1l.2.6.1 Ambient Temperature

Ambient temperature effects did not impose severe restrictions on
the selection or development of any MSRE instrument components, since
the in-cell ambient temperatures are kept below 150°F by the use of space
coolers and the temperatures in operating areas do not exceed 100°F.
(The main control areas are air-conditioned, and temperatures are kept
relatively constant at about 75°F). However, the effects of variations
of ambient temperature on the accuracy of measurements were important,
and they were considered during procurement of components and design of
the system. Also, in some areas where natural circulation was restricted
or density of heat-generating equipment was high, forced-draft air cooling
was required to maintain the ambient temperature of the components and
that inside the cabinets within acceptable limits.

1.2.6.2 Ambient Pressure

The effects of ambient pressure were important in the selection or
development of all components that were referenced, directly or indirect,
to atmospheric pressure or to in-cell pressures.

In some cases, such as determination of cell leak rate and monitoring
of building containment, the pressures themselves were of direct concern.
In all other cases, the interest lay in the effects of pressure on the
accuracy of the measurement.

Instrument components which are (or may be) sensitive to ambient
pressure generally fall into one of the following three categories:

1. those which sense the difference between an internal pressure and
the pressure of the surrounding medium and which generate a
mechanical or electrical signal or indication (pressure gages,
manometers, pressure switches, and pneumatic receivers);

2. those which convert a force, motion, or electrical signal into a
pneumstic pressure (current-to-pneumstic converters and pneumatic
valve positioners);

3. combination of 1 and 2 (pneumatic pressure transmitters and pneumatic
weigh cells).
 

33

Such instruments usually incorporate a bellows or a Bourdon tube in
the mechanism.

Pressure in the drain-tank cell can vary over a wide range (+5 to
—4 psig) during the course of normal operatlons. The pressure can vary
less in areas ventilated by the containment air system since pressures
in these areas are maintained slightly negative with respect to the
atmosphere (approximstely —0.2 to —2 in. Hp0 gage). Also, variations of
atmospheric pressure are of interest in many instances. Variations over
the range from 28.7 to 29.5 in. Hg were cbserved at the MSRE site over a
six-month period, and larger variations are possible during extreme
weather conditions. The observed variations correspond to approximately
0.5 psi. Although this value is small, it amounts to 1% of the 50-psig
measurement span of most MSRE pressure transmitters and 4% of the 12-psi
output signal span of 3- to 15-psig pneumatic transmitters.

The philosophy adopted in the design of the MSRE instrumentation and
controls system was to avoid the use of pressure-sensitive components in
areas where pressure variations occurred. Where this was not possible,
or where the use of pressure-sensitive components offered significant
advantages, the effects of pressure variations were eliminated by internal
compensation of the device or by correcting the data. The drain-tank
weigh cells are an example of the use of internal compensation. Data
correction was used to correct gage pressure data such as obtained from
the reactor cell pressure transmitter. Another form of compensation,
which is not usually recognized as such, is the location of associated
pneumatic transmitters and receivers in the same pressure environment.
Although this technique is common practice, significant errors can occur
when this effect is overlooked and transmitters and receivers are in-
stalled in areas having different ambient pressures.

1.2.6.3 Radiation Damage

All instrument components located within the reactor and drain
cells are subject to damage from nuclear radiation. However, some com-
ponents of the sampler-enricher, the chemical process system, the
chemical process system sampler, the off-gas system, and the off-gas
sampler are less subJect to radiation daemage. The radiation level in
the coolant salt and waste cells is relatively low, and radiation damsage
in these areas was not considered serious. The maximum radiation levels
in various areas of the MSRE are listed in Tsble 1.2.2. The values
listed are for peak conditions and assume that activity in the system
has built up to saturation levels after sustained full-power operation.
In general, the selection of materials for use in high-radiation
areas was governed by considerations of total integrated dose rather than
dose rate, and the use of plastics and elastomers was limited to those
areas where the total gamma dose expected during the lifetime of the re-
actor was less than 107 r and the expected neutron dose was less than
1017 nvt. Where higher dosage was expected, component materials were
restricted to metals and inorganics. Exceptlons to this rule are the
rod drive motors and all semiconductor devices. The rod drive motors
have organic insulation and lubricants and are designed to be replaceable.

 
 

Table 1l.2.2.

34

Radiation Dose Rates in Various Areas of the MSRE
During or Following Sustained 7-Mw Power Operation

 

 

 

 

 

. Gamma Neutron
Location (r/hr) (neutrons cm™? sec™1) Remarks
Reactor cell 7 x 10% 107 thermal, At 7 Mw
108 fast
5.4 x 103 Negligible® At 10 kwP
2.4 x 10° Zero power, reactor
drained®
2 x 103 Zero power, reactor
drained and
flushedd
Drain cell 4.2 x 103 At 7 Mw
4o2 x 10° At 10 kwP
2.6 x 104 Zero power, reactor
drainedC®
Fuel processing 5 x 103 W After 11 days cool-
cell ing
Coolant cell 100 ~0 At 7 Mw
Fuel sampler- 1000 Negligible During sample with-
enricher drawal
Fuel processing 20 During sample with-
sampler drawal
Off-gas sampler 500 During sampling
High-bay area < 20 x 103 At 7 Mw
Main control <1lx 1073
area
Transmitter < 75 x 1073
roam
North electric < 3 x 10~
service area
Service room <1x 1073
Water room < 10 x 10™3
Vent house < 10 x 10™3
Diesel house < 10 x 1073 Y W

 

8yith respect to gamma dose rate.

b

After 5 hr 10-kw operation following sustained 7-Mw operation.

cImmediately following above 5-hr operation at 10 kw.
dTwo days after drain following 7 Mw sustained operation.
 

35

Semiconductors are known to be extremely sensitive to both dose rate and
total dosage. The use of instrument components utilizing semiconductors
was restricted to areas outside biological shielding, where radiation
levels were expected to be relatively low. For example, the transistorized
amplifiers used with the Foxboro ECI pressure and differential pressure
transmitters were placed remote from the transmitter body when the trans-
mitter was located in a high-radiation area. In areas such as the fuel
sampler-enricher and the off-gas sampler, the maximmm (peak) radiation
levels are very high but the duration of the peak is relatively short.

In these areas, radiation-resistant components and materials were pre-
ferred, but plastics and elastomers were permitted.

1l.2.7 Physical Requirements

l.2.7.1 Wcld-Sealcd Construction

All instrument components which are an integral part of primary con-
tainment were weld sealed, inspected, and tested to ensure that helium
leakage through the body to the surrounding area would be less than 108
cm3/sec at maximum expected internal pressures. To conserve helium,
most instrument components of the cover-gas system were also weld sealed.

1.2.7.2 Ruggedness

The ability to withstand shock and vibration without permanent
damage or temporary loss of performance was & consideration in the
selection of all instrument components and was a prime considerstion in
the selection of field-mounted instrumentation. Of particular importance
was the ruggedness of those components which are located within the reac-
tor and drain cells and which may be subJject to gbuse during remote
maintenance operations.

l.2.7.3 8Size

Small physical size is generally desirable since reduction of the
size of individual components results in an overall reduction in the
size of control’panels and minimizes interferences in the field. In
areas such as the sampler-enricher the availability of space dictated
that small-sized components be used; however, in most applications, other
considerations predominated. For example, readability of receivers and
general performance characteristics were considered to be more important
than small size,

l1.2.7.4 Materials of Construction

In addition to the requirements for physical strength and resistance
to the effects of corrosion and radiation, discussed in Sects. 1.2.5.1,
1.2.5.2, 1.2.5.3, and 1.2.6.3, consideration was given to compatibility

 
 

36

of materials used in instrument components with the general metallurgical
requirements of the MSRE. For example, the use of metals (such as lead,
tin, and aluminum) with melting points below 1600°F was not permitted in
areas where they could conceivably come in contact with heated pipes and
vessels. Also, the use of dissimilar-metal welds for attachment or con-
nection of instrument components to heated pipes and vessels was not per-
mitted. The use of dissimilar-metal welds for thermocouple attachments
was avoided by the use of a Hastelloy N tab which was welded to the
Inconel thermocouple sheath in the shop and subsequently welded to the
pipe or vessel when the thermocouple was installed.

1.2.7.5 Cleanliness

Since accumulation of dirt and other foreign materials will cause
degradation of performance of most instrument components and systems,
cleanliness was an important consideration in the procurement and instal-
lation of all MSRE instrument components. However, the degree of
cleanliness required is dependent on the application and varies over a
wide range. In most applications moderate cleanliness was adequate, and
reliance was placed on the manufacturers' integrity and on preoperational
checks and inspection for cleanliness control. A much higher degree of
cleanliness was required for components which were an integral part of
the heated salt systems or of pipes and vessels connected to these sys-
tems. To preclude the possibility of foreign matter being transported
from these components to the molten salt or to heated surfaces in pipes
and vessels, stringent cleanliness control was maintained during fabri-
cation, transportation, and installation. Components fabricated outside
ORNL were inspected by Company representatives during assembly. The de-
gree of cleanliness was determined by wiping with dry surgical gauze.
Discoloration of the gauze was cause for rejection. After assembly and
testing, openings were capped, and the components were sealed in plastic
bags and cartons and remained sealed until they were installed in the
MSRE system.

1.2.8 Cost

A continuing effort was made during the design of the MSRE instru-
mentation and controls system and during specification and procurement
of components, to minimize the overall cost of the system. In noncritical
applications, cost was a primary consideration; however, in applications
where safety, opersbility, and continuity of plant operations were in-
volved, other considerations predominated. Also, where conflicts of
objectives arose, decisions were based on consideration of "cost vs
consequences."
 

 

 

37

1.3 PLANT INSTRUMENTATION LAYOUT

1.3.1 General Description.

Instrumentation is centralized in the main control area, where a
graphic control panel and operatlng console are located. Only informe-
tion needed to operate the reactor is displayed on these panels. Auxil-
iary instrument and electrical panels, relay and thermocouple cebinets,
and a data-logging system are adjacent to the main control roomn.

A second area, the transmitter room, is adjacent to the reactor cell.
The available space and the desirability of mounting certain components
close to the point of measurement dictated that this be a control ares.
With the exception of control-rod drives, thermocouples, pump speed
pickups, microphones, high-level gamma ionization chambers, weigh cells,
and some control valves, all instrumentation components are located in
areas external to the reactor containment vessels. _

Other instrument panels for auxiliary systems are located at con-
venient operating points throughout the building.

Sixty-one 2-ft modular instrument panel sections, one operating
console, two relay cabinets, one thermocouple patch panel, and two equip-
ment racks are required for the MSRE. '

1.3.2 Main Control Ares

The main control area, shown in Figs. 1.3.1 and 1.3.2, contains 12
control panels and the control console. The 12 panels comprise the main
control board, which is in the form of an arc centered on the console.

The main control board, Fig. 1.3.3, provides a full graphic display
of the reactor system and its associated instrumentation. These panels
contain the instrumentation for the fuel salt system, the coolant salt
system, the fuel and coolant pump oil systems, the off-gas system, the
Jumper board, and a push-button station for the various pumps and blowers.
The primary recorders for nuclear control are also on the main board. The
instrumentation on the console consists of position indicators, control
switches, and limit indicators for the control rods, radistor doors, and
fission chambers, and other switches required for normsl and emergency
operation of the reactor. Routine control of the reactor is accomplished
from the main control srea. Some of the auxiliary systems are also con-
trolled here, with remaining portions controlled from the local panels
shown in Figs. 1.3.1 and 1.3.4.

1.3.3 ,Auxiliary Control Area

The asuxiliary control area, Fig. 1.3.2, consists of eight auxiliary
control boards, five nuclear control boards, .one relay cabinet, one
| thermocouple cabinet, four diesel and switching penels, and a safety re-
lay cabinet. The eight suxiliary panels contain the signal amplifiers,
power computer, switches and thermocouple alarm switches, auxiliary in-
dicators not required for immediate reactor operation, the fuel and

 
 

38

coolant pump microphone emplifier and noise level indicator, and the sub- \UJ
station alarm monitors. All the safety circuit control relays are lo-

cated in the safety cabinet, and most of the operating circuit relays are

in the control relay cabinet. The relay cebinet contains only the relays

for the main control circuitry. The thermocouple cabinet contains a

patch panel with pyrometer jacks. All thermocouples in the system except

those on the radiator tubes are terminated in this cabinet. The thermo-

couples on the radiator tubes are routed to the temperature scanner and

then to the patch panel.

The five nuclear panels contain some of the instrumentation for the
process radiation system, the oil system, and the sampling and enriching
system. The health physics monitoring alsrm system, the high-level gamma
chamber electrometers and switching panel, and the reactor control nuclear
amplifiers, servo amplifiers, and other equipment for the nuclear control
system are also located here. Four panels contain the instrumentation
for the operation of the emergency diesel generators. The distribution
panels for the control circuit and instrument power are located on the
south wall of the auxiliary control room.

1.3.4 Transmitter Room

The transmitter room, Fig. 1.3.5, consists of nine control panels,
one solenoid power supply rack, and a transmitter rack. Panels 1 and 2
are for the leak detector system, and panels 3 and 4 are for fuel drain
tanks 1 and 2, the coolant drain tank, the fuel flush tank, and the fuel
storage tank weigh instrumentation. Panels 5 and 6 are for the fuel and
coolant pump bubbler-type level control, panel 7 is for the freeze valve
air control, panel 8 contains the power supply and alarm switches for the
drain tank level probes and a transducer for the float-type coolant-salt-
pump level transmitter, and panel 9 is for the sump bubbler system. The
solenoid power supply rack contains most of the solenoids for the fuel
salt system and the power supplies and distribution panels for the elec-
tric transmitters and differential transmitters. The transmitter rack
contains the remote amplifiers for the electric signal transmission sys-
tem and also the current-to-air transducers.

All electrical and pneumatic lines that connect transmitter room
equipment to input signals from the resctor, drain tank, water room, and
all other areas outside the building enter through sleeves in the floor.
Output signals from the transmitter room equipment are conducted via
feeder cable trays to the main ceble tray system, which runs north and
south in the building on the 840-ft level.

C

1.3.5 Field Panels

Additional panels are required for the auxiliary systems. These
(see Figs. 1.3.1 and 1.3.4) are located near the subsystems which they
serve. Four panels for the cooling oil systems are located in the service
room and service tunnel; one cooling- and treated-water system panel is
located in the fan house; three panels are located on elevation 852 ft
 

 

39

at column line C-7 for the sampling and enriching system. Two cover-gas
system panels are located in the diesel house. Two containment-air sys-
tem panels are provided: one at the filter pit and the other in the
high-bay area.

The reactor cell air pressure monitoring instrumentation and testing
facilities are mounted on a single panel located in the north electric
service area, which is directly below the transmitter room. Five panels
for the fuel processing system are located in the high-bay area above
the fuel processing cell. Two of these control the process, and the other
three are for the sampler. One panel located in the high-bay area on top
of the coolant cell serves the coolant salt sampler. Three panels for
the fuel off-gas analyzer and one panel for the reactor-cell-air oxygen
analyzer are located in the vent house. Two panels for the thermocouple
scanning system are located on the 840-ft level near the heater control
panels.

1.3.6 Interconnections

The control areas and the controlled systems are interconnected by
cable trays and conduit. This system includes the main cable tray sys-
tem running north and south in the building, with branch trays and con-
duits Jjolning the main tray. These main trays carry all tubing for the
pneumatic system, thermocouple lead wire, and the ac and dc control
wiring. Each category of signal runs in a different tray to avoid mixing
of the signals. Risers connect the panels and cabinets in the control
area on elevation 852 ft with the main trays. No exposed trays are in
the main or auxiliary control rooms. Safety system wiring is completely
enclosed in conduit and Jjunction boxes and is separated from control and
instrumentation wiring.

 

1.3.7 Data Room

The datsa room is designed to house the data logger-computer; see
Sect. 2.12. It contains all the data system equipment except one logging
typewriter, which is located in the main controcl room. The layout of the
equipment in the room is shown in Fig. 2.12.4 (Sect. 2.12). This room
is located in the north end of the reactor building, next to the main
control room. There are entries from the hallway and the main control
room. A large glass window is located so that the main control panel
can be seen from the data room.

The data system cabinets are installed in two rows, back to back,
running east to west about the center of the room. The front row of
five cabinets facing the control room contain the computer proper, and
the six rows facing the north end of the room contain the analog input
signal terminals and the control circuits for the typewriters, magnetic
tapes, and other input equipment. The data system operator'!s console is
located so that the reactor control panel can be seen by an operator at
the console. Two desks and several tables are located in the room for

 
 

40

use of reactor operating and analysis personnel and the computer mainte-
nance engineer. A storage cabinet for magnetic tapes is located at the
west wall of the room, and a spare parts storage cabinet is located at
the north wall. The electrical power panel for the system is located in
the northwest corner of the room. The installed equipment is shown in
Figs. 2.12.1 and 2.12.3 (Sect. 2.12).

The input signal cables for the data system are brought up to the
bottom of the room in cable trays. Holes are cut in the floor beneath
the cabinets for routing the input signal and control cables to the
cabinets.

The data room is air conditioned by two 7.5-ton air conditioners.
These same units can be used to supply air to the main control room in
an emergency, and the control room air conditioner can supply air to the
data room when necessary.
 

 

41

ORNL-DWG 64-308R

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

BUILDING 7509
[ " oFrice)
HEALTH PHYSICS
ROOM DOWN INSTRUMENT
STORAGE
] 171 [ _ AR L
\\ 5 By /’ |
OFFICE OFFICE OFFICE —_
DOWN INSTRUMENT
L Hi= MAIN SHOP
CHANGE -
. ROOM ]
: ' l
SEE FIG.}?.S.Z l,L‘ roT l|
AUXILIARY NUCLEAR
DATA ROOM CONTROL CHANGE I PENETRATION
SEE FIG.1-3.6 vay  ROOM [ _ROOM | —
CONTROL ROOM .{J HOT CHANGE ROOM !

 

 

 

 

 

" [] CONTAINMENT AIR

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  
  
  

REACTOR
CELL-

 

 

 

 

 

 

 

 

 

FUEL .
[ PROCESSING ST CK)
SAMPLER DRAIN TANK CELL
PANELS— _ | | |
- N r : VENT
[ VESSEL HOUSE
| — ROOF
—_ S
PROGESSING  MAINTENANCE :
PANELS CONTROL ROOM )i
ELEVATION B62ft Oin.

 

 

    

   
 

FUEL
SAMPLER

ENRICHER
PANELS

 

 

 

 

 

 

 

 

Fig. 1.3.1. Main Floor Layout of Building 7503 at 852-ft Elevation,

OBSERVATION

 

 

CRNL—DWG 64--630

T

 

 

 

GALLERY \\A | CiD |
| .

   

 

 

 

 

 

 

 

£ =T = = — - ? - _ - ...__._@)
, THERMOCOUPLE .
_ CABINET
-\ll 2 ' POWER
- Lefefsla]  fs]sl7]e] & oo
—— PANELS
\ e ;
oata AND AUXILIARY PANELS _ _
ATA AN AUXILIARY CONTROL AREA NUCLEAR
SUPERVISOR PANELS »— PANELS
, ROOM ' A-“"N**ia" 'zL’%_a-_.‘
lafafz]"] Isfefsfaje] |
. S ke T
" ReLav caBiNgT— T _ SAFETY CABINET—~
- - T - - i - ©

 

 

Fig. 1.3.2.

Main and Auxiliary Control Areas.

 
 

 

 

 

 

 

e

H
4

P
el Il LTI

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1.3.3.

Main Control Board.

 

 

 

 

 

ey

 
 

 

ORNL-DWG 63-8399

 

 

 

DOWN T-C SCANNER

= g

HEATER

 

|

PANELS——(TJ LTI

UP,
uP
BATTERY DOWN
ROOM LUNCH
MAINTENANGE | ROOM ,
.‘._ p .
J ROOM

    

 

 

f REMOTE |-
-] MAINTENANCE
CELL ]

    

 

 

 

WASTE
CELL

LIQuUID

 

 

 

 

 

 

 

 

   

A
i

 
  
   

LUBRICATION OIL
CONTROL PANELS

 

 

ROOM
REACTOR

 
   
 
    

]

SPECIAL
EQUIPMENT

 
 
   
   

 
 
  

 

 

 

CELL

  

 

 

 

DECONTAMINATION
CELL

 

N

- =

BU ILDING
VENTILATION

Fl LTER HGUSE

Fig. 10304.

N

i —

 

 

 

 

  
 

 

 

 

 

U X [
FUEL

PROCESSING CELL  Coarie
EQUIPMENT __H

SWITCH ROOM — |

HOUSE =
WATER
coer
PANEL

DIESEL oL BaN

DIESEL ,]Lcow OL PANELS Dowy

BUILDING 7503-ELEVATION 840 ft Oin. LEVEL

Layout of Building 7503 at 840-ft Elevation.

ORNL-DOWG 64-629

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

|
4
LDK
‘ - 2
9
: 3 | ,REMOVABLE
8 | ACCESS PLUG
WEIGHT
2 | Pump 4
: T
6 | 5 [|_SOL. RACK ||
TRANSMITTER LADDER

RACK\

 

Ir

OOWN
1l \V\I—--|

®

 

 

 

 

 

 

 

 

 

 

 

 

103.5.

Transmitter Room.

 

 

 

 
 

44

1.4 PLANT CONTROL SYSTEM

The MSRE and its control and instrumentation complex may be viewed

as a primary reactor system which generates nuclear power and rejects
heat to the atmosphere plus the collection of auxiliaries or subsystems
required to run this primary system. This discussion of MSRE plant
control is concerned with how the control system interconnects these
various systems and how they are coupled to the reactor; it is little
concerned with the reactor safety system. It is sufficient to point
out that the safety-grade instruments are not used as operational con=
trols and that every effort is made to keep the safety system instru-
ments completely decoupled from the operational control equipment. The
MSRE safety system, what it does, and why are discussed in Sect. 1.5.

It is appropriate to separate the various systems and equipment
and their associated instruments and controls into categories, thus:

1. Those operator-controlled items which exert a direct and im-
mediate influence on the state of the reactor; collectively these are
the operator's "handle" which runs the MSRE.

2. Redundant, essential auxiliaries not in (1) which, should one
unit malfunction, require immediate transfer switching by the operator
if the redundance is to be effective. Examples are the instrument air
compressors and the component cooling pumps.

3. Vital monitoring and control instrumentation not subject to
ad justment or control by the operator. These instruments produce off-
limit alarms and control actions and provide continuous information as
to the conditions in the monitored systems. Examples are the process
radiation monitors, health-physics alarm instrumentation, safety sys-
tem instruments, etec.

4, Nonredundant but essential auxiliaries which operate as self-
contained devices. These instruments either require no control or are
controlled locally and automatically. They are expected to operate
continuously and unattended. An example is the 60-kva battery-powered
solid-state ac power supply.

5., The remaining instruments whose effect on the reactor system
is either peripheral and indirect or is further modified by the in-
strumentation in (1). Instruments used for chemical and physical anal-
yses, for gathering experimental data, and for monitoring slow trends
in noncritical areas of the system are in this group.

This grouping, or categorization, has been strongly implied by

Sect. 1.3, which discusses plant instrumentation layout as it is related

to the reactor operator's use of the instruments and controls., Figure
1.4.1 is a functional diagram of the instrumentation in and directly
adjacent to the main control room. Generally, the diagram shows that
the main control room instruments are composed principally of those in
the first three groups, and the instrumentation on the operator's con-
sole is almost entirely in the first category.

There is a strong incentive to maintain continuous operation at
the MSRE; therefore the plant and the instrumentation and control sys-
tem are designed to minimize unscheduled total shutdowns caused by
equipment failures and electrical power (TVA) interruptions. Critical
operating auxiliaries such as instrument air compressors, water pumps,
cooling blowers, etc., are redundant, and switchover to the spare unit
 

45

is accomplished at the main control board. Each lube oil package serving
the salt loop pumps contains a spare oil pump. Transfer switching to
the spare oil pump is automatic on loss of flow (pressure).

Electrical power interruptions are a leading cause of shutdown
conditions. Design of the MSRE assumes that TVA-supplied electrical
pover will be interrupted several times a year by thunderstorms. TLocal
emergency power from diesel generators is provided.} The diesels are
started and stopped in the auxiliasry control room just a few steps
from the operator's console. Short-term power interruptions to the
operating equipment will not produce a total system shutdown. This
allows sufficient time for manually controlled diesel generator startup
and necessary transfer switching. Total shutdown is defined to include
a reactor drain, which produces a completely quiescent system incapable
of achieving criticality. The design and operation of the reactor and
its controls do not assume unperturbed operation with a loss of TVA
power. In fact, if the reactor is at power, the rods and the load will
scram, and it will not be possible to resume high-power operation until
TVA power is restored. The procedure following a loss of TVA power is
to restore criticality and operate at heat loss power until TVA power
is again available,

The on-line reliability required by the instrument and control
power system must meet more stringent requirements with respect to
continuity. The operator's need for good information is never more
acute than during abnormal conditions such as those produced by an
interruption of TVA power., Safety systems and high-grade interlocks
normally act toward shutdown when their power is lost, even momentarily.
Therefore, the operation of essential plant controls and instruments
does not depend on the normal TVA supply. The two-out-of-three re-
dundancy extensively employed in the plant safety system is intended to
eliminate such a dependency. The plant safety system and a typical
example of three-channel redundant design are discussed in Sect. 2.5.
Figure 1.4.2 is a simplified one-line diagram of the power system used
for the instrumentation and controls.

This power distribution system will be thoroughly described in
Sect. 4.13, but it is worth while to point out that:

1. The three-channel safety systems receive their power from three
practically independent sources within the distribution system.
Two of these are battery-powered:and will not be affected by short-
term interruptions of TVA power.

2. The controls and information channels essential to continuous oper=
ation are battery-powvered. '

The control requirements of the MSRE dlffer, depending on whether
or not the reactor loop is filled or empty and, if filled, on the amount
of power being generated. These different requirements must be ac-
commodated within the control system; that is, the interlocks which pro-
hibit or permit in one operating regime must not prevent routine and

 

15. E. Beall et al., MSRE Design and Operations'Report, Part V, Re-
actor Safety Analysis, ORNI-TM-732 (August 1964).

 
 

46

proper operation in another. Mode control, superimposed on the indi- L
vidual subsystem control channels, resolves this problem of accommodation. k=J
It does so by making all the subsystem alterations required for accom=-
modation to operating regimes responsive to a single, manually operated
control.
Figure 1l.4.3 is a diagram of the fuel and coolant salt systems,
showing the location of the instrumentation and controls which provide
mode control. It can be seen from this figure that mode control in the
MSRE is concerned with:

1. The location of the fuel salt and the flush salt, that is, wvhether
in the drain tanks or the reactor loop. Note that the control sys-
tem makes no distinction between fuel salt and flush salt. This is
because reliable and certain sensors which differentiate between
the two are not available.

2. The ability to transfer salt among the drain tanks or to and from
the reactor loop.

3. The power (flux) being developed and the rate of change of power,
both actual and potential,

4. The operating integrity of important flux instruments used to monitor
and control reactor power,

The scope of the mode control system is not extended to the aux-
iliaries, to the helium supply system, or to the off-gas system. Equip-
ment or control system deficiencies and operating errors which affect
these areas will be reflected, indirectly, to the mode control system ,
or will become immediately apparent because of alarms and/or interlocks Qiy
or by the action of the safety system. Furthermore, the operating re-
strictions imposed by the mode controls are more numerous during tran-
sitions from one operating mode to another as power is being increased.
This limits the rate of change of power to reasonable values. After
the new reactor mode has been established, many of these restrictions
required to enter the mode are bypassed by relsy seals.
Figures l.4.4 and l.4.5 are condensed block diagrams which indicate
the function and purpose of the mode controls. The manually selected
operating regimes have been designated as Off, Prefill, Operate, Operate-
Start, and Operate-Run; a discussion of these follows:
1. Off. — The "Off" mode could be designated "Not in Prefill or
in Operate” (see 2 and 3 below) without sacrificing accuracy. In "Off"
the entire MSRE system is not inoperative but the reactor is shut dowm.
When the reactor is "Off" the following conditions obtain:
a) rod withdrawal is prohibited,

b) not in automatic load control,
¢c) rod control servo is "Off,"

d) prohibits opening of the helium valves used to f£ill the reactor
vessel,

e) prohibits raising the radiator doors by manual control, above
the intermediate limit if reactor power is above 1 Mw,

f) provides a control rod "Reverse" if the power (flux) exceeds o
1.5 Mw or if the reactor period is less than 5 sec, Q‘;'
 

47

g) prevents starting the fuel and coolant salt pumps; if the
pumps are running and the control system is switched to "Off"
these pumps will continue to run because of seal contacts in
the pump control circuits,

h) '"no thew" ~ transfer freeze valves,

i) '"no thaw" — fill and drain freeze valves.

2. Prefill, — Intended to establish the necessary and sufficient
conditions required to precede a reactor start. During this period
the reactor loop is empty so that helium may be circulated to establish
uniform temperature conditions in the loop. Safety system checkouts
are being conducted, and other routine and nonroutine operations involving
maintenance and equipment verification may be under way. Salt transfers
among the drain tanks, to the chemical processing plant, or to or fron
the fuel storage tank are permitted during Prefill, The primary re-
quirement during Prefill operation is that the reactor loop be main-
tained empty. Prefill allows complete freedom in the use of the jumper
board for testing and maintenance checks and, excepting the reactor
£ill restrictions, does not superimpose additional interlocked prohi-
bitions on operating MSRE equipment.

3. Operate. — This mode establishes certain conditions required
to f£ill the reactor loop. Entering "Operate" requires that the transfer
freeze valves between the fuel storage tank and the drain tanks be
frozen and that at least one freeze valve between the reactor drain line
and one of the fuel drain tanks be open.

4. Operate-Start. — The Operate mode automatically becomes Operate-
Start when the reactor loop is filled to the correct level and the re-
actor drain valve (FV-103) is frozen. This mode permits reactor start
with power generation not exceeding 1.5 Mw provided the conditions for
control-rod withdrawal, described in Sect. 2.6, have been established.

5. Operate-Run. — This mode is obtained by manual selection when
conditions requisite to high-power operation have been met. Operate-
Run and Operate-Start are, by direct switching, mutually exclusive.
Depending on whether or not the operator chooses %o control the reactor
automatically or manually, the requirements for going into the Operate-
Run mode differ somewhat (see Fig. l.4.5).

If the operator chooses to use the automatic rod controller or
programmed load control, or both (see Sects. 2.6 and 2.8), certain initial
conditions must be met which provide & smooth transition in reactor
power generation as it becomes responsive to its load-following charac-
teristics and as the rod servo assumes control. These initial conditions
are as follows: -

A. TUsing the Autcmatic Rod Controller

l. The demand s1gnal computed by the automatic rod controller is
asking for 1ess than 1 Mw.

2. The regulating rod is not being restricted in motion by its
limit switches (see Sect. 2. 6).

 

 
 

B. Using Programmed Load Control

1. The radiator doors are positioned so that power extraction is
jimited.

2. The set-point signal which controls the radiator bypass damper,
described in Sect. 2.8, is zero.

Entering the Operate-Run mode is subject to additional restrictions
which are not contingent on the use of the automatic rod controller:

1. At least one main radiator blower must be on.
2. The fuel salt pump must be operating (rpm > 1100).

3. The range selectors in the linear power channels (Sect. 2.4) must
be in the 1.5-Mw position.

4. At least one wide-range counting channel must provide "confidence"
‘and indicate that reactor power is above 0.5 Mw and that the reactor
period is over 30 sec.

Once Operate-Run has been established, most of the requirements
listed in the preceding paragraphs are bypassed by & seal, as shown in
Fig. 1.4.5. When reactor power reaches 1 Mw the "confidence" interlock
(Sect. 2.6) is bypassed and, insofar as the mode control circuitry is
involved, the only requirement for continuing reactor operation in this
mode is that the fuel salt pump be running, one main blower be on, the
transfer freeze valves be frozen, at least one drain line freeze valve
be thawed, and no safety system jumpers be used.

The data logger-computer, adjacent to the main control area, oc-
cupies a singular position in the hierarchy of MSRE instrument and
control systems. It is added to the MSRE as an experiment intended to
evaluate the merit of such devices in reactor systems. Therefore, the
MSRE control system continues to operate whether or not the data logger
is in service. Although no direct reactor system control functions
are vested in the logger-computer, it is capable of exerting consider-
able influence on reactor system operations. This is because it pro-
vides the reactor operator with a large amount of current information
on system status and gives alarms for off-limit conditions.,

The available space in the main and auxiliary control areas re-
stricted their use to instrumenting the functions shown in Fig. l.4.1.
It was necessary, and for no other reason, to obtain the additional
space required for the remaining instrumentation by decentralization
with local control systems. In many cases, and regardless of available
space considerations, local control was a preferred choice for one or
more of the following reasons:

1. it results in control loops which are less costly to build and are
more reliable,

2., 1it eliminates problems of data transmission or retransmission over
long lines with consequent improvement in accuracy,

3. it improves operation by locating the control system directly ad-
jacent to the controlled equipment.
 

49

These decentralized controls, whose location has been discussed
in Sect. 1.3, are in categories 4 and 5 (listed previously in this
section) and are not needed continuously by the reactor operator.

Monitoring by annuncistion is augmented by scheduled, routine inspection
(the "walking log") as required.

 
 

 

ORNL—-DWG 67-8147

 

 

MAIN CONTROL BOARD

1 CORTROL ORS
1. Jumper Poard
2. Offgas System:
(a) Stack Fans ---- On - Off

(v} Miock Valves
High Bay Ventilation and Pressure
Helium Supply:

(a) Purge Flows to Salt
Pups and pump bowls

(b} Flows and pressure in
Drain Tanks

II _ TWFORMATION:
(1) As required for operator surveillance
to support control functions.
(2) Anmunciation fram all major con-
trolled ¢omponents and systema.

(¢) ¥lows and pressures to
Iube Gil Tanks

Salt Tranefers:

(a) See (k) above

(t) Freeze Valves - Thaw and Preeze
Reactor F111 end Drain:

(a) See also (4b) and (5) above

(b) Drain tank pressure venting
to offgas system

{c) Pump Bowl -~ Drain Tank pressure difference
Icad Ceontrol

(a) Main blowers:

(v) Bypass damper
Inbe 011 Systems

(a) See (Le) above
(b) 0%l Pumps:
Auxiliaries:

(a) Treated Hg0 Pumps:
(v} Cooling Tower Hz0 Pumps:
{¢) Cooling Tower Fans:

(4} Component Cooling Pumps
(e) Cell Cooling Elowers

(f) Air Compressors

(g) Rediator Anmulus Blowers

(k) Anti-Packflow Dempers on
Main and Anrmulus Blowers

Cn - Off
Marual positioning

On - Off

g g88888¢%
R838888%

3

 

 

 

DIRECT /

SURVEILLANCE
AND IMMEDIATE
CONTROL ACTION

 

   
  
 
   
  
       

DIRECT
SURVEILLANCE
]
ALARMS AND
INFORMATION
NEARLY
je— IMMEDIATE
CONTROL

   

REACTOR
OPERATOR

 

ACTION

OPERATORS CONSOLE

 

CONTROL oxs

1. Operating Mode Selecticn

2. Reactivity:
(a) Mamual Bhirming, all rods
(b) Bervo Control of Flux

() Servo Control of Outlet
Temperature

() Mamal Rod Scram
3. Reactor load:

(a)} Mamual Individual Control of Radiator
Doors and Bypass Demper

(b} Automatically Programmed Control of
Doors, Demper, and 1 Blower

(¢} Load Scram
L, Emergency Drain, Manual

5. Fission Chamber Position by Manual
Operaticn of Wide-Range Counting Chanmels

6. Drain Tank Selection for Houtine Fill
and Transfer.

I INFORMATICN
As required for operator survelllance
to support sbove cortrol functicns.

 

 

ALARMS
AND
INFORMATION

 
 
   
  
    

INSTRUCTIONS
INFORMATION

     
   

ASSISTANT

OPERATORS AND

 

 

 

 

oW e

10.

AUXILIARY CONTROL BOARDS

Antunciators
Safety System Instrumentation
Process Radiastioz Monitering Instrumentation

Health-Physics Radiation Alarm
Instrumentation

Freeze Valve Temperature Control and
Monitoring Instrumentatlion

Salt Loop Temperature Instruments
Flux Instruments:

(a) ¥, Chammel

{b) Wide-Range Ccunting Channels
(¢) Red Control Servo

Flectrical Power System Tnstruments and
Controls

(a} Voltage, Current, and Pover Indication
(b} TVA Bus Transfer Control
(c) Diesel Start - Stop

Fuel and Coolant Salt Pump Monitoring
Instruments

(a) BHoise Level
(b) Power and Current
Thermocouple Patch Panel

 
  

— INFORMATION

MANUAL OPERATIONS
AND CONTROL
ADJUSTMENTS

 

 

ALARMS, DIRECT

-
AND INDIRECT

 

SLIGHTLY DELAYED
CONTROL ACTION

 

 

Fig. 1.4.1.

ALARMS

INFORMATION

 

DATA LOGGER - COMPUTER

 

Information from all aress of the system,

 

 

 

Diagram of Instrumentation in and Directly Adjacent
to the Main Control Room.

C
7 A
PREFERRED FEEDER

TVA
ALTERNATE FEEDER
A 234, /3.81Y NO. 294, I2.B XV

 

ORNL-DWG 67-5890

 

 

 

N 7vA _ -
{ w ] j , I 500 AVA
2.8 KV‘?BOV DIESEL
‘ GEN. *5
AR AAAS /000 KW
l DIESEL o)
C .. . GEN. "7
DIESEL JOOKW
GEN. 74 o
JO0 KW . 440y AC SWITCHGEAR | | BUs _ .
W °
AL
:),.,f ; i

 

 

 

 

  
 
 

     
  
 

 

 

  

 

 

 

 

 

 

 

 

 

. . SW/ mHG‘EAR BUsS "4 fT
‘ o« 1ESKVA,
o SWITCHEFAR BUS 5 @ reIuva
! EMERGENCY
HCV-92.54 é RADIATOR e ' g esoroc § sus I , [ e
J9d0vAC] Ge MOTOR CONTROL CEN e, pocR O ! ‘ I s
’ CONTROL POWER
‘ I) ‘éJ-IO )C NTER goca TO SWITCHGEAR
INDUCTION =ity
NORMAL REG m f;w PWF VER To: =
B0V 34 ST KvA a8/ 20/1t0 YAC & 5“’&’7 “”"g"’”i"
anal.
—I:.._ I : INST. POWER & 7&mp Scapners INVERTER
= = savoir | SBY/RO- 20811 TRANSF. %3 (d) Television = 62,5 KVA.250V OC
= BATTERY 2EW, &Y JoxvA ro: ey, Keajeosy
= € SAW, 28 : o
¢ (3) Sempler-enricher
! (o) Health Physics instrunent's
N 70 DATA LOGGER
t 180V AC t Nstanusl trenster sw /120 ¥V AC
£ . £8¥ 9C BUS . { 180 V AC INST. POWER TO:
: - 3 (8) Ssfety chts,chen'l
7O 48¢ DC b0 o { () Rod Jrive control
SAFETY SYSTEM &) Freeze valres
CIRCULI TS, CHAN. *3 (@) Annuncistors
701
INVERTER (e} Sartety chis,chan *l.
1AW - gngf (b} Frecze valve femp. sw
CIRCUIT, — N . and cooling &ir control.
5 te) Fuel & coclant sslt femp.,
7O 120V AC Flow & level instruments.
st SAFETY SYSTEM &) Sarnpler-enricher insts,
CIROUITS, CHAN. *3 (@) Lube Ol Sysrems insts.
r—re————— 70 diese/ start elfreuits.

Fig. 1.4.2.

 

 

7o off pUmps in fobe oil Systems,

MSRE Instrument Power Distribution.

 

1S

 

 
ORNL-DWG €7-4549

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
    
  

 

 

 

 

 

 

  

 

     
 
 

 

 

 

 

  
 
 
  
      

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

      

 

 

 

 

 

      
 

 

 

FUEL SALT MAIN BLOWER
STATUS OF ROD L,E:f.',; ‘;‘OL':E | Sts
CONTROLLER ON" OR “OFF
JB‘:’O"::%R t. REACTOR POWER (FLUX)
: 2. INSTRUMENT STATUS
PRESSURE PUMP SPEED
OF HELIUM
REACTOR
POWER, (FLUX) COVER GAS RADIATOR
STATUS OF
STATUS OF SAFETY LoD AILSTING (POSITION)
SYSTEM JUMPERS, ST RUMENTS
("IN" OR "OUT™)
AUTOMATIC FUEL COOLANT
ROD CONTROLLER
PUMP PUMP
TOTAL WEIGHT Il— HEAT
OF SALT IN I EXCHANGER
TANKS I
| —rop orives
FUEL STORAGE
TANK OVERFLOW
FV-112  FV-#3 TEMPERATURES
t e OF FREEZE
VALVES

 

 

 

 

 

 

Fv-107

 

DIFFERENTIAL
PRESSURE
CONTROLLER

 

 

 

COOLANT
DRAIN TANK

 

 

   

FLUSH SALT

 

 

 

 
 
 

u TANK
TEMPERATURES TEMPERATURE
OF FREEZE OF REACTOR
VALVES DRAIN VALVE

 

 

 

 

 

FUEL SALT
DRAIN TANKS

 
 

Fig. 1.4.3. MSRE Instruments and Instrument Signals for Mode Control.

(4]

 
L
i,
L

53

ORNL-DWG 67-6435

 

 

 

PREFILL

 

 

. REACTOR 1S EMPTY
. REACTOR FILL AND DRAIN

VALVES FROZEN

. PERMITS SALT TRANSFERS

AMONG DRAIN TANKS

. PERMITS HELIUM CIRCULATION

IN FUEL AND COOLANT LOOPS

. PERMITS BYPASSING THE

SAFETY SYSTEM WITH THE JUMPER
BOARD FOR SYSTEM TESTING

 

 

Fig. 104'4.

 

 

CPERATE

 

1. PROHIBITS FUEL TRANSFERS
AMONG DRAIN TANKS

2. ALLOWS REACTOR FILL

3. NO JUMPERED SAFETY
SYSTEM CONTACTS

 

 

 

 

 

 

 

START RUN

 

 

H UM -

. DRAIN VALVE FROZEN
. REACTOR FULL 2. REACTOR FULL

. LOW POWER, <1.5 MW 3. POWER ABOVE t MW OR ABOVE
. ONE MAIN RADIATOR

. SERVO CONTROLS 4, FUEL SALT PUMP "ON"

 

. DRAIN VALVE FRQZEN

200 kW WITH GOOD COUNT

BLOWER MAY BE "ON" RATE INFORMATION ( “CONFIDENCE")

FLUX ONLY 5. ONE OR BOTH MAIN RADIATOR
BLOWERS "ON"

 

 

6. SERVO CONTROLS REACTOR
OUTLET SALT TEMPERATURE

 

 

 

MSRE Control System Modes.

3

e T

e
 

ogu.?o-[' .3';&

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NOT IN PREFILL no*orfF"|__ _J| "OFF"
MODE REQUEST REQUEST
i
x |
NOT IN OPERATE REACTOR _
MODE EMPTY INTERTANK TRANSFER
| VALVES FROZEN
FILL AND DRAIN
VALVES FROZEN AT LEAST ONE FILL
AND
DRAIN VALVE THAWED
NO SAFETY SYSTEM
JUMPERS IN USE
No |l ___t REQUEST
REQUEST OPERATE MODE SEAL |«
REQUEST NO
PREFILL MODE || || REQUEST

 

 

 

 

 

 

 

 

 

 

 

I SEAL I

PREFILL
MODE

 

r——
1
I
|

 

 

DRAIN VALVE FROZEN

 

 

 

|

REACTOR FULL

NOT IN RUN MODE

 

 

 

 

 

 

 

 

START
MODE

 

 

 

 

@RATE

MODE

 

ORNL-DWG 67-4609

 

 

 

 

 

LINEAR NUCLEAR
POWER INSTRUMENTATION
IN POWER RANGE

 

 

 

 

"CONFIDENCE" ESTABLISHED

IN AT LEAST ONE CHANNEL

OF WIDE RANGE NUCLEAR
INSTRUMENTATION

 

 

|

 

 

REACTOR POWER GREATER THAN
0.5 MW PER WIDE RANGE CHANNEL
WITH "CONFIDENCE"

 

|

 

 

REACTOR PERIOD GREATER THAN
30 sec PER WIDE RANGE CHANNEL
WITH "CONFIDENCE"

 

 

 

 

 

 

—+i| NO REQUEST

 

 

rRUN MODE REQUEST]

 

 

 

 

l
-

 

 

| NO LIMIT SWITCHES ACTUATED

 

REGULATING ROD UNDER MANUAL

 

- [oxqu0) SPON Bupgessdy FMSW JO WeIBETd

 

 

 

BY REGULATING ROD

 

CONTROC TROD SERVO “OFF 7

 

 

AUTOMATIC PERMISSIVE CONDITION

 

 

 

 

 

 

COMPUTED FLUX DEMAND
BY TEMPERATURE SERVO NOT

MORE THAN ONE (1.0) MW

 

 

b —

 

 

 

 

 

 

 

 

 

 

 

 

MOMENTARY SWITCH ACTUATION WITH

 

 

 

 

SPRING RETURN IN DIRECTION OF ARROW

NO DEMAND FOR
LOAD INCREASE

 

 

 

LOAD OK FOR "RUN"
MODE OPERATION OF SYSTEM

 

 

REACTOR CONTROL MODE

 

REACTOR LOAD
UNDER MANUAL CONTROL

 

 

 

 

 

 

 

 

 

—

REACTOR POWER GREATER
THAN ONE (1.0) MW

 

 

 

 

SAME
INSTRUMENTS

 

 

OR BOTH WIDE RANGE NUCLEAR
INSTRUMENT CHANNELS

"CONFIDENCE" ESTABLISHED IN EITHER

 

 

 

REACTOR POWER GREATER
THAN 0.2 MW

 

 

 

]
|

 

 

EITHER OR BOTH MAIN
RADIATOR BLOWERS TURNED "ON"

 

 

 

 

FUEL PUMP SPEED ABOVE {100 rpm

 

 

 

 

 

fuo "OFF" REQUESTJ‘-—["OFF" REQUEST]

 

 

 

 

 

 

 

bS

 
 

55

1.5 SAFETY SYSTEM

The MSRE safety system is composed of instrumentation which must
be highly reliable because it augments the containment or protects
vital and expensive equipment, or both. This section is confined to a
broad, overall description of the reliable protective subsystems in the
MSRE and the basic principles which guided their design.

Reliable protective systems for reactor installations have, in the
past, been focused principally on the reactor core, and their operation
has been centered on the behavior of the flux. In designing the MSRE
the use of reliable protective instrumentation was not limited to pro-
tecting the reactor core from the immediate effects of excessive flux.
It will be seen, as we review and describe the protective subsystems,
that safety-grade instrumentation is extensively employed to enhance
the primary and secondary containment and to ensure a reactor drain.

It is worth while to describe, briefly, some of the characteristics
of the MSRE that are responsible for the safety-grade protective instru-
mentation with which it is provided.

1. The MSRE, being liquid-fueled, does not have fuel cladding as
the first, unpenetrated containment barrier. The core vessel, heat ex-
changer, fuel salt storage tanks, and all interconnecting piping become
the primary contaimment barrier to the molten salt. In addition, this
primary contalnment is pierced by inlet and outlet lines carrying helium
used for sweep gas across the pump bowl, for bubbler level instruments,
and for drain tank pressurization. These lines violate the primary con-
tainment barrier unless they are reliably blocked.

2. In common with solid-fueled reactors the MSRE uses conventional
poison rods for control and safety. Analyses,l tests, and operating
experience have shown that this reactor 1s a very docile and stable me.-
chine having a relatively long neutron lifetime, & large heat capacity,
and an effective negative temperature coefficient of reactivity. All
hypothetical nuclear excursions in the MSRE proceed slowly and do not
develop high transient vapor pressures; undesirably high temperatures
are the consequence.

The control rods are not capable of providing absolute reactor
shutdown under all conditions. The shutdown worth in the rods, at re-
actor operating temperature, 1s lost because of the negative temperature
coefficient if the fuel salt 1n the core vessel is cooled sufficiently.

Transference ¢f fuel to the drailn tanks is the certain method of
‘obtaining absolute shutdown, and the abillty to effect such a transfer
(reactor drain) must be assured. -

 

13, E. Beall et al., MSRE Design and Operatlons Report, Part V,
Reactor Safety Analysis, ORNL~TM~732 (August 1964).

2P, N. Haubenreich et al., MSRE Design and Operations Report Part
III, Nuclear Analysis, ORNL-TM-730 (Feb. 3, 1964).

3J. R. Engel, P. N, Haubenreich, and S. J. .Ball, Analysis of Fill-
ing Accidents in MSRE, ORNL-TM-497 (Aug. 16, 1966).

 

 

 

 
 

 

56

3. The chemistry of the fuel salt does not disallow segregation4’5
of the different fluorides with a consequent increased concentration of
uranium in one of the segregated phases. OSegregated salt has been pro-
duced in the laboratory under very carefully controlled conditions. The
accidental and undetected segregation of salt in a drain tank is highly
improbable bhut has not been demonstrated to be incredible. Filling the
reactor with segregated salt may produce a nuclear excursion during the
filling operation which, ultimately, exceeds the limiting capacity of the
control rods. Rigid, reliable control of the reactor filling operation
is & necessity.

4. A temperature excursion will cause the fuel salt to expand faster
than its containment. The volume available for such expansion is limited;
therefore, it is essential to have rigid, reliable control of temperature
and fuel salt level. ©See also No. 3 above,

5. Fuel and coolant salts freeze at temperatures in the region of
840 to 850°F. Freezing the salt is not harmful, but remelting is accom-
panied by expansion, which is capable of rupturing the piping. The
coolant salt radiator is particularly vulnerasble. Loss of the radiator
would be costly and would be an intolerable setback to the MSR program.
Reliable protective measures (see Sect. 2.8) are included in the MSRE.

Principles employed in achieving reliability in reactor safety sys-
tems® 28 have been applied extensively to the MSRE. These principles
are summarized as follows:

1. Redundancy is employed so that no single failure of an instru-
ment, component, or wiring having a reasonable probability of faillure
could cause system failure. A single failure could involve all con-
ductors in a single conduit, all contacts of a switch, or, unless special
barriers are provided, the entire contents of an enclosure.

2. Testing is employed, preferably on line and without disconnecting
equipment or otherwise impairing the ability to protect during the test.
Each channel is tested separately so as to dlsclose a failed component
which would prevent protective action or a failure which could intercon-
nect two otherwise independent channels and thereby destroy channel in-
dependence and redundancy.

3. Diversity is employed wherever feasible; that is, unlike channels
are palred to accomplish a desired result. For example, a flow loss caused
by stopping the coolant salt pump is detected by both the pump speed mon-
itors and the flowmeters in the coolant salt piping.

4. Safety and control are separated so that loss of control result-
ing in an excursion will not occur simultaneously with loss of protection.
Separation is also employed so that improvements intended to enhance con-
trol or other functions unrelated to safety willl not be made, unwittingly,
to the detriment of safety.

These precepts constitute recommended design practices for what are
now thought to be the best safely systems we know how to build. Figure

 

“R, E. Thoma and H. A. Friedman, "Se§regation of the MSRE Fuel Salt
in Drain Tanks," MSR-65-15 (Mar. 17, 1965) (internal memorandum).

°H, A, Friedman, "Segregation of LiF-BeF,-UF; Fuel Salt on Freezing
in Drain Tenks, MSR-66-19 (July 12, 1966) (internal memorandum).
 

57

1.5.1 shows an example of & three-channel, high-relisbility subsystem
in the MSRE. This is a simplified diagram of the instrumentation which
closes the block valves in the instrument air lines to the secondary
containment cell if the pressure in the cell rises sbove 2 psig. It is
a representative example of a safety subsystem in the MSRE. The follow-
ing description of its design and operation is included here to i1llus-
trate how these general precepts have been reduced to practice.

The instrumentation is simple; three high-grade pressure switches
provide the switching contacts which operate the solenold valves in the
valve matrix. This matrix is arranged so that, if any two of the three
pressure switches are actuated, the pneumatic actuators (diaphragms) of
the block valves are vented to the atmosphere, the air supply to the
valves is shut off, and the spring-loaded valves close and block the in-

strument air lines.

 

63, H, Hanauer, "Design Precepts for Engineered Safeguards,” Nucl.
Safety §fi4), 408-11 (Summer 1965).

7E. P. Epler, "Dangers in Safety Systems," IRE Trans. Nucl. Sci
NS-8(4), 51-55 (October 1961).

85, H, Hansuer, "Instrumentation for Conteinment,"” Nucl. Safety 3(1),
4146 (September 1961).

9T, M. Jacobs, "Safety Systems for Nuclear Power Reactors," Trans.
Am. Inst. Elec. Engrs., Pt. I, 76, 67073 (November 1957).

105, J, Ditto, "Redundancy and Coincidence in Reactor Safety Sys-
tems," Nucl. Safety 2(4), 16-17 (June 1961); M. A, Schultz, "Reactor
Safety Instrumentation,” Nucl. Safety 4(2), 1-13 (December 1962).

1lc, G, Lennox, A. Pearson, and P, R. Tunnicliffe, Re%gégtion and
Protective System Design for Nuclear Reactors, AECL-1495 \April 1962).
121, M. Jacobs, "Safety System Technology," Nucl. Safety 6(3), 231-

45 (Spring 1965).

135, J. Ditto, "Effect of Operating Experience on Safety System De-
sign," Nucl. Safety 6(2), 183-84 (Winter 1964-1965). |

145, P, Epler, "Reliability of Reactor Systems," Nucl. Safety 4(4),

7276 (June 1963).

15K, W. West, "Instrument System Testing for In-Pile Loops," Nucl.
Safety 5(4), 374—76 (Summer 19633’.

16K, W. West, "Relative Functions of Loop Contalnment and Instrumen-
tation," Nuel. Safety 4(4), 180-8L (June 1963).

175, J. Ditto, "Failures of Systeus Designed for High Reliability,"
Nucl. Safety 8(1), 35-37 (Fall 1966).

185, P, Epler, "Safety System Reliability vs. Performance,” Nucl.
Safety 6(4), 411-14 (Summer 1965).

 
 

58

The two-out-of-three redundancy permits on-line testing without oy
system perturbation. The completeness of the test procedure employed \hw;
is an operational decision and is not limited by the design of the in-

strumentation. Testing is done by simulating an increase in cell pres-

sure by using the nitrogen cylinder(Fig. 1.5.1) as the source of pres-

sure and noting the response of the pressure gages in the valve matrix

or, if desired, by actually closing the block valves. A typical test

in channel A proceeds thus:

1. The hand valve in the line which connects the nitrogen cylinder
to the line from PSS-RC-B to the reactor cell is opened, and the pres-
sure is adjusted to the 2-psig set point. The sintered disk snubbers
provide sufficient flow restriction to maintain this pressure without
wdue loss*? of nitrogen to the reactor cell.

2. The increase in pressure actuates pressure switch PSS-RC-B and
this, in turn, deenergizes solenoid valves ESV-1Al and ESV-1A2.

3. These valves, ESV-1Al and ESV-1A2, in the valve matrix change
their aspect, but not so as to affect the pressure in the 80-psig air
header; valve ESV-1A2 vents pressure gage PI-1A5. During normal opera-
tion pressure gages PI-1Al, PI-1A4, and PI-1A5 indicate header pressure,
80 psig. Pressure gage PI-1A5 will now go to zero. The block valves
will be unaffected since there is still no open line or lines between
the block valve operators and the vent line and because the connection
between the 80-psig header and the valve operators is still maintained
through ESV-1B2, ESV-1Al, ESV-1Bl, and ESV-1C.

This test, steps 1 to 3 above, can be conducted with any channel
and without disturbing reactor operation. It does not test the actual
closure of the block valves. Now, suppose any two channels are tested ‘Ej
coincidentally. For example, if channels 1 and 2 are tested simulta-
neously, solenoids ESV-1Al, ESV-1A2, ESV-1Bl, and ESV-1B2 will be de-
energized, and, referring to the valve matrix in Fig. 1.5.1, the block
valve operators will be opened to atmospheric pressure through ESV-1CL
to ESV-1Bl1 to ESV-1C2 to ESV-1Al to ESV-1B2 to vent. Valves ESV-1A1
and ESV-1B2 now prevent transmission of pressure from the 80-psig air
supply to the block valve diaphragms, and the spring-loaded valves will
close. Such a two-channel test checks operation of the entire system.
Failure of any block valve to close can be detected by observing the
response, or lack of response, of the in-cell instruments supplied via
the block valve.

This same hasic scheme is used for protection elsewhere in the
MSRE. The protective instruments which close block valves in the inlet
helium lines operate when the pressure in line 500 falls below 28 psig
(see Figs. 1.5.7 and 1.5.2). In this situation, where protective action
is initiated by an undue reduction in pressure, testing is accomplished

 

19Me containment is normally held at -2.0 psig, and the test pres-
sure needs only to produce a differential across the snubbers of 4 psig.
The nitrogen cylinder has & volume of approximately 2 £t3 at 2000 psi.
Should this entire volume be introduced into the secondary containment,
with a volume of 18,000 ft3, the pressure rise in the containment would
be negligible. Also, the cell atmosphere is specified to be more than
95% nitrogen and would not be degraded. £;;
 

59

by venting the pressure switches to atmospheric pressure by opening an
individual hand valve and, as above, by observing the response of the
pressure gages in a valve matrix or the block valves themselves.

This same design is used for protecting against too great a re-
duction in reactor cell pressure below atmospheric (see input No. XII,
Fig. 1.5.2). 1In this particular system the pressure switches are en-
closed in bhoxes which are vented to atmospheric pressure through snubbers.
Testing is accomplished by pressurizing the boxes. This increases the
differential pressure across the pressure switches and thereby simulates
a reduction of pressure within the cell.

It is worth while to examine this particular safety subsystem from
the standpoint of the "recommended practices" previously cited. Up to
but not including the output elements (block valves), redundancy and
testing requirements are completely satisfied by the design. It should
be pointed out that an on-line test of this particular subsystem which
includes closing the instrument air line block valves 1s operationally
intolerable. The addition of a second valve in each line would improve
the reliability of the instrumented blocking system but, of course,
would not improve the on-line testing situation. It was established
while the MSRE was being designed that the c¢losed system of instrument
air lines, tanks, and compressors, with associated valves, etc., con-
stituted the second effective containment barrier (see Sect. 1.5.4).

This particular system does not employ diverse channels in obtain-
ing redundant input channels. In this particular case there is no suit-
able and reliable substitute for the simple, direct measurement of cell
pressure as it is done. The use of diverse sources of control power
substantially reduces the likelihood of spurious action caused by failed
or faulty power sources.

The pressure switches are installed in the north electric service
area and are within 10 £t of the cell wall. The piping to and from the
switches is of autoclave tubing with autoclave fittings. The electrical
interconnections are run in separate conduits, channel by channel, and
contain no other wiring. The solenoid valve matrix is located in the
north electric service area in a safety instrumentation cabinet.

As the MSRE design proceeded, a few situations and conditions de-
veloped which resulted in departures from the ideal recommended practices
outlined previously in this section. Two examples, with reasons, follow:

1.  All three of our safety system neutron sensors are located in
a single penetration because both the amount of space and its configura-
tion absolutely prohibit three separate penetrations at different loca-
tions (see Sect. 2.1).

2. In some cases the reliable instrumentation which automatically
closes block valves closes only one valve in each line rather than two
separate, independent valves in series. MSRE system design established
a criterion that a single block valve in series with a pair of check
valves was a necessary and sufficient alternate for two block valves in
series (see, for instance, Sect. 4.8).

On-line testing of the "load scram" system (refer to Sect. 2.8) con-
flicts, seriously, with reactor operating schedules and will produce
highly undesirable thermal transients. These, in turn, produce thermal
stress cycles which reduce the life of the system. In order to test the
door drive mechanism and the ability of the doors to scram when the re-
actor is down and the coolant system drained, it is necessary to bypass

 
 

 

60

the safety instruments that scram the doors since these same instruments
prevent raising the doors to perform the test. This dilemma is solved

by using the jumper board to bypass these safety instruments. The jumper
board circuitry (refer to Sect. 4.11) is interlocked so that safety system
bypassing is permitted only when the reactor is empty, Safety system
jumpering is resorted to only when absolutely necegséry and, where em-
ployed on the MSRE, was adopted only when no altgfnate method could be
found. In this particular case the ability totest was retained by this
compromise.

It is ususl and obvious practice to ggerate relays, solenoids, tem-
perature switches, etc., so that power losses cause them to change state
toward safety;?° e.g., safety system relays are operated "energized,"
and their contacts break circuits to produce the safety action. The
relay contacts which stop the component cooling pump motors (see Sect.

1.5.5) must be closed to energize the battery-powered "Stop" trip coil

in the motor starter. Motor starters, typically, operate this way, and
it is not in the best interests of reliability to attempt to redesign

or modify well-engineered, time-tested equipment of this type for reverse-
mode operation. Furthermore, this particular sgfety action is diverse

in that protection is also obtained by closing a valve (see outputs XI
and XII, Fig. 1.5.2). -

Because of the very strong incentive to keep the primary containment
simple and structurally uncomplicated, the MSRE does not have a multi-
plicity of fuel salt drain lines, each with an individual drain valve,
controlled by the safety system.

The foregoing is intended to provide a broad, overall view of the _
application of relisble, safety-grade instrumentation to the MSRE. De- : (EJ
tailed descriptions of the design and operation of these reliable sub~
systems are contained either in the remainder of this section or else-
where in this report and may be located by referring to the "Supplemen-
tary Information" column in Teble 1.5.1, or the last columa in Fig.

1.5.2. Much of the text which immediately follows is an updated ver-
sion of similar material, now partially obsolete, originally presented
in ORNL-TM-732 (ref. 1).

Figure 1.5.2 shows input-output diagrams of the MSRE protective in-
strument system. Figure 1.5.3 is an expanded signal flow diagram of the
reactor drain instrumentation (described in Sect. 1.5.1), and Table 1.5.1
elaborates and augments the information in the figures. The more detailed
descriptions which follow are referenced to the particular regions in the
reactor system which are principally involved.

e

 
   

 

20The reader is referred to sect. 1.2, "Design Considerstions,"
for a discussion of instrument failure modes. gfiy
Table 1.5.1 (continued)

 

Input
Ref.
No.

Condition or Situation Which Indicates

a Real or Potential Hazard

Causes of the Hazard, the Consequences, and the Cotrective Action

Supplementary Information

 

VII.

VIII.

X

Helium pressure in the pump bowl
greater than 25 psig

Helium pressure in the fuel pump bowl

greater than “fill permit’’ valve.

Excess radioactivity in reactor cell
atmosphere

1.

1.

. Cattses

a, Rapid unchecked expansion of fuel salt by excess temperature; see [
" and 11 above and Supplementary Information

b. Plugging of off-gas system.

. Con sequences

a. If unchecked, damage to pump seals, which are rated at 100 psig, and
possible overstressing of primary loop

b. Exceed capacity of off-gas system, with resulting threat to containment

¢. Possible loss of primary containment

. Corrective actions

a. Drain reactor vessel
b. Vent pump bowl to the auxiliary charcoal bed

Causes _
8. Excess filling rate or overfill.
b. Temperature excursion during fill (see II and III, this table)

c. Closing of HCV-533A1 nomally maintained open by administrative
control, during the filling operation.

. Consequences

Not of itself a hazard; a release of positive pressute may produce a sud-
den tise in fuel level during fill and, possibly, a nuclear excursion if
the fuel salt is segregated. See VI, this table.

. Corrective action

Drain reactor vessel

Causes )
Rupture or leak in the primary containment

. Consequences

Contamination of secondary containment and increased possibility of
contamination of area in the event that secondary containment fails.

. Corrective action

a. Drain reactor vessel

b. Close cell evacuation valve which vents cooling air loop to the off-gas
stack (valve No. HCV-565A1)

c. Close HCV-915A1 which blocks cooling air line to rod drives and con-
trol rod thimbles

d. Close block valves in the lines to and from in-cell O, analyzer

e Close block valves in steam dome condensate drain lines

NSO unAwh

. System design provides 5.0 ft? of overflow capacity, and power level scram and fuel overflow tank level sys-

tems (see I and IV, this table) protect against fuel salt expansion caused by power excursion; safety system
holds bypass valves (Fig. 1.5.4) open during operation, in which case the pressure rise will be moderate until
all the overflow volume is filled.

Redundancy: Two pressure channels, one in the pump bowl and one in the overflow tank.

. Testing: Test procedure checks entire channel, with exception of transmitter bellows (see Fig. 1.5.5).

Monitoring: Loss of helium flow to bubblers caused by either low inlet pressure or line blockage is alarmed.

. Safety only?: Yes

Coincidence: Either of the two inputs will produce cortective action.

. Draining (see Figs. 1.5.2 and 1.5.4) ensures immediate opening of the bypass valves to back up

administrative control. Venting to the auxiliary charcoal bed is less effective but useful backup.

This uses same instrumentation as VII (this table).

NN

oW

Redundancy: Two channels are used; one in the pump bowl and the other in the overflow tank.

. Testing: See VII, this table.

Monitoring: See VII, this table,

. Safely only?: Yes.
. Coincidence: Either of the two inputs will produce corrective action.

1

Red: . y Tw.o' . t ch ]
. P

. Testing: Complete testing of each channel is possible.

. Monitoring: Certain system failures produce alarms.

. Safety only?. Yes.

. Coincidence: Either of the two inputs will produce corrective action.

€9

 

 

 

 
Table 1.5.1 (continued)

 

 

Input
R:f. Condition or Situation Which Indicates Causes of the Hazard, the Consequences, and the Corrective Action Supplementary Information
No. a Real or Potential Hazard
X. Supply pressure less than 28 psig in L. Causes 1. Redundancy: Three independent channels.
helium line 500 which supplies Loss of supply helium caused by: 2. Testing: Complete testing possible.
helium to all reactor cell components, a. Empty tank 3. Monitoring: Testing meets requirements.
drain tank cell, and fuel processing b. Previous overpressure which operates relief valve and breaks rupture 4. Safety only?: Yes.
system disk 5. Coincidence: Any two-out-of-three.
c. Malfunction of pressure-regulating valve PCV-500C (or alterately, 6. Block helium lines to coolant salt system (pump bowl and drain tank)
PCV 605) which maintains supply at design-point value of 35 psig
2. Consequences
Possible loss of secondary containment (see 1b above)
3. Corrective action
Block all helium lines to reactor and fuel selt drain tank cells
X1, High radiation activity in helium linege 1. Causes 1. Redundancy: Three independent channels.
supplying fuel salt level bubblers or Reversal of flow in these lines (or back diffusion) from pump bowl, 2. Testing: Complete testing of each channel is possible,
in dead-ended helium lines to zero drein tanks, overflow tanks 3. Monitoring: Indicated, logged and alarmed.
psi, reference chambers connected 2. Conasequences 4. Safety only?: Yes.
to pressure transmitters Radioactivity inside the helium piping in normally safe areas. This 8. Coincidence: Any two-out-of-three.
activity will be contained as long as piping is not breached. 6. Flow rate, in either direction, is limited by capillaries; check valves, two in series, are used to back up
3. Corrective action block valves. The capillaries provide a long flow path at high velocity end hence reduce back diffusion,
Close block valves in helium lines to fuel salt pump bow! and
overflow tank.
X1 Pressure in secondary containment 1. Causes 1. Redundancy: Three independent channels,
less than 10.7 psia. a. Malfunction of the secondary containment pressure control system 2. Testing: Complete testing of each channel is possible.
which results in excessive pump-down of the secondary containment 3. Monitoring: Not applicable,
b. Misoperation of pumps and coolers during non-routine tests and 4. Salety only?: Yes.
equipment checkouts. 5. Coincidence: Either of two will initiate safety action.
2. Consequences 6. Pressure in the secondary contsinment is normally maintained approximately 2 psi below atmospheric (12.7 psia).
Possible collapse of the secondary containment because of excessive 7. The blowers are of the positive displacement type and are, therefore, capable of reducing the pressure well
extemal pressure below the value which endangers the containment vessel.
3. Corrective action
a. Close cell evacuation valve, HCV-565A1, in the line which is used
to evacuate secondary containment to maintain pressure at 12.7 psia.
b. Shut off both component pumps. ’
XIIL. Pressure in the secondary contain- 1. Causes 1. Redundancy: Three independent channels.
ment greater than two (2) psig. a. A rupture or leak in the primary containment which allows hot fuel salt 2. Testing: Complete testing is possible.
to mix with water in the secondary containment; in the worst version 3. Monitoring: Indicated, logged and alamed.
this is the maximum credible accident. 4. Safety only?: Yes
2 b. A malfunction in or misoperation of the pressure control system 5. Coincidence: Any two-out-of-three,
2, Consequences
Not, of itself, a direct hazard; during normal operation the reactor cell is
mainteined at a negative pressure of -2 psig (12.7 psia) to ensure inflow
in the event of a leak; the existence of positive pressure is evidence
that & malfunction or misoperation exists; a loss of secondary contain-
ment is a possible result. ’
3. Corrective action

a. Close instrument air block valves

b. Close liquid waste system block valves from reactor cell sump and
drain tank cell sump to waste tank.

. Close block valves to and from in-cell oxygen analyzer

. Close block valves to and from off-gas sampler

m® e

. Close steam dome condensate drain valves

. Close block valves in lines to the hook gage used for cell tank rate checks

¥9

 
Table 1.5.1 (continyed)

 

 

 

S9

Input
Ri;f. Condition ot Situation Which Indicates Couses of the Hazard, the Consequences, and the Corrective Action Supplementary Information
No. a Real or Potentiel Hazard
XIv. High radioactivity in the ventilation . Causes 1. Redundancy: Two independent channels.
line from off-gas sampler enclosure Leak in the off-gas sampler 2. Testing: Complete testing is possible.
. Conseguences 3. Monitoring: Indicated, logged and alarmed.
This is a loss of primary containment 4. Salety only?: Yes.
. Carrective action ' 5. Coincidence: Either of two inputs will initiate safety action.
Close block valves in lines to and from the off-gas sampler
XV. Helium pressure in fuel salt pump . Causes 1, Redundancy: Two independent channels
bowl greater than ten (10) psig. a. Same as VII, this table. 2. Testing: Complete testing of each channel is possible,
b. Clogging of off-gas system during normal operation requiring opetation 3. Monitoring: Certain system failures produce alarms. Pressure is indicated and logged.
) at higher than usual pump bowl pressure 4, Safety only?: Yes.
c. Blowback as an operational procedure to open clogged offgas system 5. Coincidence; Either of two channels will initiate safety action.
{see b above) ‘ 6. The maximum pressure rating (rupture) of some components in the sampler is less than the 150% of maximum
. Conseguences pressute (75 psig) normally required for primary containment components.
This value of pressure, 10 psig, will not endanger reactor system. This
interlock to protect the off-gas sampler and guard against a loss of
containment
. Corrective action
a. Close block valves in off-ges lines to and from the off-gas sampler
b. Prevents opening operational and maintenance valves in fuel salt
sampler-enticher (maintains containment)
XVI. High radiation activity in line No. 557 . Causes 1. Redundancy: Two independent channels.
carrying off-gas from all charcoal " a. Charcoal beds not operating comrectly (overloaded, see III above) or 2. Testing: Complete testing possible.
beds and from the coolant pump, and pump seal failure allowing discharge of activity to lube-oil system 3, Monitoring: Certain system failures are alarmed, radiation level is indicated and logged.
from the lube oil systems b. Activity in the coolant salt loop; see also V, this table. 4. Safety only?: Yes.
. Conseguences 5. Coincidence; Either of two channels will initiate safety action
Radioactive gases discharged up stack
. .Corrective action
a. Close off-gas block valve
b. Close lubq-pfl systems vent valves
XVII. High radiation activity in in-cell . Causes’ Redundancy: Three independent ch 1s

treated water system

a. Maximum credible accident with coincident rupture of in-cell water
system piping .
b. Induced activity in treated water.

. Consequences

a. Local contamination by radioactive water leak
b. Loss of secondary containment, with accompanying contamination if
radioactive material is discharged from the treated water system

. Corrective action

a. Closes block valves in water lines which are extensions of the second-
ary containment and which are outside the containment cell

b. Closes valve in degassing tank vent which is located outside of
secondary containment cell

s

 

. Testing: Complete testing of each channel is possible.

. Monitoring: Certain system failures initiate alarms. Radiation level is indicated and logged.
. Safety only?: Yes.

. Coincidence: Either of two channels will initiate safety action.

. The water lines and vent tank are extensions of the secondary containment..

 
Table 1.5.1 {continved)

 

Input
Rpef. Condition or Situation Which Indicates Causes of the Hazard, the Consequences, and the Corrective Action Supplementary Information
No. a Real or Potential Hazard
XVINl. Low temperature of coolant salt in . Causes 1. Redundancy: Three independent channels.
outlet from radiator (line 202) a, Malfunction of load control system (complex of doors, blowers, and 2. Testing: A complete test of each input channel is possible; complete testing requires dropping doors,
bypass damper) which disturbs operation. )
b. Cessation of power generation in core from any cause (scram, drain, 3. Monitoring: Thermocouple break or detachment from pipe will produce safety action in that channel. Tem-
rupture in primary containment, etc,) perature is indicated and logged.
c. Loss of coolant flow (see XIX, this table) 4. Safety only?: Input channels used solely for safety.
, Consequences S. Coincidence: Any two-out-of-three.
No hazard; warns that potential radiator freezeup may be developing (see 6. The corrective actions constitute a ‘‘load scram.”’
XIX, this table)
. Corrective action
a. Close radiator doors
b. Shut down main blowers, MB-1 and MB-3
¢, Drain coclant salt system
XI1X. Loss of coolant salt flow . Causes 1. Redundancy: Two direct flow channels which receive information from a common primary element, a venturi,
a. Coolant pump stoppage plus two independent pump speed channels.
b. Line break 2. Testing: Partial testing possible; a test which includes dropping radiator doors will perturb operation; input
c. Unscheduled coolant salt drain elements not tested.
d. Plug in line or radiator 3. Monitoring: By surveillance and comparison; flow and pump speed are indicated and logged.
. Consequences 4. Salety only?: Yes.
Unless accompanied by undetected contamination of the coolant salt, 5. Coincidence: Refer to Section 2.8.
see V, this table, no hazard exists. Unless action is taken a costly 6. These corrective actions constitute a ‘‘load scram’’; refer to Section 2.8.
radiator freezeup will ensue,
. Corrective action
2. Close radiator doors
b. Shut down main blowers, MB-1 and MB-3
XX. Either or both doors at final upper . Causes 1. Redundancy: Two independent limit switch channels which are cross connected so that if either door is at
limit Failure of first upper limit switches and/or any circuit or circuit element the final upper limit both doors ere stopped. See also XIX, this teble. Only one motor starter; it must work.
associated with these switches 2. Testing: Complete testing is possible at some inconvenience.
. Consequences 3. Monitoring: Not applicable.
a. Damage to the doors 4. Safety only?: Yes.
b. Damage to the drive mechanism 5. Coincidence: See (1) above.
c. Loss of ability to scram the doors because of cable snarling or other
damage per 2a and 2b above.
. Cortective actions
a. Stops door drive motor
b. Disengages clutches in drive train between motor and cable sheave
c. Applies brakes
XXI. Door drive motor current at overload . Causes 1. Redundancy: Only one primary element, the overcurrent relay. Otherwise this interlock is composed of two
value a. Anything which jams the doors or the drive mechanism (2) separate channels. See XX, this table, and (5) below.
b. A failure of both first and final upper limit switches and/or any circuit 2. Testing: During shutdown only.
or any circuit element associated with these switches 3. Monitoring. Wot applicable.
. Consequences 4. Safety only?: Yes.
Same as for XX, this table. 5. a. Insofar as preventing damage caused by forcing the door and drive mechanism against the hard, fixed

. Corrective action

Same as for XX, this table.

upper limit, this interlock provides diverse redundancy with the final upper limit interlock, XX, this table.

b. Prevention of damage at other doot positions than the final upper limits depends on the reliability of a
single overcurrent relay and the reliability of & single motor starter-relay.

 

99

 

 
 

67

1.5.1 Reactor Fill and Drain System

A pimplified diagram is shown in Fig. 1.5.4 of the reactor vessel,
the drain tanks, the interconnecting piping, and the control elements
required to fill and drain the reactor system with fuel salt in a safe,
orderly way. The control rods are essential to a safe filling procedure
but are omitted from this diagram in the interest of simplification.

The reactor is filled by applying helium pressure to the gas space
in the selected drain tank and forcing the molten fuel salt up and into
the core vessel. As a typical example, if the reactor is to be filled
from fuel drain tank 1 (FDI'-1), pressurizing helium is admitted via
lines 517 and 572 (see Fig. 1.5.4). The filling pressure is controlled
by pressure-regulating valve PCV-517-Al. The pressure setting of this
valve is controlled by the operator. The upstream capillary flow re-
strictor in line 517 limits the maximum inlet flow rate of pressurizing
helium. Valves HCV-544-Al and HCV-573-Al in the pipes which connect the
gas space in FDI-1 to the pump bowl and to the charcoal beds are closed.
Since the net pressure head available to produce flow decreases as the
fuel level rises in the core vessel, the fill rate becomes progressively
slower as the fill proceeds if constant inlet helium pressure is main-
tained and if the pump bowl pressure remains constant.

Helium pressure in the pump bowl is the second component of the
differential pressure that drives fuel salt into the core vessel. A
sudden reduction in pump bowl pressure during the reactor filling op-
eration would cause an unscheduled rise in salt level in the core. If,
at this time, the reactor is on the verge of becoming critical, an un-
expected nuclear excursion cannot be ruled out. The safeguard provided
is to allow filling only when the positive pressure in the pump bowl is
equal to or less than +2 psig and thus keep the maximum possible increase
in net filling pressure within safe limits. Two causes for a sudden de-
crease in pump bowl pressure are considered. First, opening valve HCV-
533-A1 after reactor filling has started would vent the pump bowl to the
auxiliary charcoal beds, which normally operate at close to atmospheric
pressure. The resultant pressure change in the pump bowl would be —2
psi. Administrative control is used to maintain HCV-533-Al open just
before and during filling. ©Second, a rupture or leak would allow the
escape of pump bowl helium to the reactor cell atmosphere, which is held
at —2 psig (12.7 psia). This condition would cause a meximum pressure
decrease in the pump bowl of 4 psi. If the fuel pump bowl pressure ex-
ceeds 2 psig, the safety equipment (1) initiates a drain by opening by-
pass valves HCV-544-Al, HCV-545-Al, and HCV-546-Al, thereby equalizing
helium pressure in the drain tanks and pump bowl, and (2) shuts off the
supply of pressurizing helium by closing valves PCV-517-Al, HCV-572-A2,
HCV-574-A1, and HCV-576-Al, This is the helium valve condition shown in
Fig. 1.5.4 and is required by normal operation with the pump bowl at 5
psig; therefore, the 2-psig channel need not be disabled during normal
operation. Additional safety considerations involving pressure in the
fuel salt system and the instrumentation used for measuring helium pres-
sures are discussed in the following section. '

Excessive pressure, 25 psig, in the pump bowl is relieved by opening
HCV-533-Al.. During reactor operation, with the bypass lines open, one or
more of the drain tanks would be subjected to this pressure. The input
signal used to open HCV-533-Al originates in either of a redundant pair

 
 

68

of pressure transmitters, PT-592B and PT-589B, on inlet lines to the pump
bowl and overflow tank respectively. These same input channels provide
the +2-psig safety signal discussed above.

- As a further safeguard during filling, the safety system requires
that all three control rods be partially withdrawn in order to pressurize
the drain tanks. The weigh cells on the drain tanks provide information
used to monitor the total amount of fuel salt moved into the core vessel.

The possible filling accidents are discussed in ref. 1. Briefly,
these accidents are (1) premature criticality during filling caused by an
overly high concentration of uranium brought about by selective freez-
ing®t+?2 in the Arain tank; (2) premature criticality during filling of
low-temperature (900°F) fuel salt of normal concentration, whose normal
critical temperature with the rods withdrawn approximately half stroke
is 1200°F; and (3) premature criticality during filling of normal fuel
salt at normal temperature with all control rods fully withdrawn. Pro-
tective action is the same for all three cases: the control rods are
scrammed, and the reactor vessel 1s drained to ensure permanent shut-
down. Rod scram is produced and vent valves HCV-573-Al1, HCV-575-A1,
and HCV-577-Al are opened by the excess flux signal. ©Since a premature
criticality occurs before loop circulation is attained, the outlet tem-
perature sensors are ineffective. The safety system also invokes a re-
cator emergency drain to enhance containment if there is evidence that
radicactivity is escaping from the primary fuel loop. These subsystems
are covered subsequently in this section.

?mergency drainage is effected by the following actions (see Fig.,
1.5.4):

1. The freeze valve in line 103, which comnects the reactor drain
tanks, is thawed. Thawing is accomplished by closing valves HCV-919A
and 919B, a redundant pair, to stop the flow of cooling air. The system
is designed with a heat capacity sufficient to thaw the plug in less than
15 min.

2. The helium pressures in the fuel drain tank and the unfilled
portion of the fuel salt loop are equalized by opening bypass valves
HCV-544-A1, HCV-545-A1, and HCV-546-Al.

3. Vent valves HCV-573-Al1, HCV-575-A1, and HCV-577-Al, which re-
lease pressurizing helium in the drain tank to the off-gas system, are
opened.

4. Pressure regulating valve PCV-517-A1 in line 517, the inlet
header that supplies pressurizing helium to all the drain tanks, is
closed and shuts off the supply of pressurizing helium.

5. The drain tank pressurizing valves, HCV-572-Al, HCV-574-Al, and
HCV-576-A1, in the helium supply lines are also closed to halt further
addition of fuel salt.

Actions 2 or 3 are immediately and independently effective in re-
versing a fill, and hence the valves are redundant. Similarly, PCV-517-

 

21R. E. Thoma and H. A. Friedman, "Segregation of the MSRE Fuel Salt
in Drain Tanks," MSR-65-15 (Mar. 17, 1965) (internal memorandum).

224, A, Friedman, "Segregation of IiF-BeF,-UF, Fuel Salt on Freez-
ing in Drain Tanks," MSR-66-19 (July 12, 1966) (internal memorandum).
 

69

Al and the individual pressurizing valves, referred to in 4 and 5 above,
form series pairs and provide redundancy. For example, it can he seen
from Fig. 1.5.4 that, taking fuel drain tank No. 1 as typical, pressure
equalization and venting are accomplished by opening HCV-544-Al and HCV-
573-Al respectively. Administrative control is used to ensure that when
the reactor is filled with fuel salt, both drain tanks, FDT-1 and FDT-2,
are empty and both of the freeze valves, FV-106 and FV-105, are thawed.
The tank condition is monitored by reference to the weigh cell and level
instrumentation on each tank.

1.5.2 Helium Pressure Measurements in the Fuel Salt Loop

One channel of the instrumentation which measures helium pressure
in the fuel pump bowl and the overflow tank is shown in Fig. 1.5.5. The
components and their installation are designed to meet containment re-
quirements.

The pressure transmitters are installed just outside the main sec-
ondary containment shell. From the standpoint of containment, the trans-
mitter housings are "blisters" on the main containment cells. Contain-
ment criteria would be satisfied by

1. venting the reference pressure side of the transmitter diaphragms
to the inside of the containment cell,

2. sealing the vent port at the transmitter,

3. connecting the transmitter's vent port to a containment-grade volume
which is maintained at a known and constant pressure.

If the transmitter's reference pressure port is vented to the containment
cell, the pressure measurement includes cell pressure. This pressure is
controlled nominally at —2.0 psig during operation, is at atmospheric
pressure during in-cell maintenance, and is well above atmospheric pres-
sure during periodic checks to verify the containment capability of the
cell, The normal and acceptable fluctuations around the nominal -2,0-
psig value would reduce the accuracy of the transmitted measurement by
an unacceptable amount. If the reference port of the transmitter is
merely sealed shut, the reference pressure and hence the transmitted
pressure would fluctuste with temperature changes in the sealed refer-
ence volume in the transmitter. Evacuating the reference side of the
transmitter was deemed unscceptable because these vital measurements
would then rely entirely on the long-term reliability of the vacuum.

The variable-volume reference chamber (see action 3 above) re-
solves these conflicting demands of containment and measurement ac-
curacy. Conceptually, it acts as a strong but extremely compliant bag
which automatically adjusts its volume to maintain an internal pressure
very nearly equal to the externally applied pressure. By connecting
the reference ports of the transmitters to these reference chambers
which are located outside the containment cells, the dual requirements
of the containment and measurement accuracy are satisfied. At the MSRE
the reference volume is housed, and the housing is vented to the off-gas
duct near the blower inlet. During operation the ambient pressure in
the off-gas duct is approximately —2.0 in. Hz0, the blower inlet pres-
sure. This ~2.0-in. Hz0 offset is not significant. The reference

 
 

70

chamber is shown in diagrem in Fig. 1.5.5 and is described in detail in T
Sect. 6.2. (ufi

Two channels are used, one in the pump bowl and the other in the
overflow tank. These normally operate at the same pressure. Any safety
signal from either channel initiates the appropriate safety action.

The system may be tested periodically during reactor operation by:
(1) observing system response to small operator-induced pressure changes
and (2) shunting the torque motor in the pressure transmitter. These
tests will establish that, in the channel undergoing test, the lines
from the pump bowl (or overflow tank) are clear and the electronic equip-
ment and associated wiring are capable of operating the output relays.

Since it takes from 10 to 15 min to thaw drain valve FV-103, this
time can be used to observe the response of the thermocouples on the
freeze valve as it heats up but before actual salt flow begins. The
valve can then be refrozen before an actual drain is initiated. In
such a test, valve HCV-533 (Fig. 1.5.4) will be opened, and the con-
trolled pressure (5 psig) in the pump bowl will be lost for the dura-
tion of the test. The response of HCV-533 can be noted by observing
the actuation of the position switch on the valve stem. This test pro-
cedure checks the entire safety channel, except the ability of the trans-
mitter measuring bellows and the associated linkage to transmit the pres-
sure.

Monitoring of these channels is accomplished by indicating and
alarming the pressure downstream from the hand throttling valves in
each helium line serving the primary elements (the bubbler tubes) in
the pump bowl and in the overflow tank. A downstream flow stoppage by
a blocked line is indicated by a high-pressure alarm; low flow caused (;;
by & loss of upstream (supply pressure, an upstream blockage by foreign
matter, or a hand valve closure is indicated by a low-pressure alarm.

The fuel level in the overflow tank is measured by the differential
pressure across the helium bubbler probe which dips into the fuel salt
in the tank. The design criteria for testing and monitoring these dif-
ferential pressure measuring channels are the same as those which guided
the design of the pressure channels described in the preceding paragraphs.
The reference chanber is not required. Two channels are employed for
safety, and either will initiate a reactor drain if the fuel salt level
in the overflow tank exceeds 20% of full-scale level indication.

1.5.3 Afterheat Removal System

The drain tank afterheat removal system, typlcally the same for both
drain tanks, is shown in Fig. 1.5.6. Once placed In operation the evapo-
rative cooling system is designed to be self-regulating and to operate
without extermal control. Reliable operation of the afterheat removal
systemn requires (1) that the feedwater tanks contein a supply of cooling
water, (2) that an ample supply of cooling water is available to the
condensers, (3) that the system includes reliable valves to admit feed-
water to the steam drums, and (4) that reliable block valves be provided
 

71

in the drain lines®3 from the steam drums. Administrative control is
relied on to ensure that the feedwater tanks contain water. Valve ESV-
806 opens to admit water automatically to the steam drum when the salt
temperature in the drain tank exceeds 1300°F and recloses at approxi-
mately 1200°F. This valve is in parallel with manual valve ICV-8064,
and the pair are a redundant means of admitting water to the steam drum.
Normally the condensers are cooled by tower cooling water, but diver-
sion valve HCV-882-Cl provides an alternate supply of water. Loss of
tower water pressure caused by a loss of water or pump shutdown is de-
tected by pressure switch PS-851-Bl, which operates diversion valve
HCV-882-CL. When this valve operates, the cooling water supply is
shifted from the tower to the process water main.

Since it takes over 12 hr for excessively high afterheat tempera-
tures to develop after a drain, there is sufficient time to effect a
transfer to the other drain tank in the event of & failure or malfunc-
tion. This is also ample time to make connections from the cooling
water system to a tank truck in the event that the normal water supply
is inoperative.

The drain lines, 806-2 and 807-2, are used to keep the tanks dry
during normal operation. They are extensions of the secondary contain-
ment and are provided with block valves. Reliable, safety-grade con-
trol instrumentation closes valves ESV-806-2A and 806-2B, a redundant pair,
when the reactor cell pressure exceeds +2.0 psig or when the radiation
monitors, RM-565A and B, in the cell evacuation line indicate excessive
radiocactivity in the cell atmosphere.

1.5.4 Containment System Instrumentation

Containment requirements are met by providing at least two inde-
pendent, reliable barrlers, in series, between the interior of the pri-
mary system and the atmosphere. For example, the two-barrier concept
is fulfilled by:

l. two independent, reliable, controlled block valves with independent
instrumentation,

2. one controlled block valve plus & restriction such as a charcoal bed
which will 1limit the escape of activity to the stack to less than the
maximum permissible concentration,

3. one controlled block valve plus two check valves,
4. two solid barriers (vessel or pipe walls),

5. one solid barrier and one controlled block valve,

o

6. one solid barrier and one check valve.

 

23These drain lines, 806-2 and 807-2, shown in Fig. 1.5.6, were added
after the MSRE was in operation. Development tests disclosed that par-
tially filled steam drums tended to corrode at the water line.

 
 

 

72

The recommended design practices outlined previously in this section
apply to the reliable instrumentation and control equipment used to op-
erate the block valves. Block valves, generally, are not located at such
a distance from the containment penetration that the lines become tenuous
extensions of the containment vessel. Valves and other devices used in
lieu of solid barriers will be routinely tested and demonstrated to be
capable of maintaining leakage below the specified tolerance when closed.

1.5.4.1 Helium Supply Block Valves

Figure 1.5.7 shows the helium supply lines to the primary contain-
ment vessel and the associated valves used for control and blocking these
supply lines against the escape of radiocactivity from the primary system
as a result of reverse flow or back diffusion. This sketch does not show
the fuel storage tank (FST) and line 530, which supplies pressurizing
helium to this tank. This line is blocked by HCV-530-Al. Two types of
input signals are used to initiate helium supply block valve closure.

The first, a reduction in the supply pressure from its normal value of
40 psig to 28 psig, actuates pressure switches and closes all the inlet
helium block valves. The second, excess radiation measured by RM-5964,
B, and C in any of the helium lines supplying the level probes (bubblers)
and pressure measuring instruments in the pump bowl and overflow tank,
closes the block valves in these lines. A reduction in heliwn supply
pressure in line 500 from its regulated value of 40 psig indicates s
leaky rupture disk or leaky piping and, possibly, a loss of primary con-
tainment.

In-service testing of the loss-of-pressure channels is accomplished
by opening the hand valves on the lines to the pressure switches on the
main supply pipe (Line 500), one at a time, and observing the action of
the relays in the two-out-of-three coincidence matrix in the control room.
Actual block valve closure is not tested with this procedure. Low- and
high-pressure alarms are provided on line 500; these will actuate before
the safety system pressure switches close the block valves., Additional
testing of the solenoid block valves in the helium bubbler lines is pro-
vided by closing each valve individually and observing the pressure change
downstream of the hand throttling valve.

The three radiation monitoring safety input channels, RM-596A, B,
and C, are tested by exposing each individual radiation element to a
source and noting the response of the output relays which produce valve
closure. Since two-out-of-three coincidence is used, this test will not
perturb the system; neither does it provide a valve closure test.

1.5.4.2 0ff-Gas System Monitoring

The off-gas system (Fig. 1.5.8) is monitored for excess radistion
in four places:

1. Iine 557. — This line receives off-gas from the main and suxiliary
charcoal beds, helium from the coolant salt pump, and helium from
the salt pump lube o0il systems and the sampler-enricher.

2. Line 528. — This line carries helium from the coolant salt circu-
lating pump. Its primary purpose is to detect an internal lesk in
the fuel-to-coolant~-salt heat exchanger. Should such a leak occur,
 

73

fission product activity will be carried into line 560 by the purge-
gas flow across the coolant salt pump bowl. This line is monitored
by RM-528B and C. Note that RM-557A and B provide a redundant indi-
cation of this activity level.

3. Line 565, — This line is used to pump the reactor and drain tank
cells down to the operating pressure of 12.7 psia. A portion of
this line continuously carries a small flow of cell air, via bypass
line 566, across the component cooling pumps which circulate cell
alr (see Fig. 1.5.8). This continuous flow is monitored by RM-
565A and B.

4, Off-Gas Stack. — Stack gas monitoring is not a part of the MSRE safety
system but is noted here for completeness. Refer to Sect. 2.11 for
a description of this monitor. Its only output function is to pro-
vide alarms. The stack gas monitor, located on the off-gas stack,
provides a final check on the off-gas just before it is discharged
to the atmosphere and after it has been filtered. Excess radio-
activity in the stack gas is alarmed in the MSRE control room, and
an glarm signal is also transmitted to the ORNL Central Monitoring
Facility.

Tt can be seen from Figs. 1.5.8 and 1.5.2 that an excess radio-
activity signal from either RM-557A or B produces three output actions,
all intended to preserve contaimment; these are as follows:

1. Closes HCV-557-Cl in line 557. This line is, in effect, the main
helium off-gas exhaust header leading to the off-gas stack filters
and carries off-gas from several sources, namely:

a) the fuel salt circulating pump,

b) the fuel salt drain tanks,

c) the coolant salt pump,

d) the coolant salt drain tanks,

e) the fuel salt sampler-enricher,

f) +the fuel and coolant salt pump lube oil systems (Fig. 1.5.9).

2. Closes valve PCV-510-A2.
3. Closes valve_PCV-513qA2.

Actions 2 and 3 block the helium off-gas lines from the lube oll sys-
tems (Fig. 1.5.9). o

Radiation monitors RM-528B and C in line 528, carrying helium from
the coolant pump, are necessary because they will provide an indication
if a leak exists in the salt-to-salt heat exchanger (from the fuel salt
loop to the coolant salt loop), Such a leak could put fission products
in the coolant salt; however, when the coolant salt circulating pump is
running, the coolant salt pressure in the heat exchanger tubes is greater
than the fuel salt pressure in the shell, - The fission product gases would
be carried from the free surface in the coolant salt pump bowl into line
528, This activity will be read first by RM-528B and C and then by RM-
557A and B. The output actions produced by RM-528B or C (see also Fig.
1.5.2 and Teble 1.5.1) are the following: (1) drain the reactor vessel,

 
 

74

and (2) stop the fuel salt pum;p.24 This also produces a rod scram if
the reactor is operating above heat loss power, 15 kw. The sequence \=J
of control actions which scram the rods is described in Sect. 2.6.

Excess radicactivity in either the reactor or the drain tank cells
is detected by RM-565A or B. Either monitor will produce protective
actions thus:

1. Closes HCV-565-A) in line 565. This line, the cell evacuation line
(Fig. 1u5.8), is used to exhaust the reactor and drain tank cells
when they are being pumped down to their operating pressure of 12.7
psia.

2. Closes the steam dome condensate drain valves ESV-806-2A and ESV-
806-2B (see Fig. 1.5.6).

3. Closes block valves HCV-566-A1, A2, A3, and A4 to and from the ana-
lyzer which monitors the oxygen content of the in-cell atmosphere.
This analyzer (Fig. 1.5.12), is located in the vent house.

4. Closes block valve HCV-915-Al, which carries exhaust cooling air to
the)rod drives and the control rod thimbles (see Fig. 2.7.12 in Sect.
2.7 e

5. Drains the reactor vessel. The reactor drain system is described
in Sect. 4.7.

These systems may be tested by inserting a radiation source in the
radiation monitor shields and observing (1) the radiation-monitor indi-
cator, (2) the control circuit relays, and (3) the output actions of the
control valves and other controlled elements which provide protection. (fi)
The three pairs of radiation monitors, RM-528B and C, RM-557A and B,
and RM-565A and B, all operate so that an excess radiation signsl from
either channel in a pair will produce safety action.

Since these are all one-out-of-two systems, on-line testing of any
channel will produce protective control actions and, to an extent, perturdb
the operating system. The system disturbances caused by on-line testing
of RM-557A and B and RM-565A and B can be tolerated if the test is of
short duration. It was necessary to provide jumpers for on-line testing
of RM-528B and C. Without jumpering, a test of either channel will stop
the fuel salt pump and, if the reactor is at power, scram the rods. This
is unacceptable operationally. Jumpering is the preferred alternative
to omitting in-service testing. Testing these safety channels is, there-
fore, subject to very strict administrative control. The jumpers bypass
contacts K-26C and K-27C in circult 147, which starts and stops the fuel
salt pump. As has been pointed out in footnote 24, these contacts do
not produce a safety-grade protective action.

The MSRE off-gas sampler will (1) utilize on-line instruments to
provide a semicontinuous indication of contaminant level and (2) iso-
late samples which may he transferred to a hot cell for analysis. The
off-gas sampler (Fig. 1.5.10) was designed and installed after the re-

 

24Stopping the pump is not required to ensure safety. It may tend
t0 reduce the rate but will not eliminate leakage.

C
 

75

actor was placed in operation. Reference 25 contains a brief, conceptual
description of the sampler as originally proposed. In the current ver-
sion the chromatograph cell has been cmitted: pending further development
work. Figure 1.5.8 shows the location of the sampler with respect to
the main off-gas system. '
The samples are obtained from line 522, which carries fuel punp
bowl sweep gas to the off-gas system. Bypass lines with valves across
the piping to and from the analyzer permit taking the sample either be-
fore or after the gas has passed through the charcoal filter and the
particle trap. The sampler is located in the trench immediately south
of the vent house. The reactor off-gas is highly radiocactive, and since
this equipment is an extension of the primary contaimment into an ares
frequented by operating personnel, the use of block valves in the supply
and return piping to the sampler is mandatory. The sampler is well
shielded and, except perhaps for the thermal conductivity cells (these
cells are tested at 20 psig), meets the general MSRE containment require-
ments with respect to pressure rating and leak-tightness. The sampler
is housed in a ventilated enclosure which is exhausted to the off-gas
stack. Continuous circulation within the enclosure is maintained by two
(for redundancy) blowers. This flow loop is monitored by two flow switches,
FS~54-D and FS-54-~C, connected to a single alarm. Excess radiloactivity
in this circulating air is detected by two separate, independent channels
of radiation detection equipment, RM-54A and RM-54B. A high-radiation
signal from either monitor will close block valves ESV-537A and B and
ESV-538A and B, redundant palrs in the inlet and outlet lines to and
from the sampler. The circuits which control these valves are shown in
Fig. 1.5.11. These valves are also closed (see output XVI, Fig. 1.5.2)
if the pressure in the reactor and drain tank secondary containment cells
rises above +2.0 psig or 1f the fuel pump bowl pressure exceeds 10 psig.
The cell pressure safety channels and the protective instrumentation
used to measure pump bowl pressures were described earlier in this section.
The atmosphere in the MSRE containment is kept at no more than 5%
oxygen, with the remalnder being nitrogen. Oxygen content is continuously
monitored by an on-line analyzer which measures the magnetic susceptibility
of the cell atmosphere. The analyzer and its operation are described in
detail in Sect. 6.4. - |
Figure 1.5.12 shows the analyzer flowsheet and the final control
circuitry which closes the block valves to and from the analyzer, The
inlet gas to the analyzer is taken from the cell evacuation line, 565,
and is discharged to line 566. These two lines form a low-flow bypass
loop across the component coocling pumps which continuously circulate the
air within the containment cells., The piping to and from the analyzer
meets contailnment requirements; the analyzer, rated at 30 psig, does not.
Block valves are required for containment and because the instrument
is located in an accessible, frequently used aresa and is not entirely
protected from mechanical damage. The block valves also permit main-
tenance and routine operations such as changing the cylinders of ref-
erence gas and purge nitrogen.

 

 

25MSRE Project Staff, Molten-Salt Reactor Program Semiann. Progr.
Rept. Feb., 28, 1966, ORNL-3936.
 

76

Block valve operation is apparent from Fig. 1.5.12. The valves }
are automatically closed if either channel, RM-565B or C, in the two- Q.J
channel radiation monitor, signals excess radioactivity in the cell

atmosphere or if the pressure in the secondary containment cell ex-

ceeds +2.0 psig. These input channels have been described previously

in this section. Complete on-line testing is possible, since block

valve closure can be checked by observing the rotameters in the ana-

lyzer. A complete test involving any two channels of the cell pres-

sure input instrumentation is not conducted during reactor operation,

since this same test, described earlier in this section, causes un-

acceptable system changes elsewhere. The radiation channels are tested

with & source, on-line, and the block valves and the control circuits

are redundant.

1.5.4.3 In-Cell Liquid Waste and Instrument Air Block Valves

The in-cell (secondary containment ) liquid waste lines are blocked
if the reactor cell pressure exceeds 2 psig (see Fig. 1.5.13 and input
XTII, Fig. 1.5.2). The normal operating pressure in the containment
cells is 12.7 psia. Excess cell pressure is a symptom of system mal-
function or, at worst, the maximum credible accident.! The protective
instrumentation and control hardware and blockage of instrument air
lines have been described earlier in this section.

1.5.4.4 In-Cell Cooling Water Block Valves

A simplified flow diagram of the in-cell cooling water system, with
instrumented block valves, is shown in Fig. 1.5.14. The signal to close L
the block valves is provided by an excess radiation level in the pump (ij
return header. Three independent sensors, RE-827A, B, and C, initiate
block valve operation when any two of the input channels indicate excess
radiation in line 827. Operation of the system is apparent from Fig.
1.5.14. Testing is accomplished during operation by manually inserting
a radiation source in the monitor shield (refer also to Sect. 2.10) and
observing that the indicated radiation level increases and that the
proper relays operate. The construction of the sensor shield is such
that each radiation monitoring channel can be tested individually. Since
the monitor contacts are arranged in two-out-of-three coincidence, test-
ing of individual channels does not close the valves. The valves may
be tested individually by operating a hand switch and observing that
flow stops in the line under test. The complete system is tested during
shutdown.
Valve ESV-DGT serves as a backup to FSV-837-Al1, FSV-841-Al, FSV~-
846-A1, FSV-847-Al and provides redundant blocking in the system. The
thermal shield is protected from excess hydraulic pressure by the rupture
disk in line 844. Pressure control velve PCV-844C and block valve FSV-
844-A1, actusted by either pressure switch PSS-844-Bl or valve position
switch ZS-847-A2 on valve FSV-841-Al, prevent breaking the rupture disk
with the transient pressure surge produced by closing FSV-847-Al., Valve
FSV-844-A1 is also closed by the action of pressure switch PSS-855-Al
when the pressure downstream from the rupture disk exceeds 5 psig.
This action serves two purposes: (1) maintains some protection of the
thermal shield if downstream pressure develops on the rupture disk, and _
(2) minimizes the loss of cooling water when the rupture disk does burst. tfi;
 

77

Any water discharged through a burst rupture disk passes into the
vapor condensing system and is contained.

1.5.5 Underpressure Protection for the Secondary
Containment Cells

Failure or malfunction of the pressure control system for the com-
ponent cooling pumps, if undetected, could lead to a dangerous subatmos-
pheric pressure reduction, causing a buckling type of failure of the
secondary containment structure. ZProtection against such an event is
provided by a three-channel, reliable system, schematically identical to
that used for cell overpressure protection deseribed above and earlier
in this section.

If cell pressure falls to less than 12.2 psia, a control-grade alarm
sounds. The safety-grade instruments (pressflre switches) actuate at 10.7
psia (input XII, Fig. 1.5.2) and produce two protective actions: (1) shut
off both component cooling pumps, and (2) close HCV-565-A1 in the cell
evacuation line (Fig. 1.5.8), thereby preventing further outflow of cell
air to the stack.

 

1.5.6 Tuel Salt Sampler-Enricher Containment Instrumentation

The sampler-enricher is fully described in Sect. 3.12 and in refs.
2629, When in use it must penetrate the primary containment and, there-
fore, is potentially capable of contaminating the area and exposing its
operators to all the various types of radicactivity associated with nu-
clear fuel. The material in this section is limited to a functional de-
scription of the more important instrumentation and controls whose sole
purpose is to prevent a loss of containment.

Figure 1.5.15 is a simplified line drawing which illustrates the
operation of the sampler-enricher. It can be seen that sampling or en-
riching is accomplished by lowering and raising the cable-suspended cap-
sule into and out of the fuel pump bowl. Throughout most of its travel
the capsule is guided by and contained in the transfer tube, which pro-
vides direct access to the molten salt in the pump bowl. The sampling-
enriching operation may be likened to withdrawing or adding water to or
from a well with the "old oaken bucket" powered by a motor-driven winch.
Containment is effected during these operations by subdividing the region
through which the capsule travels into compartments which are opened and

 

26R, . Robertson, MSRE Desisn and Operations Report, Part I, De-
scription of Reactor Design, ORNL-TM-728 (to be published).

27Molten-Salt Reactor Program Semisnn, Progr. Rept. July 31, 1963,
ORNL-3529, p. 35. .

28)Molten-Salt Reactor Program Semiann. Progr. Rept. Feb. 28, 1965,
ORNL-3812, P 24 -

29Molten-Salt Reactor Program Semiann. Progr. Rept. Aug. 31, 1965,
ORNL-3872, po 56. -

 
 

 

78

closed in sequence so that two contaimment barriers are maintained. The
regions which are considered to be primary containment are:

1. area 1A, the transfer tube between the mailntenance valve and the
punp bowl;

2. area 1B, the transfer tube between the maintenance valve and the
operational valve;

3. area 1C and the short length of transfer tube which connects area
1C to the operational valve. Note that area 1C houses the motor-
driven winch which raises and lowers the capsule.

Compartmentalization and closure of these primary containment regions is
obtained by the maintenance and operational valves and by the port which
closes the access to area 1C.

Since a complete sampling or enriching procedure requires that the
material, either fresh salt or hot sample, pass through both the primary
and the secondary containment barrier, the latter is also compartmented.
These compartments are maintained by

1. The access port, which separates the primary and secondary contain-
ment regions, 1C and 3C respectively.

2. The removal valve, which when closed, is the secondary containment
barrier across the path traversed by the capsule. Note that area
3C contains the output side of the manually operated manipulator
which the operator uses to unlatch the capsule from the cable, move
it into area 3C, and thence to the transfer cask via the removal
valve.

Figure 1.5.16 is an austerity version of the sampler-enricher in-
strument flowsheet and shows only the high-quality instrumentation whose
sole purpose is to effect contaimment. Figure 1.5.17 diagrams the func-
tions of these instruments and controls. Table 1.5.2 shows the normal
aspects or status of the valves and the access door during use and when
not in service. It is proper to point out that the sampler-enricher is
used intermittently and by personnel well trained in its operation. In-
termittent usage and functional requirements resulted in the arrangement
of containment instruments in accordance with Figs., 1.5.16 and 1.5.17.

Where redundancy is not obtained by duplicating individual instru-
ment channels which produce the same specific output action, it is be-
cause the desired protection is obtained by diversity (explained earlier
in this section).

There are additional instruments and alarms required by the device.
These lend support to the high-grade interlocks discussed herein; the
reader 1is referred to Sect. 3.12 for more information.
 

79

Table 1.5.2.

 

Operating Situation

Component Condition

 

 

Maintenance Operational Access  Removal
Valve Valve Port Valve
Capsule entering sampler-enricher Closed Closed -Closed Open
(asbove removal valve) |
Capsule in area 3A and being ma- Closed Closed Open Closed
nipulated onto the latch
Capsule latched to drive unit Closed Closed Closed Closed
cable in area 1C
Capsule in transfer tube and Open Open Closed  Closed
entering maintenance valve
Capsule in transfer tube be- Open Open Closed Closed

tween maintenance valve and
pump bowl

 

 
80

EMERGENCY
PRESSURE

AC
SWITCH-_  __
T
CHANNEL NO.l\ —'“"tm ’;?:::;B

7> 7

CHANNEL NO.2

 

 

b
-

A

   

GHANNEL NO.3\

 

     
  

4
J——rfl-—}LZ

~— -

3

Q@

@
R

-

’

~

]

Q

n

ORNL-DWG 64-647TAR

EMERGENCY
T DC

~
s

—ll
1F

0

w

w

A3,

2,
A

 

 

   

    
    

 

 

 

 

 

GAGE

L L L L
rd ¥ 7 ¥

 

 

 

PRESSURE

SINTERED
REAGTOR DISK SNUBBERS
CELL Pl
VOL = 18,000 i3 1a2

NORMAL OPERATING TVA
PRESSURE l;:g}l ;
—=2.0 psig

PI
1A3

+0C

BLOCK Esv &O)- :
VALVE 1C1

(TYPICAL)
Y

  

AIR SUPPLY
TO IN-CELL

 

   
  

(TYPICAL)

HEADER

 

COMMON PORT

/
45

GAGE (TYPICAL) M

      
 
   
   
   
       
   
  
       
 
       
 
   
   

 

HAND o ¥ L A 75
VALVES ) VALVE
k SOLENOIDS f ESV ESV ESV
(? 3 ¥ 182 1CH icz
) #  AG NEUTRAL
'PRESSURE |~ 7 DC NEGATIVE

SOLENOID VALVE

MATRIX. ‘ :
ALL VALVES

> SHOWN (N NORMAL

OPERATING MODE

WITH ALL

SOLENQIDS
ENERGIZED

 

VALVE SOLENOID

Fig. 1.5.1. MSRE-Redundant Instrumentation for Block Valves,
*2°¢'T 31

Serq ndno-qndur

 

A

TISW SU3 JO Swel

‘woqsly £98Feg

ORNL~DWG 67-4580

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FSV 841-A1, F3Y 844-A1, FSY 848-Al,

INPUT PRIMARY INPUT POTENTIALLY CIRCUIT NUMBER CORRECTIVE ACTION OQUTPUT ADDITIONAL
REFERENCE INSTRUMENTS UNSAFE CONDITION. - . REFERENCE INFORMATION
NO. : NO.
* [ RE-NSCH Rx-NSCi1-A6 - 1 28 - i .
I NSC2 NSC2 —-I REACTOR PERIOD LESS THAN +1.0 SECOND |
NSC3 NSC3 i "
REACTOR POWER (FLUX) GREATER THAN e
11.3 MEGAWATTS WHEN FUEL SALT PUMP 28 > # CONTROL ROD m . LOAD SCRAM J 1 SECTIONS [-5
MOTOR CURRENT EXCEEDS 35 AMP s ol (SEE OUTPUT NG XX) AND T1-8
RE-NSC{ Ry NSC1-A3 o S -
11 NSC2 NSC2 — ‘
RSS-NSCi-A4
NSC3 NSC3 REACTOR POWER {FLUX) GREATER THAN ' NSC2
11.3 XILOWATTS WHEN FUEL SALT PUMP / NSC3
MOTOR CURRENT IS LESS THAN 38 124 —#7, 118,49
TE-100-Al Tss- '00‘“’ FIJ'BLSA;.}’ TEMPERATURES AT REACTOR 5.2,3 28 : 30
:g 1 "i OUTLET GREATER THAN 130°F Ji 1,2,3—=18,19 —20,2 \
——- 3 JI-A
OPEN VENT VALVES; HCY 8§73,
20, 24 | HOV 575, HCV $T7, BETWEEN |
) o | DRAIN TANES AND AUXILIARY |
CHARCOAL BEDS
E_E 5998} LSS*SSQB} I FUEL PUMP OVERFLOW TANK LEVEL GREATER | 18,19 —20, 2 L———————w.*«u—uJ
6008 6008 THAN 20% f - ] Ir-—————-————v;;;’—-—-————' Y RAINS
| FV-103 AND DRAIN TANK VALVES, : REACTOR Fl SECTION I-5
RM-528B } [RSS-52891 e ——_— 26, 27 —= 18,19, —= 20, 21 [ T¥-105 AND FV-108 {LF NOT ALREADY
- - - ———————— e e e —— 11-C
RM-557-A REFER TO INPUT NO. XVI {_ovm BY-PASS VALVES; HCV-544, 1 p—
557-B —pi | HCV-545, HCY-548, BETWEEN FUEL |
PUMP BOWL AND DRAIN TANKS |
P _d
20,21 —=131,132, -
Z8S-NRRI-218A2 ANY CONTROL 10D BELOW ' R > ~
VI *FILL PERMIT" POSITION 20, 21 s [ L 127,115,116 |
NCR3 [ [ 1. STOPE FUEL SALT PUMP
' > | 3. SCRAMS POPR TS REACTOR 1 SECTIONS
_ Al HELIUM PRESSURE IN FUEL 22,23,—18,19—20, 21 L { POWER EXCEEDS 11.3 KW -5 AND [1-8
v {PSS 589 }—- BALT PUMP BOWL GREATER 22 23— 122 ( SEE INPUT BLOCK II. ?
592 & THAN 25 PIIG. 2 I
~ ~
HELIUM PRESSURE IN 20,21 —= 131,132, 133 [ [ [ BOWL. 70 AURDAARY CHARCOAL v SECTION I1-5
vt Pss-589 A2) | PUMP BOWL GREATER 20, 21 —=127, 115,116 [ BEDS BY GPENING HVC-532 AL
592 B2 THAN "FILL PERMIT" 20, 2| —=1{5 (
VALUE (2.0 PSIG) 2
BLOCK INLET HELIUM LINES TO
24,25—=18,19,20, 21 J’ FUEL DRAIN TANDS AND FLUSH TANK:
24,25, ~= 8t . N AN SUPPLY LNE
IX {?M ~569 B}—’f?ss - 365 B'}—- HIGH RADIOACTIVITY IN 24,25-—=298 M B. CLOSE HCV 572-Al, HCV 5T4-Al AND v SECTION I-3
c 365C1 REACTOR CELL ATMOSPHERE 24,25 § - HCV 576-A1 IN INDIVIDUAL HELIUM SUPPLY
24, 25— 82 — LINES TO FUEL DRAIN TANKS
46,47,48 | _ L L L L CLOSE INLET HELIUM VALVE,
PSS-500 N{ HELIUM SUPPLY PRESSURE | 127, 115,116 L, ( ( ( r . :cv “;A_:;;m TO FUEL Vi SECTION -5
X N2} —e IN LINE 500 LESS THAN 28 PSIG . ‘46,47.48—'—115 J: ( ( : | TORA
N3 {HEADER PRESSURE} 46. 47,48 =y
L >——3 CLOSE HCV 915-Al IN LINE 915 WHICH
1 . SUPPLIES COOLING AIR TO ROD VIi SECTIONS
HIGH RATDIOACTIVITY IN HELIUM : f - DRIVE UNITS AND CONTROL 1I-5 AND [1-7
: ROD THIMBLES
RM-596 A RSS-536A LINES NOS. 588, 509, 582, 593, - - .
X1 { B}—{ B~ 59, 599, 600, WHICH SUPPLY HELIUM £0,6t, 62 6‘? Toes A4 : o
C TO FUEL PUMP BOWL AND TO OVERFLOW INC'L i L & CLOSE STREAM DOME CONDENSATE DRAIN -
TANK ¢ gy | vALVES NOS ESv-t06-24 VI SECTION I-5
AND EBV-800-2B :
PSS-RC H PRESSURE IN SECONDARY | 84 %0 - A : . )
xi A CONTAINMENT LES3 THAN " | 84—=85—=312, 314 (315) _ l L L L L ' i CLOSE BLOCK VALVE IN ALL - :
K 10.7 23 . . : - . | HELIUM LINES ENTERING : : 1X _ SECTIONI-5
e A e T e U e e e e - 30,31,32—=36,37. 1 bAoA CONTAINED REGIONS - - § e e . —
"4
30,31, 32— 38, 37—=298 "
PSS-RC B PRESSURE IN SECONDARY . CLOSE BLOCK VALVES
X F}—» CONTAINMENT GREATER 30, 31,32 —=36,37 —~38,39 IN LINES SUPPLYING HELIUM T0 X i SECTION 1-8
THAN 2 PSIG . 30,31,32—=33,34 FUEL SALT PUMP BOWL AND GVERFLOW
TANK
|_30,31,32 —=36,37 L L4 _ _
—=318,319 (1 .
. i CLOSE BLOCK VALVE HCV 585-Al
XIV HIGR RADIATION ACTIVITY IN LINES 51 AND 54 : ( IN CELL EVACUATION LINE | X1 SECTION I-5
BETWEEN OFF-GAS SAMPLER AND STACK _ [ [ ’
: f SHUT OFF BOTH COMPONENT
XV P55-589 A3 FUEL SALT PUMP BOWL PRESSURE l > > - ! COOLING BLOWERS ' X1 SECTION I-5
592 B3 GREATER THAN 10 PSIG 3IMASE—318,319 L L L L
. - J ’ .
70,7 —=72 [ L [ : CLOSE BLOCK VALVES NOE. HCV 568-A1,
RM-55T A RSS5-557 Af BIGH RADIATION ACTIVITY IN I r [ [ *  HCV 566-43, HCV 566-A3 AND
RM-5578 B OFF-GAS LINE NO. 587 70,71 —~73,74 [ l HOV 568-A¢ TO AND FROM Xt SECTION I-5
—— CONTAINMENT OXYGEN ANALYZER
RM- 827A RS -827 A'l HIGH RADIATION ACTIVITY IN IN-CELL + )
1 COOLING WATER SYSTEM S3TOSBINCL A A A/ .
8 B77-AL. BL. AND €1 | CLOSE BLOCK YALVES NOS. FCV 333-A1,
L > FCV 333-A2, FCV $43-A1 AND XIV SECTION I-5
FCV 343-A2, IN LIQUID WASTE LINES
TE-202 Aq TSS 202 A2 TEMPERATURE OF COOLANT 45,6 A Ak
XVII! —e BALT AT RADIATOR OUTLET, l O Ao SO0 v ALVES TN DS TRUMENT
02 LINE NO. 302 L33 THAN S30° F ) LINES WHICH PENETRATE THE Xv SECTION I-5
SECONDARY CONTAINMENT
T-201 FSS-201 A
B :morcoomumrww. 7 TO 10 INC'L—=
E-CPG! 5$55-CPG1 n' : mm[ o ; t:;mm umnmlum ! 1,12—=13TO ! ; CLOSE BLOCK VALVES NOB. ESV 537-A
2™ . UREMENT 16 INCL® ) AND B AND ESV 538-A AND B TO XVI SECTION 1-5
7§-1D- 339 r—_—__ AND FROM OFF-GAS SAMPLER
1D-B4B | EFTHER RADIATOR DOOR | ‘
00-B3B K 255 AT FINAL UPPER LEMIT. | CLOSE BLOCK VALVE HCY 557-C2
0D-B4B > IN MADN OFF-GAS LINE TO STACK XVII SECTION I-5
- K 255 DOOR DRIVE MOTOR
K 266 CURRENT AT OVERLOAD VALUE | CLOBE VALVES PCV 510-A2 AND
sy PCV 513-A2 IN HELIUM VENT LINES XVIIT SECTION I-5
' FROM BALT PUMPE TO OFF-GAS SYSTEM. :
|
CLOSE BLOCK VALVES NOS. FSV 837-A1, g
|

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FROM FSV 847-A1, AND ESV-DGT IN THE X1x SECTION -5
OUTPUT | TREATED WATER COOLING SYSTEM
s > IL:MKDSCRAH P XX SECTlOP:l 11-8
255, 256 — 568, 13, 15
{1) 5TOPS DOOR DRIVE MOTOR :
255, 256 —= 568, 13,15 ] (2) SXSENGAGES DAIVE CLUTCE XXI SECTION 11-8

 

 

 

o et A A e 151

 

0
|
i
!

e et oAt e e ot e A

 
 

INPUT
REFERENCE
NO.

 

I

II
I
I

H

(R iy e —

INITIATING
CONDITION

 

 

 

ROD SCRAM
(a) SHORT PERIOD
(b) HIGH FLUX
(c) HIGH TEMP.

-

 

 

 

FUEL SALT TEMPERATURE
AT REACTOR QUTLET
GREATER THAN 1300°F

 

FUEL PUMP OVERFLOW TANK
LEVEL GREATER THAN 20%

 

HIGH RADIOACTIVITY IN
COOLANT PUMP OFFGAS

 

HELIUM PRESSURE IN FUEL
SALT PUMP BOWL GREATER
THAN 25 PSIG

 

 

HIGH RADIOACTIVITY IN
- EITHER REACTOR CELL OR

DRAIN TANK CELL ATMOSPHERE

 

 

ANY CONTROL ROD BELOW
'FILL PERMIT' POSITION

 

 

P

HELIUM PRESSURE IN FUEL
SALT PUMP BOWL GREATER
THAN 2.0 PSIG

 

| I RSS-NSC1-A4 nz
RSS-NSC2.-A4 124 18
‘ 1RSS-NSC3-M ne

   
   
   

CORRECTIVE
ACTION

A

 

 

OPEN VENT VALVES
- HCVY.573, HCV-575

 

82

 

 

 

OPEN (THAW) FREEZE
VALVE NO. 105

 

 

OPEN [THAW) FREEZE
VALVE NO. 106

 

REACTOR
DRAIN.
DEMAND

 

 

T

OPEN (THAW) FREEZE
VALVE NO. 103

 

 

OPEN BY-PASS VALVES

 

 

HCV.544.A1, HCV-545-A1,

 

 

NN .
:ua.:
— -
7‘5
~—

»N
NS
L/ \LS

HCV-546-A1

 

 

 

 

CLOSE MAIN HELIUM SUPPLY

doAvgov oy v

 

 

VALVE, PCV.517-A1 AND BRANCH
LINE SUPPLY VALVES, HCV.572-A1,
HCV-574-A1, AND HCV-576-A1

 

 

 

ORNL DWG 67~4644

EFFECT

REACTOR

 

BLOCK INLET HELIUM LINES USED
TO PRESSURIZE FUEL SALT DRAIN

 

1 1O FUEL SALT DRAIN TANKS

 

 

 

LEGEND

| ¢

o B
CIRCUIT NUMBERS ——j 1

COINCIDENCE OF A
AND B REQUIRED TO GET C

Fig. 1.5.3. Input-Output Diagram of the MSRE FuTl Salt Fill and Drain Safety System.

 

 

TANKS. DOES NOT INCLUDE HELIUM
PURGE LINE VALVES ESV 519A

 

AND ESV-5198

 

 

 

]
 

 

 

83

 

System Conditisn

 

 

 

 

 

e

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ORNL-DWG 63-8395R

  
    

 

    
     
 

 

 

 

 

 

 

 

 

 

 

 

ESV
5198

ESV
519A

CLOSED WHEN
INLET HELIUM PRESS.

IS LESS THAN 28 psig,
(SAFETY SYSTEM INPUT NO. X}

 

  
    
 

 

 

   
  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fig. 1.5.4.

 

PraeFill Cparate !
Velva Ne. Pra-rill Norm Drain Inte i
with Circ. Nomat Fill brom Fils from Fill fram —— == Emerg. 1
Mellws He Operation FDT#1 FDT#2 FFT  FOT#1  FDT#2 FFT Drain ;
PCY 512, Fill prass o x x o ° o X X x X _ 1.
roguiate L
HCV 572, Fill, FOT #1 x % x 0 X x X X %X
HCV 574, Fill, FDT #2 X x x x o x x x X X
HCV 876, Fill, FET X x x x x o x X XX OFF-GAS TO
HCV 544, By pusa 0 o o X Q o a £ E 0 HOLDUP AND CHARCOAL
. o o
Hev S4By pove o o £ v o6 x & £ o o INLET HELIUM GOOLER BEDS
) LINES 140 liters
He §78; Vo X x ox ox oxox T ° r CHARCOAL
HCV 877, Vent X x X H x o © : FILTER
HEY $33 Al o x X o o 0 x x X X | ?l-; RATF:C LE
HCV 119 AG B xox o x x x X X X X | g
HCY SO0 Al o o o 0 x x o x X X I
HCY 210 A o o o X o x X 0 X X t M 2l
ey sty ase! o x X x x X x x x X R | OVERFLOW
Hoy st e o o 0 0 0 o o o o & : t t ! ! TANK
ey 52z a Hg fetdewn e ° o 0 0 ° o 0 o o SAFETY -— —= EMERGENCY DRAIN _[
:: :::,. Reel drsin valve : : < : o : g ‘),( : g g g SYSTEM | QPEN HCV-533-A M e | ey
FY 106* X X 0w X* 0 X X o X x 0 1NPUT NO.V“
FY W7 x X x x x x % X X x :
BYPASS LINE ‘ 0 AU
v ior X F o X x x o x o xx —Gad 52l ; —GeD §6D—+ CHARCOAL
K =—Chaed; O '-.mu; E - aither cpan ar closed. [* FUEL SALT
'Durlnl narmal operation both FY 105 and FY 106 are kept apen. . V‘
Tuev 519 AmB opened afrer sompleting fill and before cpamtion te satwe that drain line 103 Is clearsd. ‘! &
EHCY 523 closed enly whan blowing selt aut of everflew tank. - i‘l )
- [
INITIAL i
LOADING ‘ 1 REACTOR
~ CONNECTION 1)) VENT ‘; VESSEL
E7)— 86 { | - HCv-
HGV- LINE ! 577-Af
HCV-544-Al - HCV & Y ore
Cv-54 * \ 545-A1 | % N 546 G—;[*
° > Hev- o
| * HCV-573-Af @ 575-At | *
b @ ' FV103 Bion 6108
FREEZE
FVi04 VALVE
FV105 j : x X COOLING
TO FUEL FV106 1 ? AIR
i QO ysn TanK — TO FUEL
S : - PR
TANK | og) P07
FV 109 D € 3 FV107.
b | 50 @ HcgJA X | @ ; i
WASTE SALT Z 910 A1 SO9n > 1 ]
DISPOSAL " 57 f‘—"\§77
L1~ ==~ @ foer————eee ‘;"
' @ | i srapH | " '
| SR nov T | o
I FUEL TANK 908 A b I FUELl
DRAIN | " JFLUSH
CAPILLARY I TANK j No-2 A E TANK :
NO.{ . i £ . ,
FLOW RESTRICTOR L H L Hov 4 ! |
HELIUM pcy  ST2:Al 574-A1 L 576-M- X
SUPPLY 517-At x (—Yx | Ml 0 A
HELIUM 35 peig * ) |
FROM (547 - (578) .
HEADER, N b T 1
LINE 500 CAPILLARY o NOTE:
‘ g FLOW RESTRICTOR _ VALVES MARKED WITH ASTERISK,
(TYPICAL) : THUS
{ *
|
ARE SAFETY SYSTEM
‘ BLOCK VALVES
X X 549 ]
HCV B19A HCV519 !
i : FREEZE VALVE

 

 

Diagram of Reactor Fill and Drain {f;System.

COOLING AIR
 

 

 

 

 

 

 

 

 

 

84

 
   

 

 

 

 

 

 

 

 

 

 

 

 
   

 

ORNL-DWG 64-627R

 

 

ALARM

 

 

 

-

FROM FUEL SALT

OVERFLOW TANK PRESSURE
TRANSMITTER

~METER

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NQTE : :
OPERATION OF THE TEST SWITCH SIMULATES THE APPLICATION * TO SAFETY
OF PRESSURE TO THE TRANSMITTER AND CHECKS ALL SYSTEM
COMPONENTS IN THE SAFETY CHANNEL EXCEPT THE
CONVERSIDN OF PRESSURE TO FORCE BY THE TRANSMITTER
BELLOWS)| SINGLE ALARM
SWITCH
, DUAL ALARM SWITCH
' SWITCH CAPABLE OF
VENT TO | PRODUCING TWO DIFFER-
STACK NTAINED. ZERO | ENT SAFETY INPUT
] SIGNALS
8 psig REFERENCE N%‘”' oy
&5 CHAMBER. RATED 50 psig | 2 psig TO DATA
AND TESTED AT 100 psig 1 : LOGGER
SLACK Cerdeeres e,
DIAPHRAGM - T
{ ] TesT switck J [
fifl 6 & > Qume _A'A'A'l'_
H [=40 TO S5O0ma £ 4008
° - r - 1=10 T0 50 mo
S~ WELD SEALED PRESSURE \ISOLATION
HCV TRANSMITTER WITH PRESSURE- AMPLIFIER
593|83 TO-CURRENT TRANSDUCER-AMPLIFIER.
INLET (592) RATED AND TESTED AT 250 psig
HELIUM * 27/ v
TO PRESS
TRANSMITTER
USED FOR CONTROL
REFERENCE LINE TO
FUEL PUMP BOWL
NLET TO OVERFLOW TANK, b TO FUEL PUMP
HELIUM BOWL GAS SPACE

 

SAME AS ABOVE

Fig. 1.5.5. Typic?.l Chennel of Safety-Grade Pressure Instrumentation for Use in Primary Containment.

 
e e e i e

 

Voo »*
516 Al {

m
% u
\/
A
\/
A
3
<

¢ sieaz

  
 

 

 

85

 

 

TO FUEL

PUMP

a;
B EOD——D—H<
EED—td—<

 

 

e e e e

 

 

 

 

VENTED TO
FILTERS AND THENCE
TO OFF-GAS STACK

EXCESS FLOW
VALVE
§ _RUPTURE DISK
: / 50 psig

 

CEnm)

  

 

 

 

 

 

 

  
 
  
 

 

 

 

TO FILTERS AND THENCE TO
OFF-GAS STACK

 

 

 

__igl RELIEF
{ “VALVE
HELIUM SUPPLY peV
ey R
- 4 =<} HELIUM
STORAGE
RAD PCV
MON. 2 6054
3000 -—-)4——-—-;LP-€EE}—>4L—-

 

 

 

 

 

  
 
 

X

*x

K

HCV
595 B1

i HCV
Y 595 82

LOW PRESSURE

ORNL-DWG 63-8398R2

HCV
E 59583
TO COOLANT SALT

PUMP BOWL BUBBLERS

-

 

 

 

 

 

 

 

 

 

 

 

  
  
  

 

 

PT
A

n
n

 

 

PRESSURE GAGE} AND PRESSURE SWITCHES WITH HIGH AND
ALARM IS TYPICAL OF ALL BUBBLER LINES

[ HC
et *gsggss

TO LEVEL PROBES,
(BUBBLERS) IN FUEL
SALT OVERFLOW

| TANK.

) TO LEVEL PROBES

{BUBBLERS) IN FUEL
SALT PUMP BOWL.
>

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fig. 1.5.6.

 

CAPILLARY
RESTRICTORS

&3

 

 

 

 

\
HELIUM PURGE LINE

P\ LINE NO. 103

-

' SECONDARY
CONTAINMENT

 

 

SSIs

. NOTES:!
1, AN EXCESS RADIATION SIGNAL FROM
RE 596, (ANY 2 OF 3) CLOSES HELIUM
SUPPLY VALVES , HCV 593 Bi, B2, B3, AND
HGV 599 B1, 82, B3 TO BUBBLERS IN
FUEL PUMP BOWL AND TO BUBBLERS
IN}OVERFLOW TANK, RESPECTIVELY.
i
§

 

|

MSRE Drain Tank Afterheat Removal System.

PURGE FLOW
TO REACTOR DRAIN

2. A LOW HELIUM SUPPLY PR
IN LINE 500, (ANY 2 OF 3
PRESS. SWITCHES) CLOSES
BLOCK VALVES MARKED WIJH

ASTERISK, THUS *i

 

 

 

FSSURE

HELIUM

POV . = HCY
. A G ' ¢ 1
G $10 'll; -} TO LUBE OIL § o D *gsggaz
- X SYSTEMS FOR FUEL AND | o
— » POV L COOLANT SALT PUMPS ! ' « & Hey
] C T 5134l St .@ ~y 59984
X . .l L_—_T— X
PV OV % 10 COOLANT y i o5
NG DRAIN TANK L
5“ 1 rxfl o I
FOV A* .
. 5121 ] :
(512 N T0 COOLANT PUMP f;
| & E
201 (804~ [
CLOSES i
BLOCK VALVES ' }
517 SEE NOTE 1 [
- o 2 OUT OF 3 el
TO FUEL STORAGE COINCIDENCE e
TANK AND CHEMICAL MATRIX %= “iNPUT |
PROCESSING SYSTEM NO.X1 !
' ‘ 2 OUT OF 3 CLOSES !-
SNUBBER | — 3INDEPENDENT ____ [ ___ .| COINCIDENCE | — —=BLOCK VALVES
SIGNAL, SAFETY MATRI SEE NOTE 2 |
| Y SYSTEM INPUT NO.X ! X !
I} : '{J
vl - w
I | THREE CHANNELS A
| | FOR INPUT SIGNAL.
PRESSURE SWITGHES !
1| ACTUATE AT 28 psig CAPILLARY FLOW |
INDIVIDUAL TESTING OV .“
OF EACH CHANNEL pCV 572 Al ‘:’ AND ARE SECONDARY CONTAINMENT BARRIERS
BY OPENING HAND 517 Al *i N I
VALVES TR \ Qo=
574 At ' . /
* .
e ; 57 NN 574 T0 FDT-2
57641 } s
C,, oy - ~GTO—— NN 79 = TO FF}
5194 * 1

3. LINE AND ASSOGIATED

PXM'S ARE A ZERO psig REFERENCE
SYSTEM WHICH MAINTAINS
CONTAINMENT AND PRESERVES
ACCURACY OF THE PRESSURE
TRANSMITTERS DURING
FLUCTUATIONS OF CELL PRESSURE

 
 

 

COOLING TOWER
PUMPS

P3
B

 
 
  

 

 

HCV-882
G

 

 

NO.2

 

 

 
 

COOLING WATER
TO OTHER
COMPONENTS

 

 

 

TO
CONDENSATE (GO t-Ptt-

STORAGE TANK

 

ORNL-DWG 63-8388R

 

 

 

 

 

 

 

 

 

 

o 7O OFF-GAS
com_mg«—@ 2 TO COMPONENT O TACK
FROM TOWER COOLING PUMPS
PROCESS RUPTURE
WATER MAIN #] oisks A ®
— i 3
o
® —I* "~ 33
> 30-in. MOTOR
OPERATED
BUTTERFLY
TO VAPOR CONDENSING :
_@ @-. SYSTEM VALVES
b (SEE NOTE 1)

 

  

 

 
 

)
FEEDWATER
TANK NO.A

 

 

TC DRAIN TANK
CONDENSER NO.2

FROM RUPTURE
DISK IN COOLING

WATER LINE 2
, FEEDWATER

 

 

 

o
)

@
r—-@ ESV-806
I —ple

 

 

 

CONDENSATE

TO REACTOR  \@
* SUPPLY LINE THERMAL SHIELD

STEAM

 

| L L

L LTl

 

 

  

LCV-806A

 

 

 

 

 

 

 

NOTES:

. THESE VALVES ARE CLOSED DURING
NORMAL REACTOR OPERATION. VALVES
ARE OPENED ONLY DURING MAINTENANCE
OPERATIONS WHEN THE REACTOR
CELL 1S OPEN.

2. VALVES MARKED BY AN ASTERISK, THUS

*

ARE SAFETY SYSTEM BLOCK VALVES,

Fig. 1.5.7.

 

'~
im

 

OSUONNN SN SNNNESNSSNSS SN

   

 

~

 

# - REACTOR CELL
g RN TANK EXHAUST LINE
A7 | . steam 30-in. DIAM
A 1t DRUM
A\ 1
i
-

DRAIN LINE
FROM. STEAM
DRUM ON
FTD-2

SIGNAL TO CLOSE FOR
EXCESS RADIOACTIVITY
IN REACTOR CELL OR
FOR HIGH PRESSURE

-

 

 

 

FUEL {>2.0psig } IN REACTOR
Il pRAIN I CELL. REFER TO INPUT
TANK t CONDITIONS NOS. IX AND
(TYPICAL} | X1t
"
77 Z 7777777 77777 STEAM DRUM

 

 

Secondary Containment Regions.

 

 

PUMP, CAPACITY -10 gpm

  
 

 

 

X X
ESV ESV
806-2A 806-28B

 

CONDENSATE
DRAIN TANK

TO FLOOR DRAIN

 

 

 

Diagram of System Supplying Helium to Primary and

     
 

 

 
  
 

    
  

 

 

 

 

 

 

   
   

 

 

 

 

 

 

 

 
    
   
    
 

    

 

 

 

  

 

 

 

 

 

 

 
   
    

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

  

 

 

 

    

  
    

 
    
       

   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
 

 

 

 

 

  
 
  
   

 

 

 

 

 

 

 
 
 

 

 

 

 

 

 

 

 

 

  

 

 

   
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[
'L'
e VENT LINE OXYGEN _
' , FROM FUEL DRAIN TANKS ANALYZER ORNL-DWG 63-8397R2
: AND FLUSH SALT TANK - 5D a. DRAINS REACTOR
FROM ' T SAFETY SYSTEM b. BLOCKS STEAM DOME FONDENSATE DRAIN
gfig&ifi § (342> INPUT NO. IX _’r“-"‘ c. (B)LOEKS LINES TG AND [FROM
] A e 2 ANALYZER
— TO IN-CELL COMPONENT r 4 , o Bloc )
COOLING AIR HEADER & A | . BLOCKS COOLING AIR TO ROD DRIVES
Q) OFF-0AS STRAINER % !
| . 8] SAMPLER - REACTOR CELL ALARM
OFF-GAS HELIUM FROM ‘ #c HOV (BLOCK) EVAGUATION LINE
FUEL SALT PUMP , 565A1 \VALVE {
BOWL, LOWER LINE R !
PRESSURE BLOWERS rrrrrrrrbrrrr -
: ' STACK
ey - AUXILIARY [
- ) CHARCOAL BEDS [T V< >-GE2 MO(l;\l‘}?'OR OFF-GAS
; ACK—__
—22 o G5 CHARCOALL,-B_EDS"I DD
ey J_NoS. 1aND2 [
924 0 L ;o )
OFF-GAS STy = (?g
HELIUM FROM FUEL HELIUM FROM @ } ] @-I\J—DQ—-—
SALT PUMP, UPPER LINE PARTICLE CHARCOAL COOLANT SALT PUMP 25 RM SaFeTY ‘
TRAP FILTER 528 . . r
: ‘ B SYSTEM SAFETYY |
| SNt sysTEm |} R Al
CAPILLARY POV %Iy e NO. V1 AT % FILTER R
FLOW ELEMENT § MBA2 T e —— —7— === —1< Ino. xvI \
| & 53D——=piq : o -
HELIUM FROM BLOCK VALVE L ' HCV i | -]
COOLANT DRAIN TANK 534 Pr—e } (BLOCK s57c¢ XL
AND LUBE OIL SYSTEMS POV | % .J o VALVE)
51042 " B,
—GEe0 . —
1 /93"5\ SAMPLER- 4
| = ENRICHER
CHARCOAL , - — ;
TRAP H— ) - —@2D Fr B M 927
5
r 2 J MOTOR OPERATED
2 SPECIAL === ) G BUTTERFLY VALVES
EQUIP ROOM ~_i i —
’\ 1 P 05
VENTILATION AIR RUPaRE , | P30 B
FROM: ~ ] S | 3
1. LIQUID WASTE CELL pL L § ] o THIS 30-in. DIAM LINE
2. DECONTAMINATION CELL TT A1 ; R USED ONLY WHEN REACTOR
3. REMOTE MAINTENANCE CELL IS OPEN oumr;e
PUMP CELL MAINTENANCE TO OBTAIN
4. HOT STORAGE CELL IN FLOW TO CELL
5. FUEL STORAGE TANK VENTILATION
CELL - AIR FROM notes:
IN-CELL COMPONENTS 6. SPARE CELL SERVICE TUNNEL ;
RODS AND RODODRIVES o 1. COMPONENTS MARKED WITH ASTERISK,
FREEZE VALVES, PUMP BOWL ETC ; THUS &«
s Li—LL. i ———(E32) v , PERFORM INSTRUMENTED
/ | b A SAFETY FUNCTIONS
/ ].—.@5 COOLANT
 ereeze CELL d o 2. AIPES AND DUCTS LARGER THAN 2-in. DIAM
qvawve | TS (PR EQUIV} ARE DENOTED THUS
/ ‘ B
s 8
REACTOR CELL 4 VENT
DRAIN .
TANK CELL/ VAPOR i HousE
PROCESS WATER CONDENSING ;
TANK NO.2 ‘fi”
FILTER. 250
CONDENSING cfm
VT — [t
‘ FROM RUPTURE DISK ON
; THERMAL SHIELD COOLING
WATER LINE
i
4
Fig. 1.5.8. MSRE 0ff-Gas System.
C
f
)
I
b
i
l

 

 
 

 

 

 

 

 

 

 

 

 

 

 

SIGNAL TO CLOSE
- FROM RADIATION MONITORS
RM-557A ORB, SAFETY SYSTEM INPUT XVI

ORNL-DWG 63-8393

 

 

 

 

 

-
I
| 53
LOG COVER GAS OFF-GAS FROM 53 .
e PrESs GonTRO ——|—  SooranT - T0 OFF-AS.
ALARM | SYSTEM | SALT PUMP ‘
< | STACK
N QUICK ED BREATHER, CONNECTS
SIGNAL TO CLOSE . | DiscONNECT TO FUEL SALT PUMP
WHEN INLET HELIUM -———- o | A INTERCONNECTING OIL
PRESSURE IN LINE 500 ¢ ==V 1 | RETURN LINE FROM
IS LESS THAN 28 psig raoar |1 rov / [ COOLANT SALT PUMP
(SAFETY SYSTEM INPUT X) 513-A1 L 593 A-2
. |
HELIUM I ADDITION
SUPPLY, 513 o | LINE O ey
35 psi
Pl 510 A = I SALT PUMP
ALARM 1A
+ ~ _N
LOG OlL SUPPLY ~
— TANK FOR c—-——-l
Ren FUEL SALT
o PUMP —— (70—
OT-1
OTI-B = ¢ (15— EXCESS FLOW
\OT-2) ~ RETURN FROM
PUMP OUTLET
ALARM - — . TO OIL
€ (714) D<= | PUMPS
¢ - [~ —————————— e [ FOP-1 AND
‘ FOP-2
S %
; —
g’) NOTES:
oiL 1. BOTH LUBE OIL SYSTEMS
DRAIN ARE SIMILAR. NUMBERS
LINE ENCLOSED THUS ()
ARE EQUIVALENTS IN
¥ COOLANT SALT PUMP
COOLING QUICK LUBE OiL SYSTEM
WATER DISCONNECT

 

 

Fig. 1.5.9.

ASTERISK,

2.VALVES MARKED WITH

THUS *

ARE SAFETY SYSTEM
BLOCK VALVES.

Lube-0il System Off-Gas Monitors.

 
 

 

HELIUM

2

 

39

 

SIGNAL. TO CLOSE =4— —— ——~

BLOCK VALVES
ESV 537 A AND B

~— — ~* SIGNAL TO CLOSE
BLOCK VALVES
SAFETY ESV 338 A AND B
SYSTEM INPUT
NO. XIV

— FLOW SWITCHES
L —®-

R RM
546

 

 

 

 

 

  

 

 

 

 

 

Dt
V5228

   

 

   
   

   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LOSS OF

@ ,> T FLOW ALARM

ORNL-DWS 67-2519

TO
AUXILIARY
CHARCOAL. BED

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  
    

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

 

 

 

 

 

 

 

   
   
   
    

 

 

 

 

 

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LEVEL s
INDICATING 4
@ CONTROLLER 0
TO FILTERS
= > LEv-50A i AND OFF-GAS
¥ STACK
1 . J‘:I
]
I (fi
g XVS0A XV508 !
PRESSURE
RECORDER
# . ‘
; 2227 L L lr L A rd 2 L L 2 L
. 11
4 ] LiQuip —u—@ LEVEL SWITCH
NITROGEN ‘ 1
VIE Y CYLINDER . ‘/4_6\ /
TTTITTT = SPARE / //////,/,4, /t-"TL " "A \2A /D|SCONNECT i1
4 VIOA VI0B — o — i Ty vizn
' D4 v J_¥vA _ __(conthoLLen . g
L |— ¥4 1 POWER TO f
7 HEATERS wi2¢ g
¢ 1
wower o @ bme bbbl AR /
1 ft OF SMALL TR 7 2155 Y sramiess | __H _ _ _TorreEssurE
] DIAM Cu TUBING = ///f STEEL CEWAR | r {VACUUM) INDICATDR
] LeveL prose—"1 | Hifl RS E (___) ! /
b % A [~LEAD SHIELDING A N i - S ~ (1o EQUIPMENT
TO VOLUME HOLDUP: ] A S =i ENCLOSURE
AND THENCE TO V - /, L= (75— MOLECULAR SIEVE : i
CHARCOAL BEDS 4 7 )] MATERIAL IN 4 |- SAMPLE 4 PRESS
_ SIGNALS TO { 7] weLDED STEEL e SaMPLE Fe-—ff ——— =R
CLOSE FROM SAFETY 1 1 : |
SYSTEM INPUT NOS SEAARRAEREINAAANANS 4 | BOTTLE SIGNALS TCL *nr
XU XV XV A CLOSE FROM SAFE
‘ | : | @ P | e SYSTEM INPUTE NOS
TEMPERATURE R _I Xl XIV | xv
P yeiE Sy g’gfigfl:fiww INSTRUMENTATION: |—— — e — —= ‘ 4 4 }
4 ' L o. RECORDER v B
CELL ——— e —
+ L —r— ] b. CONTROLLER - t“; : }
vs80 ] ¢. TEMPERATURE HIGH ALARM
T+ Tz /1 ] SWITCHES (5) i —
- ) ‘
] g i
- £ 77
/ £ (20)- 4
1 Cu0y V-20 i [
[ SCRUBBER ViK ‘ /
: V30 1
_._’Q (M) ’
* G2 THERMAL = ]
DG4 CONDUCTIVITY I
A X X CELL 1
I esv- ESV- veon [ —"lo0o=- {75 &
Y veer [ s3ma  s37e ESV- H
M1 xv808 xV73 } ] 538-d £
‘ XVE0A b g /
11 f m : 4 ]
Y / & o .
“ VfflsG &L bl 2 » i /
o / /] ]
TO AUXILIARY % ’ 2Ll 2T
MELIUM SUPPLY (CYLINDER) ; i1
USED TO PERIODICALLY [
cvsTev CHECK PERFORMANCE OF - = z T T L Z =z T TR E ST T Z TIFITITITT 77 7 Z TP L R RZZ)
THE OFF-GAS SYSTEM 0
T0 PRESS @ @ ;
RECORDER B __GD
i
b
HIGH ALARM--35psig HIGH ALARM - 110 psig
NOTE: . LOW ALARM-- 3 psid. LOW ALARM- 90 psig
1. VALVES MARKED WITH ASTERISK, ' } RELIEF t
THUS: i vn £ | ] ‘;‘EI#%NT PRESSURE !
SYSTEM BLOCK VALVES PRESSUR . ) [
SWITCH I 125psig  SWITCH I
*
—J —J
5 TO 30 100 psig

VE4A
STD
SAMPLE

 

 

 

 

psig\

 

 

 

H

ELIUM

CYLINDER

 

 

 

 

 
 

 

379
25 kVA

 

PSS 589A3
. -
OPENS WHEN
FUEL PUMP
BOWL PRESS.

EXCEEDS
10 psig -/

)

o

PSS 592 B3

 

o

 

 

SAFETY SYSTEM
INPUT XV

e,

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

|
|
- 90
E ORNL-DWG 67-1296
30 34 - 32 36 37 38 319
v - |
48V DC . )
L
48V DC N , _
R L
1vA DIESEL ) ; -F(Pseismssws)
1 L
25 kVA | D ,
N\ Ny \
A~ OPEN WHEN FUEL _I_ / _L
T KA 379F - KB379F —~ 51648 51658
T K3QA ~—— K3{A T— K30C T K3iC ] PUMP BOWL 7 7T
7 PRESSURE EXCEEDS (TEST) (TEST)
10.0 psig
., T 4 4
d°K366 . OPEN WHEN REACTOR —— K376 —— KA3{BA Z" KB3BA
CELL PRESSURE /
_J EXCEEDS 2.0 psig
PSS-RC-B | PSS-RC-F | PSS-RC-G  _|_ A1 A1 -
e . .y T K30F —K32A ——K30D ——k32C - OPEN ON HIGH
7“\(’% 71— /_ ACTIVITY IN OFF-GAS |
<44 Rs-54- SAMPLER ENCLOSURE —— RS-54-
OPEN WHEN REACTOR T RS-54-A2 A 2T, RS-54-B2
CELL PRESS. >2 psig :
' S162 A :l_ KABIBC 51634 I |KB 318C
TTKMF " K32F T K3MD ——K32D (RESET) ]- (RESET) I+ :[—
: (R I-3194 CR I-3198
KAZSB KB 3188 ESV ESV ESV ESV
537 538 537 538
A B . B A
| = "l KB 318
} |l<325 K36B
I
K30 K3 | | | ING
S S LSS k32 K37 2 . 0} )
L 319, 318 319, 318
318, 348,
) £ ) _ J J
L l ) L 1 Y Y
: \ ) OFF-GAS SAMPLER BLOCK VALVES CLOSED WHEN DE-ENERGIZED OFF-GAS SAMPLER BLOCK VALVES
1 3 .
‘ SAFETY SYSTEM ; ‘
INPUT XIII 38,3 38, 37
39, 298 39, 298
81, 81, 318 81, 81, 318
\ J
Y
BLOCK DEMAND FOR: 1. LIQUID WASTE SYSTEM
2. STEAM DOME DRAINS
3, OXYGEN ANALYZER
* 4, OFF-GAS SAMPLER
Fig. 1.5.11. Block Valve CircuitT for O0ff-Gas Sampler.

 

 

 
 

 

 

]

 

 

  

91 \

! i . &
20 psig ) !

RELIEF VALVES NOTE: ?.f;

VENTED TO VALVES MARKED
ATMOSPHERE _ WITH ASTERISK, - 3I

THUS * b

5 psig/ B

{

ARE SAFETY SYSTEM \

BLOCK VALVES |

REFERENCE ‘ fi
GAS 2 MEASURING 7
5% 0 100 20 CELL !
95% NZ min i

 

 

 

 

REFER TO INPUT
IX FOR OTHER
= SAFETY ACTIONS

   
       
 

2000 cm3/min

 

 

 

 

  

 

 

 

 

    

 

 

 

 

 

 

 

 

- PRODUCED BY /
RM 565 BOR C _ —
7. | SYSTEMSTSFEE NO. X111 —@ PRESSURE
, | GAGE
CELL PRESSURE >2.0 psig ROTAMETERS ¢
g
CKTS' @ PCV-566-A
30,31, 32 S
l T A ATMOSPHERE
‘ i 1 : i . ‘
( CKTS - N =
- - 36, 37 | - “\BLOWDOWN
. - | VALVE
> - - ; - = CKT 298
. | _CKT x HCV-566-A2
8 _ .. 298,
R x HCV-566-A
TWO-CHANNEL *
‘ RADIATION MONITOR, SAFETY
SYSTEM INPUT IX
RM l | (F o)
585 - — — — —— — >4 69
{CKTS} . - | | o
24,25 | | ; — | CKT | REFER TO SAFETY
| —_ ——-—-i | ~ [ NO.80 ] SYSTEM QUTPUT XI
CELL | | INST AIR LINE
EvAcUATION LINE: | _|_ A
FROM OUTLET OF §—<365) I
COMPONENT
COOLING PUMPS + 4 psig " = TO FILTERS AND
FF-GAS STA
HCV-565-At OFF-GAS STACK
TO INLET -2 psig
OF COMPONENT = s 566)- -

COOLING PUMPS

MANUAL SWITCHES
FOR INDIVIDUAL
CONTROL OF EACH
VALVE; LOCATED ON
JUNCTION BOX N
VENT HOUSE

 

5_11 5V AC

 

2p8

ORNL-DWG 67-764

 

—11

d |

— HS-566-A5A

IN CELL §

CONTAINM

 

 

:@ HCV
566 -

Al

 

—— HS-566-A{ =~ HS-56

CONTACTS OPEN WHEN
EITHER RM-565-B OR RM-565-C
~ K24G INDICATE EXCESS RADIQACTIVITY ——

CONTACTS OPEN WHEN

~K36D PRESSURE% IN SECONDARY 4

ENT CELLS EXCEEDS T
+ 2.0 psig

MANUAL SWITCHES
ON INSTRUMENT PANEL
IN VENT HOUSE —____ ==

VACUATION LINE NO. 5657

 

wh

HS5-566-A58

K256

K37D

 

B-A3 :E HS-566-A2

 

 

 

cv HCV
56 - 566~

A3 A2

!

 

 

o~ HS-566-A4

HCV
566-

aq

 

 

 

Sy~

E
BLOCK VALVES ARE CLOSED V‘{HEN SOLENOIDS ARE DE-ENERGIZED

Fig. 1.5.12. Block Valves to a.nd from Cell Oxygen Analyzer.

FINAL CONTROL CIRCUIT
CELL AIR OXYGEN ANALYZEiR BLOCK VALVES

P,
 

SERVICE
AlR

 

100 psig
AR

Tl

Ny
PCV
3328

 

UNION

 

 

SECONDARY

 

 

 

 

/ CONTAINM ENT\

REACTOR :

 

NITROGEN
et SUPPLY
50 psig MAX
HAND
VALVES
PRESSURE
INDICATOR
SINTERED

DISK SNUBBER

ORNL-DWG 63-B396R

PRESSURE SWITCHES

o
b
I

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

—— -

(ACTUATE AT +2 psig)

 

 

 

 

CELL, @ 2 ouT
NOMINAL A3 SAFETY OF 3
OPERATING n @-—-'--— SYSTEM  b==-e{ MATRIX OF [F—)
ever | 4 PRES?;{D,,;Q / n | INPUT NO. SOLENOID | |
TRANS. - DRAIN i t127pskl] I e @ 4 XN VALVES i
TANK CELL ST 1 |
! : f RCFS™ '
| & T |
PUMP SUMP A rev %L Fev : : ‘
@D 3 mar T 333z | | .
=] = DT | i
] Dn ol L N, I
"LEVEL J o P339 I | : | I
E {BUBBLER) - SUMP SAMPLE [ — o —— l
FCV ' | '
’ BOMB * *
NN GER L4 G
K 0 INSTRUMENT | CLOSE BLOCK  DRAIN LINES
LINES WHICH | VALVES TO FROM AFTER-
& - D LIOUID PENETRATE { AND FROM HEAT REMOVAL
2 WASTE SECONDARY | IN-CELL O, ggm;” STEAM
TANK CONTAINMENT I ANALYZER
NOTE: VALVES MARKED WITH 11,000 gol CELL I
ASTERISK, THUS &% ;
—i—— CLOSE BLOCK

 

Fig. 1.5.13.

ARE SAFETY SYSTEM BLOCK

VALVES.

VALVES IN VENT-
ILATION LINES TO
AND FROM OFF-GAS
SAMPLER

In-Cell Liquid Waste and Instrument Air Block Valving.

 
 

 

   

 

 

93

 
 
 
   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ORNL-DWG 64-638 A

 

 

 

 

 

 

 

 

  

 

 

 

 

 
 
 
 
 

   
  
   
      

 

 

 

   

 

 

 

 

 

 

 

 

 

| TO VAPOR
_ — CONDENSING
fl DIESEL HOUSE MAIN SUPPLY SYSTEM
: e~~~ HEADER T GAS
‘ psig L6
FILTER! : —.826) COOLER
(573 l ! TO OIL
VENT TO SURGE TANK -(829) f | TREATED | o COOLERS
l__l | I WATER f G) FOR COM
CENTRIFUGAL GAS . | COOLER | v COOLING PUMPS
SEPARATOR ) ) UMPS
Stpsig | |
| FROM COOLING 3
TREATED WATER IGY TOWER
PUMPS — T \877 ALARM
'
i £ K
S DX
! ESV @
! i DT VENT
PURGE AIR 1; o PRESSURE X &
] SWITCH B @
& 1 TANK ) SEE NOTE No.2-|” RUTTURE @ TO
€7D 3 | ~. COOLANT
_ ,4 FUEL PUMP ) SALT PUMP
CHEMICAL TO FEEDWATER ; MOTOR T [3esig 4 MO
ADDITION"S TANK o N ~J - JTOR
' o 7 7T T Tl AT T
1
PURF(?EO hflqm GG 874 ngOM SPECIAL \ f
SuppLY | (876)— | EQUIP ROOM | ‘ ‘ 1
; FROM N
SURGE TANK COOLANT N J
. j SALT PUMP ‘| 4— DRAIN
A 8psig MOTOR 1 NUCLEAR | “ Tank
- i INST
3 INDEPENDENT RADIATION Fsv 1! E PENETRA | CELL
i v -
MONITORS RE BAZ;DA,CB : 837 x A C % TION IR :
2 OUT OF 3 SN | v (1|1 U
+ COINCIDENCE | — ~ v e — - — — — ] SAFETY SYSTEM Ly * ] esv X 847 / ‘ yd \ f
[ Marrix INPUT NO. XVII x L gae * / AIR N 9
| 3 RELIEF % a30)—U /] COOLERS |~ [ /
| SAFETY SYSTEM ‘ VALVES Fsv | | ~ §
L SUTPUT NOLXIX NOTES: 1. ON EXCESS RADIATION SIGNAL FROM ANY 100 psig 8at [*T— 625 | ~—T0 N p
e TO BLOCK \;'ALVES, 2 OF 3 RADIATIOCN MONITORS ALL VALVES \ ‘||§l'—' ,/ THERMAL tflg_ THERMAL N 1/
SEE NOTE NO.{ MARKED WITH ASTERISK, THUS <% ARE CLOSED ZF] IF] ] SHIELD SHIELD SLIDES A
1
_ % — SECONDARY
2. RUPTURE DISK AND PRESSURE SWITCH PROTECT » &4 1 CONTAINMENT
THERMAL SHIELD FROM RUPTURE IN THE EVENT : - @3 ~ q
OF EXCESS WATER PRESSURE 0 : N ’
WASTE TANK ! Z 7 7 7 7 ZZ Z z 77 ]

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
 

v o

 

TRANSFER TUBE
(PRIMARY CONTAINMENT

LATCH STOP -

PUM7

CAPSULE DRIVE UNIT—

AREA {C
{PRIMARY CONTAINMENT) -~

SAMPLE CAPSULE

OPERATIONAL AND
MAINTENANCE VALVES 4 ; Ll T

94

ORNL~-DWG 63-5848R

 

 

> REMOVAL VALVE AND
w7 SHAFT SEAL

PERISCOPE
LIGHT

X

 

 

LATCH-_|
ACCESS PORT-_|

CASTLE JOINT (SHIELDED
WITH DEPLETED URANIUM)

 

 

MANIPULATOR

/ - AREA 3A (SECONDARY
/ _ —I CONTAINMENT )

 

 

SAMPLE TRANSPORT

%-L:l CONTAINER
: LEAD SHIELDING

 

 

 

 

AREA 2B (SECONDARY
CONTAINMENT)

852' ELEVATION

S o

SPRING CLAMP
DISCONNECT —

 

 

 

   

 

CRITICAL CLOSURES
REQUIRING A BUFFERED
SEAL

EXPANSION SECTION

 

SAMPLER-ENRICHER SCHEMATIC

 

 

 

MIST SHIELD
CAPSULE GLIDE

Fig. 1.5.15. Sampler-Enricher Schematic.

 

J
 

   
 
  
      
  

     

  
  
  

   

BUFFER HEADER
40 paig

CKT,
- 280

 
  
 
       
 
  

To .
INSTRUMENT H3V

AIR HEADER 678 B2

 

95

————aeA37T

REN/R . ‘
A&

INST
AIR HEADER

 

    
  

    
 

  

\
I

 

HCV HCY
RV-AZ | Rv-A

HSV
CKT HCV
675 a2 383

6794

 

 

  

    
   
   
  
 
   
  
 
 
 
 
 
 

    

   
 
    
  
  

PUMP NQ.2

CKT
381

 
  
 
  

REMOVAL

H5V
€808 VALVE

     
   

   
 

2755\"111 PE PSS AIR CYLINDER

- SAFETY
CKT 393

ceT
A294

FEEE9A

  
 

CAPSULE

AREA 44 CRIVE

CKT.
sy

 
   
 

AREA
ic

 
  
 
 

 

. AREA 4A MANIPULATOR

 

  
 
 
 

 

CAPSULE
AREA {B

 

HSV .
6598

CKT
T“g3re

[
8382

  

«—CKT
aA3re

TYPICAL DOOR
LATCHING ACTUATORS
(AIR CYLINDERS)
TOTAL NO. =8 .

  
   
 

 
 

   

OPERATIONAL
VALVE 220v
moTop  3-PHASE

KT
62~

{ .
L o CKT : )
ST o
oot

MOTOR !

       
 

 

VACUUM

 
    
 
  
  
 
 
  

 
 
 
 

MAINTENANCE
VALVE

 
 

HSV
6688

 
 
   

CKT
265 :
220v i
3-PHASE
HSY ;
AREA 4A 6558 1
-———— :
CKT

366 :
B376 "

SAFETY

Fig. 1.5.16. Sampler-Enricher Simplified Flow Diagram.

 

  
 
 
 
  
   
   

INSTRUMENT
AIR HEADER

5048

EXCESS
FLOW

 

ORNL-DWG 676695

TO FILTERS
AND OFF-~GAS
STACK

        

     
    

   

EXCESS
FLOW
VALVE

 
 

 
    
 
 
     
  
  
  

   
  
 
 
  
 
  
 
       
 
 

  
  
     
     
  
   

 

 

 

 
 

 

ORNL-0WG 6T-6696
PRIMARY INPUT ‘ INITIATING CONDITIONS ‘ CORRECTIVE ACTIONS
INSTRUMENTS

 

 

PREVENT OPENING REMOVAL VALVE

 

 

 

 

 

 

 

 

f\..t\l'\..—..1

PE PSS —(362)
670 }= == 670 }==—=(360)—-» REMOVAL VALVE OPEN (365)
8/ B — (368)

_ — (366)— —s| MAINTENANCE VALVE OPEN |—(359)
BUFFER PRESSURE <40 psia (368) —
‘ L]
' OPERATIONAL VALVE OPEN |—{359) — I
_____(363)_______, , (359)

. PREVENT PENING CAP! RT '
(LIMIT SWITCH) (368) . VENTS OPE SULE ACCESS PO _
—— — ——— ——— — . — . —— ————— —-—=————= ’
HSV-6784 NOT CLOSED [ o 1
. / ’ PREVENTS OPENING MAINTENANCE VALVE
’ ’ ' MAINTAINS CONTAINMENT: INSTRUMENTED
CLOSURES TOGETHER WITH INTERLOCKED

PE PSS —1(359) —————— T T e e e - OPERATION OF MAINTENANCE VALVE ,
669 }-— —| €69 —{369)— -» ACCESS PORT IS OPEN (362) ‘ | OPERATIONAL VALVE, ACCESS PORT AND
B 8 b (365) . _| CLOSE VALVE HSV-678-81 IN LINE BETWEEN | REMOVAL VALVE MAINTAINS A MINIMUM
|

SPCA
ST

 

 

 

 

 

 

 

 

 

PREVENT OPENING OPERATIONAL VALVE

 

 

 

 

 

 

 

PSP
L W W N

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

e
7T
PN

 

 

 

 

 

 

 

 

==
|
¥

 

 

 

 

 

S
SPSa
St

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VACUUM PUMP NO.1 AND CAPSULE CHAMBER {C OF TWO CONTAINMENT BARRIERS AND

’ PREVENTS DIRECT ESCAPE OF ACTIVITY
| TO BUILDING OPERATIONAL AREAS OR
= i TO SURROUNDING AREAS OR INDIRECT
—(362) ESCAPE ViA THE HELIUM SUPPLY AND
680 - —(A394 )~ ~— ~ ~ —| MANIPULATOR COVER REMOVED
(365) - CLOSE VALVE HSV-678A IN LINE BETWEEN VACUUM BUILDING CONTAINMENT AIR SYSTEM.
) PUMP NO.1 AND CAPSULE CHAMBER, AREA 1C

 

 

 

 

 

 

 

 

L

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PSS
589 s wn cn[AFTY) e e == —(362)
A3 (368)

FUEL PUMP BOWL PRESSURE >10psig L

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

e (365) > o] CLOSE VALVE HSV-677-A IN LINE 677
5 - ———e8r9) — — —— (381) BETWEEN AREA 3A AND VACUUM PUMP NO.i
’ Luuuu
-(a380) l
— —{A3TT )= (381) A
HIGH RADIATION LEVEL IN ANY (D360) L ] cLoSE BLOCK VALVE AS FOLLOWS:
BUFFERING HELIUM SUPPLY LINE [ (nag0) ‘ A HSV-657D IN HELIUM PURGE LINE TO AREA 1C
(LINES Noo. 699, 837, 668) OR L ———-(B 382 B. HSV-6688 IN HELIUM BUFFER SUPPLY TO
(c380) OPERATIONAL VALVE

 

 

- = EITHER HELIUM OFF-GAS LINE (3934
NO. 675 OR NO. 684 C. HSV-655B IN HELIUM BUFFER SUPPLY TO
615 (B377 )ty MAINTENANCE VALVE

D. HSV-680B IN SUCTION LINE FROM MANIPULATOR
COVER AND MANIPULATOR BOOT TO VACUUM
PUMP NO, 2

 

 

 

 

 

 

are) PRESSURE IN OF 542 [ (D380} \— N\
SURE IN OFF-GAS LINE NO. (9901 —

GREATER THAN 7 psi
@ {8378) ‘ P29 L (¢380)
. CLOSE BLOCK VALVE HSV-675-Af

CLOSE BLOCK VALVE HSV-659 IN LINE FROM
AREA 2B TO VENT IN AREA 44A

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CLOSE BLOCK VALVE NQ. ESV-542A iN
DISCHARGE LINE FROM VACUUM PUMP NO.1{

 

 

 

 

 

 

 

CLOSE BLOCK VALVE HCV-6T9A

 

 

 

Fig. 1.5.17. Sampler+Enricher, Input-Output Diagram of Safety-Grade Control Actions.

 

 
 

2. SAFETY INSTRUMENTATION AND REACTOR CONTROL

2.1 NUCLEAR INSTRUMENTATION: INSTALLATION AND IOCATION

All permanent neutron sensors are located in a single penetration.
The penetration is a 3-ft-diam pipe installed at an angle of 42° to the
horizontal so that its lower end is opposite the midplane of the reactor
core and its upper end terminates on the main floor in the high-bay area.
Figures 2.1.1 and 2.1.2 are plan and elevation views, respectively, of
the installed penetration. The lower end of the penetration passes
through the thermal shield, and the end closure plate is essentially
flush with the inner periphery of the thermal shield. The penetration
is, from a containment standpoint, an extension of the secondary contain-
ment shell. The lower end of the tube is welded to the containment shell,
and the upper end is embedded in the earth fill and the concrete floor.

A bellows-type expansion Jjoint accommodates thermal expansion between
these points. Since penetration was installed during modifications to
the containment shell, it was stress-relieved and pressure-tested at the
same time.

The penetration is filled with water to within approximately 1 ft
from its upper end. A float-type instrument monitors the water level and
gives an alarm when the level changes more than 4 in. Water is added
with a hand valve adjacent to the upper end of the penetration in the
high-bay area. A 5-gpm pump circulates the water in the penetration to
reduce temperature gradients and maintain a uniform concentration of cor-
rosion inhibitor. The inhibitor, containing lithium nitrite (ILiNO,) and
lithium borate (LiH,BO3), has 810 ppm of NO, and 57 ppm of boron. The
solution is sampled periodically and tested to maintain the pH at 9.0 %
0.2.

The penetration is designed to accommodate ten ion chambers. Each
chamber is located in an individual guide tube; four tubes are 5 in. ID
and six are 4 in. ID. The configuration of these tubes within the
penetration and the types of chambers assigned to them are shown in Fig.
2.1.3. The guide tubes are not made of single lengths of 30-ft-long
tubes; instead subassemblies, each approximately 10 ft long, were made
by welding the tubes into end plates, or bulkheads, and the subassemblies
were bolted together when installed in the penetration. The tubes were
constructed this way (Fig. 2.1.4) because there was not enough headroom
behind the upper end of the penetration to ease the handling problem at
assembly. The tubes are open to the water in the penetration, and the
upper, or last, bulkhead plate serves as the cover plate over the end of
the penetration. Individual, smaller cover plates are used over the
upper end of each tube. These contain the necessary gland-type fittings
for signal leads and push rods for chamber positioning. Figure 2.1.5
shows the upper end of the penetration with the guide tubes and individual
cover plates installed. One of two ORNL model Q-2545 wide-range counting
channel drive units (see Sect. 2.3) is shown installed in the penetration.

97

 
 

98

The mounting flanges on these drive units fit the drilling for the cover
plates, so that a complete drive unit is handled as a module which is in-
serted in a tube and bolted in place.

Farly critical tests disclosed that the curve of neutron flux in
the penetration vs distance deviated grossly from the desired exponential
type of curve. The deviation was beyond the capebilities of the compen-
sating function generator (see Sect. 2.3) in the wide-range counting
channel. Cadmium sleeves® were placed around guide tubes 6 and 9 to
shield the fission counters from neutrons which entered from the side
and distorted the curve of count rate vs distance. The design of the
shields, their location, and their effect on the count rate as a function
of distance in guide tube 6 are depicted in Fig. 2.1.6.

Figure 2.1.7 is a diagram of the interconnection wiring layout. As
much as possible the safety system wiring was separated from control and
power wiring. It was not feasible to separate the first runs of cabling
from the drive units to the Jjunction boxes on the reactor cell wall.
These jumper cables (described in more detail in Sect. 2.7) contain all
the electrical leads in a single well-protected bundle.

The safety system interconnections, consisting of the wiring to the
clutch coils and the potentiometers in the rod drive unit and the signal
and chamber voltage leads to the safety chambers in the instrument pene-
tration, are in individual and separate conduits to the control room.
Except where absolutely necessary, these safety interconnections are
unbroken by terminal blocks, comnectors, etc. All the in-cell wiring
(excluding jumper cables) is entirely with mineral-insulated, copper-
sheathed cables.

Control-grade wiring, not subject to the restrictions imposed by
separation, protection, and independence, is run in trays and conduits
as dictated by cost and convenience.

 

1MSRE Project Staff, Molten-Salt Reactor Program Semiann. Progr.
Rept. Feb. 28, 1966, ORNL-3936, Pert 1, p. 44.

 
99

 

ORNL-DWG 64-984R

 

 

 

 

 

 

 

 

UPPER END OF NEUTRON
INSTRUMENT PENETRATION

/

/

REACTOR
CELL

/

/

 
 

ION CHAMBER
IN GUIDE TUBE,
NEUTRON
INSTRUMENT
PENETRATION

  
 
    

BF3 CHAMBER”
TUBE

 

BF3 N
CHAMBER TUBE

 
  
  

 

REACTOR VESSEL

  

 

   
 
 

THERMAL
SHIELD

 

*USED ONLY DURING
INITIAL CRITICAL TESTS

MSRE Plan View of Nuclear Instrument Penetration.

 

Fig. 2.l.l.
 

100

ORNL-DWG 64-625R
| 24t 2in.

:‘.l
¢ FLANGE FACE
NEUTRON INSTRUMENT
JUNCTION BOX |

HIGH BAY AREA I 41° 50’

/ WATER-SANDC ANNULUS

 

 

       
     
  

 

  

 

 

 

 

 

 

 

 

 

 

 

  

 

 

FACE OF INST.
FINISHED FLOOR L~ SHELL FLANGE
EL. 8521t °i"-\ EL.851ft Bin.
2 EARTH FILL
&Y 3 WATER
® LEVEL
5 Q,\)’ 849t 8in.
&
ot
S g W
_ WATER LEVEL INSTRUMENT
FARg
p CHAMBER GUIDE
TUBE (TYPICAL)
REACLOR A ¢ END OF 4B-in. o% SLEEVE
THERMAL - EL. 841t +3 in.
SHIELD : Batft tg in
CONCRETE
SHIELDING ~ ELEV. :
837+t 7in. 48-in.0OD OUTER SLEEVE
ASSEMBLY (WITH EXPANSION JOINT)

 

 

 

 

~~EXP JOINT Q

SECONDARY
¢t CONTAINMENT 5
PENETRATION EL. 834f1 55z in

   
   
    

 

 

 

 

 

MIDPLANE
OF CORE
830 ft 8 in. - _ L EL.830 # 3in.
SHELL
ION 36 in.
CHAMBER f._4" |-
(rypicaL) ff 355 in 10,

 

 

 

 

 

 

 

 

N INSULATION

 

REACTOR CONTAINMENT
CELL

Fig. 2.1.2. MSRE Elevation View of Nuclear Instrument Penetration.
 

101

ORNL-DWG 66-10143

   
    

 

LINEAR CHANNEL

 

LINEAR CHANNEL

 

 

 

 
   

 

 

  
    

‘||||||||l’ NoY Ne2
SPARE_GUIDE ' BFy COUNTING
TUBE b CHANNEL
WIDE RANGE ;| SPARE GUIDE_
COUNTING CHANNEL NO | TUBE
WIDE RANGE SAFETY CHANNEL N2I

 

COUNTING CHANNEL N9 2

    

SAFETY. SAFETY
CHANNEL NO3 CHANNEL No 2

   

 

HOLES N2 3,4,5,6,9 610 — 47 DIA HOLES

 

HOLES N2 1,2,7 & 8 5{D|A HOLES
COVER PLATE DIA ~——wemmmmm39 1" DIA '

Fi.g. 2.1.3. Location of Neutron Sensors Within Instrument Pene-
tration. ‘

 
 

102

PHOTO 66306

 

 

to Imstallation

1lor

Guide Tube on Shop Floor Pr

Chamber

104.
ion.

2

Fig.
in Penetrat

 

 
         

PHOTO 48571

b
o
w

 

Fig. 2.1.5. Upper End of Penetration with Guide Tubes and Individual Cover Plates Installed.

 

 
 

NORMALIZED COUNT RATE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ORNL-DWG 66-2741

  
 
   
 
 
 
 
  
  
 

 

10° .
MSRE GUIDE TUBE NO.9 N
COUNT RATES IN GUIDE TUBE T a
NO.6 BEFORE AND AFTER CONCRETE FILL ‘, _
oot L \  ADDING CADMIUM SHIELDING 9 oy -
= / SECTION THROUGH
— REACTOR SHIELD— NUCLEAR INSTRUMENT
~ \ /. PENETRATION
— \ \\ GUIDE TUBE
102 = X ‘ A NO. &
= VN )
: \ (LI REACTOR
— ‘ \ ;o CONTAINMENT
o0t \ MIDPLANE ’ Sin.
= \ \ OFCORE | 4
S
10"5 =— CURVE "B" COUNT \ \ l
= RATE WITH CADMIUM ) '
—  SHIELD l m
B ¢
6 REACTOR
10 ° = CURVE "A" COUNT RATE — VESSEL
= WITHOUT CADMIUM
— SHIELD
B 1 CADMIUM SHIELDING
107 SUBASSEMBLY — TYPICAL
0 20 40 60 80 IN GUIDE TUBES THIS LENGTH 100%
x, DISTANCE WITHDRAWN (in.) 6 AND 9 (CADMIUM WRAP
{0 ft-0in. A 10 t-Oin. SECTION A-A -

 

 

  

 

‘ LOCATION OF

 

Fig. 2.1.6.

 

 

T Y 8]1:3[1 @ GUIDE TUBES

\OUTEF\‘ SHELL REMOVED
FOR CLARITY—SHADED WEDGES
ARE CADMIUM —UNSHADED WEDGES
ARE ALUMINUM '

Cadmium Shielding of the Fission Chamber Guide Tubes.

 
 

105

ORNL-DWG 66- 4101

 

JB-t19 fi JB-115 (SPARE)

 
 
  
  
  
  
    
  
   
  
  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

¢
CELL PENETRATION NO.XI ]
MAIN
MINERAL JB-112 (SPARE) 1
INSULATED sy ] g CONTROL
| JB-109 ~ ¢ BOARDS
{S)F (1 | —a INCLUDING
| JB-110 D / CONSOLE
&) SEPARATE
JB-1t4 7CONDUITS [
Ly g
CELL PENETRATION Ri / / -
%comouws , 4
- 1
/1 || | _caBLE TRAYS
1 . [ -
JB 1
JB-41 \20 /
] CONDUITS AND g AUXILIARY
CABLE TRAYS
FLEXIBLE i " g%%ggL
JUMPER CABLES I’;
ROD DRIVES J8-40
JB-67 fé\ H :
o/ 3
JB-68 ~ %
NUCLEAR S$)— 77 1 >
INSTRUMENT )
PENETRATION JB-69 e 2 7~
SEPARATE NUCLEAR
\ CONOU|TS SAFETY
\TO SAFETY CHAMBERS CABINET
TO LINEAR POWER CHAMBERS,
REACTOR FISSION CHAMBERS AND BF, CHAMBERS CONTROL
CELL 7 ROOM

JB-JUNCTION BOX
(S)- SAFETY SYSTEM WIRING

Fig. 2.1.7. MSRE Interconnection Wiring for Nuclear Instrumentation.

 
 

106

2.2 BF; INSTRUMENTATION (o

2.2.1 General

The MSRE is equipped with one channel of sensitive BF3 counting
equipment. The counting chamber is located in guide tube 2 (Figs. 2.1.4
and 2.1.5). The electronic instruments used with these chambers follow
typical practice (Fig. 2.2.1).

This sensitive BF3 channel is required to get counting-rate '"con-
fidence" at the neutron source level when the reactor is less than half
filled or when it is being filled with flush salt. Except for the pre-
amplifier, the electronic instruments shown in Fig. 2.2.1 are mounted in
the nuclear instrument cabinet in the auxiliary control room. As soon
as confidence is established by one or both wide-range counting channels,
the BF3 chamber is withdrawn manually to prevent its being damaged.

2.2.2 BF3 Counter
The neutron counter is & BF3 counter from Reuters-Stokes Company,

No. RSN-28A, procured on UCNC purchase order No. 568-1724, May 11, 1964.
The specifications and characteristics are as follows:

Shell (shell is cathode)

OQutside diameter 2 in. gfij
Wall thickness (wall is the 0.55 in.
cathode)
Overall length 12 in.
Active length g.13 in.
Material Aluminum
Anode 0.002-in.-diam wire in-

sulated from the shell
with ceramic insulation

Filling Enriched BF3; (96% *°B) to
a pressure of 40 cm Hg
abs

Performance

Thermal-neutron sensitivity 15 counts sec™t (nv)™*

Saturation curve See Fig. 2.2.2
 

107

For use in the MSRE, the counter is encased in a weighted water-
proof can, described by Instrumentation and Controls Division drawings
Q-2719-3 and -4. A jointed push rod is used as a handle to position the
counter within the guide tube in the penetration.

2.2.,3 High-Voltage Power Supply

The high-voltage power supply is manufactured by Electronic Research
Associates, model 25/10UC. The output from the power supply is contin-
uously adjustable from 500 to 2500 v dc, positive or negative, by six
step-switch positions and a fine control. Maximumn load current is 10 ma
for any voltage. The total amount of ripple, hum, and noise is less
than 5 mv rms. ILine regulation is #0.005% for a +10% change of line
voltage. Load regulation is a 60-mv change from no load to full load;
recovery time is less than 10 msec. Front panel meters indicate from O
to 10 ma and from O to 2500 v dc. The input is 115 # 10 v ac, 60-hertz,
single-phase, l-amp.

2.2.4 Preamplifier, ORNL Model Q-1857

The preamplifier consists of a three-stage feedback loop, followed
by a resistance-capacitance differentiator, and a second three-stage
feedback loop. The third stage of the second loop is a power stage to
drive a long, low-impedance transmission line. The gain of each loop is
about 20. A 2.5:1 voltage loss occurs in the differentiator, so that
the overall gain is about 150. Variable compensation is provided across
the feedback resistor in each loop to produce satisfactory transient
response. The preamplifier power supply is self-contained.

2.2.5 Pulse Amplifier, ORNL Model Q-1875

The output of the ORNL model Q-1857 preamplifier is developed across
a 100-ohm resistor in the amplifier chassis. This resistor serves as
the characteristic impedance termination for the transmission line from
the preamplifier. The signal is coupled to & gain control,whose output
supplies. the signal to the pulse amplifier..

The pulse amplifier has two separate three-stage ampllflers with
feedback loops. The compensation on each feedback loop is adjustable:
compensation is used in the first amplifier to adjust the rise time of
the amplifier and in the second amplifier to make the transient response
satisfactory. The gain of each loop is approximately 100, but, due to
losses in the output cathode followers, the overall gain is about 5000.

The output of the main amplifier is available at "low" and "high"
output jacks. The low output is intended for driving long cables and
has a maximum value of 5 v. The high output will deliver approximately
100 v. '

A pulse-height selector (PHS) is included on the amplifier chassis
for measuring pulses between O and 100 v. The PHS is direct reading with

 
 

108

an accuracy of approximately 0.5 v. Two PHS outputs are provided: the
first, a positive pulse with an amplitude of 3 v and a width of 0.4 usec,
intended for driving a count rate meter, appears at CN6; the second, with
an amplitude of about 20 v negative and of slightly longer duration, ap-
pears at CN5. The second is intended for driving a scaler.

The amplifier contains its own power supply and is designed to
operate with 115-v, 60-Hz power.

2.2.6 Scaler, ORNL Model Q-1743

The scaler has & fast input decade consisting of a type 6700 beam
switching tube, a Schmitt trigger, and slow decades which are Ericsson
GC-10B glow transfer tubes. ZEach glow transfer tube is driven by & de-
coupled 1AG4 tube. The glow tube stages are followed by & pulse shaper,
register driver, and a six-digit mechanical register. The instrument
contains a regulated power supply. The input resolving time is 1 usec,
with a counting loss of less than 0.2% at 20,000 random counts per
second.

2.2.7 Logarithmic Count Rate Meter, ORNL Model Q-751

This instrument measures the average rate of a series of electrical
pulses. The input pulses are the output from the pulse-height selector
(Sect. 2.2.5). The pulses are randomly spaced, positive 3 v amplitude
and 0.4 psec long. The output of the instrument is logarithmic and spans
four decades. The average counting rate, in counts per second, is dis-
Played on a meter. In addition, provision is made for remote readout on
either a remote meter or a 10-mv recorder, or both. The indicating meter
is graduated from 1 to 10,000 counts/sec.

2.2.8 Confidence Trips

This instrument is composed of two Control Data Corporation,
Magsense level comparators. Each unit is designed to accept an input of
O to 100 pa dc. The trip is continuously adjustable in this range. The
trip level and hysteresis are adjustable by potentiometers mounted on
the rear panel. The output consists of two SPDT relsy contacts.
 

109

ELECTRONIC RESEARCH

 

 

 

 

 

 

 

 

 
  
 
 

ASSOCIATES
2.5/10UC
CHAMBER
POWER
SUPPLY
r
)
BF3 COUNTER Pg]IT:vSE
REUTERS-STOKES AMPLIFIER
RSN -28A RC13-10-57

 

 

 

 

ORNL-DWG 66-2446

 

 

 

 

 

(=

      

PULSE
PREAMP
RC13-10-56

Fig. 2.2.1.

 

DECADE

SCALER

Q-1743-C

+ - RC13-10-59
LOG COUNT - + = ¥
RATE METER |— TRIP COMP TRIP cognp
RC13-10-58 LCR>10cps LCR<10 cps}
—HFTT< K1

CAL USE|+ cONSOLE
O ((LO-

 

 

 

 

 

 

 

 

 

 

 

 

—H:‘HWHKZ

 

 

 

 

 

 

 

TO BF-
CONFIDENCE CIRCUIT

 

Diagram of BF3; Counting Channel.

 
 

110

ORNL-DWG 66 —10019

 

 

 

 

 

 

 

 

 

 

 

 

 

{0
nmn
IO 8 /I
P ¢+’
b — 0————./
b 1
o 1
x ©
L
o
w
—
5
o 4
O
2
0.9 1.0 {11 {.2 1.3 14 1.5

ANODE (kilovolts)

Fig. 2.2.2. Typical Plateau Curve for Reuters-Stokes BF3 Counter
Type RSN-28A0
 

111
2.3 WIDE-RANGE COUNTING CHANNELS

2.3.1 Principle of Operation

The wide-range counting chammel employs a 2-in,~diam, 6~1/2-in,-
long fission chamber as the neutron sensor and is useful from startup
(with a fully fueled core vessel) to full-power operation at 10 Mw. The
principle of its operation, described elsewhere,l’2 is repeated here as
a convenience to the reader.

The design of this wide-range counting system is explained by ex-
amining the behavior of a movable neutron sensor submerged in, or sur-
rounded by, & neutron reflecting and absorbing medium in which the neu-
tron attenuation with distance is approximately exponentiasl. For purposes
of explanation it is sufficlent to consider the idealized case in which
neutron attenuation as a function of distance from the neutron source is
exactly exponential. For this idealized situation

CR = Pe ¥ | (1)

vhere CR is the count rate in counts per second, P is the reactor power
(assumed proportional to flux), x is the distance from the reactor, and
L is the attenuation coefficient of the medium surrounding the fission
chamber., Rearrangement gives

-~

log P = log CR + HX . (2)

It is apparent from Eq. (2) that log P is the sum of two easily obtained
numbers: the logarithm of the counting rate (log CR) and the distance,
x, of the sensor from the neutron source multiplied by a constant, M.
Inverse reactor period is obtained in the usual way by differentiating
Eq. (2) with respect to time.

Figure 2.3.1 is a simplified diagram of the arrangement of the in-
struments that perform the operations of measuring the neutron flux and
distance, obtaining a logarithm, adding, and differentiating. 1In the
MSRE (or any other installation), neutron attenuation is not ideally ex-
ponential,3 as assumed in the preceding paragraph; instead, u varies
with x, and the form of this variation can only be established by exper-
iments with the equipment installed for use at the reactor. An adjust-
able position~-sensing device, the ORNL model Q-2616 function generator,
produces a signal proportionsl to ux, The adjustment feature provides
a means to compensate for variations in p with x and, further, permits
these adjustments in situ.

 

1R. E. Wintenberg and J. L. Anderson, Trans. Am, Nucl. Soc. 3,
45455 (1960).

2J. L. Anderson and R. E. Wintenberg, Instrumentation and Controls
Div. Ann. Progr. Rept. July 1, 1959, ORNL-2787, p. 1l45.

3MSRE Project Staff, Molten-Salt Reactor Program Semiann. Progr.
Rept. Feb, 28, 1966, ORNL-3936.

 

 

 
 

 

112

The fission chamber is moved toward or away from the reactor by a
servomechanism which attempts to maintain a constant output from the
count rate meters. The value of this constant output (the count rate
set point) is, within limits, arbitrary. It should be high enough to
ensure a good signal-to-noise ratio in the input to the count rate
meters, but it should not be so high that fission counter 1life is seri-
ously reduced. A typical value for the count rate set point is 10,000
counts/sec. These wide-range channels can provide useful operating and
control information as long as the counting rate is in the range from 1
to 100,000 counts/sec. Limiting values of count rate are used to pro-
vide control system interlocks, discussed in detail in Sect. 2.6. The
operation of a wide-range counting channel is explained in the discus-
sion by tracing its response as the reactor goes from subcritical to
full-power operation. Figure 2.3.2 shows curves of count rate and
chamber position during a traverse of the reactor through its power
range. The curves are based on the assumption that the count rate set
point has been established at 10,000 counts/sec.

In the source and very low power region, where the count rate is
less than the set-point value of 10,000 counts/sec, the error signal,
which is the algebraic difference between the actual count rate and the
set point, is negative. This causes the servomechanism to drive the
chamber toward the reactor until its lower limit is reached. The cham-
ber will remain inserted at the lower limit until the reactor power is
sufficiently large to produce a count rate of 10,000 counts/sec. While
the chamber is at the lower limit, ux is constant, and (see Fig. 2.3.1)
the rise in reactor power is followed by the output of the logarithmic
count rate meter. When the reactor power is high enough to produce
10,000 counts/sec with the chamber at the lower limit, the error signal
becomes positive and the servomechanism withdraws the fission chamber
to maintain the count rate constant at 10,000 counts/sec. Changes in
reactor power are now indicated by changes in the "compensated position,'
ux, the output of the ORNL model Q-2616 function generator.

If, for example, the count rate set point is changed arbitrarily
from 10,000 to 12,000 counts/sec while the chamber is partially with-
drawn and the reactor is in steady state, the servomechanism will insert
the chamber a sufficient distance to satisfy the increased count rate
request. The decreased value of px will exactly equal the increase in
log CR, and the sum of the two, log P, will remain constant, as it
should., Again, suppose that, with the reactor in steady state, the
operator switches from servo control of position to manual control and
arbitrarily withdraws the chamber a short distance, The decrease in
log CR will be balanced by the increase in px, and their sum, log P,
will remain constant., Now, suppose the operator continues to withdraw
the chamber manually so that the counting rate approaches 2 counts/sec,
which has heen established as the useful threshold operating value for
the system., The count rate signal will contain s higher percentage of
spurious electrical input "noise," and, also, the random variations in
the neutron flux will become more apparent as the count rate is de-
creased.

In common with all counting instruments of this general type, the
response of the count rate meter becomes progressively slower as the
count rate decreases, The loss in response is such that when the count
rate is reduced to about 500 counts/sec, the logarithmic count rate

1
 

113

meter is unable to follow the change in count rate produced by manual
chamber withdrawal, Therefore, in such a case, the indicated power
would lag and would be higher than actual power. This response lag
would continue to produce an error, and the indicated power reading
would be higher than actual power until the chamber had stopped moving
and enough time had elapsed to attain steady state in the new position.
This situation obtains regardless of whether the chamber is being in-
serted or withdrawn manually. In manual insertion at count rates below

500 counts/sec, the indicated power will lag and appear lower than actual
power. As the count rate is lowered, the output of the counting system,
log P, may become erratic and fluctuate about the average value. At
very low counting rates the ratio of useful signal to noise decreases
and accuracy suffers. If chamber withdrawal continues until the count
rate becomes less than 2 counts/sec, the confidence circuits will be
actuated and the "no-confidence" interlocks governed by that channel
will be established. If the reverse process takes place, the chamber
may be inserted until the counting rate becomes 50,000 counts/sec, at
which point the confidence circuits will also be actuated. This upper
bound of system operation was established at this value to keep the
instruments within their operating range. The confidence circuits and
their functions are discussed in Sect. 2.6.6.

From the foregoing it is evident that, if the count rate is 500
counts/sec or more, the servo need be fast enough to follow only normal
maneuvers; any transients too fast for the servo to follow will change
the count rate so that the chamnel will read correctly. This technique
has several advantages: the operator need not switch range or take any
other action, the system covers a very wide range of reactor pover,
manual withdrawal of the chamber and the dead time induced when the
chamber is withdrawn are eliminated, and the constant, optimum count
rate of the amplifier is maintained when sufficient flux is available.

Figure 2.3.3 is a detailed block diagram of a wide-range counting
channel as used in the MSRE and includes the ORNL model Q-2609 fast-trip
comparators (described in Sect. 2.5) which produce the trip signals re-
gquired by the reactor control system. The increased number of operational
amplifiers shown in Fig. 2.3.2 are required to obtain signal gain for
impedance matching to output devices and for signal inversion (sign
change).

The detector, preamplifier, and radiation~resistant interconnecting
cable are contained in an integral assembly, ORNL model Q-2617. This
assembly, approximately 2 in. OD, is flexible so that a guide tube or
thimble, curved if required, can be installed in the reactor shielding
leading to the core. The assembly is waterproof and can operate con-
tinuously in an ambient temperature of 100°C while surrounded by either
air or water. ' .

The detector is a fission chamber with concentric cylindrical elec-
trodes coated with 1 mg/cm?® of 23°U over a total area of 860 cm®. The
chamber is well saturated with 200 v applied; the operating polarizing
potential is 270 v. The collection time is approximately 80 nsec. The
pulse-height characteristics of the chamber, obtained by using the pre-
amplifier described below, are shown in Fig. 2.3.4. It is evident that
garma. pileup presents no problem, even in fields as high as 2 X 106 r.
The chamber has ceramic insulation entirely, and the special cable con-

 
 

 

114

necting the chamber to the preamplifier is designed to withstand a .
garma~-ray dose of 1010 r, o

The output stage of the preamplifier drives one side of a balanced
line, the other side of which is terminated symmetrically. This sym-
metry and careful attention to shielding and grounding make the assembly,
as demonstrated in many field tests, very insensitive to electrical noise
pickup.

The receiving end of the bhalanced line feeds a pulse transformer
for common-mode rejection and clipping to give an approximately sym-
metrical waveform. This avoids base-line shifts due to changes in
counting rate and aids in keeping the discrimination level constant.

Pulses from the pulse transformer are sent to the pulse amplifier
and count rate meter, ORNL model Q-2614. Following a calibrated at-
tenuator the pulses are amplified in two feedback stages, each with a
gain of 10, and enter a biased amplifier whose variable bias level de-
termines the discrimination level. Only pulses that exceed the dis-
crimination level are counted. The output pulses from the biased-ampli-
fier discriminator are shaped and applied to a conventional logarithmic
count rate cirecuit of the Cooke-Yarborough type. The time constants
are a compromise between the desire to have rapid response and the
necessity to prevent excessive fluctuation in the period signal.

The output of the log count rate circuit is applied to an ORNL
model Q-2605 operational amplifier (1A in Fig. 2.3.3) whose gain is
adjusted to give an output of 2 v/decade, or 10 v full scale. The
function generator output is applied to amplifier 2B through the nor-
mally closed contacts of Kl. The gain gives an output of 2 v/decade.
Amplifier 2B is also used in a test mode and will be described later. Qij
The outputs of amplifiers 1A and 2B are summed, with a gain of 1/2, in
amplifier 2A, yielding an output signal proportional to reactor power.
The span of the sumning amplifier 2A is 10 v, or 1 v/decade. The out-
puts of the log count rate amplifier (1A), the summing amplifier (2A),
and the gain amplifier (3B) are indicated on panel meters in drawer W-1.

The generation of a period signal from the reactor flux signal is
accomplished with operational amplifiers 3A and 3B. The output from
amplifier 3A is the approximate derivative of the log P input with a dc
gain of 4 (product of C 308 and R 331). To prevent excessive noise in
the period signal a 250-kilohm input resistor and a l-uf feedback ca-
pacitor are provided to limit the low- and high~frequency noise gain
respectively. The output of amplifier 3A is amplified by amplifier 3B
and is offset so that O to +10 v corresponds to a period of —~30 to +5
sec, An infinite period is +1.428 v provided by the offset network at
the input of the amplifier., The amplifier gain is 24.6. The pulse
amplifier and count rate meter module, ORNL model Q-2614, has, in ad-
dition to the log count rate output, a simple diode pump circuit (linear
count rate circuit) whose output is used as the signal for the chamber
position servo. This circuit has an output of approximately 1.75 v at
10% counts/sec. This signal is compared with the demand potentiocmeter
(servo level) in amplifier 1B. Amplifier 1B has a voltage gain of 50;
further voltage and power gain are provided by a servo amplifier, ORNL
model Q-2615, which has an approximate voltage gain of 3 and whose output
drives the servo motor directly. In addition to the chamber, the motor
drives a tachometer whose output is applied to the servo preamplifier Q;J
 

115

1B and with a polarity opposite that of the input signal; this negative
feedback loop provides servo stability.

To provide control interlocks, eight fast-trip comparators, ORNIL
model Q-2609, are used. Two fast-trip comparators receive their input
from the log count rate amplifier (1A). Comparator 1 trips if the
comnting rate is less than 2 counts/sec, whereas comparator 2 trips if
the counting rate is greater than 50,000 counts/sec., Their output
(relay contacts), in series with the "calibrate-operate" relay contacts,
provides counting channel confidence if all eight comparators are prop-
erly plugged into the instrument cabinet drawer (see Sect. 2.5 for ad-
ditional discussion of confidence). Summing amplifier 2A provides the
input to three fast-trip comparators. The first comparator operates if
the power "sags" below 200 kw while in the "Run" mode; the second oper-
ates when the power is above 500 kw, thus giving permission to enter the
"Run" mode; and the third initiates a control rod "reverse" if the
pover exceeds 1.5 Mw in the "Start" mode.

Several tests are provided to ensure that the system is operating
properly. There is contained in the pulse amplifier module (Q-2614) a
10%- and 10-cps oscillator which may be applied to the input of the
pulse amplifier by proper positioning of the gain switch on the front
panel. In addition, with the gain switch on period test, the period
test relay (KL) must be actuated by a push button in drawer W-1. This
switches out the normal inputs and feedback resistors of the function
generator amplifier and switches in a 10-pf feedback capacitor and a
selectable input resistor. With an input of 25 v applied through the
gain switch, this amplifier thus generates a voltage ramp which pro-
duces a 5-, 25-, or 30-sec period indication as selected. An additional
push button in drawer W-1 causes an adjustable voltage source to be ap-
plied to amplifier 2A to test its fast-trip comparator. "In" and "out"
push buttons on the same drawer provide normal override of the normal
servo signal from the output of the Q-2615 module,

The chamber drive mechanism is a ball-bearing lead screw with a
linear speed of approximately 72 in./min and a total stroke of 90 in.
The direct=-current, variable-speed drive motor has an integral tachom-
eter and is protected from overload by a slip clutch. The position~
sensing components are connected directly to the lead screw shaft ahead
of the slip clutch. -

The position-sensing train contains a ten-turn potentiometer whose
output is connected to a meter in drawer W-l. In addition, a one-turn
data-logger potentiometer and synchro transmitter for driving a position
indicator on the console is provided. Upper and lower limit switches
restriet the overall travel of the unit.

2.3.2 Fission Chamber and Prégmplifier Assembly

The‘following description has been excerpted from ORNL-3699 (ref.
4). The 3/4-in, fission chamber described in ORNL-3699 has been re-

 

4D, P, Roux et al., A Miniaturized Fission Chamber and Preamplifier
Assembly (Q-2617) for High Flux Reactors, ORNL-3699 (October 1964).

 
 

116

placed with one of more typically standard dimensions (2 in. diam) with .
greater sensitivity. The excerpted text has been altered accordingly. &,J

2e3.2,1 Introduction

To meet the space and environmental requirements for high-perform-
ance reactors, an articulated assembly (Fig. 2.3.5) consisting of a
fission chamber, a preamplifier, and flexible cables has been developed.
Because high-flux reactor cores are usually inaccessible, it becomes
necessary to use a detector that is small and movable in a tube which
can be bent to resolve the access problems at each reactor. The rel-
atively low sensitivity of a small chamber is compatible with the large
neutron source level encountered in such reactors. Locating the pre-
amplifier close to the fission chamber drastically reduces the suscep-
tibility of the counting channel to electrical noise pickup, so that the
system responds predominantly to neutrons; comsequently, the reactor
operator is assured of an adequate source. The assembly is particularly
suitable as part of a wide-range counting channel,l but also can be used
as part of a conventional counting channel. .

The entire assembly is waterproof and can operate continuously at
a temperature of 100°C ambient. The maximum outside diameter of the
assembly is 2 in. (chamber diameter). The fission chamber and the cable
connecting it to the greamplifier can withstaend a total integrated gamma
radiation dose of 101Y rads; the preamplifier can withstand at least 108
rads.

2.3.2.2 Preamplifier ‘iJ

Circuit
The preamplifier circuit (Fig. 2.3.6) consists of two cascaded
feedback amplifiers: a charge-sensitive input configuration (Vl and

VZA)’ followed by a voltage-sensitive asmplifier (V2B’ V,, and V;) with

symmetric output. The signal pulses are differentiated both at the in-
put and at the output of the preamplifier, giving the pulse shape shown
in Fig. 2.3.7. The gain of the preamplifier is 0.75 x 1012 v/coulomb.
This corresponds to a system output pulse height of 150 mv for a nominal
50-Mev fission fragment. The counting loss for randomly spaced pulses
is 10% at a counting rate of 10° counts/sec.

The advantages of a charge-sensitive configuration are that, over
a wide range of detector capacitance, (1) the output signal height de-
pends only on the charge generated within the detector and is insensitive
to the capacitance of the detector and connecting cable (variation of
input capacitance from O to 200 pf produces a gain change of only 10%),
and (2) the decay time of the detector pulse is also insensitive to the
capacitance of the detector and cable (variation of input capacitance
from O to 200 pf produces a decay time change of only 10%).

The preamplifier output is connected to a balanced and shielded
cable which is terminated at its receiving end by a pulse transformer.
The common-mode electrical fluctuation signals picked up by the two
signal leads are canceled in the pulse transformer., In one application
at a reactor the common-mode rejection was greater than 95%.
 

117

The double differentiation reduces the effects of pulse pileup.
With the first differentiator at the input to the preamplifier, the max-
imum counting rate is limited by coincidence loss rather than by bias
shifts. The pulse transformer serves as the second differentiator. The
second differentiation time constant is determined by the ratio of the
primary inductance of the transformer to its terminating resistance.

The combined effect of both differentiators eliminates any duty-cycle
shift in the main-amplifier discriminator threshold. Figure 2.3.7 is a
photograph of the fission pulses at the main amplifier input. The in-
tegrals of the individual pulse areas on either side of the reference
are equal.

Component Selection

The operating temperature, the radiation requirements, and the per-
missible overall diameter of the assenmbly demanded prudent selection of
the components used in the preamplifier,

Tubes. — Temperature and radiation conditions precluded the use of
transistors; consequently, flying-lead subminiature tubes were selected.
Nuvistors were considered but were rejected because their diameter is
too large to mount components side by side with the tubes in the allotted
space.

Resistors. — Resistors were limited to those of wire-wound and de-
posited-carbon types. The wire-wound resistors (miniature power ratings)
were used in all critical circuit locations sensitive to the value of a
resistor; deposited-carbon resistors were used in noneritical circuits.

Capacitors. — Capacitors were limited to those of porcelain and
solid tantalum electrolytic dielectrics. The particular ceramic capac-
itors used (Vitramon type VK20) have maximal operating conditions of
150°C and 200 v. A 10%-rad gamma dose results in a capacitance variation
of less than 1%. The tantalum capacitors (Texas Instrument type SCM)
are used only for bypassing in circuits which can tolerate high leakage
currents and considerable capacitance variations. The operating tem-
perature of the tantelum capacitors is limited to 125°C. As a result,
they are located in the preamplifier layout, where negligible heat power
is dissipated (see the following section). Irradiation tests made at
ORNL, on four type SCM tantslum capacitors to an accumulated dose of 108
rads showed an increase of less than 5% for the dissipation factor.

 

Provisions for Operation at 100°C Ambient

For continuous operation of the preamplifier in air or water at
100°C ambient, the following provisions were made:

1. The preamplifier was potted in a mixture of 70 wt % epoxy Helix
P-430 and 30 wt % epoxy Dow Chemical DER 732 to which was added 6% of
Helix hardener B. This particular potting compound improves the heat
transfer and increases the mechanical rigidity of the preamplifier.

The advantages of using this compound are that it is only slightly brit-
tle at room temperature, it shrinks minimally during curing (the shrink-
age of some epoxies during curing has caused tube and tantalum capacitor
breakdowns), and its thermal expansion coefficient is compatible with
that of the preamplifier components.

2. The tube filaments are heated with a voltage of only 5.5 v
(6.3 v rating) to minimize the heat-power generation.
 

 

118

3. The tantalum capacitors (125°C max) are located at the ends of
the preamplifier, whereas the subminiature tubes are positioned in the
center of the preamplifier. The ceramic capacitors (150°C max) are also
located at the ends, except for a group which is placed in a gap between
the first and the second tubes as shown in Fig. 2.3.8.

Two different tests were performed to establish that the capacitors
operate below the manufacturers! specified maximum temperatures when the
preamplifier is in a region with an ambient temperature of 100°C. In
the first test the preamplifier was placed in still air at 100°C in an
oven, In the second test the preamplifier was immersed in water at 98°C.
In both tests five thermocouples were located inside the preamplifier
close to the components of interest, and the time profiles of the tem-
peratures were recorded. The results indicated that the equilibrium
temperatures of all capacitors were at least 6°C below the manufacturers!?
maximum specified temperatures in the first test and 14°C in the second
test. The first test lasted ten days; during this time no change in the
preamplifier gain or output pulse shape was observed.

Separation Distance of Preamplifier to Chamber

The separation distance between the preamplifier and the fission
chamber should be short to satisfy the electrical noise pickup consid-
eration, but must be long enough to limit the radiation damage to the
preamplifier. (The preamplifier was designed to withstand an accumu~
lated dose of 108 rads over one year of continuous operation.) The
evaluation of the effects of the accumulated dose should be separated
into two parts: +the dose accumulated during operation of the reactor
at power and the dose accumulated during reactor shutdown. In light-
water-shielded reactors, the dose accumulated during reactor shutdown
is considerably alleviated if the neutron counting rate is restricted
to 10* counts/sec or less. The reason for this is that photoneutrons
generated in the water by the residual fission product gammsa rays will
give a neubtron counting rate that makes the insertion of the fission
chamber and preamplifier assembly into a higher gamma flux unnecessary
(see Sect. 2.3). For application in light-water-moderated reactors, a
separation length of 4-1/2 ft between the fission chamber and the pre-
amplifier is adequate, This distance is also sufficient to maintain
the preamplifier in a gamma flux less than 10% r/hr (or 10% r/year)
when the reactor is at full power.

2.3.2.3 Flexible Cables

Cable Between Fission Chamber and Preamglifier

The cable between the fission chamber and the preamplifier is a
BIW 50-ohm coaxial cable enclosed in an external inorganic insulation
sheath (spaghetti). The sheathed cable is inserted into a 1/4-in.-ID
corrugated flexible metal tubing fitted with stainless steel braid and
casing., The BIW ceble is a flexible, high-temperature (500°C max),
radiation-resistant coaxial cable. It consists of a 24-gage stranded
nickel-clad copper center conductor, an inorganic insulation, and a
nickel-clad copper outer braid 0.200 in. in OD. Its capacitance is 35
pf/ft. The corrugated tubing provides watertightness and flexibility
 

119

with negligible elongation. The measured linear-expansion coefficients
of the cable assembly are approximately 2 X 10™ per 1b and 1 X 107>
per °C.

Cable Between Preamplifier and Main Amplifier

This cable is a Raychem No, 10023 cable. It has preirradisted
polyethylene dielectrics and jackets, is radiation resistant, and is a
multilead coaxial cable., The center member of this composite cable is
a shielded and Jjacketed two-conductor coaxial cable for the signals;
around the center member are wound three 26-gage and two 20-gage hookup
wires for preamplifier supplies, and over all of these are a nickel-clad
copper shield and a preirradiated polyethylene jacket. The maximum
overall OD is 0.324 in. The cable will withstand a maximum temperature
of 125°C and an sccumulsated dose of 5 x 10% rads. Following this ex-
posure the cable can still be coiled on a form whose diameter is ten
times the overall cable diameter.

The Raychem cable is also enclosed within a watertight metallic
envelope which may be varied for different reactor applications. The
metallic envelope also serves as an electrical shield. For example, a
stainless steel hose covered with polyvinyl chloride is used at the Oak
Ridge Research Reactor (ORR).

2.3.2.4 Electrical Shielding Layout

Multiple electrical shields are provided to prevent excessive elec-
trical noise pickup in the fission chamber and preamplifier assembly.
Figure 2.3.9 shows, schematically, the general shielding and grounding
layout. A first (or inner) shield covers the entire path of the signal
from the fission chamber to the main amplifier input. This shield in-
cludes the cathode of the fission chamber, the outer braid of the BIW
coaxial cable, a solid brass foil surrounding the preamplifier, and the
two braids of the Raychem multilead coaxial cable. The preamplifier
commonh mode, or ground, is electrically connected to the inmner shield,
which is electrically insulated from an outer shield, or shell, of the
assembly. This outer shield includes the fission chamber casing, the
corrugated flexible metal tubing between the chamber and the preamplifier,
the preamplifier casing (insulated from the brass foil shield), the me-
tallic envelope surrounding the Raychem cable (described previously),
and a shielding which forms an extension of the metallic envelope to
the main amplifier in the reactor control room. The grounding of the
inner and outer shields is discussed in Sect. 2.3.2.5.

2.3.2.5 Low Pickup-Noise Performance of the Assembly

Extensive experimentation with different counting channels using
this assenmbly was required to reduce its susceptibility to electrical
noise pickup. The principal source of electrical noise pickup is elec-
tromagnetic radiation from ac power lines which are shock excited where
some piece of equipment is turned on or off. The sensitivity to noise
pickup has been minimized by the short separation distance between the
preamplifier and the chamber, the large output signal from the pream-
plifier, the balanced configuration with common-mode noise rejection,
and the multiple electrical shielding.

 
 

120

The lowest noise pickup is achieved with this assembly when the
inner and outer shields are connected together in several places, for
example, at the junction box and at the main amplifier, as shown in Fig.
2.3.9, This is contrary to the generally accepted precept of avoiding
ground loops. Apparently, the capacitive coupling between shields de-
feats any attempt at isolation of the system from the building ground.
With the connections described herein and shown in the Fig. 2.3.9, the
pulses from pickup are no larger at the main amplifier input than the
pulses of the alpha particles produced in the fission chamber, even
when the assembly is located in the noisiest reactor installations
available at ORNL.

2.3.3 Preamplifier Power Supply

2.3.3.1 General

The fission chamber and preamplifier dc power supply provides three
regulated output voltages from an unregulated input supply of —32 + 4 v
for use with the fission chamber and preamplifier assembly ORNL model
Q~-2617-1. The three outputs are: +300 v for polarization of the fission
chamber, +110 v for the preamplifier anode supply, and —22 v for the
preamplifier vacuum tube heaters and for biasing.

The -22 v is derived directly from the —32-v battery supply through
a series regulator and a current-limiting eircuit. The other two volt-
ages, +300 v and +110 v, are developed by a dc-to-dc converter with a
series preregulator.

2.3.3.2 Construction

The fission chamber and preamplifier dc power supply is contained
in a module 4.25 in. wide, 4.72 in. high, and 11.90 in. deep. It is a
standard "three-unit" plug-in module of the ORNL modular reactor in-
strumentation series depicted on drawings Q-2600-1 through Q-2600-5.

The circuits are on two printed circuit boards mounted parallel to
each other and enclosed in a perforated metal shield to reduce electrical
radiation and coupling to other modules. Adjustments and test points
are accessible through the shield from the top of the module.

2.3.3.3 Application

The module is intended to supply all required voltages to the fis-
sion chamber and preamplifier assembly. Because the assembly is potted
and unrepairable, the povwer supply is designed to limit currents and
voltages to protect both the assembly and the power supply ageinst
demage from almost any conceivable combination of crossed connections

or short circuits.

2.3.3.4 Specifications

Overall specifications for the preamplifier power supply are given
in the following table.

General

Power required =32 * 4 v dc, 0.5 amp max
Ambient temperature range 0 to 55°C
 

 

121

—22=V sSuUpply

Output voltage range —20 to —24 v dec

Output current range 200 to 400 ma

Voltage regulation +19

Current limiting Adjustable to limit the output cur-

rent to no more than 110% of nor-
mal operating current from normal
to short circuit

+300-v supply

Output voltage +300 £ 15 v dc
Output current 0 to 100 pna
Current limiting 3 ma max, any load
Noise and ripple 100 mv max

+110-v supply

Output voltage +110 + 10 v de
Output current 0 to 15 ma

Current limiting 100 ma max, any load
Noise and ripple 10 mv max

2.3.3.5 Circuit Description of the —22-v Supply

The —22-v supply consists of a voltage regulator (Q8, Q9, Ql0) and
a current-limiting circuit (Q7, D12, D13). The limiting circuit pro-
tects the series heater string of the preamplifier from damage when any
of several possible fault conditions occur.

The action of the limiting circuit is similar to that of a con-
stant-current circuit. The base voltage of Q7 is held constant at +2 v
with respect to the —32-v supply by the two Zener diodes D12 and D13,
The breakdown voltages of the diodes are 12 and 10 v, respectively, but
they are connected in opposition so that the reference voltage is the
difference in the two voltages. This arrangement yields a sharper knee
and a stiffer reference voltage than a single low-voltage diode. The
emitter voltage is different from the base voltage only by V be the base-

emitter voltage drop of the tran51stor, vhich is fairly constant. Thus,
the emitter voltage is constant across a fixed resistance R22 and R26,
yielding a constant current in the emitter of Q7, provided that the
collector-emitter voltage is large enough to keep the tran31stor out of
saturation. When "normal" output current is flowing (less than the limit
current),'the voltage at the collector of Q7 is less than 2 v more pos-
itive than the —32-v supply, and Q7 is saturated. 1In this condition

Q7 81mply acts like & series re31stor and does not control the output
current. It is only when the output current tends to increase above
normal that Q7 comes out of saturation and limits the output current to

1 _ vz'_ Vfie
. . T ———————— ,
it pog 4 R22

 
 

122

where VZ is the difference in the breakdown voltages of D12 and D13 and (

v

e 18 the forward base-emitter voltage drop of Q7.

The voltage regulator consists of Q8, Q2, and Q10. The output
voltage is sensed by the base of Q9 and is compared with the wvoltage
of reference diode D14 in the emitter of Q9. The amplified difference
on the collector of Q9 is applied to the base of Q8; Q8 provides current
gain only to drive the base of the output transistor Ql0. The regulated
output voltage appears between the emitter of Q10 and ground. Diode D15
is used to protect Q8 from turnon transients.

The output voltage is adjusted with trimpot R30. The current at
which the circuit limits is set with the "current limit" potentiometer
R22.

2.3.3.6 Circuit Description of the +300-v and +110-v Supply

The supply is designed to operate from a nominal 32-v station
battery with a terminal voltage variation from 28 to 36 v de. This
wide variation makes necessary a voltage preregulation, which consists
of transistors Ql, Q2, Q3, and Q4.

The preregulator output voltage is sensed by resistors R7, R8, and
RO and applied to the base of amplifier stage Q3. A reference voltage
(16.8 v) generated by Zener diode string D2, D3, and D4 is applied to
the emitter of Q3. The amplified difference appears at the collector
of Q3 and is applied to driver Q2 and pass transistor Q4. A constant
collector current is provided for Q3 by transistor Ql, Zener diode DI,
and the associated network. Qfi)

The preregulator output (test point TPL) is filtered by Cl, C2, and
R27 and is applied to the dec-to-dc converter.

Q5, Q6, T1, and the associated circuitry comprise a free-running
square-wave oscillator inverter. Networks Cl5-R32 and Cl6-R33 round
the edges of the square wave somewhat to avoid the generation of sharp,
high-frequency spikes, which may be coupled to other circuits. The
110-v output is obtained from a full-wave rectifier and filter, and the
300-v output from a voltage tripler. The supply can be short circuited
without damage. Most transistor inverters will stop oscillating when
overloaded. The oscillator transistors can be damaged unless their non-
oscillating current is limited to a safe value. Current limiting by
series resistance in a primary lead is undesirable because power will be
wasted and the inverter will have poor load regulation., On the other
hand, biasing so that the transistor current goes to zero in the non-
oscillating condition will not allow oscillations to start when the
short is removed. The current-limiting scheme used here consists of a
combination of clamping and series-emitter resistance to set the current
to a predetermined value. R1l and R12 bias the bases of Q5 and Q6 into
conduction. R13 and Rl4 limit the transistor currents in the nonoscil-
lating condition to a little less than the oscillating currents. The
voltage drop across these resistors is less than the value that causes
appreciable current flow through D5, D6, and D7 until oscillation begins.,
In the oscillating condition, the drops across R13 and Rl4, respectively,
are limited by the diodes to 1.4 v. The low dynamic resistance of the
diodes assures a stable, nonoscillating current value.
 

123

2.3.4 Pulse Amplifier

2.3.4.1 General

The pulse amplifier and count rate meter amplifies and counts
pulses from a fission chamber. The input sensitivity is such that some
preamplification is required. The module consists of a pulse amplifier,
a pulse-height discriminator (PHD), a logarithmic count rate meter of
the Cooke-Yarborough type, a linear count rate meter, and two calibration
oscillators (10 and 104 counts/sec)

2.3.4.,2 Construction

The pulse amplifier and count rate meter is constructed in a module
5.6 in. wide, 4,72 in. high, and 11.9 in, deep. It is a standard "four-
unit" plug-in module of the modular reactor instrumentation series de-
picted on drawings Q-2600~1 through Q-2600-5.

The pulse-height discriminator and the linear and log count rate
circuits are constructed on one printed circuit board. The pulse am=-
plifier and the two oscillators are constructed on separate boards.

The pulse amplifier and discriminator count rate boards are housed in a
cadmium~plated steel compartment which covers the entire top of the
module. The two boards within this compartment are shielded from each
other by a cadmium-plated partition. The oscillator printed circuit
board is mounted horizontally at the back end of the module beneath the
compartment.

The front panel controls include a ten-turn potentiometer for the
pulse~-height discriminator and an 18-position switch for amplifier gain
control (13 positions) and module calibration control. A BNC connector
is mounted on the front panel to provide a signal for a scaler.

2.3.4.3 Application

The pulse amplifier and count rate meter is one element of a wide-
range counting channell for monitoring neutron flux over a ten-decade
span. It amplifies pulses from a fission chamber and preamplifier as-
sembly%* and provides logarithmic and linear count rate output signals.
An output pulse is also provided to operate a scaler.

The pulses from the preamplifier assembly are bipolar in shape,
vhich eliminates the problem of duty-cycle shifts in the pulse amplifier.
The pulse amplifier, however, can be used with positive unipolar pulses.
Count rates up to 10% counts/sec of unipolar pulses 1 psec wide can be
accommodated, with a resulting shlft in effective pulse amplitude of less
than 1%.

The logarlthmlc output 51gnal is a current which drives an external,
conventional operational amplifier, The output of the operational am-
plifier is used to operate indicabtors and other circuits.

The linear outpul signal is also a current which drives an external,
conventional operational amplifier. The output of the operational am-
plifier is used to operate other circuits. 1In the wide-range counting
channel, this linear signal is used as the control signal for a servo
system.

 
 

 

2.3.4.4 Specifications

124

Overall specifications for the pulse amplifier are as follows:

Pulse amplifier

Gain

Rise time (10 to 90%)

Linear pulse output
(100-ohm load or
greater)

Saturated output

Attenuator control

Pulse-height discriminator

Range

Integral nonlinearity
(including pulse
amplifier)

Output pulse for scaler

Amplitude

Rise time (10 to 90%)
Fall time (10 to 90%)
Pulse width

Log count rate output

Range
Amplitude

Accuracy (at 30°C)

Temperature effects

Linear count rate output

Range
Amplitude

90 % 5
Less than 0.07 psec
0 to +5 v

Less than 7.5 v for pulse widths
less than 0.5 pusec

13-position, 100-ohm ladder type
at amplifier input in 1, 1.5, 2,
3, 5, and 7 sequence

0.25 to +5 v with ten-turn Helipot
(500 divisions)

Less than +0.2% of 5 v from 0.25 to
5 v at 30°C and varies less than
0.03%/°C of its 30°C value between
0 and 50°C

+3.5 £ 0,25 v into load of 100 ohms
or greater

0.05 psec

0.05 usec (no output cable)

Varies with pulse amplitude in
excess of PHD bias

1 to 10° counts/sec in five decades

0 at 1 count/sec and up to approx
40 pamp at 10° counts/sec

Output deviates less than *3% from
the true log reading at any point
with regularly spaced input pulses

Output deviates less than *1% from
the 30°C value for any temperature
from O to 30°C; from 30 to 50°C,
output deviates less than +3% from
the 30°C value at each point

0 to 2.5 X 10* counts/sec
Approximately 170 pamp at 10%
counts/sec
 

Accuracy (at 30°C)

Temperature effects

Power reguirements

Voltage
Current drain

Regulation

Ripple

10 count/sec oscillator
Stability

Thermal error
Output pulse

Output pulse load
Pover supply

10% count/sec oscillator

Calibration accuracy at
70°C |

Thermal error

Output pulse

Output pulse impedance
Power supply '

Ambient temperature range
(all'units)_

125

Output deviates less than the equiv-
alent of +25 counts/sec from the
true counting rate from O to 10%
counts/sec with regularly spaced
input pulses

The deviation of the 10* count/sec
point from its 30°C value is less
than 0.3%/°C from 0 to 30°C and
less than 0.15%/°C from 30 to 50°C

+25 + 0,01 v; =25 + 0.01 v

75 ma from +25 v supply; 25 ma from
=25 v supply

+0.04% or better against +10% line
changes and with load changes
from no load to full load

Peak-to-peak ripple less than 0.01 v

30 ppm at 20°C with vertical ori-
entation of spring balance wheel
axis; 300 ppm at 20°C in any other
orientation

11 ppm/°C from O to 30°C

-11.7 v, 6 msec width, less than
20-psec rise time (10 to 90%)

50 kilohms minimum

~12 v £ 10% at 0.15 ma average; 3-ma
peak per pulse

Positive 0.000%; negative 0.004%

—4 ppm/°C at 70°C

8-v peak-to-peak square wave; less
than l-psec rise time (10 to 90%)

800 ohms |

=12 v + 10% at 7 na

0 to 55°C

2.3.4.5 Theory of Operation

General

The following description of the module (Fig. 2.3.10) is divided
into five main groups: (1) pulse amplifier and control switch; (2)
pulse-height discriminator, which includes the shaper stage and emitter-
follower; (3) pump driver, which includes the flip-flop, Q-25 as a

 
 

 

 

126

limiter-amplifier, and Q16 and Q17 as the complementary emitter-follower
drive; (4) pump circuits, which include both the log and linear pumps;
and (5) test oscillators.

Pulse Amplifier and Control Switch

The pulse amplifier consists of two fed-back groups which are cas-
caded to achieve an overall gain of 100. Each group has a voltage gain
of about 10, These two stages of amplification are preceded by a ladder-
type attenuator, where the input impedance is a constant 100 ohms at all
settings and the impedance, looking back from the amplifier input, is
50 ohms. The attenustor is part of an 1l8-position switch that (ls pro-
vides attenuation of the input signel in 13 positions, (2) disconnects
the amplifier input from the attenuator and grounds it through 100 ohms
in two "off" positions, (3) disconnects the amplifier from the attenuator
and applies 1.0% counts/sec to its input, (4) disconnects the amplifier
from the attenuator and spplies 10 counts/sec to its input, and (5) dis-
connects the amplifier from the attenuator and supplies a dc voltage for
application to a 5~sec period generator circuit that is external to the
module. Also, in all positions other than attenuator positions, the
control switch provides a dc voltage which actuates a front panel light
and can be used to actuate an external alarm.

The pulse smplifier design is tailored to amplify pulses of the
shape shown in Fig. 2.3.11A. This pulse shape is produced by a pre-
amplifier which double differentiates the pulses from a fission chamber
with a 0.125-pusec time constant. (The second differentiation is made
at a pulse transformer which terminates the balanced transmission line
driven by the preamplifier.) The preamplifier has a O.l-psec integrating
time constant. The amplifier may also be used to amplify unipolar pulses
clipped to 1 psec width or less, with the possibility that appreciable
base-line shift may occur at counting rates grester than 5 X 10%
counts/sec.

Both fed-back groups are of identical design. Each fed-back group
is a three-transistor configuration, with the first two transistors Ql
and Q2 constituting a differential pair. The output from the second
collector Q2 drives the third transistor Q3, which is an emitter-follower.
Feedback is made from the emitter of Q3 to the base of Q2. The output
signal is taken from the emitter-follower, and the input signal drives
the first base QL of the differential pair. This results in a group
with an output pulse of the same polarity as that of the input signal.
The pulse gain of the stage is very nearly (R6 + R?)/R6, neglecting the
shunting effect of R8 and R6. The measured”’ high-frequency feedback
factor for the stage was 10.

The fed-back group is dc-coupled &and has excellent de stability by
nature of the differential input and a dc feedback factor in excess of
100, The bias in the amplifier has been selected so that both positive
and negative portions of the bipolar input signal will be clipped pro-
portionately under overload, thereby retaining its bipolar nature.

 

5The procedure for measurement is given by E. Fairstein, Pulse
Amplifier Manual, ORNI~-3348, p. 20 (Oct. 26, 1962).
 

127

A closed~loop analysis, utilizing the hybrid-=n equlvalent circuit,
shows that the predominant time constant is nearly C bR16 [(Rb +
R15)/R151, where C,, 2nd Rb are the collector transition capacitance and
base resistance of Q2 respectively.

The output impedance of the stage was computed to be 12.6 ohms,.®

The ac input impedance of the stage is very nearly equal to that
of the base resistor Rl of the input transistor Ql, because the emitter
impedance of QL is R2 (5.1 kilohms) in parallel with the looking-in
impedance of Q2, which is nearly 300 ohms because of the feedback to
the base of Q2. Thus, with an effective emitter impedance of about 300
ohms, the impedance looking into the base of Q1 is sbout 30 kilochms for

an h_, of 100,
fe

Capacity coupling is used between the two fed-back stages and on
the output to the pulse-height discriminator. These coupling time con-
stants are in excess of 300 usec, which is adequate to eliminate the
effects of any further differentiation. The bipolar nature of the input
signal eliminates any possible duty-cycle shifts across these capacitors.

Pulse-Height Discriminator

The pulse-height discriminator (PHD) is based on a biased amplifier
scheme which is very similar to that used in the pulse amplifier. The
PHD control potentiometer R26 has ten turns, and the dial has 500 divi-
sions. The position of R26 determines the differential bias that exists
between the bases of Q7 and Q8. Since Q8 is conducting at any position
of this potentiometer, any positive input signal applied to the base of
Q7 must exceed this differential before Q7 is brought into conduction,
and any portion in excess of this differential is amplified by a factor
of 10.

The voltage drop across the PHD potentiometer R26 must be 5 v to
achieve the full~range control of 5 v for pulse-height discrimination.
The voltage can be trimmed to this value by adjusting R32. The "zero"
of the PHD can be trimmed by adjusting the values of R24 and R27.

 

 

 

 

e, (a)

6 . _ V (open circuit) _ (é;)

The output impedance R = T (short c1rcu1t) (A)/R ) s
where

A = open-loop gain, 100,

A" = closed-~loop gain, 10,

_R0 = open-loop output impedance.

. _ base impedance of Q3
In this case, Ro = re h of O3

: fe
4
- 26 + 22 =126 ,

100

 
 

128

An ac-coupled Schmitt trigger is used to shape the pulse from the
biased amplifier., The trigger sensitivity is 2.5 v. A more sensitive
trigger will create stability problems even though any sensitivity
changes are reduced by a factor of 10 when referred to the pulse am-
plitude, The sensitivity cannot be less than 0.5 v, because this is
gbout the amplitude of "feed-through" pulses of the biased amplifier.

Another consideration for keeping the Schmitt trigger sensitivity
large is to relax the bandwidth requirements of the biased-off amplifier.
The triangular-shaped character of the positive portion of the amplifier
pulse places a bandwidth burden on the biased-off amplifier for the
pulses which barely exceed the threshold level. The larger the pulse
required to actuate the Schmitt trigger, the greater the output required
from the biased amplifier. These larger pulses, because of their tri-
angular shape, will be wider at the base line and will require less
bandwidth from the amplifier. ,

The 2.5-v sensitivity of the Schmitt trigger results in PHD poten-
tiometer control that is ineffective below a pulse amplitude of 0.25 v.
This is only 5% of the 5-v full range and is considered to be only a
minor limitation. Trigger sensitivities in excess of 2.5 v would result
in even less usable portions of the PHD potentiometer and would not be
desirable,.

Transistor Q7 of the biased amplifier must have a base-to-emitter
breakdown voltage greater than 5 v. The 2N2432 transistor designed for

inverted chopper applications has a 15-v BVEBO rating.

The pulse out of the Schmitt trigger is applied to emitter~follower
Ql2. The magnitude of this pulse is +3.5 v, and its width depends on
the amount that the pulse amplifier pulse exceeds the bias setting (of
the PHD). The emitter-follower output drives the succeeding binary
stage and an external scaler. The recovery of the pulse at the emitter-
follower will be slow at the termination of each pulse if an untermi-
nated cable is used to make connection to a scaler, because the charged
cable will hold Q12 off and must be discharged through R47, a 6.2-
kilohm resistor.

Punp Driver

The pulse from the Schmitt trigger and its emitter-follower does
not have the proper amplitude or the width to drive the log and linear
pumps. A binary stage (also called a flip-flop) is used to further
shape the pulse. The output pulse of the flip-flop is rectangular,
having a width equal to the time elapsed between two successive pulses.,
This method of shaping automatically provides the pump circuits with
wide pulses without any increase in dead-time losses. The consequent
division of the pulse rate by a factor of 2 must, of course, be con-
sidered in the pump design.

The flip-flop design composed of Q13 and Ql4 is a saturated type
(i.e., the "on" transistor is driven into saturation) with resolution
capabilities of 107 counts/sec. When either Q13 or Q14 is "on," the
other is "off." The positive pulse from the emitter-follower acts to
turn the "on" transistor off, and the regenerative nature of the circuit
then switches the state of the flip-flop. Diodes D2 and D6 serve to
steer or apply the pulse to the base of the "on" transistor. To under-
stand how the steering is achieved, assume QL3 to be "on" and Q14 to be
 

129

"off." The collector of QL3 will be near +8.5 v, and the collector of
Ql4 will be near ground. Diodes D6 and D5 are in series and are back
biased by the difference in potential between the collector and base of
Ql4 (about 8.5 v). The base of Q14 is clamped to a potential slightly
more positive than +8.5 v by D4. (The only purpose for D3 and D4 is to
limit the back bias applied to Q13 and Ql4 when they are turned off.
With these diodes the back bias can never exceed about 0.5 v.) ‘In con-
trast, diodes D1 and D2, which are also in series, are only back biased
by a few tenths of a volt. Thus, a positive input pulse will take the
route through D2 (and to the base of the "on" transistor) in preference
to that through D6 because of the greater bias on D6.

Diodes D1 and D5 aid in another menner. They help discharge ca-
pacitors C19 and C20, respectively, by providing a low-impedance path
to €21 (a 2.2-pf capacltor) through the collector of the "on" transistor
between input pulses. These capacitors will acquire some charge as the
input signal proceeds to turn off the "on" transistor and, if permitted
to accumulate or to not sufficiently recover, can cause a malfunction
of the flip-flop.

The collector swing of Q13 and Ql4 is approximately 8 v. This
value is marginal to provide reliable operation of a pump circuit. Also,
the pump circuit input impedance is quite low and would drastically load
the flip-flop and impair its speed. Thus, some further amplification is
still required, and some impedance isolation is needed., It should be
recoghized that any amplification process must also achieve high ampli-
tude stability to achieve good pump performance. Transistors Ql5, Q17,
and Ql6, along with diodes D13, D14, D15, D16, and D17, are used to
perform this task. Diodes D13 and Dl4 are fast-recovery conventional
diodes, and diodes D15, D16, and D17 are 5.2-v Zener diodes. The role
of D7 will be explained below.

Amplification with controlled amplitude is accomplished by Q15,
the two fast diodes, and the three Zener diodes., The collector current
of Ql4 forward-biases diode D7 and turns Q15 off "hard." The collector
of Q15 is caught at approximately =17 v by the series string of the two
fast diodes and the three 5.2-v Zener diodes. When Ql4 is turned off,
D7 is released and QL5 is turned on "hard" by the base drive through
R53. Thus, the collector swing of Ql5 is from —17 v to essentially O v,
The two diodes in series with the Zener diodes isolate the large capac-
itance of the Zener diodes from the collector of QL5, permitting fast
rise and fall times. One diode is adequate for this isolation, but
two diodes give better temperature compensation for diode effects on
the diode pumps. = The Zener diodes have a specified rating of O, 005%
per °C change, and the variation of the saturatlon voltage of QL5 is
less than & few tenths of a millivolt per °C.

It should be apparent that the scheme just descrlbed is one where
the collector current of Ql4 is sampled rather than its collector
voltage, so that ampliflcatlon is not achieved in the usual sense. Hov-
ever, the method employed is one where no loading is placed on the flip-
flop, permitting it to operate at maximum speed.

Transistors Ql6 and Ql7 comprise a complementary emitter-follower
driving stage which applies the 17-v pulses to the pump circuits. The
necessity of a complementary design over that of a single emitter-fol-
lower can be explained if we momentarily include the pump circuits in

 
 

130

the discussion. The following section will discuss these in greater
detail. The negative-going step of the 17-v pulse proceeds to charge
the feed capacitors of the pump circuits (C26 through C30 for the log
pumps and €39 for the linear pump) through their respective diodes

(D18, D20, D22, D26, D28, and D32) to the full 17 v. On the positive-
going edge of the pulse {or the return to ground), these capacitors -
must now be discharged quickly to O v to be prepared for the next pulse.
This discharge path must proceed through the second diode of each pump
into the smoothing capacitor or output capacitor of each pump for proper
action of the pump., At this time Q17 is biased off and cannot provide
this discharge. Q17 is off, since its base is at or near ground, and
its emitter is at —17 v because the feed capacitor is behaving as a 17-v
battery. With Q16 in the circuit as the NFN complement, it will be
biased "on" and will permit the feed capacitor to discharge.

Punp Circuits

Logarithmic Pumps, — The log pump design is composed of six pumps
and is based on the earlier work of Cook.e--Yarboroug‘h.7 The dec currents
from each pump are summed at the common junction of R88, R90, R92, RY%,
R96, and R98 and are delivered to the summing junction of an external op-
erational amplifier. The composite response of six pumps is shown in
Fig. 2.3.12. BSince the output voltage of each pump is positive, the
conventional current flow will be out of these resistors. An additional
current of opposite polarity is supplied through R113 and is adjustable
by the "calibrate" control potentiometer R112. The gain of the externsal
amplifier and hence the "span" of the log count rate meter are con-
trolled by the parallel cambination of R115 and R116. For trimming
purposes the value of R116 is adjusted. A 250-kilohm feedback resistor
for the operational amplifier, in addition to a 1l-kilohm resistor which
forms a voltage divider network with R115 and R116, is located at the
operational amplifier. If these resistors were located in the pulse
amplifier and count rate meter module and the module were unplugged,
it would open-circuit the feedback loop on the operational amplifier
and cause the operational amplifier to saturate. It is not advisable
to leave these amplifiers in this state for extended periods of time.

The operation of the pump circuit, discussed briefly in the pre-
ceding section, will be described in more detail here. As charge from
the feed capacitor is transferred to the smoothing capacitors C32 through
C37, a voltage is developed across these capacitors which causes the
current flow through any shunt resistance such as R88 and R87 of the
first pump, R88 is essentially returned to ground since it is tied to
the suming junction (a virtual ground) of the external operational
amplifier. At a steady count rate, there is an equilibrium condition
established where the rate of charge, or current inflow, is equal to
the current outflow, and a steady dc voltage (with superimposed statise-
tical variation) is established across each smoothing capacitor.

 

"E. H. Cooke~Yarborough and E. W. Pulsford, "An Accurste Logarithmic
Counting Rate Meter Covering a Wide Range," Proc. IEEE, Part II, 98,
196-203 (April 1951).
 

131
The voltage on each smoothing capacitor will bear the relationship8

V.nRC
1
v

='-_—__,
© 1 & nRe

where

input pulse amplitude,

detector count rate divided by 2,

capacity of feed capacitor,

b Q 53|—'-<:
It

total shunt resistance across smoothing capacitor,

This response is shown graphically by any of the six curves in
Fig., 2.3.12. For small values of n, where nRC is small compared with
unity, the response is nearly linear as a function of n, the count rate.
As n becomes larger, the response becomes nonlinear (appearing to be
linear on a semilog plot) and ultimately reaches a saturation value of
Vi when nRC is much greater than unity. As the count rate increases,

each pump becomes successively saturated (pumps with the largest RC
product saturate first), resulting in a constant output current from
each pump.

The Cooke-Yarborough principle will show end effects when a limited
number of pumps are used to approximate the logarithmic response. To
compensate for this, the two end pumps deliver about 10% more current
than the four middle pumps. This is accomplished by making the value
of the feed resistors R88 and R98 smaller than that of the other four
feed resistors R90, R92, R9%, and R96. The values of the shunt re-
sistors R87, R89, R91, R93, R95, and R97 are adjusted to keep the pump
time constant RC at values which differ by a factor of 10.

 

8The derivation is as follows:

Vo = ioR s
where
._i‘ =& - (Vi— IV.O)C - (V - )Ilc
o At l?n i o *
Thus
v = (Vi~— vo)nCR

V,nRC
=T ¥ nRC °

 
 

 

 

132

The value of the total shunt resistance R across each smoothing
capacitor was made as small as possible, but still permitting reasonable
values of smoothing capacitors (i.e., values less than 100 uf). The
product of the resistance and the smoothing capacitor values determines
the statistical noise superimposed on the de current, The values shown
were determined by experiment on the complete wide~range counting chan-
nel, The first three time constants involving C32, R33, and C34 were
selected to keep the period noise at reasonable values while the wide-
range counting channel was behaving as a straight counting instrument.
The remaining three time constants were selected to optimize the speed
of response of the counting chammel.

The leakage of the smoothing capacitors and diodes D19, D21, D23,
D25, D27, and D29 behaves as an additional shumt resistance across the
various pump outputs., The 1N914A is specified to have a maximum leakage
of 0,025 pa at a reverse bias of 20 v at 20°C. This will have negligible
effect on the performance of the pumps. The electrolytic capacitors
C32, €33, and C34 were purchased with a specified leakage not to exceed
0.2 pa at 25°C at a working voltage of 20 v, which is equivalent to a
dc leakage resistance of 100 megohms. A reduction in leakage resistance
to 50 megohms would represent an error of 2.5% of reading over only a
small range of the scale. Also, errors caused by leakage of the capac-
itors will not accumulate, because as each pump goes into saturation,
its output current is a function of only the pulse amplitude and the
magnitude of the resistor feeding the summing junction of the opera-
tional amplifier. In addition, any errors caused by the three electro-
lytic capacitors, since they apply to the pumps at the low end of the
scale, are negligible at the high end.

The other critical components of the various pumps, such as the
feed capacitor and output resistors, are high-quality, high-stability
+1% components, or better.

The effect of the variation of diode potentials in the pump is
equivalent to a variation of the amplitude of the input pulse. The
effect is such that, at higher temperatures, the input pulse appears
bigger and there is greater output from the pump. More clearly, as the
forward drop of D18 reduces with a temperature increase, the feed ca-
pacitor will charge to a larger voltage. Also, the forward drop across
D18 is less, and more charge is transferred. The two diodes D13 and
D14 in series with the three 5,2-v Zener diodes have a tendency to com-
pensate for this. As the temperature rises, the forward drop of these
two diodes will be less and will result in a reduced pulse amplitude.

Linear Pumps. — The linear pump circuit is designed to give a linear
output current signal up to a value of about 170 pa for 104 counts/sec.
This current is fed through R99, a 10-kilohm resistor, into the summing
junction of an external operational amplifier. This smounts to a voltage
of +1.7 v at the output of the pump.

Without any attempt (such as bootstrapping) to improve linearity,
the output signal would depart from linearity by nearly 9%. This can
be computed from the general count rate expression given in the preceding
 

 

133

section with RC = (R99)(C39) = (10%)(0.0022)(107%¢) and n = 5 x 103
counts/sec. The bootstrapping circuit consisting of QL8 and Q19 serves
to effectively increase the magnitude of the input pulse by an amount
equal to the output dec voltage. Discounting the small drop in R117,
any change in the output voltage appears at the anode of D32 and is in
a direction to increase the voltage to which the feed capacitor is
charged with each input pulse. Thus, the output current without boot-
strapping is

. (vi - vo)c
i =e—
1/n

This becomes
[(vi + vo) — vo]C

i = s

1/n

 

which is independent of v_. Here all terms have the same meaning as in
the preceding section. '

The cascaded emitter-follower arrangement (Darlington pair) is used
to raise the looking-in impedance of the bootstrapping circuit, thereby
reducing its loading effect on the output voltage. The voltage drop of
the base-to~emitter voltages of Q18 and Q19 plus the drop across R117
is of sufficient magnitude to ensure that D31 is sufficiently back
biased during the charging time of the feed capacitor to avoid a leakage
of charge from the smoothing capacitor.

Temperature effects in the linear diode pump are due primarily to
changes in the two diodes D31 and D32. Variation in the forward volt-
ages of these two dicdes is compensated for by changes in input pulse
amplitude in a manner described in the preceding section. Diode leak-
age currents and leakage in the electrolytic smoothing capacitors are
negligible, particularly since the value of the output resistor is only
10 kilohms. - - -

Temperature effects caused by the bootstrapping scheme are small,

but are not negligible. Vbe changes of Q18 and Q19 will have a signif-

icant effect on the output. Thesé changés will predominantly show up
as a change in emitter potential of Q19 of about 4 mv/°C. Only slight

changes of Vté due to temperature are seen at the base of Q18, because

the 10-kilohm base impedance of QL8 is ‘so much smaller than the loocking-
in impedance of Q18. The variations at the emitter of QL9 will change
the magnitude of the bootstrapping voltage with temperature. At 50°C
(assuming 4 mv/°C) the change in bootstrapping signal from the 30°C
value is 120 mv, which is a chenge in output signal of [0.120/(17 x
20)]100, or 0.03%/°C, where 17 v is the amplitude of the input pulse,
This change is in a direction to increase the output signal. If the
output signal from the bootstrapped configuration had been taken from
the emitter of Q19, the 0.03%/°C value will be increased by an addi-

 
 

134

tional [0.120/(1.7 x 20)]100, or 0.3%/°C, at 10* counts/sec. This oc- o
curs because the pump output voltage (1.7 v at 10% counts/sec) receives

the full effect of the Vfie changes.

The actual temperature drift observed on the pump operating at 10%
counts/sec is three times worse than 0,03%/°C. At 5000 counts/sec the
measured drift is more nearly 0.03%/°C. The cause of the increased
drift at the 10%-count/sec rate, which nearly amounts to an additional
2 mv/°C, is not definitely known.

Ico and the base current of Q18 will flow through R99 into the

suming junction of the external amplifier and sppear as signal currents.
Ico effects will be negligible, because 0,001 pa is typical for Q18 and

Q19 (NPN silicon). Temperature effects on hFE are also small, since the

base current of Q18 is about 0.5 pa, or about 0.3% of the full-scale out-
put (i.e., 170 pa at 10% counts/secs. The hFE value varies sbout O.4%/°C
in the range O to 50°C.

Test Oscillators

 

lO—count/sec Oscillator. — This is a Swiss-made (Zenith model
E59GJ) electromechanical oscillator with a spring balance wheel mounted
in ruby bearings. The spring balance wheel is driven by an electronic
circuit containing two transistors and two coils. The two coils are
fixed and are located coaxially above and below a permanent magnet set
in the rim of the balance wheel. The axis of the magnet is parallel to
the axis of rotation of the spring balance wheel. As the magnet passes ‘sj
through the region between the coils, a voltage induced in one coil
(the pickup coil) turns on a transistor amplifier which has the second
coil (the drive coil) as a collector load. The current in the drive
coil imparts a force to the balance wheel in a direction to sustain its
movement. The output pulse is taken from the collector of the amplifier
transistor. The other transistor is connected as an emitter-follower
and provides the necessary power amplification for the signal from the
pickup coil. '
The oscillator produces an output pulse of the same polarity each
time the magnet passes under the coils. This results in two pulses for
each complete cycle., The time duration between successive pulses can
differ by as much as 3 msec; however, the sum of the two intervals re-
mains precisely at 0.1 sec (i.e., a 1lO-count/sec rate). The variation
in time duration arises because the spring on the balance wheel is
wound in one direction and is unwound in the other direction.
104-count[§ec Oscillator. — The lO‘-count/sec oscillator is crystal
controlled by & 10%-count/sec quartz crystal. The oscillator consists
of an Engineered Electronics Company. (EECO) plug-in unit T=-107, re-
quiring a standard nine-pin miniature tube socket. The quartz crystal
(EECO type H145-31) 1s mounted separately. The T-107 unit contains
three transistors, two of which are used as a two-stage common emitter
amplifier with feedback from the second collector to the first base
through the impedance of the crystel. There is a full 360° phase shift,
and the circuit will oscillate at a frequency which experiences neither
phase shift nor apprecisble attenuation through the crystal., The third
transistor serves as an emitter-follower output stage. Q,j

 

 
 

135

Oscillator Shaper. — Since the output waveforms of the 10- and the
10%-count/sec oscillators are widely different, preshaping is required
if a uniform pulse is to be applied to the pulse amplifier. Q20 and
Q21 form a conventional Schmitt trigger for this purpose. Q21 is nor-
mally on and Q20 is off. The sensitivity is such that about 4 v is
needed for triggering. The output pulse from the collector of Q21 is a
positive pulse which is sharply differentiated by €38 and R86. The
resultant pulse is about 0.1 v in amplitude. A negative pulse of about
the same amplitude is obtained, but it is of the wrong polarity to
trigger the pulse-height discriminator.

 

2.3.5 0,1-hp Servo Amplifier, ORNL Model Q-2615

2.3.5.1 @General

The O.l-hp dc servo amplifier is a dc power amplifier that can
supply & maximum of 75 w power at voltage and current limits of 25 v
and 5 amp respectively.

2.3.5.2 Construction

The servo amplifier is constructed in a module 4.22 in. wide, 4.72
in. high, and 11.9 in. deep. It is a standard "three-unit" plug-in
module of the modular reactor instrumentation series depicted on drawings
Q=-2600-1 through Q-2600-5.

The four output transistors are mounted on separate heat 51nks;
these are supported by four rods that connect the front and back plates
of the module., The four intermediate transistors of the amplifier are
mounted on smaller separate heat sinks; these are clustered on a metal
plate supported by the four tie rods.

The input transistor and most of the other components of the am-
plifier are mounted on a printed circuit board near the front panel of
the module.

The series limiting resistors for the output transistors are
mounted on the rear plate. All decoupling resistors and capacitors are
mounted on a metal plate supported by the four tie rods and located near
the rear of the module. This metal plate also shields the amplifier
from the heat that is dissipated in the limiting resistors.

2.3.5. 3 Application

The servo amplifier drives a Globe Industrles, Inc., type BD dc
motor with a 27-v armature. It can drive this motor under all con-
ditions from no load to blocked rotor. The motor is used as the servo
motor to position a fission chamber in a wide-range counting channel.

2.3.5.4 Bpecifications
Specifications for the O.l-hp dc servo amplifier are as follows:

Voltage gain 3 v/v £ 10% noninverting
Maximum linear output +28 v at no load; *25 v with 12-ohm
(supply voltage * 32 v) resistive load; and %15 v with

3-ohm resistive load

 
Nonlinearity
(with 12-ohm resistive
load)

Maximum power output
Output impedance
Input impedance

Input de offset

136

Less than 0,1 v deviation from
straight line drawn between max-
imum positive and negative outputs

75 w
30 milliochms

4700 ohms for signals not exceeding
10 v

Negative 0.8 v

 

(input voltage for zero

output)

Rise time (10 to 90%) less than 2
msec for input step

Zero drift with tempera- Less than 9 mv/°C from O to 50°C;
ture the output decreases as the tem~
perature rises

Transient response

Povwer supply requirements
Voltage
Current drain

Positive and negative 32 v * 4 v
5 amp maximum

Ambient tempersture range 0 to 55°C

2e3.5.5 Theory of Operation

General

The O,l-hp dc servo amplifier is a de-coupled amplifier with feed-~
back around two voltage-gain stages and two cascaded emitter-followers.
The emitter-follower stages are complementary NPN and PNP pairs to per-
mit the output to swing negative and positive with respect to ground.
The last emitter-follower stage is a parallel combination of two
transistors to increase its power handling capabilities.

Circuit Description

Reference is made to Instrumentation and Controls drawing Q-2615-1.
The input signal is applied to the base of Ql, a PNP silicon transistor.
A l-kilohm resistor R2 in series with the base limits the maximum load
Placed on the input signal in the event of any failure in the servo
amplifier. Diode D2 limits the base-to-emitter voltage on Ql when large
negative input signals are applied under blocked rotor conditions.

Negative feedback is applied to the emitter of QL through the re-
sistive network R3 and R8. The feedback ratio is R3/(R3 + R8), which
glves s closed-loop voltage gain of spproximately 3.

The circuit shown produces a dc offset between input and output.
With no input, the voltages will be as shown (+2.4 v on the output and
O v on the input). For the output to be at a zero potential, the base
of the input transistor must be at a negative 0.8 v to keep Q1. in a
conducting state.

 
 

 

137 .

Voltage gain in the loop is obtained from Q1 and Q2. Q3 is a cur-
rent source which functions as a high-impedance collector load for Q2
while still providing adequate current to drive the emitter-follower
stages under all design conditions. When the servo amplifier is driving
positive with respect to ground; part of the collector current of Q3 is
diverted into the base of Q5. When the servo amplifier is driving neg-
ative with respect to ground, all the Q3 collector current flows through
Q2, and Q2 must be capable of handling this current plus the required
drive current into the base of Q4.

Transistor Q4 and transistors Q6 and Q8 in parallel function as an
emitter-follower chain; they operate when the servo amplifier ig driving
negative with respect to ground. Transistor Q5 and transistors Q7 and
Q9 in parallel operate when the servo amplifier is driving positive with
respect to ground. The transistor not operating is held in a back-
biased state by the base-to-emitter voltage of its complement.

" Diode D1 in the emitter of Q2 permits Q2 to be turned off "hard"
when the amplifier is delivering its full positive output. Any small
collector current could create a large dissipation in Q2, since Q2
will have in excess of 60 v from collector to emitter.

Capacitor Cl, connected from the base to the collector of Q2, along
with the collector impedance of Ql, shapes the open-loop response to im-
prove the high-frequency stability. The total capacitance at the col-
lector of Q1 is increased in magnitude by the Miller effect. This re-
sults in a smaller value of capacitance for the same shaping of the
open-loop response. This internal time constant, coupled with the
compensating effect of C2 across R8, stabilizes the amplifier over its
entire range of operation with as much as 0.22 pf capacitance in shunt
with the output. _

The behavior of the amplifier with a step input signal is different
with positive and negative input signals. With a negative input step,
Ql and Q2 are immediately driven into a higher conducting state, and the
output rise time is exponential in character and is controlled primarily
by the value of C2. With a positive step, QL and Q2 are both immediately
turned off in the absence of a return signal from the feedback network.
Thus, the current from Q3 flows into Cl, generating a ramp until there
is sufficient signal from the feedback network to return QL to a con-
ducting state and thereby restore the closed loop. Under these con-
ditions the output wave shape will have a ramp-type leading edge.

'~ Resistors R9 and R12 in the emitter of Q6 and Q8 tend to balance
the current contribution of each transistor, even with large differences
in transistor ‘parameters, such as current gain and transconductance.
Resistors R10 and R13 are used for the same purpose with transistors
Q7 and Q9.

Resistor Rll, which is a series combination of three l-ohm resistors,
protects transistors Q6 and Q8 under severe load conditions. With a
blocked rotor condition the Globe Industries type BD motor will behave
as a 3-ohm load, and the maximum dissipation possible in either parallel
transistor is &bout 27 w. This is assuming supply voltages of *36 v.
These potentials are possible when the batteries that normally pover
this module are fully charged. Resistor Rl4 provides similar protection
for transistors Q7 and Q9.

 
 

138

The collectors of Q4 and Q5 are connected to resistors R1l and Rl4 .
respectively. This prevents damage to these transistors under overload
conditions.

2.3.,6 YVernistat

2.3.,6.1 General

The Vernistat adjustable function generator is composed of two
separate, but integral, units: a function adjusting assembly and an
interpolating Vernistat potentiometer. A function is set up simply by
manually adjusting the positions of sliders on the function adjusting
assembly panel. The panel is marked off in rectangular coordinates,
with percent output as the ordinate and shaft position as the abscissa.
The sliders provide a visual plot of the function that is set into the
function generator. By rotation of the shaft of the interpolating
Vernistat with an excitation voltage applied, the output voltage curve
conforms to a series of straight-line interpolations hbetween voltages
set up by the slider. Clockwise rotation scans the function from left
to right (i.e., from slider 1 to slider 34). |

2.3,6.2 Construction

Vernistat Function Adjusting Assembly

The function adjusting assembly is approximately 1 by 7 by 8 in.
and contains (1) a 10l-tap voltage divider; (2) a 34-pole, 10l-position t:j
printed-circuit switch; and (3) a function adjusting panel. '
The voltage divider has a total of 10l equally spaced taps. These
taps divide the input voltage into 100 equsal voltage increments.
The 34-pole, 10l-position switch is a rectangular coordinate array.
A printed-circuit grid consists of 101l parallel lines connected sequen-
tially to the voltage-divider taps. Each of the 34 sliding contacts can
be moved independently across the grid lines so that each slider may
contact any of the 101 voltage divider taps. The voltage divider taps
are spaced at 1% increments, and therefore any voltage may be selected
to within *0,5%.
A panel, marked off in rectangular coordinates, mounts directly
over the printed circuit switch so that the 34 sliders protrude through
slots in the panel and can be manually adjusted. The Y axis is pro-
portional to voltage, and the X axis is proportional to the position of
the interpolating Vernistat shaft. The X axis represents a range of
approximately 11 shaft turns.

Interpolating Vernistat Potentiometer

The interpolating Vernistat consists of (1) a series of commutator
bars which correspond to the sliders of the function adjusting assembly,
(2) a switching mechanism, and (3) a 360° toroidal resistance element
precisely tapped at 120° intervals. Connection of the function adjusting
assembly to the commutator bars of the interpolating Vernistat is made
through a multiconductor cable. This cable is an integral part of the
 

139

interpolating Vernistat and plugs into the function adjusting assembly.
This is the only connection made to the function adjusting assembly.

Rotation of the shaft of the interpolating Vernistat switches the
taps of the interpolating resistance element one at a time along the
commutator and simultaneously controls the potentiometer output wiper.
There are approximately three interpolations per shaft turn of the
interpolating Vernistat.

2.3.6.3 Application

The Vernistat adjustable function generator provides a convenient
means of generating mathematical and empirical nonlinear functions.

The function generator is used in the wide-range counting instru-
ment to modify a linear position signal so that it is equal to the
logarithm of the neutron attenuation.

2.3.6.4 GSpecifications

Overall specifications for the Vernistat function assembly are
given below:

Vernistat Function Adjusting Assembly

Ad justable points on 34
rotation axis
- Resolution of slider ad- 1%
Justment
Maximum input voltage 50 v
Ambient temperature range 0 to 55°C

Interpolating Vernistat Potentiometers (size 18, 1l-turn continuous
rotation units)

Linearity | +0,02%

Maximum output impedance 540 ohms

Minimum output-voltage 0.01%
increment

Ambient temperature range 0 to 55°C

2.3.6.,5 Applicable Drawings

~The Instrumentation and Controls Division drawing number and sub-
title for the Vernistat adjustable function generator is Q-2616-1,
Circuit. - ' o o :
2.3.6.6 Theory of Operation
Figure 2.3.13 shows the electrical relation of the Vernistat in-
terpolator commutator bars, interpolating resistance element, and out-
put wiper. By synchronization of the switching of the interpolating

resistance element taps along the commutator bars with the movement of
the potentiometer wiper arm, the voltage output becomes a series of

 

 
 

140

linear voltage interpolations between adjacent commutator bars. The
interpolating resistance element, used repetitively for each shaft
turn, is a 360° toroidal potentiometer precisely tapped at 120° intervals.

Switching of resistance element taps from one commutator bar to
the next only requires about 30° of shaft rotation, whereas a complete
interpolation requires approximately 120°, Therefore, the switching
process of the interpolating resistance element is a noncritical oper-
ation. No discontinuities of output occur, since in each instance as
the output wiper approaches a new commutator bar, the next interpolating
resistance element section is already in position. Switching of the
taps of the interpolating resistance element along the commutator bars
is accomplished with a planetary gear reduction.

The output wiper is so synchronized with the switching operation
that it is always on an energized section of the resistance element.
This results in continuous, smooth interpolation throughout the output
voltage range.

The heart of the switching mechanism is a planetary gear reduction
that consists of three elements: an intermal tooth gear with as many
teeth as there are commutator bars, a planetary gear with one tooth
less, and an eccentric on the shaft which keeps the two gears in mesh.
These gears are shown schematically by the eccentric cirecles in Fig.
2.3.13. Because of the one-tooth difference, one shaft rotation results
in a counterrotation of the planetary gear, which is equivalent to the
angular spacing between commutator bars.

The resistance element is mounted on the planetary gear and rotates
with it at a reduced speed. The commutator wipers, connected to the
resistance element taps, are also mounted on the planetary gear. The
output wiper is attached to the Vernistat shaft. Because the resistance
element rotates, the output wiper moves from one tap to the next in less
than 120° of the shaft rotation.

The 34 sliders of the function adjusting assembly equal the number
of commutator bars in the interpolating Vernistat. Eleven shaft turns
(3960°) are required to generate an entire 34-chord function. Each
chord represents 116.47° (3960°/34) of shaft rotation.

Sliders 34 and 1 are adjacent electrically; therefore, a repetitive
function may be generated by continuous rotation of the input shaft.

2.3.7 Dual DC Amplifier

2.3.7.1 General

The ORNL model Q-2605-1 dual dc smplifier is designed and manu-
factured by Electronic Associates, Inc., as the EAT model 6.720. The
unit consists of two independent high-gain amplifier circuits packaged
on an etched-circuit board. The amplifiers are transistorized and de-
signed for optimum stability and frequency response, Each amplifier can
be used in conjunction with appropriate networks to perform linear com=-
putations such as summation, integration, and multiplication by a con-
stant.
 

141

2.3.7.2 Specifications
Specifications for the dual dc amplifier are given below:

Output voltage range +1.2 v min (no load);
+10 v min (20 ma load)
Offset (at the summing junction) +20 pv, max
unity-gain inverter with 10~kilohm
resistors
Output current at *10 v 20 ma min
Frequency response (=3 db) for a ' 200 ke min

unity-gain inverter with 10-kilohm
resistors (20 uv p-p input)

Noise (p-p) from dec to 300 ke 400 uv rms max

2.3.7.3 Amplifier Balancing

The amplifiers should be periodically balanced to assure accuracy.
Under normal circumstances, the amplifier will remain balanced for
periods of weeks., However, at intervals it is desirable to check this
condition, and if an amplifier is found to be unbalanced, then an ad-
justment should be made. The period bhetween balance checks depends to
a large extent on the application of the amplifier., For uses which
might be unusually sensitive to amplifier unbalance or integrator drift,
the amplifier should be balanced at more frequent intervals. In any
case, maintenance personnel should recognize the fact that many amplifier
and network malfunctions can be detected by checking amplifier balance.
Consequently, it is recommended that a check of amplifier balance be
made biweekly. If the check indicates that the amplifier balance is
within tolerance, no adjustment need be made.

2.3.7.4 Theory of Operation

Basic Block Diagram

The dual dc amplifier consists of an EAI model 6,715 dual dc ampli-
fier card housed in a special package., The components for one channel
are shown in Fig. 2.3.14. The major components consist of the stabi-
lizer amplifier, the chopper, and the dc amplifier. The circuit is ar-
ranged so that the drift-free characteristics of an ac amplifier are
used to maintain constant de amplifier balance by providing a voltage
to the input of the de¢ amplifier which tends to maintain the suming
junction at virtual ground., The resulting circuit has excellent long-
term stability and allows the use of a wide~bandwidth dc amplifier
without the necessity of frequent manual balancing.

Inputs to the amplifier are applied through an external input im-
pedance Zin' " The dec and low-frequency components of the signal voltage

at the summing'junction (SJ)_cannot pass diréctky to the input of the
de amplifier section because of Cl. Instead, they are connected through
R3 to contact 9 of chopper Dl. A chopper, or synchronous vibrator, con-

 
 

142

sists of a coil-driven vibrating reed 8 (Fig. 2.3.14) that alternates
between contacts 9 and 7 on each half cycle of the coil excitation volt-
age. The chopper alternately grounds contact 9, producing a 60~-cps
square~wave input to the stabilizer amplifier. After amplification, the
resulting signal is demodulated (or synchronously rectified) at the
second contact 7 of the chopper. The resulting signal at contact 7 is
a pulsating dc signal whose polarity is the same as the polarity of the
signal at the summing junction. The dc signal is filtered by RE8 and C2
and applied through R7 to the input of the dc amplifier section. Thus
dec and very low-frequency signals are amplified by the stabilizer am-
plifier and by the dc amplifier.

The circuit from contact 9 of D1 to contact 7 is a modulated
carrier-type amplifier that provides high-gain de¢ amplification with
no drift. The stabilizer is phase-sensitive; if the polarity of the
suming junction signal changes, the phase of the modulated signal
changes and the polarity of the pulsating dc output voltage changes.

High-frequency components of the input signal are passed through
Cl to the dc amplifier and are amplified by the gain of the dc amplifier
only. The open-loop gain of the amplifier thus depends on the frequency
of the input signal. At very low frequencies the gain is extremely high
because the stabilizer amplifier is placed in series with the de am-
plifier. At higher frequencies the gain is decreased but remains high
enough to satisfy all expected operations when the feedback loop is
closed.

Any component of the amplifier output voltage due to drift in the
dec amplifier section is fed back through the feedback impedance Zf to

the summing Jjunction of the amplifier. Since any drift-produced voltage
has a very low frequency, it will be amplified by the stabilizer section,
filtered, and then applied as a drift-correction signal to the input of
the de amplifier section. The drift-produced component in the output is
reduced by a factor equal to the effective gain of the stabilizer sec~
tion., The amplifier would require balancing every few minutes without
stabilization. The drift compensation produced by chopper stabilization
allows the amplifier to be used for weeks without attention.

The amplifier in the stabilizer section has a very high gain. Since
it is connected to the summing junction, it serves as a monitor of the
summing junction voltage. Under normal circumstances the input current
of the operational amplifier is equal to the feedback current, and the
suming Jjunction is at virtual ground. If the currents are not equal,
the amplifier is not performing properly, and the summing junction de-
parts from virtual ground. This rise in voltage is amplified by the
stabilizer and results in an output signal which msy be connected through
the appropriate push-button switch to the balance monitoring meter cir-
cuit.

DC Amplifier Section

Refer to Fig. 2.3.1l5 for the following description. The summing
Junction of the operational amplifier is connected to the input ter-
minal. The ac components of the input signal are applied to the base
of transistor QL through R2 and Cl. The input signal is also connected
through R3 to the input of the stabilizer section., Two reverse-connected
 

 

143

diodes CRLI and CR2 are connected from the input to ground so that Cl
cannot be charged to a high voltage should an overload occur. This
feature allows the amplifier to recover rapidly following an overload
condition. The voltage at this point is normally less than the diode
conduction point.

Transistors Ql and Q2 comprise the amplifier input stage. Tran-
sistor Q2 is connected in a common-emitter configuration, with R7 (in
etched~circuit resistor network NWl) and thermistor R15 providing self-
bias. Transistor Ql is used in the emitter-follower configuration and
uses the voltage drop (approximstely 0.3 v) across the base-emitter
diode of Q2 as its operating voltage. The emitter-base resistance of
Q2 provides a load for Ql. This configuration gives the amplifier a
relatively high input impedance, The hase circuit of QL is completed
through R8 (in NW1), R1l, and the balance potentiometer. These compo-
nents form a voltage divider between —15, +15, and +25 v. The balance
potentiometer sets the optimum operating point for Ql, as indicated by
a zero output from the stabilizer section.

The high-frequency rolloff of the input stage is controlled by C3
and R5.

Temperature compensation is provided by thermistor RL5 and resistor
R6, vwhich tend to keep the collector of Q2 at a constant potential re-
gardless of temperature variations. The stabilizer output is connected
through R8 and R7 to the input of Q1.

The output of Q2 is coupled to the base of Q3 through NW1l-R5. Bias
for Q3 is provided by NW1l-R4 and NW1l=-R5. The feedback network consisting
of R10 and C5 provides the proper high-frequency rolloff for the Q3
stage.

Capacitor C4 provides correct pha51ng for higher frequencies, The
collector load for Q3 consists of resistors NWi-R3 and NW1l-Rl.

Resistor NW1l-R3 provides direct coupling from the output of Q3 to
the base of Q4, as well as forming a voltage divider with NW1-R1l to set
the operating point for Q4. The Q4 stage is connected in the common-
emitter configuration. The emitter is connected to +15 rather than
ground, to establish the correct operating points for Q4, Q5, Q6, and
Q7. The collector load for the stage consists of NWl-R2. Capacitor
C7 provides high-frequency degenerative feedback for this stage, and
the network consisting of C6 and R11l controls the high-frequency rolloff
for Q4 and Q5.

The collector of Q4 is connected to the base of Q5 through an in-
candescent lamp DS1l. The filament of this lamp has a high positive
temperature coefficient of resistance, providing an increase in resist-
ance with an increase in current flow. This stabilizes the operation
of Q5 by limiting base drive. The Q5 stage is connected as an emitter-
follower, with resistor R12 providing the emitter load resistor. Diode
CR3 provides a small forward bias for output tran51stor Q7, eliminating
crossover distortion in the output stage.

The output stage consists of transistors Q6 and Q7, connected in a
complementary-symmetry configuration. ‘This circuit arrangement provides
the advantages of push-puwll operation with a single-ended input. Both
transistors are connected as emitter-followers. Since transistor Q6
(PNP) conducts with a negative input and transistor Q7 (NPN) conducts
with a positive input, one of the transistors delivers current to the

 
 

144

load regardless of input polarity. With a zero input, both transistors g=J
conduct equally, and the voltage drop across the load is zero. Incan-

descent lamps DS2 and DS3 perform a function similar to that of DS1;

by providing ean increase in resistance with an increase in current,

they protect the output transistors from excessive current flow., Re-

sistor R13 provides a dc feedback to the base of Q4 which tends to keep

the output of the amplifier at zero volts with a zero input and compen-

sates for minor transistor and temperature variations.

Stabilizer Section

The stabilizer section consists of a four-stage direct-coupled
amplifier (Q8, Q9, Q10, and Qll), input and output coupling capacitors.
(c8 and C12 respectively), and a 60-cps chopper (Dl1). The stabilizer
preamplifies the dc and very low-frequency components of the signal
appearing at the amplifier summing junction and applies the resulting
signal as an input to the dc amplifier section.

Stabilizer Amplifier. — The stabilizer amplifier receives its input
from the suming junction through resistors R3 and R9. The chopper
grounds the junction of R3 and R9 60 times each second, making the input
appear as a series of pulses between ground and the input level. These
pulses are coupled through C8 to the base of transistor Q8.

The input stage of the stabilizer consists of transistors Q8 and
Q9. Transistor Q8 is connected as an emitter-follower and uses the
base~emitter voltage drop of Q9 to provide operating voltage. The cir-
cuit arrangement of Q8 and Q9 is similar to the arrangement of QL and
Q2 in the dc amplifier section and provides a relatively high input .
impedance. Resistors NW2-RL and NW2-Rll provide bias for Q8. Capacitor ‘sJ
C9 filters high-frequency transients from the input waveform. Resistor
NW2-R2 provides the emitter load for Q8 and, together with NW2-R1Z2, pro-
vides bias for Q9. Transistors Q9, Q10, and Qll are connected in the
common-emitter configuration and are directly coupled through resistors
NW2-R4 and NW2-R6. Capacitor CLO provides high-frequency degeneration
for the Q11 stage, removing unwanted high-frequency components from the
output waveform. Resistor NW2-R8 provides a feedback to the Jjunction
of NW2-Rl and NW2-R1l, adjusting the bias on Q8 to maintain the stabi-
lizer amplifier transistors at the correct operating point. The net-
work consisting of R1l4 and Cll provides phase correction for very low
frequencies and filters high frequencies from the NW2-R8 feedback loop.

The stabilizer amplifier consists of an emitter-follower input
stage vwhich is noninverting and three common-emitter stages which pro-
vide an overall phase shift of 540°, This constitutes an apparent 180°
phase shift, or an inversion from input to output. This cannot be
tolerated by the overall amplifier, since the dc amplifier section pro-
vides a 180° phase shift. Any feedback under these conditions would be
regenerative, and the amplifier would not be usable. For this reason
contacts 7 and 8 of the chopper demodulate the output of the stabilizer
amplifier to provide a pulsed output to the filter network (R8 and C2)
having the same polarity as the input. This is accomplished as described
below.

Chopper. — The chopper used in the EAT model 6.720 amplifier is a
specially designed high-speed relay. It consists of a double=-pole

 

 
 

145

armature assembly which is driven by a 60-cps ac source and which al-
ternates in position from one set of contacts to the other at this rate.
Figure 2.3.14 shows how one pole of the chopper (pin 8) alternately
grounds the stabilizer input (pin 9) and the stabilizer output (pin 7).
The closing of contacts 8 and 9 at a 60-cycle rate causes the stabilizer
input to appear as a series of pulses, This permits amplification of
very low frequencies or de¢ levels while isolating the amplifier operating
levels through the use of a coupling capacitor. The closing of contacts
8 and 7 effectively shifts the phase of the output by providing a short
r-c charge or discharge time for Cl2 when closed and a longer time
(through R8) when open. This operation is more easily understood with
the use of examples,

If the input to the summing Junction tends to go positive, the in-
put to the stabilizer amplifier consists of a series of positive pulses.
The output waveform at the collector of Qll then consists of g series
of negative-going pulses, However, during the time that the input pulse
is present (positive), the output (negative) at the junction of (12 and
R8 is connected to ground through contacts 7 and 8 of the chopper. This
allows Cl2 to charge rapidly to the level at the collector of Qll. The
chopper arm then closes to contact 9, driving the stabilizer input to
ground.

The collector of Ql1l goes from its negative level toward ground
at this time, and the positive change is coupled through C1l2 and R& to
the input of the dc amplifier. The dc restoring action of contact 7
and the arm of the chopper thus makes the apparent output a series of
positive pulses which are filtered by C2 and R8 and provide a dc input
to the de amplifier through R7.

If the input to the summing Jjunction tends to go negative, the
stabilizer input is a series of negative pulses. The output at the
collector of Q11 is a series of pulses from a negative level toward
ground. In this case, the chopper provides a short-time-constant dis-
charge path for Cl2 when the collector of Qll is close to ground. As
contacts 8 and 9 of the chopper break and contacts 8 and 7 close, the
collector of Qll goes negative and the change is coupled through Cl2
and R8 to filter capacitor C2.

Stabilizer Filter., — The stabilizer output filter, con51sting of
capacitor C2 and resistor R8, has a time constent of 3 sec., This is
extremely long with respect to the stabilizer output waveform, conse-
quently reduclng the ripple at the junction of R8 and R7 to a negllgible
level.

‘Stabilizer Functions. — The stabilizer performs the apparently dual
functions of preamplifying dc and very low-frequency input signals and
malntalnlng the amplifier summing junction at a point very close to
ground potential over wide variations in amplifier balance, When the
amplifier feedback loop is closed (as it must be) and no input is ap-
plied, the amplifier output should be zero volts. Any departure of the
amplifier output from this point is coupled through the feedback resis-
tor to the summing junction. This causes the stabilizer to generate a
correction voltage which returns the amplifier output and, consequently,
the suming junction to zero. If an inpubt signal is applied to the
summing junetion, the stabilizer again generates a voltage. In this
case, however, the output of the dc amplifier is shifted from ground

 

 

 
 

 

 

146

potential to produce an output with a polarity opposite to that of the
input and a magnitude equal to the input voltage multiplied by the ratio
of the feedback resistance to the input resistance. This output pro-
duces a potential at the summing junction equal in magnitude and opposite
in polarity to the input signal, returning the absolute potential at the
suming junction to a point very close to grownd. It is in this way that
the stabilizer attempts to keep the summing junction at ground regard-
less of input voltage changes or variations within the dc¢ amplifier,

2.3.8 Fission Chamber Drive

2.3.8.1 Description

The fission chamber drive, ORNL model Q-2545, is shown in Figs.
2.3.16 and 2.3.17. This unit contains a direct-current motor and as-
sociated drive train for positioning the preamplifier and fission cham-
ber assembly. In addition, there is a position-sensing train for pro-
viding position signals to the servo power amplifier and to the data
logger.

Performance specifications are:

Stroke 90 in.
Chamber velocity 72 in./min
Environment 150°F in water containing 2000 ppm

sodium nitrite corrosion inhibitor

A ball-bearing lead screw turning at 288 rpm provides the rota-
tional-to-linear motion conversion with an efficiency rating of ap-
proximately 90%. A water-resistant calcium-complex-base grease was
selected as the lubricant for the lead screw. The ball-bearing nut is
attached to a guide block which rides on nylon runners between two
aluminum guide rails mounted within & 3-3/4-in.-OD stainless steel drive
tube.

A thrust tube connected to the guide block is attached to a cabling
rig which is connected to the preamplifier and fission chamber assembly.
The fission chamber signal cable, sheathed in Tygon tubing for water
protection, and a piece of music wire are coiled into a helix. These
are held together with nylon spiral wrapping to form a spring-loaded
coiled cord. This helix provides the necessary cable takeup and is
coiled loosely around the thrust tube between the cabling rig and the
lover end of the drive tube. This cabling rig rides on nylon rollers
inside the 4~in,-ID instrument penetration tube. (This tube is not a
part of the positioner assen&flyu)

The direct-current drive motor with Integral gear reducer and
tachameter is protected from any torque overloads by a disk-type slip
clutch. The position signsl system is directly connected to the lead-
screw shaft ahead of the slip clutch by a pair of precision gears.

The position signal system consists of a ten~turn auxiliary posi-

' tion-sensing potenticmeter driven by a 48:1 ratio reducer, to provide
7-1/2 revolutions for 90 in, of chamber travel. This, in turn, drives

o
 

147

a 10:1 ratio reducer which is connected to a one-turn position-sensing,
data-logger input potentiometer. On the same shaft there is a synchro
transmitter for driving a position indicator on the console.

A ten-turn Vernistat interpolating potentiometer, previously de-
scribed, is gear-driven from the shaft of the ten-turn auxiliary position-
sensing potentiometer to provide ten revolutions for 90 in. of chamber
travel. This interpolating potenticmeter provides the position feed-
back signal to the function generator amplifier (ORNL model Q-2616).

Upper and lower limit switches are actuated by rods which are
tripped by the guide block at each end of its travel. These rods are
held captive in grooves between the guide rails and the drive tube.
This permits mounting of the limit switches in the motor drive assembly
where they are readily accessible,

2.3.8.2 Drive Motor

The permanent magnet dc drive motor is a Globe Industries, Inc.,
type BL-7, 27 v, with a 30.7:1 ratio gear reduction and a 1-7/8-in.-
square flange mounting. It has an integral permanent maghet dec gen-
erator, type LL-1l, which produces a minimum of 1.8 v per 1000 rpm at
no load. The motor has a 350-to0-450-rpm no-load speed range, rated at
137 in.-oz torque, part No. 102A276, purchase order No. 62X-20042
special; the output shaft is 5/16 in. in diameter by 3/4 in. long with
a 1/8-in.-square key seat.

2.3.8.3 Lead Screw

The actuator assembly is a commercial-quality ball-screw type, No.
1000-0250-C1l, by Saginaw Steering Gear. The screw is 8 £t 6 in. long.
The screw threads have a 1-in. pitch diameter, a 0.250-in. lead, and a
0.820-in. root diameter, and are right-hand threads. The nut has a 1-
1/2-in.-square body with a 1.583-18NS thread. The screw and nut are
heat-treated 17-4 PH stainless steel., The balls are heat-treated type
440C stainless steel, with every other ball 0.002 in. undersize,

2.3.8.4 Position-Sensing Potentiometer

The position-sensing potentiometer, which provides the input to
the data logger, is by Beckman Instruments, Inc., Helipot No.
5203R5KL.25RS. It is a single turn with servo mount, ball bearings, and
double-ended shaft extensions. The characteristics are: 5000 ohms,
+0,25% linearity tolerance, and 3 w.

2.3.8.5 Synchro

The synchro is a Norden No. 121F1A torque transmitter, 115 v, sin-
gle phase, 60 cps ac. Its characteristics are: three-phase stator,
0.38 in.-oz torque gradient, 0.50 in,-o0z frictional torque, and *8 min
electrical error, The shaft is 0,2405 in. in diameter with ASA spline
and threads.

 
 

148

2.3.8.6 Auxiliary Position-Sensing Potentiometer

The auxiliary position-sensing potentiometer is by Beckman Instru-
ments, Inc., Helipot No. 7603R1KL.15RS. It is a ten-turn potentiometer
with servo mount, ball bearings, and double-ended shaft extensions. The
characteristics are: 1000 ohms, *#0.15% linearity tolerance, and 5 w.

2.3.8.7 Vernistat Interpolating Potentiometer

The Vernistat interpolating potentiometer is a Perkin-Elmer Cor-
poration Vernistat No. 2X5. TIts characteristics are: interpolating,
3960°, electrical rotation (continuous), 34 chords, 470 ohms maximum
output impedance, 0.004% approximate angular resolution, and size 18
servo mounting, part No. 124-0118.

2.3.8.8 Gear Reducers

The two gear reducers are by Metron Instrument Co. One, Metron No.
9B48R, has a 48:1 ratio with a 15-min maximum backlash, servo moumt,
and 3/16-in.-diam shafts. The other, Metron No. 9A10R, has a 10:1
ratio with a 15-min maximm backlash, servo mount, and 3/16-in.-diam
shafts.,

2.3.8.9 Slip Clutch

The Sentinel Manufacturing Corporation makes the type 40, size
2000 single-disk slip clutch. It is a coupling type with a 6 in.-1b
setting, a 5.16-in. bore-through disk hub, no bore in the housing hub,
and a 1/2-in.-diam housing hub.

2.3.8,10 Limit Switches

The snap-action limit switches are Micro Switch units, No. BZ-
2RW82255-A2, with a short roller lever, 6 oz operating force, and a
rating of 15 amp at 125 v ac.
ORNL~-Dwg .66-3994

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TACHOMETER
D.C. sSERVD
MOTOR
SERVO
22‘?356 TIONS , AMPLIFIER
MODEL ©-26/¢ X COUNT RATE
FUNCTION GEN. ol SET POINT
€ -
LEADSCREW SEC NOTE | | vounr pars |
_ METER
‘ LOG 4 LoG
WATER FILLED ) 74 PULSE 105 | €& POWER
PENETRATION | COUNT RATE
- AMPLIFIER METER - ;\.’ DIFFERENTIATING
A
_ | | SomINe MBLIFIER
4 | AMPLIFIER
o | REACTOR
N /7 - o P T
C bo-se Nore S .
PRE-AMP /= THE FUNCTION GENERATOR IS AN ADJUSTABLE,
MON~ LINEAR DC FOTENTIOMETER WHICH PRODUCES
FISSION A MODIFIED CHAMBER FOSITION SIGNAL. THE
REACTOR CHAMBER SIGNAL MOBIFICATION COMPENSATES FOR CHANGES
IN THE NEUTRON ATTENUATION COEFFICIENT, i,
SHIED WITH POSITION, X.

 
     

  
   
      
      
      

TS
e,
ol

X
&
KRR

e

2y

3

.

=

QD

  

Fig. 2.3.1. MSRE Wide-Range Fission Channel Block Diagram.

 

 

6v1

 
 

 

COUNT RATE (counts/sec)

Fig. 2.3.2.

150

ORNL-DWG 66-7635

 

 

 

 
  
   

 

 

 

 

COUNT RATE SET POINT (10 k counts/sec) 7
ACTUAL COUNT RATE "
ACTUAL CHAMBER POSITION
(SEENOTE 1) “oeny
~ WITHDRAWAL
/ / CURVE, s = CONSTANT
"2 cps

 

 

 

LOG REACTOR POWER—>

*NOTE 1: THIS SOLID LINE CURVE IS NOT NECESSARILY REPRESENTATIVE OF AN
ACTUAL OR TYPICAL CURVE BUT ILLUSTRATES THAT THE ACTUAL
CURVE WILL DEPART FROM THE IDEAL STRAIGHT LINE.

100

50

Actual and Ideal Curves of Count Rate vs Reactor Power.

WITHDRAWAL DISTANCE ,-x
 

Q-2617 ASSEMBLY

L

r A

=

 

 

 

 

|
1

FISSION
| cHaMBER PREAMP |

_______ T

LINEAR =
POTENTIOMETER

FISSION CHAMBER
POSITION SIGNAL
FOR READOQUT

FISSION CHAMBER
POSITICN SIGNAL
FOR READOUT AT
CONSOLE

SYNCHRO TORQUE
TRANSMITTER

 

LCG COUNT
= RATE SIGNAL
FOR READOUT

 

 

   

 

LINEAR

COUNT
RATE METER

 

 

 

COUNT RATE
SET POINT.
o

TACHOMETER
VERNISTAT
INTERPOLATING FUNCTION
POTENTIOMETER GENERATOR
VERNISTAT FUNCTION Q-2616

ADJUSTING ASSEMBLY ‘

Fig. 2.3.3.

 
 

je—- LOG COUNT
RATE SIGNAL

PRODUCES TRIP COUNTING
SIGNAL WHEN COUNT CHANNEL
RATE IS LESS THAN 2c¢ps | *CONFIDENCE"

PRODUCES TRIP
SIGNAL WHEN COUNT
RATE EXCEEDS
50,000 cps

 

NOTE: ’ :

"Q" NUMBERS REFER TO OAK RIDGE
NATIONAL LABORATORY INSTRUMENT
AND CONTROL DIVISION DRAWING
NUMBERS

SUMMING
AMPLIFIER

LOG REACTOR
POWER SIGNAL
FOR READOUT

     
 

GAIN
AMPLIFIER

  

DIFFERENTIATING
AMPLIFIER

   

ja— LOG REACTOR
POWER SIGNAL

PRODUCES TRIP
SIGNAL WHEN
REACTOR POWER

1S LESS THAN 200 kw

 

 

 

————————a= ELECTRICAL SIGNAL
————— == MECHANICAL DRIVE

 

“RUN SIGNALS
Q-2609 PERMIT" TO REACTOR ¢
CONTROL,
PRODUCES TRIP " SYSTEM
SIGNAL WHEN
REACTOR POWER
EXCEEDS 500 kw
CONTROL ROD
Q-2609 "REVERSE" WHEN
IN START MODE Y

PRODUCES TRIP
SIGNAL WHEN REACTOR
POWER EXCEEDS 1.5 Mw

OPERATIONAL AMPLIFIER

MSRE Wide-Range Counting Channel.

    

ORNL-~DWG 66- 4102R

REACTOR PERIOC
SIGNAL FOR
READOUT

FAST TRIP
COMPARATOR
{TYPICAL)

CONTROL ROD
"REVERSE"
AND ALARM

PRODUCES TRIP
SIGNAL WHEN REACTOR
PERIQD IS LESS THAN
5 sec

" INHIBIT ROD
- -° 2608 = I THORAWAL"
PRODUCES TRIP
SIGNAL WHEN REACTOR

PERIOD IS LESS THAN
25 sec

 

 

"RUN PERMIT"

PRODUCES TRIP
SIGNAL WHEN REACTOR
PERIOD IS LESS THAN
30 sec

1Ss1

 

 
 

counts/sec

152

ORNL—-DWG 67-11922
0

5 PULSE HEIGHT CHARACTERISTICS OF
2-in. FISSION CHAMBER

FISSION CHAMBER WX—- 31095 CONNECT-
ED TO ORNL MODEL Q-2647 PRE -
AMPLIFIER AND A{ AMPLIFIER WITH

2 GAIN OF 64

10

COUNTS DUE TO NEUTRON

10

\ @ AND NOISE PILEUP

 

107
0 1 2 3
PULSE HEIGHT SELECTOR

Fig. 2.3.4. MSRE Wide-Range Counting Channel.
 

153

PHOTO-87826

      

 

 

 

 

 

 

 

Fig. 2.3.5. "Snake" Assembly.

 
 

 

 

154

ORNL-LR-DWG 69732R

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

+300v
3500 +110 RECEIVING END
[ T 1oy OF PREAMPLIFIER
- I_‘_-\
gma Ima k3 : ol
-4 - - vi—o—]
z TPUT
EW oot i “ it 1008
It
3 1 0.1 ) L
3 53 220k 5 ]
30k = z 2 PIC H-TY .
oot = . Vo % 602! ; L
e ' £ 20k 7995 3
4 = 0001
ks OO 15k 3 o0 | z "3_‘&-
oot - }‘—
o ; N
30k 001 A \—
o TR T ar I -
INPUT oot | el9n Y TOME,., koaz T4t
+ 7995 z
: L ot 82.5k 1
Z 10k s
2
o] 2500
£ *14.7
-22v
+0v
F-o,

Fig.

Fig. 2.3.7.

 

 

2.3.6. Preamplifier Circuit Diasgram.

PHOTO P-55826

PULSE IHEIGHT

 

Fission Pulses at the Main Amplifier Input.

o
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

r ) . 1
’ \ . : ‘ 7 "
’ 155 N .
fi : . -
\
i -
i ! . . X
. T ’.I . . \ » . ~
' . A . : ORNL-DWG 64-7741R
S R C . C = AMPLIFIER s ’
PREAMPLIFIER JUNCTION BOX ) (IN CONTROL ROOM) i
i - , — i e e — s ey . ‘ ) '
, — | | o |
T e oz I
i o . a - < | ! RMER
FISSION o , > < L s ity
CHAMBER il ‘ z /i\L"“ 1
T T ) FN"TTTTN 7\ = ‘ ,
o [ () L Je ]
L Hi— T TN T 'z ) ‘,
e i 4 7 :
. } r— g Pruvras —
.‘ I N - _ ¥
1 - .
. . 1 . :
\ $ . . b
| ——t . :
. b e e e | :
: BUILDING \ . _]_ BUILDING __|_ BUILDING
. ' = GROUND - = GROUND = GROUND :
L | T ' © . TWO BRAIDS OF RAYCHEM COAXIAL CABLE - g
.o ‘ . {ALL BRAIDS TIE TO JUNCTION BOX) L
| Fig. 2.3.9. - General Shielding end Grounding Layout of the Assembly. :

 
 

 

 

 

 

 

156

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

    

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

 

 

 

 

 

 

 

 

 

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   

 

 

 

   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  
   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

-

!

Fig. 2.3.10. Pulse Amp

’

fier and Count Rate Meter Circult.

 

 

 

‘ v \u_ . j .
1 ' . ORNL DWG. 67-10702
e .
1 AMPLIEER Xig —— [ AMPLIEIER X{2 —— [ FLLE - FLOP AND. EUME DRIVER
@i . L) ANt 25V . .
o # “‘V"“ Lb . ”W‘ 7 v Pl“"i%o;,! '
r— _“;_ - — o [ ewarag rd8.4) ,‘\’:.\r--—hfil(cl !
. | 28 S'IA I ::z A‘C‘
r—AANA > . F"'—'J
) ' . 249 1’*" I s as per v L0 "‘:
e Sae & Py ig ‘
’ VW —- l cor. haov D, S
o i/
I :"“:. ‘:‘J:‘ . | 8.3 . Hfl'fglb T YT
VvV - [-1§
| |42 s el 3 sMbghite eg zer|
I RS s I 7T 2 AR
L %E:&l ' ce T 4 oz % o
- -
. l :.'_ 22 Ser I i rffl »
o802 &9 7
l VWY 0 l g ad A 29SS 0)
% e 3 o _ . r ¢ - 76k ,"‘""‘ o8V
| : WA o | si1a sac ~s10 aaek we-2304s _J et £52
I3 |&% 33 o I1- o o o ° ' ‘ &1 awe
e y . o e o ° o 4
| 3 77 Q% | ° ° . ° " o .
43¢
_ I‘ A o™E i 0 ° ; o ‘o
TR gty o s T . .
L Y I ‘
o w [ e :»gg‘ vl e o o o
2 -"-"\fvu:—-—w“ ] 1 e .o ° ° '
. 281 o282 ! o o o , -
"3 0w | Casog T sigas T Geans T eiomk :
zar : ‘ - :
by |03 . . . o SERVO (INEAR PyYmP .
" $ 288 | ° "o o o -+ e Ve Caee ok SELawe
‘8 L2 o , -2 1L gev : = ‘
3 W | o o o v cas | el cee 7o i - t < P1(13)
T s : EANET: ‘ |
' [ : artey + | '
i ’ o
| o ° - , .
| - : ° TE 00D rla{-’yu 1532 9 ] vy
] 25V q/9
= rite} (5) P10 ook ave ’
o ;:f/ Gcw. a7 sadv ’
1700 - : .
f Z"z;'o i - I ’ /
——— L L s0c. ) '
pPr(s} ,
w ' - ’
la AAN—ttn = 28V
L St MO T £ S - ‘
: *| a2y - ’ -
gse I 4, A1l resisters VeW, 25% axcept o3 noted.
Lo Lews Z.5m denoles 15temeg * Aupa SLAL dboveifed corken rasistor. ~
, >3 # ‘ : - . onl
-:p‘o’l ~ T'gf 4 10KC )0.35.’ 3. A/ B8 :fim:’m with veltwater with 10 s, ' ' 'onpé“:ggfig'?g. v
. z . ) (7] or greafer inpu . s e fvcel g . i :
e 14— i . Yl R S s e v Byecalane s MAINTENANCE OR
" frm-mmm=e § = oo grounded. : CONSTRUCTION
E o Sea00 i:""‘ ! o, Thase r:u’.l/hr uolves will very Frovm one moduke fo e L
i tesmr T
L [/ . i .
: , e S -
{ I ‘ . | PARTS &45T 2]
. 1 ‘ ASSEMELY RCI3-3-t
w '’ . POWTED CHCUIT BOARD - IR seIE
i i AMETALPNOTO FPANEL RLID- 15 -
\ 7 - - OLTAILS [RE13-13-
AV resistors §w, t3% CHASSIS & DETALS REIBAS |
) ‘ . REFERENCE DAAMNGS W, ML
. . : \ e mwww S L ANDER SOV
. AMR INPYT " oUT WASED AMR OUT (bt frigpering) SCALER DRIVE (ke Frigperiog) A
: | | "~ WP DEIVER OUT MOOULAR REACTOR
T R STy T C (AXS@ 500, dmp Ot Avies 2 8.3V)  (AvS @508, Amyp Owt Roks & £.87) (60 cps Count Lrde @t Amp. input) — T T OULAR REACTOR INSTRULENTATION
> } — . - . - Sl A J
gg%&-;g,;»?w s, e T - ] : A ) L A - 71 s lrd Jaciter? tA a; Lo Tia PULSE_AMPLIFIER 4ND
S St T S | ua Lo et e | 10 ¥ H T rrod e Lo wmiin ] ke COUNTRATE METER
TAT e ' ‘ T3 : eresfes Taug=io-sa 37| 708
.‘; % . _ 'l‘*l‘ "th'" *Lfi-l'- ' L ..l 1 e14r (03 |- 13- 14 €2 | Tea mf./RCU/T
’ .- . Poser|n] Iuca3oiz-ee | 3ea + INSTAUMENTATION ANO CONTROLS Divisien
- - ‘r “"L "‘"’l"‘ F-evet| K |mpt-13-18 Kt | Ju#
C . ‘ ' ¢ . 1-143| R0 Jacci3-13 -4 | 704
‘ _ e Re  j&C-41-18~14 *i.A
. s fow - ! 3
SHHAD 56 17 -0m Q- 2418/

 

 

 

 
 

VOLTS

VOLTS

157

ORNL-Dwg. OT-7512

 

 

® InpuT OUTPUT

VOLTS

 

VOLTS

 

 

c A } ] ? 1 ? ] c 1 - ]

OUTPUT-NO OVERLOAD
© - | (D) OUTPUT- X2 OVERLOAD

1 } 1 ? i ? i

 

 

\\______////”fifisec'

(E) OUTPUT - X10 OVERLOAD

Fig. 2.3.11. Pulse Amplifier Waveforms.

 
 

158

ORNL=-DWG 67-7040

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6 —

4!’: Rr
-Q J;CI
=
PLJ“ t = - = =AW /
W e — - — —AAAL /
g b - e - —w~
-
Y b = = — —AAA /
% - -—f“ RE
e
o 6§ /
s rIr Lo -2€

o
%23 o
3 /
S /
"
'§ 2
3 /
I
S /
1 .
ur"" . No.
- P pump 8| pymp 225 | pump 105
0.5 5 S0 So0 S000 Sx10*
COUNTS PER SECOND

Fig. 2.3.12.
Pump Response Where Cn X Rn =

0.1%*

Camposite Response of Six Diode Pumps with Individual
Cl X Rl.
 

159

 

A
""'_'"

A A AAADMA
vITVYeSYYVW

 

 

 

  

The output wiper has just passed commutator bar 2 and is interpolating
between bars 2 and 3. Resistance element tap A is Jjust about to dis-
engage from commutator bhar 1.

 

 

 

 

 

As the output wiper moves in a clockwise direction, the output voltage
changes linearly from the voltage on commutator bar 2 to that on com-
mutator bar 3. Resistance element tap A has disengaged from commutator
bar 1 and is switching to commutator bar 4.

     
 

VYT VY Y-t

AAAAAL NN

 

 

 

 

The output wiper is approaching commutetor bar 3. Resistance element

tap A has completed switching and is in contact with commutator bar 4.

Continued clockwise rotation of the output wiper Wlll result in smooth
interpolation past commutator bar 3.

Fig. 2.3.13. Electrical Relation of Vernistat Interpolator Com-
mutator Bars, Interpolating Resistance Element, and Output Wiper.

 
 

 

160

ORNL-DOWG 67-7036

 

 

r'—-—"——_———_—{z_'g"a ___________ ]
R2
Ein-{ 3._,._3.—@—4 —AAN ' {( p—] DC AMPLIFIER E
s CRI i—[jcnz
‘b
$ ke = TO OUTPUT
MONITORING
cs c12 CKTS

. snanuzan l"
'—“R“g"fi AMPLIFIER H

 

 

 

 

 

 

 

Y

Fig. 2.3.14. Dual dc Amplifier Card Simplified Block Diagram,
One Channel.

TO BALANCE MONITORING CIRCUIITS

ORNL-DWG 67-T7T038

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

- ————
i
|
|
I
|
a3ve I Aemee
= - |
Waig |
T
o 5
sor e ———
lll.‘ "~
-av 2ws
o
wur EOrur —
Lid
Y Fo [T
Lg d
00w
-
n 1
Z20N I |
b
=t
P
f
f
L
2
o£r
he P )
o3 GO—d = 3 NOTE: PIN CONNECTIONS
t 'Y SHOWN FOR CHANNEL 2.
=

 

 

 

s rPoA
e
$ BAL MOMTOMNG

Fig. 2.3.15. 6.715 Amplifier Card. Simplified Schematic, One Channel.
 

|
i
i
i
{
f

 

 

 

 

 

 

 

 

i
|
|
|
|
|
;
|
!
i
|
i
[
t
£
i
!
¥
i

 

DRIVE MOTOR, WITH
INTEGRAL TACHOMETER
AND GEAR REDUCER-

UPPER AND LOWER
LIMIT SWITCHES

161 oo

PHOTO 67688A

SYNCHRO TORQUE
~ TRANSMITTER

DATA LOGGER
POTENTIOMETER

10:1 GEAR REDUCER

VERNISTAT
INTERPOLATING
POTENTIOMETER

AUXILIARY
POSITION SENSING
POTENTIOMETER

 

Fig. 2.3.16. Fission Chamber Drive-Motor Drive Assembly.

 

 
 

 

ORNL-DWG 66-4234

THE VERNISTAT INTERPOLATING POTENTIOMETER : s
IS PART OF MODEL Q-2616 FUNCTION GENERATOR. /
10 TURNS EQUALS 90 in. OF CHAMBER TRAVEL. -

      
  

    

 

  
     
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  
 
 
   

LT
SWITCH 90 TEETH 7Y%, TURNS EQUAL 90 in. OF
CAM 0 40 TEETH s CHAMBER TRAVEL (OR 1 TURN
| VERNISTATLE EQUALS 12 In, CHAMBER TRAVEL)
SIZE 3 4 ‘ =
l SYNCHRO 1:1 RATIO ¥4:1 RATIO {08 TEETH
POTENTIOMETER - SSoa
REDUCER E—{ REDUCER .
. 1070 1 /E 48 10 { 288-rpm RATED SPEED SAGINAW BALL BEARING .
‘ : , 1O-TURN UPPER AND LOWER LEAD SCREW, 4 threads/in.
270° ROTATION EQUALS - 120 TEETH—"" POTENTIOMETER {:1 RATIO T2 UM switches

90 in. OF CHAMBER TRAVEL

GLOBE TYPE
90 in. TRAVEL PREAMPLIFIER FISSION

SLIP CLUTCH wos teeTd L .
(8in.~Ibs) - 22 In/min o CHAMBER

ORNL MODEL Q-2617

 

 

 

 

 

RETRACTABLE CORD

Fig. 2.3.17. MSRE Drive Unlt for Wide-Range Counting Channel, Block Diagram.

[A*)

 
 

163
2.4 LINEAR POWER CHANNELS

2.4.1 Description

These linear power channels (Fig. 2.4.l) comprise the instruments
used for the most accurate determination of reactor power and for input
to the rod control servo system. These compensated ion chambers and
associated power supplies, ORNL models Q-1045 and Q-995, respectively,
were removed from the HRT and reconditioned for use in the MSRE. The
design of the chamber, testing and compensation procedures, and its
high-current saturation characteristics have been described in two
ORNL docum.ents,l’2 applicable portions of which are included later in
this section. The MSRE chambers, unlike the illustration in ref. 1,
are equipped with motor-driven remote compensation adJustment and do
not use a continuous flow of nitrogen.

The Q=995 power supply is a conventional regulated supply designed
to provide the requisite positive and negative voltages to the two sec-
tions of the chamber. The negative voltage adjustment is used to assist
compensation in accordance with ref, 1. For the circuit diagram see
Fig. 2.4.2.

The picoammeter is a Keithley Instruments, Inc., model 418-20
(Sect. 2.4.3). It has an overall range from 10732 to 1072 amp, ac-
complished by range switching. Range switching is described in Sect.
2.6; it may be done locally at the instrument or remotely at the con-
sole., Detailed specifications and performance characteristics, ab-
stracted from the manufacturer's instruction manual, are given in Sect.
2.4.3. Figure 2.4.1 shows only one channel of linear input instru-
mentation. For a more complete diagram the reader is referred to Sect.
2.6,

Either of the two channels may be used to supply input to the
linear recorder on the main control board and to the regulating rod
controller. The output channel not being recorded is read out on a
console-mounted meter. The strip-chart recorder is a two-pen, self-
balancing potentiometer type arranged in a somewhat unorthodox fashion
in order to record both the output voltage of the picoammeter and the
range switch setting unambiguously. _

This simultaneous record of picoammeter output and range setting
is unambiguous because the range setting uses the left-hand 40% of the
chart width and the picoammeter output is restricted to the remaining
60%. Therefore the chart traces do not overlap or cross over at any
time, and there can be no question as to trace identification after the
paper roll is removed. The above is 1llustrated by Fig. 2.4.3, the
chart paper used for this power recorder.

 

1lH, E. Banta and S. H. Hansuer, Testing Procedures for Reactor
Instrumentation, Section J, Compensated Chaflber Field Testing, ORNL~-
CF-56-5-30 (Feb. 8, 1954). —

27. L. Kaufman, High Current Saturation Characteristics of the
ORNL Compensated Ion Chamber (Q-1045), ORNL~CF-60-5-104 (May 25, 1960),

 

 

 
 

164

2.4.2 Visual Readout Device, Series 360

A visual readout device, mounted above the linear power recorder
and legible to personnel in both the control room and the visitors'
area, displays the range setting multiplier so that the reactor power
can be read at a distance by simply noting the position of the indi-
cating flag on the right-hand pen of the linear power recorder. This
readout device (Fig. 2.4.4) consists of an assembly of optical pro-
jection modules which display selected characters (numbers, letters,
symbols, etc,) on a translucent screen located flush to the main board.
In the MSRE the projection lamps in the modules are selected by the
range selector switches on the console.

2.4.3 Keithley Model 418-20 Picoammeter:
Specifications and Description

RANGES: 10™1? to 10™2 amp full scale in twenty-one 1X and 3X
overlapping ranges. Any range may be selected at the main chassis
location or from a remote location,

ACCURACY ¢ iEZ’ of full scale from 1072 to 108 amp; +3% of full
scale from 3 X 10~ to 10°%? amp.

ZERO DRIFT: With source voltages greater than 1 v and after a
30-min warmup, the drift is less than 1% per 8 hr on any range.

RISE TIME, MAXIMUM (seconds, from 10 to 90% of final current):

Range No External With 50 pf With 500 pf With 5000 pf

 

 

(amp) Capacitance Across Input Across Input Across Input
10712 0.03 0.06 0.4 4.0
10711 0.005 0.01 0.035 0.4
1010 0.004 0.004 0.006 0.04
10™° 0.004 0.004 0.004 0.006
1078 0,004 0,004 0.00% 0.004
107 and <0.001 <0.00L <0,001 <0,001

RANGE SWITCHING TIME: 5 msec maximum,

INPUT: Grid current is less than 3 X 10714 amp. Change in input
voltage drop is less than 1 mv for full-scale deflection on any range.
Input resistance increases from 0.1 ohm at 10™R-amp range to 1000
megohms at 10712%-amp range in decade steps.

QUTPUT: A *3-v output at up to 1 ma is developed for full-scale
meter deflection. Impedance is less than 1 ohm. Polarity is opposite
to input polarity. Noise is less than 2% rms of full scale on 10732
amp range. Provision is made for lower voltage outputs.

ZERO CHECK: Allows zeroing without disturbing the circuit.

REMOTE CONTROL: Local or remote control selected by front-panel
switch, Remote range switching requires a five~bit binary input with
 

165

binary "1" corresponding to the 10™2-amp range in numerical order to
binary "21" corresponding to the 10™12?-amp range. Zero check requires
a separate input signal. All inputs require closure to ground.
CONNECTORS: Input: Teflon-insulated uhf-type receptacle.
Output: Amphenol 80 PC2F receptacle.
Remote: Cannon DA15S.
Remote control: Winchester type XAC 34-S-F-2-A-016G.
TUBE COMPLEMENT: One 5886.
POWER: 105125 v or 210-250 v, 50-1.000 cps, 22 w.

2.4.4 Procedure for Field Testing and Compensating
Compensated Chamber Q-10453

Re4e4el Description

The compensated chamber (Fig. 2.4.5) really consists of two cham-
bers, one of them boron-coated. The output current is the sum of the
currents of the individual chambers; since the high-voltage electrodes
of these individual chambers are at potentials opposite in sign (one is
+600 v; the other, —300 v), the output current will be the difference
of the two chamber currents. The current from the boron-lined chamber
is proportional to the neutron flux and to the gamma flux, while the
mcoated chamber responds to gammas only. By making the gamma responses
equal, the output current is proportional to neutron flux alone, even
in the presence of a high gamma flux.

It would not do to make the coated and uncoated chambers identical;
they would then have to be placed in the same location in the reactor.
What is done is to build them very close together and then make one
adjustable to accommodate differences in gamma flux at the two chamber
locations. The process of finding the best adjustment is known as
compensating the chamber. It must be done in the reactor at the exact
location where the chamber is to be used. The reactor itself is used
as a source of gamma radiation.

2e4o4.2 Testing

Insulation Tests

The purpose of these tests is to determine whether the leakage
current of the chamber is negligible compared with the operating cur-
rent., To do this, one applies a high direct voltage to the high-voltage
electrodes and observes the leakage current with a sensitive device.

Two high-voltage supplies are needed: +1000 v and +500 v. They need
not be well regulated, but they must be well filtered and have a low
noise and hum output. It is desirable to operate them from a sine-wave
Sola constant-voltage transformer., Connect the +1000 v to the positive
high-voltage receptacle on the chamber; the +500 to the negative high-
voltage. Connect the output to a current-measuring device capable of

 

3This section (written by J. C. Gundlach and S. H. Hanauer) was
excerpted from ref. 1 (Specification 126),

 
 

166

indicating a current of 10712 amp. This may be an electrometer; often
it is convenient to use the log N amplifier, calibrated as per Q-915-6,
The ground (or low) side of the log N or electrometer must be comnected
to the ground side of the high-voltage supplies, since the receptacle
shells are not comnected to the chamber., This may be done with a clip
lead, but in view of the high voltage involved, a wire properly secured
to a screv is safer. A leakage current greater than 1 X 1012 amp is
excessive, and the chamber must be disassembled and cleaned by someone
experienced in this job. Do not attempt this in the field.

Compensation

1. The preferred method of compensation consists in varying pile
povwer level and comparing the output of the chamber to be compensated
with the pile level as read on another instrument, usually the fission
chamber. The pile is run at a high level for half an hour or more (to
build up gammas); the flux is then changed as quickly as possible to a
lower level. The procedure is trial and error; increase the high-to-
low flux ratio as the compensation gets nearer and nearer the correct
value. The reference instrument will give the ratio of the two flux
levels; compare this with the ratio as measured on the test chamber,

If the ratio from the test chamber is too low, the chamber i1s under-
compensated, and the compensation must be increased. If the ratio from
the test chamber is too high, the chamber is overcompensated, and the
compensation must be decreased.

2. The compensation may be varied by screwing in or out the com-
pensating adjustment on the chamber and by varying the negative potential
on the compensating electrode. Changing the adjustment of the chamber
varies the relative volume of the uncoated chamber; this is how the
compensation is usually changed. The adjusting screw is turned clock-
wise to decrease the compensation of an overcompensated chamber; turning
it counterclockwise increases the compensation. When the adjustment is
nearly correct, turning the adjusting screw 30° will change the (nega-
tive) gamma current by about 1%. The effect of this change on the total
current will, of course, depend on how large the gamma current is with
respect to the neutron current, and this will in turn depend on how
large the gamma flux is compared with the neutron flux. Changes in
negative potential on the high-voltage electrode of the uncoated cham-
ber may also be used to adjust the compensation. Decreasing the voltage
decreases the compensation; increasing the voltage (more negative volts)
increases the compensation. The magnitude of the change in compensation
depends on the gamma current and on the position of the negative high-
voltage electrode, which is moved by turning the compenssating adjustment.
The effect of a 30-v change may be equivalent to as little as 1/20 turn
change in the compensating adjustment, or to as much as 1/2 turn.,

At newer installations, means are provided for turning the compen-
sating adjustment remotely, so that it is not necessary to dismantle
lead cables, shield plugs, and the like. Compensation of chambers so
installed is far better carried out using the compensating adjustment
exclusively, with negative high voltage set at its maximum value, since
the uncoated chamber has better saturation characteristics at higher
voltages, Where chambers are installed without means of remote ad-
justment, it will, in some cases at least, require considerable time

o
 

167

and effort to make each change in the compensating adjustment. One may,
if access is difficult or time short, aim at slight overcompensation
with full negative high voltage and then decrease the voltage as a final

adjustment. It is especially necessary in this case to guard against
leaving the chamber slightly overcompensated (see No., 6 below). A
principal reason for avoilding this method lies in the variable effect
of the voltage adjustment — it is quite possible that compensation can-
not be achieved at any reasonable voltage and that the chamber adjust-
ment will have to be turned again.

DO NOT adjust a compensated chamber to operate with the negative
high voltage less than —50 v.

3. The choice of flux level at which to perform this experiment
is not easy, in some cases. Usually the only instrument one can believe
as & reference is the fission chamber, because only that device permits
rejecting all signals due to gammas. One must use flux levels such that
the low level gives a sufficient counting rate to permit good statistics
in a reasonable time and the high level gives a counting rate less than
10,000 counts/sec, at which rate the error due to resolving time in the
A=l amplifier starts to be important.

4, One must take care that the control rod positions are as
nearly alike as possible for the two flux levels; variations may cause
"shading" effects which impair the validity of the experiment.

5. In reactors vhere the y-n contribution to the shutdown flux is
negligible, the compensation may be checked, at least approximately, by
leaving the log N recorder chart running during any shutdown of 6 hr or
more., The flux will decrease on a period which approaches the 80-sec
half-life of the longest-lived delayed neutrons. If, at some point,
the flux deviates from this 80-sec-period straight line, and this is
not explained by lattice or experiment changes or something similar,
then one can usually sssume the chamber compensation is incorrect.
Upward deviation (toward a constant level instead of a constant period)
indicates undercompensation; downward deviation indicates overcompen-
sation.

6. It is best in the period channel to err on the side of under-
compensation. Overcompensating the chamber will result in a negative
output current; as the current passes through zero during startup the
period circuits will scram the reactor. Prolonged negative current
will induce "sleeping sickness" in the 9004 diode in the log N.

7. It is not a foregone conclusion that every compensated chanmber
can be exactly compensated in every reactor. In cases where the cham-
ber cannot be compensated with the adjustment available, the dimensions
of the cups will have to be changed. This is not a job for the field;
the ORNL Instrument Department Counter Laboratory should be consulted.

 

 
 

 

168

2.4.5 The Use of a Colloidal Dispersion
of Boron in 0Oil to Cbtain a Uniform
and Easily Applied Coating of Boron*

(This specification supersedes ORNL drawing Q-1045-11)

The process of applying a boron coating to graphite,” as developed
at ORNL, is to quickly heat the boron-painted graphite electrode in an
inert atmosphere to a temperature sufficient to drive off the oil car-
rier. The following specific steps are used here to obtain a known
thickness of boron coating.

l. Heat to a dull red color by means of an induction furnace, the
graphite electrode which is to be coated, to drive out some of the
collected gases and surface contamination. A flow of nitrogen®
over the piece during heating and cooling prevents oxidation.

2. Weigh graphite electrode.

3. Apply the dispersion of boron in o0il with brush to the graphite
electrode. A thick coat, but not sloppy, on fine-grained graphite
results in a final coating thickness of approximately 0.8 mg/cm?.

4. Weigh the painted graphite electrode; 20% X weight of applied dis-
persion + cm® of painted surface = desired coating thickness (20%
by weight of the dispersion is boron). The desired coating thickness
for a single-plate chamber is 0.8 mg/cm? (£0.4 mg/cm2 =~ 90% current).
The desired coating thickness for s 4-plate chamber is 0.5 mg/cm?;
the desired coating thickness for a l6-plate chamber is 0.3 mg/cm?.

5. Under a strong flow of nitrogen, heat the painted graphite electrode
to a temperature at which no more oil is being driven off (dull red
heat) and allow to cool quickly. It is important that the nitrogen®
flow carry away the oil vapors quickly and that the flow is continued
until the coated graphite electrode has cooled to near 100°C. Boron
oxidizes quickly at temperatures above 200°C.

6. The coated electrode may be weighed again to check the thickness of
coating. It is expected that some amount of the graphite will be
lost by oxidation.

2.4.6 High Current Saturation
Characteristics of the ORNL Compensated
Tonization Chamber (Q-1045)7

The saturation voltage and current characteristics of the ORNL
compensated ionization chamber (Q-1045) have been measured with special

 

4Excerpted from ref, 1l; this portion was written by J. C. Gundlach.

°Magnesium, brass, aluminum, etc., may also be satisfactorily
coated.

SNitrogen with 10% hydrogen is perhaps better.
"Excerpted from ref. 2.
 

169

regard to high voltage and current ranges. The chamber was sealed in
an enclosure containing dry nitrogen at 15 to 20 psia.

The chamber was secured at a position in the grid plate of the
Bulk Shielding Reactor such that the sensitive volume was approximately
15 in. from the reactor core face on the horizontal center line of the
reactor. This position was chosen so that the chamber current at full
power would be of the order of 1 ma with only a small gamma background
error (5%) at a reactor power three decades lower.

The chamber was connected as shown in Fig. 2.4.6. The output of
the regulated high-voltage power supplies was measured with a D'Arsonval
microammeter (1/2% F.S. accuracy) with 1% precision resistors in series,
High currents (107 amp and up) were measured with a D'Arsonval micro-
ammeter and lower currents with a Leeds and Northrup micromicroammeter
(model 9836A).

The reactor was held at power levels between 1 kw and 1 Mw, and
the chamber voltage was varied in 200-v increments. The data are shown
in Fig. 2.4.7. The actuasl reactor power was 4% lower than the indicated
power at 100 kw and 10% low at 1 Mw due to the decreased neutron at-
tenuation in the shielding caused by decreased water density at higher
temperatures. ‘

It can be seen from the curves in Fig. 2.4.7 that the neutron-
sensitive volume is well sabturated for currents less than 100 pa at any
voltage above 600 v. For high accuracy the chamber should therefore be
operated only at currents of 100 pa and below with the standard power
supply Q=995. The saturation voltage for 800 pa is approximately 2000
v. The inaccuracy at 400 pa at 600 v is about 20%. Since the chamber
can easily withstand high potentials, there is no reason why it cannot
be operated at 1 ma with a suitable power supply. _

Thanks are due K. M. Henry and the staff at the Bulk Shielding
Facility for their help in making the measurements.

 
 

 

POWER SUPPLY
Q-998

 

 

170

ORNL-Dwg., 66-3912

 

 

 

RANGE
CHANGER

- RANGE SIGNAL

 

 

 

 

 

=

COMPENSATED
ION CHAMBER

Q-1043

 

PICOAMMETER

 

 

REACTOR FLUX,LINEAR

> SIGNAL FOR READOUT AND

CONTROL.SEE FIGURE £.28,
PO® TM-TBE.

“Q" NUMBERS REFER TO OAK RIDGE
NATIONAL LABORATORY INSTR. 8
CONTROL DIV. DWG.NUMBERS .

Fig. 2.4.1. MSRE Linear Power Channel. Two installed.
r,,_‘,_ e T g 3t me g s

 

 

171

 

ORNL DWG. 67-10700

 

 

 

 

 

 

 

 

 

  

 

 

 

 

 

 

 

 

   

 

  
     
   
  
   
  

 

 

 

 

 

 

 

  

 

 

 

 

 

 

 

 

 

   

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

o 7
T=rr. {J"s e €T
Block /IPL-28 000 ;:,”-’ .o
Jut put Gas Adapted 4 ST
From {======:(e) 220
\chamber) RG-62/ AN A
S /. Sutput;  RG-62/t Cas
Q8 reld P, - Pl
gPJ JQC’O.JS‘I rel EXTERN AL to  § ——== :Z;_é) gr,, S
AlAaRWV ZIKT @/yano.—
2 Cre <Y nret % 3
‘ i er 3
) G % reeniho
315 - ’%\‘U j:,) FOuz, C-RIOV L0276 = l}* g
m RS R23 Aorsad with precen \v"\s
= ‘]‘ o /0/:!;9 .5';;35 band F70v P 6OV : \\\
Use hioh vort J oo Approx 6804 Sekedf A AAAA ,+(,\ ‘\- W'—;S;on 3or /pcfedgoaa Nen
‘s for roltage - 0 operste ry. Setween ] / Sy cose ” ~ .
wire, 1515 poin W 508 sen | ety = - === 00
Yo ovtpurt
= ezo £/ £ g‘d g
T/ / oL ZON 5K EOW A 7 soov Cns
Sols ey MWN— @) z50 27000
30 /4 \ SREGY g Chassis & coble
- C'ec"{ 03; con. % b red
A t cu Sk ¥
- . C/ :\/oooy /000”—\_ R/O fl!/ 9/3 | CO/Of Cad&d
: sy tozuf ot il EWea.
‘ == =T r000v o
‘ — ~ = - or! ! L gy
‘ ‘ % _ B //pos. ceramic
: o = Wg;’é.‘:”;e‘?a’p&gfifl PJ'_‘- : /g; l' .Shorh'ng A
| A Ny omeg | SCREW WG voL7AGE ALY,
. ”UYOAP/ay- ‘ }“ ‘ /g:{
: N =  O0-J0wg ‘ I
‘ Al Speciol hermetrically O-350Vscole §
NE-JII | Segled Fransformer R7 RE RO
PLassh S ! roorammég.sedpa 220 gek
'S AAAN AAAA
R ] ; 7
LAt ) Lot sg- oON -
¥ 6oo¥ coor T+ S$3 rr::fi:i‘f-z_(g“:: Efi
0//4;“1 oif ‘*."3¥ ! , 39
\ ¢ 5 )
/ smp g/aw,a = At
. g-to- J00¥ cne] See A
E‘ LoD} 1PC 27000| et
B Chassis & coble
; C‘o;}. » be green
' Colko
Note: Copy Femished T1S 7 caded
L ModiFreatron for use with MTR Galvanometer ‘Pate 2-/-56 NOTE:
B> e, (Blaw—-Knox Ttem ¥ 854)only - Al resistors [ wetf except as nofed.
E1-M-10 @ Negative connecter jo be gas adgpred
aSper @-900-7 (1)
- NOT CLASSIFIED
Py b.Add | 1PC 27000 gas adapted as per A 75 llr ek
S1F1/ 9-303 -7(1) latéled Oatput from Port of Blaw-Knox Item Na 650-4C ¢ 654-2C
Chamber :
REVISIONS Vs erucvee Sescieres OAK RIDGE NATIONAL 1. ABORATORY
s &
é “labeled " Output to Galvanometer I‘; /70| 1 |General rensiotms .4
'\f ' A Egnsfarr‘ner £ ipgr] rvr v POWE R SUPPLY
0 FOR MFORMATION OMLY e g chage 1 1. COMP ION, CHAMBER
% |3 Vo C/ Lhrw o s J. Gonet /s * .,
Q ”mm '” ” ‘ 3 '4 “'Maam/ C‘/PCU/T ,.‘,‘:‘v_~
r____H .".T!T”ANCI OR :e, < 73 w T A
CONSTRUCTION L Do o feR0 seax
Term, Dlock L aded o S | I Q- 9951 25| C
: {
| |
Fig. 2.4.2. Circuit Diagram of ORNL Model Q=995 Pc’twer Supply.
".

 

 

 

 

 

—
172

ORNL-DWG 67-€595

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

i
A
3 Pl 12|18 (18| 18| 30
H NT
1 10 20 SO 40 50 60 [0 H#O Q0| ||| oo
&
.. 1 ‘
.
..... - L CHH 1 i
*
3
:
z
| RANGE 2
2 D(i|14 1B | 1B )
L ':‘m q z
( 10 20 30 40 50 ¢0 0 80 90 100 3
®
:
.
<
5

 

 

Fig. 2.4.3. Chart Paper Used for Strip-Chart Recorder.

 
     

F

 

ig.

 

 

2ebrits.

PHOTO 88131

The 1EE Series 360 readout meets human engineering require-
ments for distance viewing by displaying characters up to 2" in
height. The unit operates on a rear-projection principle. When
one or more of the 12 lamps at the rear of the unit is lighted,
it illuminates the corresponding film message, focuses it
through a lens system, and projects it onto the viewing screen
at the front of the unit.

Visual Readout Device, Series 360,

 

=
~J
w

 

 
ORNL-DWG 67-7039

174

 

oFf SAs Now

    

   

        

  

             

                                   
 

    

 

 

 

 

  

 

  

    

     

 

  

  

i
W X
59 : , E1i o1
o &5 3 3 : 85 8 g
3 o e bLE 23 P o s 2 9 %
3 88 y23k  ¥g == E 82 0y . oy
: 833 B aufY & . 25 Z, Jy 5 8 2
3§y £23 g3f, Speg LRl g3 3 g2 ¢ § ¢
ef3 338 w<Sy B 3R "¢ Ty 5w O
oo w33 BB S Eouf I ., 51 B a7
¥ el g3 Bl 4B 3 283 8
38e 35E  Enal -
S S N, i s }
N 5

AN

     

  

————1 K[

s

\Nm\\\\\\\\\
AN 77777777 ] i , Qi 2
R I T T AT Y A O AT IS S WAl AT s

e e S e R R e e B e R S TS

 

 

 

 

 

 

     
 

 

NEUTRON ABSORBING MATERIAL
AN ALLOY
AL NN
SE
wASNIIM ALY
COMPENSATING Y VOLUME .—

FOR PROTECTION OF CABLES

AND CONNECTORS
BORON COATED SURFACES

NEGATIVE ¢ POSITIVE
VOLTAGE CABLES FROM
H.V. POWER SUPPLY
INSULATOR (sansute)
GRAPHITE CORE INSULATED
FROM MAGNESIUM CASING
QUARTZ INSULATOR SPACER
¥ VOLUME ADJUSTMENT

GAS TIGHT

(o-ans gasssy)

 

ive,

OUTHDE DMAMITER OF CHAMBLA 3-JA
APPRORMATE LENSTH OF ChHAuBER 38"

Chamber, Neutron Sensit

ization

Compensated Ion

Fig. 2.4.5.

 
 

175

ORNL-DWG 67-7037
+/ T\~ 0-100pa

 

 

 

 

 

 

 

 

 

 

 

 

METER, 1%
20 MEG.?

t l% >
__________________ 7 T
Fr-- - === = - ====3 D 9-2KV
o O SUPPLY

I NOTE: NEGATIVE TERMINAL -

1l DISCONNECTED

| THROUGHOUT TEST _

|| THROWOVER SW.

I e et B v
* i -JL i SiG T._

- 1

 

 

 

WESTON
0-50,100,500,1000 Ja
METER ,1% F.S.

 

 

 

 

 

ORNL
COME ION CHAMBER

(Q-1045)

Fig. 2.4.6. Schematic Diagram of ORNIL. Compensated Ionization
Chamber,

 
 

176

-3 ORNL~-LR-DWG 48162
5X10

SATURATION
CURRENTS
822 ua

407 pa

82 pa
42.5 pa

10 8.5 ua

4.4 pc

170
10 0.88 ua

NEUTRON IONIZATION CURRENT {gmp}

SHUTDOWN -y BACKGROUND

 

19
0 400 800 1200 1600 2000 2400
COLLECTOR VOLTAGE

Fig. 2.4.7. Saturation Charascteristics of ORNIL Compensated Ioni-
zation Chamber (Q-1045).
 

177
2.5 ROD SCRAM SAFETY SYSTEM

2.5.1 Rod Scram Safety Channel — Input Instrumentation

The control rods are scrammed by excessively high flux, short reac-
tor period, and excessively high reactor outlet temperature. The safety
system employs three independent channels for inputs to the safety sys-
tem logic and requires that any two out of three indicate unsafe con-
ditions in terms of either flux, period, outlet temperature, or circuit
integrity to produce a scram. Table 2.6.1 in Sect. 2.6 lists control
rod actions and the conditions which produce then.

A typical channel of neutron flux input instrumentation is diagrammed
in Fig. 2.5.1. It consists of a neutron-sensitive ion chamber, a period
safety module, a f‘lux-amplifierl and ion chamber high-voltage supply, &a
test module, and fast-trip com.parators.2 The outputs from the period
safety module and the flux amplifier are the reactor period and power
level signals which become the inputs to the fast-trip comparators.

Flux amplifier sensitivity is adjusted by changing the size of a feed-
back resistor. In the MSRE the flux level trip point has two settings,
depending on whether or not fuel salt is being pumped around the loop.
Current relays in the fuel salt pump motor three-phase supply are used
to determine whether the pump is circulating salt or idling in helium.
These relays provide the signals used to actuate switching relays which
change the value of the flux amplifier feedback resistance by a factor
of 1000 and thereby provide rod scram trip points of 15 kw or 15 Mw.
Figure 2.5.2 diagrams the circuitry which shifts flux level trip point,
and Fig. 2.5.3 is a block or signal flow diagram of this circuitry. The
fast-trip comparator is a fast-acting electronic relay with sufficient
power-handling capacity to operate small relays and similar logic and
control devices external to.the instrument. It also contains two small,
fast-acting electromechanical pilot relays which have greater power-
handling capacity with somewhat reduced response time. The "on-off"
outputs of the pilot relays in the comparators are the primary input
signals to the safety system logic and to the control system. Detalled
descriptions of these instruments are given in Sects. 2.5.3 to 2.5.8.

The temperature input signal instruments are block diagrammed in
Fig. 2.5.4. The measuring thermocouples (refer to Sect. 6.7) are com-
posed of two individual thermocouple wires, Chromel and Alumel, welded
adjacently but separately to the fuel salt outlet piping, thus forming
a grounded junction. Each thermocouple wire is contained in an individual
- Inconel sheath and is insulated from this sheath by magnesium oxide. This
construction, using individual, separated wires for each leg of the
thermocouple, is used in preference to a dual thermocouple assembly (both
wires in a single sheath), so that if a thermocouple breaks or becomes

 

1Ronald Nutt, Instrumentation and Controls Div. Ann. Progr. Rept.
Sept. 1, 1963, ORNL-3578, pp. 103—+%.

2J. F. Pierce and D. C. Shattuck, Instrumentation and Controls Div.
Ann. Progr. Rept. Sept. 1, 1963, ORNI-3578, pp. 105-6.

 

 
 

178

detached from the pipe, an open circuit is created. An open-circuited g‘J
thermocouple causes the emf-to-current converter to indicate a failure '
toward safety, that is, upscale.

Thermocouple emf (in the 25-mv region) is amplified by a Foxboro
Company type 693 emf-to-current converter which provides an output cur-
rent, linear with input emf, of from 10 to 50 ma into an impedance of
from 600 to 150 ohms for the selected input range of the thermocouple,
in this case 0 to 1500°F. The type 693 converter uses magnetic amplifiers
to obtain voltage and power amplification, contains no moving parts, and
employs solid-state diodes where required in the circuitry.

The 10- to 50-ma output from the type 693 converter is the input
signal to the high-temperature trip switch. This switch, a Foxboro model
63 alarm, compares a set-point voltage with a voltage developed by the
input current from the type 693 converter and actuates an alarm relay
when the input signal voltage is greater3 than the set-point voltage. A
contact on the alarm relay, closed during normal reactor operation, pro-
vides the high-temperature input signal to one channel of the rod scram
safety system, as will be pointed out subsequently.

The emf-to-current converter also supplies a signal, the voltage
drop across the 400-ohm resistor, to an isolation amplifier. This ampli-
fier provides a barrier between the safety system instruments and the
remaining nonsafety instruments which make up an input channel. The
isolation amplifier transmits the input signal in the forward direction
to the remaining current-actuated switches but decouples the safety
instruments in the reverse direction. This virtually eliminates the
possibility that the effects of malfunctions or misoperation, calibrations,
etc., of the nonsafety instruments will be transmitted in the reverse QEJ
direction to the safety system.

The isolation amplifier is a Foxboro Company N111IF magnetic ampli-
fier designed specifically to amplify the output of Foxboro type 630
pressure transducers and to be compatible with the other Foxboro compo-
nents in Fig. 2.5.4. The amplifier has an input of 0.2 to 4.0 ma into
10,000 ohms impedance and an output of 10 to 50 ma into 600 ohms load.

The remaining two current-actuated switches in Fig. 2.5.4, whose
outputs are labeled "Alarm" and "Control Rod Reverse," are Foxboro dual
type 63 alarms, both in a single case.

The meter is a Foxboro model M65PV-OHT. This is a D'Arsonval cur-
rent meter designed to operate over an input from 10 to 50 ma dc.

2.5.2 Rod Scram Safety Channel — Qutput Instrumentation

The output section of a typical safety channel (channel A) is
diagrammed in Fig. 2.5.5. From the left side of the figure, it can be
seen that the four trip relay contacts in the input instruments are in
series and are maintained closed during normal reactor operation. These
contacts are located as follows:

 

3In other applications an alarm mey be produced when the input
signal is less than set-point voltage. This mode of operation (low
alarm) is accomplished by a simple wiring change. -
 

179

1. high-temperature trip (Toutlet greater than 1300°F) in the Foxboro
model 63 alarm switch, Fig. 2.5.4;

2. channel integrity monitor trip in the Q-2634 MSRE test module, Fig.
2.5.1;

3. high'neutron flux trip in a Q-2609 fast-trip comparator, Fig. 2.5.1;

4. reactor period trip (v £ +1.0 sec) in a Q-2609 fast~trip comparator.

A fifth set of normally closed contacts formed by a manual "Test" button
is also included, followed by & seal contact in parallel with a "Reset"

push button. During normal reactor operation relays KAl to KA5 are

energized. These relays, push buttons, and associated indicating lamps
make up the ORNL model Q-2623 relay safety element, which provides the
contact multiplication needed to produce the safety actions required.

The contacts of relays Khl to Kfi? are interconnected with similar con-

tacts from corresponding relays in channels B and C to produce three
two-out-of-three coincidence matrices in the power circuits to the rod
drive clutches. A typical matrix appears on the right-hand side of Fig.
2.5.5. Relay KA4 provides one of the control rod "Reverse" signals and
the "Seal" contact, and relay KA? is used to open the drain tank vent
valves and close the radiator doors (load scram). Figure 2.5.6 shows &
block diagram and the additional circuits which operate the vent valves,
radiator door, etc.

Each rod drive clutch (see Sect. 2.7) receives its power through
its corresponding contact matrix, and it can be seen that a loss of clutch
current (rod scram) requires that relays in at least two safety channels
be deenergized. This permits testing of individual channels during
operation without disturbing the reactor and also allows the disabling of
any one channel for maintenance. Kach leg in the two-out-of-three matrix
shown in Fig. 2.5.5 contains a 100-ohm resistor and a current meter in
series with a pailr of relay contacts. These meters function as input
channel monitors, as can be seen from the following example. Assume that
channel A is being tested during operation. This may be done with either
the test routine built into the Q-2634 test module (see Sect. 2.5.6) in
channel A or, by using the thermocouple test assem‘bl;y.4 A less complete
test is initiated by pushing the "Test" button in the Q-2623 relay safety
element shown in Fig. 2.5.5. In any case, relays KAl to Kfi? will be

deenergized and thereby produce open circuits in two of the three branch
circuits in each of the Q-2623 coincidence matrix monitors. From Fig.
2.5.5, it can be seen that the meters labeled "A and C" and "A and B"
will change to show zero current. The total clutch current will now be
carried by the third leg in the matrix, and meter "B and C" will change
upscale to reflect this change. The 100-ohm resistors are required to

 

“Molten-Salt Reactor Program Semiann. Progr. Rept. Jan. 31, 1964,
ORN1~3626, p. 44.

 
 

 

 

 

180

ensure equal current division among the three legs in the matrix. With-
out these resistors very small differences in relay contact resistance
would produce large inequalities in the currents normally carried by the
three meters. This resistor is sized so that its resistance must be at
least an order of magnitude larger than any anticipated value of total
relay contact resistance in series with it. Also, it must not be so
large that it reduces clutch current to the "Scram" point when it assumes
the total current load of the clutch, as it must, when one channel is in
"Scram" mode. Tests on the prototype rod drive show that a typical
clutch will transmit 39 in.-1b torque at 22.6 v, whereas the scram torque
produced by the weight of the rod and unbalanced drive mechanism compo-
nents is approximately 12 in.-1lb. Thus, it can be seen that there is
ample margin to prevent undesirable scrams during testing or in the event
that a single channel be tripped as by removal for maintenance or mal-
function.

The 32-v Zener diode across the clutch coil prevents high peak re-
verse voltages that would otherwise take place when the clutch coil cur-
rent is interrupted.

Figure 2.5.7 is a functional diagram of all three channels and
consolidates the contents of Figs. 2.5.1 to 2.5.6.

2.5.3 Safety Chambers

These are Reactor Control Inc.? ionization chambers type R.C.
16-(2-2.88k) (Fig. 2.5.8). Specifications are as follows:

General
Integral cable construction with redundancy on both signal and
high voltage
Cable volume separate from chamber volume
No organic materials used in the chamber or cebles

Construction: all welded, guard on signal

Mechanical
Maximum diemeter 2.5 in.
Chamber length 7.25 in.
Sensitive length 4,25 in.
Integral cable length 45 £t

 

PUCNC Purchase Order No. 56X-71207, Jan. 24, 1964.
 

181

Material

Outer shell
Inner electrodes
Cable sheath and conductor
Insulation
Detector
Cable end seals
Cable

Electrode coating

Resistance at 25°C
Electrode to ground without cables
Electrode to ground with 45-ft cable

Maximum ratings
Applied potential
Temperature
Operating characteristics

Thermal neutron sensitivity
Gamma sensitivity

Saturation

99.97% pure nickel
1100 aluminum

Stainless steel

Alumina ceramic
Alumina ceramic
Al203

Enriched 0B

>101% ohms
>1012 ohms

1000 v dec
200°¢

1.6 x 10714 amp/nv
5 %x 10712 amp r~t hr

See curve in Fig. 2.5.9

2.5.4 Period Safety Module,® ORNL Model Q-2635

2.5.4.1 Description

General

The input, or current-sensing element (logarithmic diode), of the
period safety module (see Fig. 2.5.10) is connected in series with the
flux amplifier input. The voltage across the logarithmic diode is
differentially amplified with a very high input impedance amplifier so
that the chamber current passes undisturbed into the flux amplifier
module. This voltage is further amplified and differentiated to give
outputs proportional to the logarithm of the current and its period

 

6This description of the Q-2635 Module is taken from the Instruction
Manual, pp. 49, written by E. N. Fray, Instrumentation and Controls

Division, Aug. 25, 1965.

 
 

182

(time required for the current to increase by one e factor) respectively.
The input current range is from 1030 o 10°4 amp. In the usual appli-
cation the period output serves as an input to a nuclear reactor safety
system; hence the name "period safety."

Construction

The period safety module is 1.40 in. wide, 4.72 in. high, and 11.90
in. deep. It is a standard "one-unit" plug-in module of the ORNL modular
reactor instrumentation series depicted on ORNL drawings Q-2600-1 to
Q-2600-5. ' ,

The circuits are on a printed circuit board which is completely en-
closed by a shield. The outputs are displayed on front-panel meters.
Test points and access holes to trimming potentiometers are located
along the top of the shield enclosure.

Application

The period safety module is primarily intended to continuously
monitor the neutron flux and period of a nuclear reactor. Since the
module is not intended to measure reactor power accurately, the panel
meter on the output of the logarithmic amplifier is calibrated in "log
current” from 10~° to 10~% amp. The output of the period emplifier is
displayed on a panel meter which is calibrated in seconds from -30 to +1.

Specifications
Overall specifications for the period safety module are as follows:

Period

Output voltage range

Output current
Scale

Zero drift
Power required

Ambient temperature range

Log current

Output voltage

Output current

Scale

Zero drift

Input leakage current
Power required

Ambient temperature range

-0.033 to +10 v for =30~ to +0.1-
sec period

0.1 ma into 100-kilohm load
=30 to +1 sec

Less than 20 mv/month

+15 v dc with regulation *0.1%
0 to 55°C

Approximately 1.67 v/decade with
zero voltage point determined by
"Hi Cal" setting

1 ma into 10-kilohm load

10~10 o 10~% amp

less than 50 mv/month

Less then 10~13 amp at 25°C
+15 v dc with reguletion 0.1%
0 to 55°C
 

Applicable Drawings

183

The following list gives the drawing numbers (ORNL Instrument
Department drawing numbers) and subtitles for the period safety module:

Q-2635-1
Q-2635-2
Q-2635-3
Q-2635-4
Q-2635-5
Q-2602-6

Circuit

Details

Metalphoto Panel
Printed Circuit Board
Assembly

Parts List

The following list gives the drawing numbers and subtitles for the

plug-in chassis system:

Q-2600-1
Q-2600-2
Q-2600-3
Q-2600-4
Q-2600-5

2.5.4.2 Theory of Operation

Genersal

Assembly
Details
Details
Details
Details

The ionization chamber current passes through a thermionic diode in
the period safety module and then into the flux amplifier (Q-2602) or

equivalent.

proportional to the logarithm of the current.

The voltage drop across this "log" diode is approximately

The diode voltage is

applied to a very low leakage differential amplifier, whose output is
further amplified with a second differential amplifier to give the “log

11

current” output.

The "log current" output is differentiated with an

operational amplifier to generate the "period" output.
It is required that the leakage of the input difference amplifier

be small compared with the flux amplifier input leakage.

This leskage

current must come from the ionization chamber current, and if the leak-
age current is excessive, the current amplified by the flux amplifier

will be in error.

Circuit Description

The input current flowing through the thermionic diode V1 develops

a voltage across the diode that is essentially logarithmic over the cur-
rent range of 10710 to 10™% amp., This voltage is applied to a difference
amplifier which uses insulated-gate field-effect transistors (FET's) as
active elements (Ql). The gate leakage current of the FET's is extremely
small, so that essentially all the signal current flows through the diode
and then into the flux amplifier. The gates are protected against over-
voltage transients by neon tubes Il and I2. (Ordinary Zener diodes are
not adequate to furnish this protection because of their high leakage
current.) A constant-current circuit, comprised of transistor Q2 and
resistors R7, R8, and R9, furnishes the bias current for the difference

 
 

184

emplifier and appears as & large source load impedsnce to improve the
common-mode rejection ratio. The gain of the difference amplifier is
approximately 2.5. Its output is applied to a Fairchild type ADO-3
differential amplifier whose gain is adjustable from 2.67 to 4 by the
trimming potentiometer R11l ("Io Cal"). The particular gain required is
determined by the characteristics of log diode V1, and it is adjusted
to give approximately 1.67 v/decade at the output of the "log current”
amplifier. Trimming potentiometer R18 ("Hi Cal") is required for proper
scale adjustment of meter Ml.

The "log current" output is differentiated by an additional ADO-3
eamplifier whose gain (product of C4 and R25) is such that a 1-v output
corresponds to a l-sec period.

Two significant smoothing time constants are associated with the
"period" amplifier. They are determined by the product of R20 and C4
and R25 with C5, and each is approximately 100 msec.

2.5.4.,3 Operating Instructions

Installation

The period safety module is & module in the ORNL modular reactor
instrumentation series. ILike the other modules in this series, it has
standard connectors and dimensions and has a pin-and-hole code on the
rear plate so that the module will not be inserted in a wrong location
in a drawer. The module is installed by placing it in its proper lo-
cation, inserting the module firmly, and tightening the thumbscrew. The
module may be plugged in with power on without damage.

Operating Controls

Log Current Panel Meter. — The log current panel meter is calibrated
to indicate current from 10—° to 10™% amp. This represents a voltage
swing of =10 v; however, the output voltage measured with respect to
ground at a particular current will vary from unit to unit. This is de-
termined by the "Hi Cal" setting, which adjusts for variations of input
diode characteristics.

Period Panel Meter. — The period panel meter is calibrated to in-
dicate reactor period from —30 to +1 sec. This is a voltage range from
-0.033 to +1.0 v. The meter is mechanically zeroed to give an "w" in-
dication with no voltage applied.

Zero Adjustment. — "Bal 1" is for zeroing the output of the insulated-
gate difference emplifier Ql with TPl and TP2 shorted together. "Bal 2"
is for zeroing the output of the "log current"” amplifier with TP3 and
TP4 shorted to ground. "Bal 3" is for zeroing the output of the "period”
amplifier any time when the input is not changing.

Test Points. — The test points are locaeted at the top of the front
side of the shielding enclosure. These are used primerily when zeroing
or balancing the instrument, as described sbove.

 

 

 

 

Connections

All connections are made through the rear connector P29 when the
module is inserted.
 

185

Operating Procedures

 

The balance of the insulated-gate difference amplifier, log current
amplifier, and the period amplifier should be checked periodically for
drift. If correction is required, the following procedure should be
followed:

l. Place a jumper between TPl and TPZ2 and measure the voltage between
TP3 and TP4 with a Triplett meter (or equal). Adjust "Bal 1" until
the voltage is zero.

2. Place the jumper across TP3 and TP4 and TP6 (ground). Adjust
"Bal 2" until the voltage between TP5 and TP6 is zero.

3. The period amplifier may be zeroed at any time the input is not
changing by adjusting "Bal 3" until the front-panel meter indicates

"e'" or until the output is zero.

2.5.5 Flux Amplifier and Ion Chamber High-Voltage
Supply, ORNL Model Q-26027

2.5.5.1 Description

General

The flux amplifier (Fig. 2.5.11) is a low-level dc amplifier that
amplifies current in the range of 10™10 o 30™4 amp from an ionization
chamber. The current from the ionization chamber is proportional to
reactor neutron flux in the usual application; hence the name "flux
amplifier.” .

An ion chamber high-voltage supply, & de-to-dc converter, is con-
tained in the same module with the flux amplifier to provide +250 v to
polarize the ion chamber. The two sections are electrically independent.

Construction

The ion chamber high-voltage supply and the flux amplifier are in a
single module 2.83 in. wide, 4.72 in. high, and 11.90 in. deep — a
standard "two-unit" plug-in module of the modular reactor instrumentation
series depicted on ORNL drawings Q-2600-1 to Q-2600-5.

- The circuits are on two printed circuit boards mounted side by side.
The output is displayed on a front-panel meter. A balance meter, mounted
in the top front of the module, is visible when the module is plugged in
and the drawer is withdrawn. Near the meter is a "zero" push button and
a trimming potentiometer for balancing the flux amplifier.

Application
The ion chamber high-voltage supply and flux amplifier are intended
primarily to continuously monitor neutron flux in a nuclear reactor. To

 

” _
Written by J. L. Anderson, Mar. 3, 1965.

 
 

 

186

this end the panel meter is calibrated in percent power from O to 200%.
However, the amplifier may be used, with or without the ion chamber
high-voltage supply, wherever it is desired to measure current in the
range 10~8 to 10™% amp full scale.

The amplifier has two internal feedback resistors and provisions
for connecting an external feedback resistor to establish any desired
scale calibration vs current within the capability of the instrument.

A flux reset mechanism Q-2603, a companion unit, can be used with
the flux amplifier to continuously adjust the feedback factor or gain
over a 3 to 1 range. The flux reset mechanism is a small instrument
servo that adjusts the feedback ratio of the flux amplifier so as to
force the flux amplifier output to agree with another signal, typically
computed heat power.

Specifications

Overall specifications for the flux amplifier and ion chamber high-
voltage supply are given below.

Flux Amplifier

Output voltage range O to +12 v linear for positive
current (flowing into ampli-
fier); O to —~12 v for nega-
tive current

Output current 30 ma into 300-ohm load
Scale 0 to 200% power
Zero drift Iess than 1 mv/day at con-

stant temperature; less
than 10 mv for O to 55°C

Input leakage current Iess than 10710 amp at 25°C

Response time 10 to 90% rise time in less
than 100 psec with a 200-
kilohm feedback resistor
and 0.002-uf capacitor on
input

Power required +25 + 0.25 v dec with regulation
+0.1%; —25 + 0.25 v dc with
regulation 0.1%

Ambient temperature range 0 to 55°C

Ion Chamber High-Voltage Supply
Qutput voltage +250 * 25 v dc

Input power required +32 t 4 v de and 200 ma
maximum
Output current Rated 5 ma continuous; will

deliver ~50 ma into a 3-
kilohm load or 1 ma minimum
into a short circuit
 

187
Overload protection

ILoad regulation
Line regulation
Output ripple and frequency

Adjustments
Starting

Ambient temperature range

Applicable Drawings

Undamaged by any overload, in-
cluding a short circuit

less than 15%, O to 5 ma
Iess than 10%, 28 to 36 v dc

ILess than 50 mv at 5 ma load;
~8 ke

None

Self-starting, no load to full
load

0 to 55°C

The following list gives the drawing numbers (ORNL Instrument
Department drawing numbers) and subtitles for the ion chamber high-

voltage supply and the flux amplifier:

Q-2602-1 Circuit

Q-2602-2 Details

Q=-2602-3 Metalphoto Panel
Q-2602-4 Printed Circuit Board
Q-2602-5 Assembly

Q-2602-6 Parts List

SF-239 Fabrication Specification

The'following list gives the drawing numbers and subtitles for the

plug-in chassis system:

Q-2600-1 Assembly
Q=2600~2 Details
Q-2600-3 Details
Q-2600-4 Details
Q-2600-5 Details

2.5.5.,2 Theory of Operation

Generalr

The ion chamber high-voltage supply and flux amplifier consist of a

stable, direct-coupled low-leakage emplifier and a self-contained high-

voltage supply for ionization chamber polarization.

The chanber voltage

supply consists of a series preregulator, to regulate the battery input
voltage, and an unregulated dc-to-dc converter. ,

Circuit Description of the Ion Chamber High-Voltage Supply
The power supply is designed to operate from a nominal 32-v station

" battery with a terminal voltage variation from 28 to 36 v dec.

This wide

variation makes necessary a voltage preregulator consisting of transistors

Q9, Q:LO) Q,ll, and Q,l2.

 
 

188

The preregulator output voltage is sensed by resistors R24 and R26
and applied to the base of amplifier stage Ql1l. A reference voltage
(16.8 v) generated by Zener diode string D4, D5, and D6 is applied to the
emitter of Qll. The amplified difference appears at the collector of Q11
and is applied to driver Q10 and pass transistor Ql2. A constant col-
lector current is provided for Qll by transistor Q9, Zener diode D3, and
the associated network. The preregulator output (test point TPl) is
filtered by C3, C4, and R27 and is applied to the de-to-dc converter.

Q13, Ql4, T1, and the associated circuitry comprise a free-running
square-wave oscillator; D7, D8, and D9 assure that the circuit will be
both self-protecting and self-starting. Capacitors C6 and C7 round the
edges of the square wave somewhat to avoid the generation of sharp, high-
frequency spikes which may be coupled to other circuits.

A square wave of approximately 250 v peak-to-peak amplitude and
frequency of approximately & kc appears on winding 1-3 of transformer
Tl. This voltage is rectified by diode bridge D10-D13 and is filtered
by a pi-section RC filter composed of C8, C9, and R32. The output is
approximately 250 v de with less than 50 mv of 8- or 16-kc ripple.

The output voltage vs load current is shown in Fig. 2.5.12. When
the output is short-circuited, the circuit continues to oscillate at a
very low amplitude and supplies about 1 ma of current. The circuit will
recover undamaged upon removal of the short circuit or overload.

Circuit Description of the Flux Amplifier

The flux amplifier converts a low-level current from an ionization
chamber to a usable voltage. The current range is determined by feed-
back resistor R33, which may be paralleled by R10 or an external re-
sistor. The input current is converted to a full-scale voltage of 10 v
at the output of the amplifier.

The amplifier is an operational type with a high open-loop gain and
a high open-loop impedance (Fig. 2.5.13). Only a small leakage current
flows in the input of the amplifier; therefore, all the signal current
flows through feedback resistor Rf. The voltage produced at the output
is

Eo (V’) = ISRf )

where I, is the signal current in amperes and Re is the resistance in
ohms.

The sensitivity of the flux emplifier can be adjusted by flux reset
mechanism Q-2603. Instead of feedback resistor Rg being connected di-
rectly to the output as shown in Fig. 2.5.13, it is connected through a
voltage-dividing network to the output as shown in Fig. 2.5.14. Poten-
tiometer R6 is motor driven to adjust the output voltage (with constant
input current) until the flux amplifier output agrees with an independent
signal as might be derived from & heat-power computer. The output volt-

age is then
R6é + R7
Bo = L Re (_0536 TR >’

where O is the potentiometer setting as indicated in Fig. 2.5.14.
 

189

The flux amplifier is composed of eight silicon transistors and a
silicon diode. Input device Ql is a field-effect transistor which has
low gate-leakage current. In the specified range of input current, the
field-effect transistor is a satisfactory electrical replacement for an
electrometer tube and is far more rugged.

Some unusual characteristics of the field-effect transistor are
used advantageously in this particular amplifier. The field-effect
transistor drain-voltage drift with temperature is a function of the
drain current. When the drain current is larger than approximately 30
pna, the temperature coefficient is positive. When the drain current is
less than approximately 30 pa, the temperature coefficient is negative.
The field-effect transistor is biased at approximately 45 pa so that its
net current drift will be in a positive direction to cancel out drifts
of opposite direction due to the remaining transistors and diodes. The
voltage gain from gate to drain of the field-effect stage is about 20.

The remaining transistors are operated in standard configurations.
Transistor Q2, an emitter follower with near unity voltage gain, imped-
ance matches field-effect transistor QL to the following gain stage.

Q3 and Q4 comprise a differential high-voltage-gain stage. The gain
from the base of Q3 to the collector of Q4 is about 500.

Transistors Q5, Q6, Q7, and Q8 are complementary emitter-follower
power-gain stages with unity voltage gain. The function of these four
transistors is to allow the output to swing plus and minus 10 v and
deliver up to about 30 ma of current to the load.

2.5.5.3 Operating Instructions
Installation

The chamber high-voltage supply and flux amplifier is a module in
the ORNL modular reactor instrumentation series. ILike the other modules
in this series, it has standard connectors and dimensions and has a pin-
and-hole code on the rear plate so that the module will not be inserted
in & wrong location in a drawer. The module is installed by placing it
in its proper location, inserting the module firmly, and tightening the
thumbscrew. The module may be plugged in with power on without damage.

Operating Controls

Panel Meter. — The panel meter is callbrated to indicate power from
0 to 200%; this corresponds to a voltage output of O to —10 v. If the
amplifier is to be used with a- negatlve 1nput current the meter leads
should be reversed. :

Balance Meter. — A zero—center balance meter on the top of the
module is visible with the module inserted and the drawer pulled out.
The meter is used with the push button and zero adjustment located at
the edge of the printed circuit board nearby to correct for drift
periodically. '

Zero Adjustment. — The zero adjustment is used to balance the de
amplifier to correct for drift.

Zero Push Button. — This push-button switch short-circuits the in-
put of the amplifier so that it may be balanced even when signal current
is present.

 

 

 

 
 

190

Connections

A1l connections are made through the rear connector P9 when the
module is inserted. A Jjumper between pins 2 and 3 of P9 is provided so
that if the module is removed from a drawer a warning signal is given.

Opersting Procedures

The balance of the flux amplifier should be checked periodically by
depressing zero push button S1 and observing balance meter M2. If the
meter reads anywhere on scale less than plus or minus full scale when
the push button is depressed, the balance is satisfactory. With the
push button released the meter should read upscale the same amount as
the front-panel meter reading. If adjustment is necessary, turn zero-
adjustment potentiometer R3 clockwise to move the indicator in a positive
direction or counterclockwise to move the indicator in a negative di-
rection.

There are no adjustments on the chamber high-voltage supply.

 

Precautions

Since the output of the high-voltage supply can be lethal, care
should be taken not to place fingers in the rear portion of this module.

External connections to the ionization chamber should be made with
the power off or the module unplugged to avoid possible damage to field-
effect transistor Ql.

2.5.5.4 Maintenance Instructions

General

This module is designed to operate continuously with a minimum of
maintenance and adjustment. Zero adjustment and voltage test points
are accessible from the top of the drawer with the module inserted and
the circuits energized.

Periodic Maintenance

 

The amplifier balance should be checked (see Operating Procedures,
above) once every three or four weeks.

The high-voltage output should be checked every three or four
months by measuring with a voltmeter at the test points. The white
point on the module is ground test point TP3; the red point is the high-
voltage ocutput test point TP2; and the gray point is the preregulator
output test point TPl. The voltages at the test points should read
(with respect to TP3); TPl, +25 + 1 v; and TP2, +250 = 25 v.

Calibration Procedures

There are no calibration procedures.
 

e

191

2.5.6 MSRE Test Module, ORNL Model Q-26348
2.5.6.1 Description

General

The MSRE test module (Fig. 2.5.15) is a special-purpose unit designed
to supply calibration signals for testing the response of parts of the
safety system of the MSRE. The module provides two calibrated current
ramps at different rates to check the response and approximate calibration
of the flux amplifier and associated fast-trip comparators. An adjustable
steady-state current can be substituted for the ramps for more precise
calibration. In addition, the module provides two steady-state currents
for calibration of the "log current” portion of the period safety module
and two voltage ramps for calibration of the "period" portion of the
period safety module and associated fast-trip comparator. An ion chamber
undervoltage monitoring circuit is provided in this module. All these
are initiated by push buttons from the module front panel.

Construction

| The module is 2.83 in. wide, 4.72 in. high, and 11.90 in. deep. It
is a standard "two-unit" plug-in module of the ORNL modular reactor in-
strumentation series depicted on drawings Q-2600-1 to Q-2600-5,

The circultry is constructed on two large printed circuit boards
mounted within the module.

Application

The module is intended to supply signals for both preoperational
and on-line testing of the nuclear safety system of the MSRE. Although
the signal types and circuitry used are generally applicable to any re-
actor safety system employing the ORNL modular reactor instrumentation
series, the signal levels and rates for this module are tailored es-
pecially for the MSRE.

opecifications

Output Ramps. — The basic ramp generator supplies a voltage ramp
of 0 to +14 with a rate of +1 v/sec. This ramp voltage is applied to
suitable multiplier resistors to obtain the required current ramp. The
output currents are: high rate (300 kilohms), O to 46.7 x 10™% amp; and
low rate (300 megohms), O to 46.7 X 10™2 amp.

Output Currents, Steady State. — The output currents are adjustable
with a ten-turn precision potentiometer on the front panel calibrated to
be direct reading from O to 100. The output currents are: high current
(200 kilohms), O to 100 x 10~° amp; and low current (200 megohms), O to
100 x 10™% amp.

Log Current, Steady State. — Two calibration currents are derived
from the ion chamber high-voltage supply by suitable multiplier resistors

 

 

8This material was taken from the Instruction Manual, pp. 514,
written by E. N. Fray, July 28, 1965.

 
 

192

for current calibration of the period safety module. They are: high
(25 megohms), 10™° amp; and low (250,000 megohms), 10~° amp.

Period Calibration. — The +1-v/sec ramp is applied to the log cur-
rent amplifier in the period safety module through a suitable input re-
sistor. This produces a constant output at the period amplifier for
calibration purposes. Two approximate calibration points are provided:
+1 sec period (500 kilohms) and +2 sec period (1 megohm).

Undervoltage Monitor. — The circuit continuously monitors the
polarizing voltage of the ionization chamber on a return lead from the
chamber. When the chamber voltage is greater than 200 * 10 v, a green
light labeled "Normal" on the front panel is 1it. When the chamber
voltage for any reason drops below 200 + 10 v, the circuit changes state
and lights both a red "Low" indicator lemp and a yellow "latch" indicator
lamp. When the voltage is restored, the "Low" indicator is extinguished,
and the "Normal" light agein comes on. The "Latch" light remains on
until the front-panel "Reset" push button is depressed. The relsy that
actuates the indicator lamps has additional contacts (single pole, double
throw) for use in external circuits. An additional front-panel push
button labeled "Test" simulates a low-voltage condition to the monitor
circuit without affecting actual chamber voltage.

Power Requirements. — The module requires +32 * 4 v unregulated and

 

 

 

+25 v * 0.1% regulated.

Ambient Temperature Range. — The ambient temperature range is 10 to

 

55°C.

Applicable Drawings

The following list gives the drawing numbers (ORNL Instrument
Department drawing numbers) and subtitles for the MSRE test module:

Q-2634~1
Q-2634-2
Q-2634-3
Q-2634-4
Q-2634-5
Q-2634-6

Circuit

Details

Metalphoto Panel
Printed Circuit Board
Assembly

Parts List

The following list gives the drawing numbers and subtitles for the

plug-in chassis system:

Q-2600-1
Q-2600-2
Q-2600-3
Q-2600-4
Q-2600-5

2.5.6.2 Theory of Operation

General

Assembly
Details
Details
Details
Details

The MSRE test module is & special-purpose module designed to pro-
vide signals to test parts of the nuclear safety system of the MSRE.
 

193

Although it was originally intended to have a general-purpose test
module which would be applicable to several reactors, and such a module
Q-2601 was designed, it soon developed that a single test module would
not suffice because of the different instrument sensitivities and varied
functions of the several reactor systems under design. Consequently, a
separate test module was designed for each reactor that uses this type
of instrumentation. In spite of the unique project application of the
module and because of the general applicability of the cirecuits used in
the module, a "Q" number was assigned to the MSRE test module for the
convenience of designers of future systems.

Circuit Description

 

Ramp Generator. — A linear voltage ramp is generated by charging a
capacitor with a constant current. In circuit diagram Q-2634-1, it is
seen that the base of transistor Q1 is held at a constant potential with
respect to the +25-v supply by Zener diode D1. This in turn causes the
emitter voltage of QL to be constant across a fixed resistor R2, estab-
lishing constant emitter current. To a first approximation, transistor
collector current is equal to emitter current, regardless of collector
voltage, until saturation is reached, that is, until the collector volt-
age equals the emitter voltage. Thus, the collector current of Q1 is
constant and flows into capacitor Cl.

In the standby condition, the capacitor is short-circuited by con-
tacts of relays Kl and K2 and by contacts of push buttons S7 and S8.
When any one of these contacts opens, the capacitor begins to charge.
The rate of change of voltage across the capacitor is determined by the
magnitude of the current and the size of the capacitor. In this case

y_1
t " ¢
-6
_ 20 X 107" amp _ v/sec .
20 x 1076 r

The voltage across Cl is sensed by a very high beta Darlington-pair
emitter follower Q2 and Q3. The maximum amplitude of the ramp is limited
by saturation of Ql and Zener diode D1 to about 15 v across Cl or 14 v
at the emitter of Q3. :

-Current Switching. — The MSRE test module is designed to provide
test currents for both the flux amplifier and the period safety module.
Since the input of the flux amplifier is in series with the log diode of
the period safety module, any test current will be sensed and indicated
by both instruments. Since the flux amplifier has 100% feedback to the
input terminal, there is no input voltage offset. This means that a
relatively low-voltage current source is adequate for generation of its
test currents. For application to the period safety, a better current
source is required, since the voltage across the log diode is not con-
stant but changes with input current. To this end the calibration cur-
rents for the period safety are produced by using the chamber high-voltage
supply and suitable multiplier resistors. The "Rate" test currents and
the "Adjustable" test currents are intended for use with the flux ampli-
fier only; further, application of either of these currents causes the

 

 
 

194

period safety to indicate an incorrect current, which should be ignored.

Since all test currents are applied by way of a second ionization
chamber signal lead, which is separate all the way to the chamber plates,
a test signal must travel to the chamber and back to the safety channel
input. In this way a successful current test verifies that the chamber
is connected.

Flux Amplifier. — For steady-state calibration or checks, a voltage
adjustable from O to 20 v by a front-panel Helipot may be applied through
either a 200-kilohm or a 200-megohm resistor to the amplifier input by
energizing relay K4 or K3 respectively. The corresponding currents are
0 to 100 pa and O to 100 na. The Helipot dial labeled "Current Adjust”
is read directly from O to 100 units.

The voltage ramp described sbove may be applied through a 300-kilohm
or a 300-megohm resistor by energizing relay K1 or K2, respectively, re-
sulting in current ramps ranging from O to 46.7 pa and O to 46.7 na. The
ramp is initiated by a second contact of Kl or K2, which removes the
short circuit from capacitor Cl. |

Period Safety. — Fixed calibration currents for the period safety
module are generated by applying the chamber high voltage (approximately
250 v) through either a 25- or a 250,000-megolm resistor, resulting in
currents of 10™° or 10~? amp. These currents are initiated by energizing
relays K5 and K6 respectively.

To check the calibration of the period amplifier, the voltage ramp
is applied to the input (terminal 6) of the log current amplifier. Sub-
sequent differentiation in the period amplifier results in a constant-
voltage output (constant indicated period) whose magnitude is determined
by the generated ramp rate and the gain of the log current amplifier.

Two calibration points are provided by applying the voltage ramp through
either a 500-kilohm or a l-megohm resistor; the result is a period in-
dication of about 1 and 2 sec respectively. Actually, the l-sec period
test should always generate a period slightly less than 1 sec, so that
the l-sec fast-trip comparator will trip. These tests are initiated by
depressing push buttons S7 or S8 to generate the 1- or 2-sec period.

Chamber Voltage Monitor. — In a manner similar to the signal lead,
a separate high-voltage lead is returned from the plates of the ioniza-
tion chamber. This voltage is continuously monitored by & circuit con-
sisting of transistors Q4 through Q8. If the voltage, normally 250 v,
is interrupted or reduced below approximately 200 v, an undervoltage
alarm occurs.

The sensed voltage is reduced from 250 to 100 v at R5 by two Zener
diodes, D2 and D3. The voltage is further reduced to 20 v at the base
of Q4 by the dividing action of R5 and R6. The emitter of Q4 is biased
at 10 v, so that the transistor is reverse biased and not conducting
under normal conditions. Since the collector of Q4 is near ground po-
tential, the Darlington emitter follower Q5 and Q6 and the relay drivers
Q7 and Q8, driven by the emitter-follower output, are also not conduct-
ing. A normally closed contact of K7 energizes the green "Normal" lamp
on the front panel.

When the input voltage drops below 200 v, the Q4 base voltage is
reduced to below 10 v, and Q4 conducts. The collector voltage of Q4 in-
creases to 10 v, turning on Q5, @6, Q7, and Q8 and energizing both K7
and K8. The contacts of K7 extinguish the "Normel" lamp and light the

 
 

 

195

red "Low" chamber voltage lamp. A second set of K7 contacts controls
external circuits. K8 seals itself in and will remain energized, light-
ing the "Latch" lamp, until input voltage is restored and "Reset" button
S2 is depressed. This enables the operators to identify a momentary
chamber voltage fault.

The voltage monitor circuit is tested by pressing "Test" push button
S1 on the front panel. This reduces the voltage at the base of Q4, simu-
lating & low input condition without causing significant reduction of
the chamber voltage itself.

2.5.6.3 Operating Instructions

Installation

The MSRE test module is one of the ORNL modular reactor instrumenta-
tion series. Iike the other modules in this series, it has standard
connections and dimensions and has & pin-and-hole code on the rear pleate
so that the module will not be inserted in & wrong location in a drawer.
The module is installed by placing it in its proper location, inserting
the module firmly, and tightening the thumbscrew. The module may be
plugged in with power on without damage.

Operating Controls on Panel

Chamber Voltage Monitor. — Three pilot lamps indicate the state of
chamber voltage. The green "Normal" light is on when the voltage is
greater than 200 v. The red "Low" light is on when the voltage is less
than 200 v. The amber "Latch" light comes on when the voltage drops
below 200 v and remains on until the "Reset" button is pressed. When
the "Test" button is depressed, it causes a simulated low voltage to test
the monitor.

High Rate. — When the "High Rate" button is depressed, a current
ramp of 3.33 ua/sec is applied to the safety channel input.

~ Low Rate. — When the "Low Rate" button is depressed, a current ramp
of 3.33 na/sec is applied to the safety channel input.

High Current. — When the "High Current" button is depressed, a cur-
rent, adjustable from O to 100 pa by the "Current Adjust" potentiometer,
is applied to the safety channel input.

Iow Current. — When the "Low Current" button is depressed, a cur-
rent, adjustable from O to 100 na by the “Current Adjust" potentiometer,
is applled to the safety channel input.

'High log Current. — When the "High Log Current"” button is depressed,

 

a current of 107> amp is applied to the safety channel input.
Low log Current. — When the "ILow Log Current" button is depressed,

 

a current of 107° amp is applied to the safety channel input.

l-sec Period. — When the "l-sec Period" button is depressed, a volt-
age ramp is applied to the period safety module, resultlng in an output
indication of approximately a l-sec period. .

2-sec Period. — When the "2-sec Period" button is depressed a volt-
age ramp is applied to the period safety module, resulting in an output
indication of approximately a 2-sec period.

 
 

196

Connections

A1l connections are made through the rear connector P28 when the
module is inserted. A jumper between pins 4 and 12 is provided so that
if the module is removed from a drawer, a warning signal may be given.

Operating Procedures

 

All tests are initiated simply by depressing the proper push button
on the front panel.

2.5.7 Fast-Trip Comparator, ORNL Model Q-2609°

2.5.7.1 Description

General

The fast-trip comparatorlo circuit (Fig. 2.5.16) compares the magni-
tude of two input dc signals having opposite polarities and produces an
output voltage having either of two possible values, depending upon which
input voltage is larger. Two electronic outputs drive logic circuits ex-
ternal to this unit, and there are also two relsy drivers within the
unit. The change in voltage from one level to the other is completed in
less than 200 psec after the trip signal occurs. The relays can change
states in approximately 10 msec. Each relay has one set of contacts for
external connections and one set to perform an indicating function on
the front panel. One relay can be connected to hold a trip indication
after the trip has cleared, and the other relasy indicates the immediate
state of the circuit.

Several external connections can be made that allow the circuit to
trip for a variety of input conditions. With a reference serving as one
signal, the circuit can trip on a positive or a negative input signal
and on an increasing or a decreasing signal. For the case of two ex-
ternal signals A and B, tripping action can take place when the magni-
tude of A is greater than or less than that of B, provided A and B have
opposite polarities.

Construction

The fast-trip comparator is constructed in & single module 1.40 in.
wide, 4.72 in. high, and 11.90 in. deep. It is a standard "one-unit"
plug-in module of the modular reactor instrumentation series depicted on
drawings Q-2600-1 to Q-2600-5.,

The circuit is constructed on & printed circuit boasrd mounted within
a shielding enclosure with removable sides.

 

Token from Instruction Manuasl, written by J. L. Anderson, Instru-
mentation and Controls Division, Apr. 13, 1965.

107, F. Pierce and D. C. Shattuck, Instrumentation and Controls
Div. Ann. Progr. Rept. Sept. 1, 1963, ORNI-3578, pp. 105-6.
 

197

Application

The fast-trip comparator is intended primarily to be used as a
voltage level discriminator for safety and control functions in a nuclear
reactor. For maximum flexibility the unit has two inputs, so that it
may be used either to compare two signals or to compare one signal with
an external reference. The circuit is bistable in nature; that is, there
is no change in output indication until the predetermined trip level is
exceeded, at which time the output suddenly changes from one state to
the other. The trip level is nominally zero volts; that is, the two in-
ruts must be of opposite polarity, so that when the magnitude of one in-
put exceeds the magnitude of the other, the circuit changes state. By
use of suitable external jumpers the circuilt can be arranged to trip on
either net positive or net negative input.

Two types of output are available. The logic output, intended for
use in fast safety systems, is —10 v normally and O v when tripped. The
switching time is less than 200 psec. Normally the logic level will
revert to normal as soon as the input signal drops below the trip level.
However, by use of external Jumpers, the circuit can be made to latch,
or seal, the logic output in the trip state until manually reset, pro-
vided the trip signal persists for 10 msec or more.

The second type of output is provided by two relays. Both relays
are driven by the logic signal described previously and respond ac-
cordingly. Kl may be arranged to latch if the trip signal persists for
more than 10 msec; the relay will go to the trip state and remain there
until manually reset, regardless of whether or not the logic level
signal is arranged to latch. This arrangement is sometimes called a
"secram catcher," in that it allows a momentary trip to be located and
identified after it has disappeared. K2 operates directly off the logilc
signal and will be in the same state. Contacts of both relays are
available for actuating external circuits.

Specifications

Specifications for the fast-trip comparator are as follows:

Trip range The trip range shall be adjustable
from +1 v to +10 v or from —1 v to
-10 v

Trip point accuracy - .Once.the trip point has been set,

variations in temperature from
10°C to 55°C and aging of compo-
nents should not cause the trip
point to change more than 50 mv
" referred to the trip circuit input
signal : ‘

Trip point hysteresis When the signal falls 60 mv below
the trip point, the circuit shall
reset itself; the circuit shall not
reset less than 40 mv below the trip
point

 
Input impedance

Logic output

Tripping time logic level

Relay outputs

Power required

Ambient temperature range

Indication

Test and reset

198

150 kilohms, either input

In the normal state the logic level
output shall be =10 v = 1/2 v, 20
me meximum drain; in the trip state
the logic level output shall be O v &
1/2 v

The change from normal to @bnormal con-
dition (~10 to O v) shall require
less than 200 psec

Type 1 is a DPDT relay having contacts
rated at 2 amp at 32 v dc and 2 amp
at 115 v ac; this relay must change
state in less than 100 msec

Type 2 is a fast-latching relay that
will operate in less than 10 msec;
the purpose of this relay is to in-
dicate the location of a momentary
trip signal

+15 v £ 0.25 v de with regulation of
0.1%; =15 v * 0.1 v dc with regula-
tion of 0.1%; +10 v + 0.1 v dc with
regulation of 0.1%; —32 v = 4 v dec,
unregulated

10 to 55°C

Front-panel indicator lights shall
show the immediate state of the
trip, that is, "Trip" or "Normal,"
and elso "latch," which indicates
that & momentary trip of 10 msec or
more has occurred

Front-panel push buttons shall cause
the circult to trip regardless of
the input signal ("Test") and to
reset the latech indication ("Reset")

Applicable Drawings and Specifications

 

The following list gives the drawing numbers (ORNI, Instrument De-
partment drawing numbers) and subtitles and fabrication specification
number for the fast-trip comparator:
 

199

Q-2609-1 Circuit

Q=2609-2 Details

Q-2609-3 Metalphoto Panel

Q-2609-4 Printed Circuit Board
Q-2609-5 Assembly

Q=-2609-6 Parts List

SF-253 Fabrication Specification

The following list gives the drawing numbers and subtitles for the
plug-in chassis systems:

Q-2600-1 Assembly
Q-2600-2 Details
Q-2600-3 Details
Q-2600-4 Details
Q-2600-5 Details

2.5.7.2 Theory of Operation

General

The fast-trip comparator is composed of three functional parts: a
voltage comparator, logic switching circuits, and relay drivers.

The input stage, consisting of Q1 and Q2, is a compound (Darlington)
differential amplifier having & high degree of temperature stability and
a high input impedance. This stage drives a simple differential ampli-
fier Q3, which, in turn, drives a Schmitt trigger circuit Q4. These
three stages make up the voltage comparator.

All transistors after the Schmitt trigger circuit act as switches
and are either off (open) or saturated (closed). Transistor Q5 acts as
a buffer to prevent the Schmitt trigger circuit from being affected by
variations in the load. Electronic output points are located at the
collectors of Q6 and Q7.

Two double-pole, double-throw relays Kl and K2 each provide one set
of contacts for the operation of external circuits and one set for the
operation of indicator lamps on the front panel of the trip circuit. Re-
lay K1 may be connected to hold the "Iatch" indicator lamp Il from the
time a trip has occurred until the manual reset switch S2 has been de-
pressed, even if the signal level decreases below the trip point. Relay
K2 energizes indicator lamp I2 ("Trip") or I3 ("Normal"), depending upon
the existing state of the circuit. Either or both of the relay drivers
Q8 and Q9 may be driven from either electronic output. For operational
flexibility the connections to the electronic outputs and the relay
drivers are made externally through plug P/. The following sections
provide a detailled discussion of the design and operation of the various
stages of the circuit. :

The Voltage Comparator

The 1nput stage Q1 and Q2 is a compound differential amplifier. The
compounding Q1 provides high input impedance. The two inputs are applied
to a single base, rather than differentially to the two bases, so that
no shift in output will occur when the two inputs are of equal magnitude

 
 

200

at various levels from =10 to +10 v. The 2-kilohm trimming adjustment
R2 is used to balance the input resistors Rl and R3. The output of the
first stage appears at the collector of Q2A and is coupled to the second
stage through R10 and R1Oa.

The second stage Q3 is a simple differential amplifier that provides
additional voltage gain to increase the sensitivity of the amplifier.
Overall negative feedback is employed from the collector of Q3B to the
base of QLA (R36) to adjust the sensitivity to the desired level and to
improve the temperature-drift characteristics. The de level is adjusted
by trimpot R10 to establish the correct trip point.

The output of the second stage Q3 is directly coupled to the Schmitt
trigger circuit Q4. The Schmitt trigger circuit is a regenerative bi-
stable circuit that provides the actual voltage level discrimination.

The output of the Schmitt trigger circuit and all succeeding stages have
only two stable states, "Normal" and "Trip."

Jogic Switching Circuits

Loading effects on the Schmitt trigger circuit are buffered by an
isolation stage Q5. The bistable signal is then coupled to Q6, where
the logic levels are established. When the collector of Q5 (and the base
of @) is in the "high," or more positive, state, Q6 is biased off,
allowing Zener diode D1 to be fired through R25. The logic level output
at pin A of P7 is then —-10 v, as determined by the breakdown voltage of
Dl.

In the "low" state, when the voltage at the base of Q6 is less
positive (actually slightly negative), Q6 is saturated, shunting Zener
diode D1, and the magnitude of the output at pin A is near zero (less
than 0.2 v). The Q7 stage is nearly identical to Q6 and provides an in-
verted logic level output for maximum flexibility; that is, when the
level at pin A is =10 v, Q7 is saturated, producing "zero" level at pin
J. Conversely, when the level at pin A is "zero," Q7 is cut off and the
output at pin J is =10 v.

The inherent speed of response of the entire electronic circuit, from
a sufficient level change at the input pin T to a logic level change at
either pin A or pin J, is about 10 psec. However, this speed of response
has been intentionally lessened to about 120 usec by capacitors Cl to C4
to reduce the tendency to respond to sharp noise spikes.

Relay Drivers

Either logic output may be connected to either or both of the two
relay drivers Q8 and Q9. Normelly KL is intended to pick up when a trip
(abnormal) condition exists. To accomplish this, the base of Q8 is con-
nected through R30 and pin X of P7 to a logic output that is at =10 v in
the "Trip" state, namely, either pin A or pin J. Note that "Trip" and
"Normal" are related to the character of the input signal and refer to =
signal which may be either too large or too small and either positive or
negative. The proper connections for a desired signal and function cen
be determined by referring to the connection table on circult diagram
Q-2609-1.

One set of contacts of K1 is used to latch in the coill of Kl to keep
it energized after a trip has occurred and cleared. This optional func-
tion is accomplished by comnecting pin 4 of P7 to battery ground (pin W)e
 

201

Relay K2, driven by Q9, is normally connected so as to drop out in
the trip state. This relay is intended to show the immediate state, and
no provisions are made to latch it.

One set of form C contacts is available from each relay to operate
external circuits. |

The logic level output may be latched in the trip state by using
the cutput contacts of relay Kl. Pin b is connected to pin B, and either
positive or negative 15 v is connected to pin F, depending upon the nature
of the input signal. When this connection is used, K2 also latches, be-
cause it is driven by the logic signals.

2.5.7.3 Operating Instructions

Installation

The fast trip comparator Q-2609 is a module in the ORNL modular
reactor instrumentation series. Iike the other modules of the series,
it has standard connectors and dimensions and has & pin-and-hole code on
the rear plate so that the module will not be inserted in a wrong location
in & drawer. The module is installed by placing it in its proper location,
inserting the module firmly, and tightening the thumbscrew. The module
may be plugged in with power on without damage.

Operating Controls

 

The only integral operating controls are the "Trip Test" and the
"Reset" push buttons. The "Trip Test" push button causes the circuit to
trip by overriding the input signal. The circuit will remain in the trip
position if the screwdriver-actuated push button is rotated clockwise
after being depressed.

"Reset" is a momentary push button that releases relay K1 and the
"Latch" indication. :

In a good many applications of the fast-trip comparator, a single
signal will be compared against a reference. The reference can be fixed
by a simple external voltage divider, or it can be adjusted by means of
8 Helipot located in the drawer into which the trip circuit is plugged.
This adjustment .is shown on the circuit diagram as R4 and is, in effect,
an operating control of the trip circuit.

Connections

All connections to the fast-trip comparator are made through the
rear connector P7 when the module is inserted. After initial calibration
is completed, there are no adjustments or comnnections to be made within
the module itself. However, a high degree of flexibility is provided
through external connections. The various possible modes of operation
and the connections required to achieve them are detailed in the con-
nection table on circuit diagram Q-2609-1 and in the following section.

Operating Procedures

Input Signals. — The input signels to the trip circuit should be
supplied from a low-impedance source (500 ohms or less). A single signal
may be either positive or negative within the range of #10 v. The magni-

 
 

202

tude of two different signals may be compared, but they must be of oppo-
site polarity. The input terminal for a single signal is pin T, and an
external reference voltage of opposite polarity is required on pin M.

If two signals are compared, the reference voltage is not required, and
the second signal is connected to pin M.

Reference Voltage. — The external reference voltage is required on
pin M when the input is a single signal. This reference must be exactly
equal in magnitude to the desired signal trip point and of opposite
polarity. The source impedance should be 500 ohms or less. In applica-
tions where the trip point is to be changed occasionally, the reference
may be derived from a 500-ohm precision potentiometer connected to a 10-v
supply. A potentiometer with 0.1% linearity will be sufficiently ac-
curate to allow direct reading of the potentiometer dial as the trip
voltage. Such a potentiometer is shown on the circuit diagram as Ré4.

In applications where infrequent or no changes in trip point are
anticipated, the reference should be derived from a 10-v supply and a
fixed voltage divider with a total series resistance of approximately
500 ohms.

It should be noted that, within the accuracy specifications of the
trip comparator, the trip point is directly equal in magnitude to the
reference voltage, and any drift or inaccuracy of the reference will re-
sult in equal error of the trip point. The accuracy specifications do
not apply in the range —1 to O to +1 v, and adjusting the reference to
a trip point in this range should be avoided.

Signal Polarity and Direction. — Since the comparator is designed
for general-purpose use, it is capable of providing a trip signal for
any of the following conditions:

 

 

l. positive input signal increasing to a value greater than arbitrary
pdsitive reference value;

2. positive input signal decreasing to a value less than arbitrary
positive reference value;

3. negative input signal decreasing, becoming more negative than
arbitrary negative reference value;

4. negative input signal increasing, becoming more positive than
arbitrary negative reference value;

5. when input signal "A" is greater (more positive) than input signal
"B," both "A" and "B" positive;

6. when input signal "A" is less (more negative) than input signal "B,"
both "A" and "B" negative.

Different external connections are required for different types of
input signals to achieve proper output sense. These connections are
shown in the table on the circuit diagram (Fig. 2.5.16). The column
headings refer to the nature of the signal; for example, the second
column is headed "Pos. Signal, High Trip." This means that the input
signal may range from O to +10 v, and trip will occur when the signal is
greater in magnitude than the reference. The fifth column is headed
"Neg. Signal, Low Trip," which means that the signal range is O to =10 v
and that trip occurs when the signal is smaller in magnitude than the
 

203

reference. The column entries under the selected heading show the volt-
age or destination for the pin or terminal in the same row of column 1
on the left. '

The preceding discussion of the second column, lsbeled "Pos. Signal,
High Trip," is continued. The first row shows pin T as the signal in-
put. Pin M connects to terminal 1, which is the wiper of the reference
potentiometer. Pin M could go instead to the pickoff tap of a fixed
divider if a fixed trip point is desired. Pin L connects to +10 v to
provide the proper test voltage. Pin A is Jjumpered to pin K to provide
proper drive to Q8. Pin J is Jjumpered to pin Z to provide proper drive
to Q9 and is also the correct logic level output for driving externsal
circuits.

Iatching. — Latching instructions are not shown in the table in
Fig. 2.5.16, but they are shown at the appropriate connector pins on the
circuit disgram. With no latching, K1, K2, and the logic level outputs
will all indicate the immediate state of the comparestor. Connecting pin
d to battery ground causes only Kl to latch, that is, to remain in the
trip state after a trip signal has cleared until the reset button is
pressed.

If it is desired to also latch the logic level ocutputs in the same
manner, it is necessary to jumper pin b to pin B and connect an appropri-
ate voltage to pin F, as shown in the table. In this condition all out-
puts, Ki, K2, and both logic levels will latch and remain in the trip
state after a trip-level signal occurs.

Precautions

Relay Contacts. — The contacts of the relays used in the fast-trip
comparator circuit are rated for resistive loads only. If inductive
loads are necessary, appropriate contact-arc suppression techniques
should be employed. _

Transistors. — Some of the transistors used in the circuit un-
avoidably have small reverse base-emitter voltage ratings. Most ordinary
laboratory-type ohmmeters, such as the Triplett 630 or the Simpson 260,
have sufficiently high voltage on some resistance scales to permanently
damage these transistors. The common practice of using an ohmmeter to
check transistors when trouble-shooting should be avoided in this unit.

Trip Point near Zero Volts. — The trip-point accuracy specifications
do not apply at trip voltages near zero. Owing to possible inaccuracy,
trip points between —1 and +1 v should be avoided.

2.5.8 Coincidence Matrix Monitor, ORNL Model Q-26241%
2.5.8.1 Description
The coincidence matrix monitor is designed to monitor and indicate

on front-panel meters the current through each leg and the total current
in a two-out-of-three relasy matrix.

 

1lmgken from Instruction Manual, written by E. N. Fray, Instru-
mentation and Controls Division, July 23, 1965.

 
 

204

Construction

The coincidence matrix monitor is constructed in a module 5.66 in.
wide, 4.72 in. high, and 11.9 in. deep. It is a standard "four-unit”
plug~-in module of the ORNL modular reactor instrumentation series depicted
on drawings Q-2600-1 to Q-2600-5.

Application

The coincidence matrix monitor is intended to monitor and to regu-
late the current supplied to a safety-rod scram clutch, or magnet, in a
nuclear reactor. Figure 2.5.17 is a diagram of g typical application,
where relay contacts A, B, and C come from separate safety channels.

Appliceble Drawings

The following list gives the drawing numbers (ORNL Instrument De-
partment drawing numbers) and subtitles for the coincidence matrix
monitor.

 

Q-2625-1 Circuit

Q=2624-2 Details

Q~2624~-3 Metalphoto Panel
Q-2624-5 Assembly
Q-2624-6 Parts list

2.5.8.2 Theory of Operation

As indicated in Fig. 2.5.17, the total current delivered to the
clutch is adjusted by resistor Rl. If all the relay contacts are closed,
and since resistors R2, R3, and R4 are equal, the current will divide
equally in the three legs of the matrix. The total current goes through
the clutch and returns to ground through the "clutch current" meter.

The maximum voltage that can be applied to the clutch is limited by Zener
diode D1 to +30 v. An external meter may be connected between pins 10
and 14.

If a single channel trips, two legs of the matrix are opened and
all the current flows through the remaining leg. Therefore, the tripping
of either of the two remaining channels causes the third leg to open,
which interrupts the clutch current. With two legs open, the resistance
of the matrix is increased by & factor of 3; thus resistors R2, R3, and
R4 must be small enough so that the current delivered to the clutch is
not decreased to less than a reliable holding current. To ensure that
the clutch coil can be deenergized, the monitor must be able to detect
leakage paths around the relay contacts. If the leakage resistance is
small enough, sufficient current can be supplied to keep the clutch
energized with the contacts open. For example, suppose channel A has
been tripped. However, one contact, instead of completely opening, can
now be represented by resistance Rx. The minimum resistance value of

interest can he found by the equation

. E
‘em T R, +R_+R_’
¢ X
 

205

minimum cluteh holding current,

juy
td
i 1l

clutch resistance,

E = maximum supply voltage.

The clutch current will divide between the branches B-C and A-B, where
the current through A-B is given by the equation

i=1 —2_
X “emRy +R_°

X
The requirement is that the current ix be easily detected on the meter
A-Bo

2.5.8,3 Operating Instructions

Installation

The coincidence matrix monitor is a module in the ORNL modular re-
actor instrumentation series. Iike the other modules of this series, it
has standard connectors and dimensions and has a pin-and-hole code on
the rear plate so that the module will not be inserted in a wrong lo-
cation in a drawer. The module is installed by placing it in its
proper location, inserting the module firmly, and tightening the thumb-
screw. The module may be plugged in with the power on without damage.

Operating Controls

 

Current Adjustment. — A recessed screwdriver adjustment, labeled
"Clutch Current Adjust," is located on the front panel. The proper
operating clutch-coil current determines this adjustment.

Panel Meters. — The panel meters are calibrated to indicate from O
to 250 ma. These meters are in series with the clutch and indicate coil
current directly.

 

 
TO CHANNELS ] =%
NB“ AND llcll

 

la—-
—
La—

RELAY

MATRIX

 

 

 

3 INDEPENDENT SIGNALS
FROM FUEL PUMP
CURRENT SENSORS

"TEST"
{MANUAL)

SIGNAL FROM
REACTOR OUTLET TEMPERATURE
INSTRUMENTATION PRODUCES

 

 

 

 

 

 

RELAY MATRIX PROVIDES
SWITCHING SIGNAL
WHICH REDUCES FLUX
AMP. GAIN

 

 

 

 

 

 

 

 

 

 

TEST MOQULE

 

Q-2634

 

PRODUCES TRIP SIGNAL

WHEN:

{. CHAMBER LOSES VOLTAGE

 

 

 

 

 

 

 

 

TRIP WHEN REACTOR OUTLET
TEMPERATURE EXCEEDS 1300°F

1

FOXBORO
TYPE 63
CURRENT
ACTUATED SWITCH

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CONTROL
ROD
“REVERSE"

ON
SCRAM

CLUTCH
CURRENT
METER

 

ORNL-DWG 66-5123R

CONTROL

 

"8"—e= COINCIDENCE

FROM
RELAY SAFETY
ELEMENTS IN
CHANNELS
llBll AND Ilcll

SEE NOTE 2

2. CIRCUIT CONTINUITY LOST
I~ \ T 3. TEST" {MANUAL) PROVIDES . .
l—| CURRENT TO FLUX AMPLIFIER ELAY
| FEEDBACK TO SIMULATE HIGH FLUX *1 SAFETY
GAIN ADJUST) | T ELEMENT
NEUTRON | | wn
SENSITIVE ION | A
CHAMBER { TEST | q-2623
_’
— | PERIOD | ¢ FAST TRIP
{— AMPLIFIER COMPARATOR RESET
— Q-2635 __l i Q-2609 —
| - | \Pnoouces SCRAM TRIP SIGNAL IF:
| | 1. REACTOR FLUX, ¢, EXCEEDS 1.3 MW
. CHAMBER HIGH | Yy AND FUEL SALT PUMP CURRENT
. VOLTAGE POWER EXCEEDS 3% amp OR IF
| SUPPLY |
L _| 2. REACTOR FLUX EXCEEDS 14.3 MW AND
FUEL SALT PUMP CURRENT LESS
T T T T T T T e e — T | FAST TRIP THAN 35 amp
€ COMPARATOR
Q-2609
PRODUCES SCRAM TRIP SIGNAL
SAFETY CHANNEL "A", FLUX INPUT $ IF REACTOR PERIOD € +1.0 sec
{ TYPICAL, ONE OF THREE )
FAST TRIP u "
COMPARATOR CONTROL ROD "REVERSE
Q-2609 {GROUP INSERTION OF ALL RODS)
NOTES: 4. Q-NOS. REFER TO ORNL INSTRUMENT AND
CONTROL DIVISION DWG NOS, PRODUCES TRIP SIGNAL
2.ROD SCRAM REQUIRES THAT THE COINCIDENCE :zFxgEE:gsTogoFlian(
MATRIX MONITOR RECEIVE AT LEAST TWO (2) .
TRIP SIGNALS FROM ANY TWO OF THE THREE
SEPARATE INPUT CHANNELS "a" "B" AND "C" $ PRODUCES TRIP SIGNAL
IF REACTOR FLUX
3.REFER TO OWG RC-i3-9-53, ORNL INSTRUMENT EXCEEDS { MW
AND CONTROL DIV, FOR DETAILS, ALL
3 CHANNELS
FAST TRIP

Fig. 2.5.1.

 

]

 

COMPARATOR [—————= "SAG" BYPASS

 

Q-2609

 

MSRE Safety System for Control Rods.

C

IIBH

MATRIX
MONITOR
Q-2624

Wl Wm 8
C'—e1"a"AND "B

IIBIIAND Ilcll ;‘
“c AND"A"Q)

 

ROD CLUTCH

~CHANNEL MONITORS
(METERS)

ZERO READINGS ON ANY 2
METERS INDICATE THAT
A SCRAM TRIP ORIGINATED

 

IN THE INPUT CHANNEL

 

COMMON
TO BOTH METERS

Block diagram of typical channel.

50C

 
 

 

 

 

292
A
r N
i P
L CURRENT TRANSFORMERS,
> 3
o’ ou t
PH 2
FUEL SALT ‘E?
PUMP MOTOR i | ER
3 BT 2 Ut 1
KA 292 K | ke 292

 

 

 

B 292
KE 292
293

3¢, 440V

PHASE CURRENTS:
{. FULL LOAD~-5C amp
2. NO LOAD-20 emp
3. ONE PHASE OPEN,

NO LOAD-35amp

CURRENT RELAYS
SET TO TRiP AT

 

35amp
KD 292 KF 292
‘ 293 294
" ' 295 294 295
TVA-DIESEL -BUS
. { 293 294 295 ‘
¥ B ’ . —
S12t A J _ S122A J S123A J
b—l : K293B >_| l K 2948 ._| K 2958
(SEAL) , {SEAL) {SEAL)
TIME DELAY TIME DELAY TIME DELAY
TO OPEN TO OPEN TO OPEN
o |LaKaze24 —KB292A KC 292A
- :[/KE 2024 . o KF292A :l:,,xo 2924

THESE RELAYS

 

ORNL-DWG 66-9125R

WHEN THIS CONTACT IS

CLOSED

AMPLIFIER SENSITIVITY IS REDUCED

BY A FACTOR OF 1000. {

 

 

 

 

  

 

 

 

 

 

 

 

 

REFER TO

CKT 275
276
277)

1.3 MW)

200k
AN
200 meg L # k2934, TIME DELAY TO OPEN
T (K294 A, K295A)
INPUT SIGNAL OUTPUT SIGNAL TO
FROM PERIOD  — F U aoar = FAST TRIP
SAFETY MODULE COMPARATORS
RM-NSC1-A1
NOS. IN PARENTHESES igm::ggg:‘x; TYPICAL FLUX AMPLIFIER SWITCHING
DESIGNATE FLUX WHICH CHANGES TRIP LEVEL BY A
AMPLIFIERS IN FACTOR OF 1000 (FROM 1.3 kW TO
CHANNELS 2 AND 3
426
A
r ~
— ?
_L K292D _L ' | K294C_I_ K 294D
K292¢

WHEN AT LEAST 2

OF THESE RELAYS

ARE ENERGIZED THE
FLUX LEVEL TRIP POINT
1S AT 150% FULL POWER

 

ARE TIME - K293 K294 K295
DELAYED TO'
- 11.3 MW)
 DE-ENERGIZE ¢
275, 293 276,294 277,295
426, 426 426,426 426,426

Fig., 2.5.2.

 

K293C

 

K 293D

 

 

A

FLUX SCRAM SETPOINT INDICATORS

(LOCATED ON CONSOLE)

MSRE Flux Level Scram Trip Point Switching.

0T

 
CHANNEL NO.{

 

 

CURRENT IN PHASE NO.1{
TO FUEL SALT PUMP MOTOR

 

 

;

 

 

RELAY KD 292
ENERGIZED WHEN

 

RELAY KA 292
ENERGIZED WHEN

 

 

 

 

 

 

 

 

 

 

 

 

 

CHANNEL NC.2

 

 

CURRENT IN PHASE NO.2
TO FUEL SALT PUMP MOTOR

 

 

1

l

 

 

RELAY KB 292
ENERGIZED WHEN

 

RELAY KE 292
ENERGIZED WHEN

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CHANNEL NO. 3

 

 

CURRENT IN PHASE NO. 3
TO FUEL SALT PUMP MOTOR

 

 

1

l

ORNL-DWG 66~9124R

PRIMARY
INPUTS

 

RELAY KC 292
ENERGIZED WHEN

 

 

RELAY KF 292
ENERGIZED WHEN

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CURRENT GREATER| |CURRENT GREATER CURRENT GREATER CURRENT GREATER CURRENT GREATER CURRENT GREATER
THAN 35amp THAN 35 amp THAN 35 omp THAN 35 amp To THAN 35amp THAN 35 amp
I l____ __________ J { CHANNEL[ o _ 3 ] I
e e e — e NO.2 ¥ e o e e e e e e e -
~|/‘ i conTacT | * |
MANUAL MANUAL I MATRIX MANUAL |
REQUEST REQUEST REQUEST
SwiTCH |~ = = SEAL l CHANNEL CHANNEL swiTch |~ SEAL| | swiron |F——-= seac | |
5924 NO. 3 CONTACT NO. 4 5422 | S 123 I
| MATRIX CONTACT I |
MATRIX |
‘ | | | |
CHANNEL NO.t ] CHANNEL NO.2 ] CHANNEL NO.3 !
RELAY KA 292 |— — — — — RELAY K292 |— ——= — — — RELAY KF 292 | —— — — —
CONTACT CONTACT CONTACT
CH:RP?IGAEL TANN c FEOME
-~ =~ CHANNEL r~CHANNEL
NO.2 ¥ nNoz I Y nNO
CHANNEL NO.2 CHANNEL NO.3 CHANNEL NO.1
RELAY KE 292 RELAY K 292 RELAY KD 292
CONTACT CONTACT CONTACT
. i
RELAY WHEN ANY TWO OF THESE RELAY RELAY
K 203 THREE RELAYS ARE ENERGIZED, K294 DIRECT ELECTRICAL K 285
I ROD SCRAM SETPOINT IS AT * CONNECTION *
| REACTOR POWER (FLUX) = 11.2 MW | |
| } ————— INDIRECT CONNECTION I
' ‘ {SWITCH OR RELAY CONTACT) I
SENSITIVITY SENSITIVITY SENSITIVITY
CONTROL CONTROL CONTROL
FLUX AMP NO.t FLUX AMP NO.2 FLUX AMP NO.3
(CONTACT IN {CONTACT IN (CONTACT IN
RELAY 293) RELAY 294) RELAY 295)

 

 

 

Figo 2-5-3-

 

 

 

 

 

 

 

CONTACT MATRICES

PROVIDING INPUT
CHANNEL REDUNDANCY
TC ACTUATE QUTPUT

QUTPUT

 

Flow Diagram of Switching Signals that Change Reactor Power Set Point for Rod Scram.

80¢

 
 

" N/

  
  

MEASURING

 

2

 

 

 

 

 

 

o

 

09

ORNL-DWG 64-626A

CURRENT
ACTUATED SWITCHES

INPUT III

 

 

 

 

 

 

 

 

 

 

) (¥

 

 

+THERMOCOUPLE
TE-100-AI

TE-100-A2

CHANNEL NO.2

TE-100-A3

CHANNEL NO.3

SPARE

LINE NO. 100

 

 

 

 

 

 

 

 

 

 

 

 

TEST ASSEMBLY: . CONTROL ROD
o. ELECTRICAL O ALARM  REVERSE
_ HEATER ( REFER TO 0 T_
b. TEST THERMO- SECTION I-5) DATA ,
COUPLE LOGGER
(SEE NOTE {.) ' - — |
= | R EH] (5]
FOXBOR - | .
oot Box TS0 SWITCH , FOXBORO | | Ts-100-a1 [ TSS-100 |
EMF 1'0 o TYPE 63 o (r 1
ISOLATION |
CURRENT AMPLIFIER - - —1-
CONVERTER 100
Lo o
-0 o 400 0
-0
o o : 3 : 10-50 ma
10 TO 50 mo METER
SAME AS ABOVE
NOTE:

~~————REACTOR OUTLET PIPE

1. POLARITY SHOWN FOR TEST
THERMOCQUPLE IS THAT USED TO
TEST SYSTEM RESPONSE TO A
TEMPERATURE INCREASE

Fig. 2.5.4. Diagram of Instruments Used to Measure Temperature in
a Typical Safety System Input Channel.

 
OUTPUT CONTACTS AND RELAYS FROM ONE CHANNEL OF

SAFETY SYSTEM ( TYPICAL OF ALL THREE CHANNELS,

CHANNEL"A" SHOWN)

+32vDC ¢}

RELAY CONTACT,
PART OF Q-2609
FAST TRIP
COMPARATOR

RELAY CONTACT,
PART OF Q-2601
MONITOR AND
TEST UNIT

RELAY CONTACT,
PART OF Q-2609
FAST TRIP
COMPARATOR

TEST

RESET P——I

OPENS WHEN REACTOR
OUTLET TEMPERATURE EXCEEDS
1300° F

OPENS WHEN FLUX EXCEEDS

IS MW{OR11.2 kW IF FUEL SALT PUMP
CURRENT 15 LESS THAN

35 0mp)

OPENS IF ION CHAMBER
LOSES VOLTAGE, OR IF INPUT
SYSTEM CIRCUIT CONTINUITY iS5 LOST

OPENS IF REACTOR PERIOD
IS 1.0sec OR LESS r

+32 Vv OC

15-v AC

2—1——e

7 MANUAL
SCRAM SWITCH
CONTACTS

QRNL-0WG 66-1002{R

ROD DRIVE CLUTCH CONTROL CIRCUIT,
( TYPICAL OF ALL THREE DRIVES)

LUTCH
CURRENT ADJUST.

     

@ 2624 COINCIDENCE
MATRIX MONITOR
(TYPICAL 1 OF 3)

 

T0
SIMILAR
CIRCULTS,

OTHER RODS

RELAY SAFETY
ELEMENT Q-2623
TYPICAL (1 0F 3)

 

Kad-1

 

 

 

 

"POWER"

 

 

Ka4

 

 

 

27k
"HOLD" LAMP;
“ON" DURING
NORMAL
OPERATION "TRIP" LAMP:
Kyt Kp2 Ka3 Ky4 KpS WITH ALL "ON" WHEN
i RELAYS CHANNEL
| ENERGIZED HAS BEEN
TRIPPED
1 ) 1 J
fom 14 { \
+0-v BATT

-7

Q-2624
COINCIDENCE

MATRIX

MONITOR
(TYPICAL 1 OF

 

 

RELAYS K,1 TO K,5 {INCL) ENERGIZED DURING

NORMAL OPERATION

Fig. 2.5.5‘

NOTES:
1.Q-NUMBERS REFER TO ORNL INSTRUMENT AND

CONTROL DIVISION DWG, NOS,

2. ALL RELAY CONTACTS AND SWITCHES SHOWN

 

3)

ZENER
DIOCE
32V

   

 

CONTACTS IN RELAY
SAFETY ELEMENTS,
Q-2623, IN

! CHANNELS

'| A,BANDC

 

B AND C

CHANNEL MONITORING
METERS

_,— ROD DRIVE CLUTCH,

 

X

 

_CEUTCH PART OF ROD DRIWVE,
COIL-130 ohms DE-ENERGIZE TO
DC RESISTANC SCRAM

 

     

CLUTCH
CURRENT
METER

VOLTAGE SIGNAL
~ CLUTCH

CURRENT TO

CONSOLE |METEF!

 

 

EXCEPT AS NOTED, CIRCUIT ELEMENTS SHOWN
ABOVE COMPRISE A TYPICAL COINCIDENCE
MATRIX MONITOR, Q-2624.

WITH SYSTEM ENERGIZED AND OPERATING NORMALLY.

3. THIS RELAY {K44) PROVIOES ONE OF THE “REVERSE"

ON SCRAM CONTACTS; TYPICALLY CONTACT NO. RSS-NSC1-A4
iN CIRCUIT NO. 248 ON DWG D-HH-B 57327.

Diagram of Safety System Rod Scram Circuits.

01¢

 
 

77 o e st e bl st

 

+32vDC

 

 

211

 

 

 

 

 

 

ORNL-DWGS 66~10020R

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

 

248 249 250
¥ {
—L SAFETY SYSTEM
T~ | RELAY CONTACTS IN
| FAST TRIP COMPARATORS :
[ T oraet cnmersn | 1 1
SWITCHES ELEMENTS, TS, - -
CHANNELS A,B CONTACTS
TEST AND C. - - | £4-3 AND K4-4
POWER TRIP IN RELAY
RESET TO SEAL CONTACT, Efgngu
RELAY K4 = = CHANNEL "A"
' 248{ (TYPICAL) . TK 249 TKZSO
Tk ?
3000
SEAL CONTACT :
' Ka-1L ACROSS RESET K5-1 . 48V DC MBVAC(TVA) {15V AC{TVA-DIESEL)
—E_-. \ —E...— \ _E_. \ L PUSHBUTTON _T__. ¥ ’ ¥ ’ " T ' )
K2 K5
2 2 2 0 2 K3 - 2 K4 2
cowc:otnce ' COINCIDENCE COINCIDENCE
MATRIX MONITOR MATRIX MONITOR MATRIX MONITOR K4-4 THESE CONTACTS KS5-4 " T CONTACTS
RGD DRIVE NO! ROD DRIVE NO. 2 ROD DRIVE NO.3 OPERATE RELAY K5-1 IN Q-2623
o - K4-3 AND LAMP IN K5-3 RELAY SAFETY
T . T T_.  CKT NO.248 T v 1) "HOLD" ELEMENTS
ZENERT
DICDE
- RELAY SAFETY ELEMENT (TYPICAL) Ka125 KB125 Ke12s
ORNL MODEL Q-2623 ; ' .
{ L i
¥ 1 ¥ 1 T ¥
CHANNEL CHANNEL CHANNEL
. A B . c . . 48V DC c
7 o T ¥
1 1 1 L KAI25A 4 KB1254 "]_KCIZSA -L KA1250 L KB125D L KC1250
SAFETY TRIPS SAFETY TRIPS SAFETY TRIPS I I I I I I
i FLUX, PERIOD FLUX, PERIOD FLUX, PERIOD KB125C " KC125C KA125C KB125B T KC125B KA125E
AND AND | :| |______——_|
( TEMPERATURE TEMPERATURE TEMPERATURE
0-2623 [ 0-2623 . e Q-2623 TO Q-2624
RELAY SAFETY [—* |RELAY SAFETY ™™ |RELAY SAFETY}|—>} COINCIDENCE MATRIX < <
ELEMENT [ ELEMENT [*J) | ELEMENT *] MONITORS, ROD DRIVES KA1248 KB1248B ‘
: NOS. 1,2, AND 3
RELAY RELAY RELAY 1
KA 125 KB 125 KC 125 KA124 KB124
RELAY RELAY RELAY ¢ ;
K248 K 249 K 250 ;
A~ : 3 > ¢ 1.' '.2 ¢ ! “7 4!8 1!9 ¢
{ X 7 l l - 4av DC l l ’
> ) 3 ;
L .
[ 4 ’ i 4
l ’ b P r\ | I | I
OTHER 2
TWO-OUT-OF THREE TWO -OUT~OF - THREE TWO-0UT-OF -THREE EONTACTS
CONTACT MATRIX CONTACT MATRIX CONTACT MATRIX KAI24E KB124C KA124 A KA124C KA124D
{CIRCUIT 186) {CIRCUIT 124) { CIRCUIT 124) I I 3 1_ ‘41" _J('
KB 124 A KA {24 F OTHER
RELAY RELAT | | | CONTACTS
KA124 KB 124 .
" X [
i [ i ’ {
| | | | 5} i
PLOT
LOAD VNE\:‘%'D HCV HCV
CRAM 7 A 7 77 A2
VALVES s Kafl KB1| KA{2 KBi2 {7 PICAL) 5 342 575 A2 s
L i

Figl 2.5.6.

v
LCAD SCRAM
WHEN EITHER KA11 OR KA 12 DE-ENERGIZED

MSRE Nuclear Safety System Circuit Details.

L

J

et —Lflwavmw

 

F

DRAIN TANK VENT VALVES,
575-Al AND 577-At OPEN WHEN THESE
SOLENCIDS DE-ENERGIZED

HCV'S 573-A1

 

 

 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   
  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

      

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   
  
  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

:
i
i
i. 212
— e — e e e e cwe BRVOGA—
: ”e
o 9 wosi vowr e —efotl | pwrome DRAWER S$-2A Fa
| S pmen] e || 4w e 7 RAHICEAS & |
o a"z""’" S | [ Ry ‘ cas-pos cv-s-sop < hagtintees AN
I wrwscras] {owseran]  amincras I — — — — — :95; — T T T T R T T YRS T wx !—‘ I Fe —I
b S — l m I : . l 2 l cova Yot
b — e VWA BN SSI-AT - 49-u3¢-AL RIS-MBC-M r | L Add 7RI o, CL/ TN
BLAWER S-1A4 ; S npoa wir, SO0 iy 1 11 d}m' A3 RI8-daqe » I g _(hd.o.o' S L s ot Sl
RANSBCN AL ¥ v “w M y 961812 ~TA -t e R RO
< $ I.”.l le KIC. Ao, & Woloxe, sad x::.:r-.d e l B WLEL-AY <o C .
Q-2719 A\ st T ) ‘ |~ zC e g o = <o0 A6 HYAsEs PaArTIOw I e cnTdnl I
RE-uBC-A Famiot N,j‘;{,,,. i, 2C13-9-13A REI3-9-13A Ty
R udti- .‘T ‘“;\7“ >1%0% ; >110 % > 10 Te ifi“ FRRImT) o : I . B
- L - Az ] Cv. ‘
) uearh “:n.i"'.; T | — e 800 8 “‘m”f’r‘& __d)——w
SR ~ e . v
l!l 23 G /000a. L “‘e'd’:"a’-‘t: C—scisis-7a = curey cuesenr
vibes wor v = _411.“': fexsmsea-ns TR (cosrass) by
loact Pose lprpy i -
||:. b o £ kst JRhbuboeAe < . _:44 ' l
_1‘ v F TEST  CAIRE Cardrdii 'T’cu-han ; A s-2es ‘;T-—-' } _l::, I consawr | des
L NN VOLTACE APOars FOR a Cs ca-gun ] sz, uren
| 2o s aiiein| |3 1< |2z — e
| p - - A m s B
(pwns-m) T-uEAL-A i T I Kigiy- 74, ficra (ERTEL v owerns
]S E v, S, W, W, W,
LAY IAPETY mr(-l) '1: Lv van T ”E — — —
ne or$- Vore v
32v GH”““A | E.t‘b Ty Jml‘-l "ORAWER _5-3
. RX— WNeC - A7
—— AL S el S—  — — VRN AP, TR . SS— — 4
00y 7 — T — ,: an e | g WER S 2 ] date:
e v vl Tve ave-er] lewmcs £a2v f‘ (y M6 AG l A Aarnass showrnr for Led Ao. I only.
WME dia] [ (MY 4V o0 el l - oo Car-t 808 Cug-ual J 8 Far Leds Aon. & & 3, connections ave
iS4 “2.";’ w""'a' “: r m——-—u—_p— - - :——au—-—nfln—n-—_— 4~l— o, sa— -__“ T c “m/m‘
s nsct-hd ' ‘ : —
' = J— a,;_! £00 ssag —l ey _ | ) £00 il | €00 AR2Z]Cod No.3
! “a VWV : ¢ EM-NSC-AT RYTUBCEAY ase-uske-At R3%-used-Al ‘d’ Cn-3-006 A\ CAr3 2054 | CHT-20¥4
LRAWER S-18 Wf‘z f‘l ems-aul e by, I wor 1 T d"’ wov oy I -2V s S DOED |cirS-2088 | cvr 32048
R NBHC2-AL 1 o sy, | a3 L0EC | cmstosc | cirsdove
( ATC, Mo L KLC Aot
Q279 -————‘Wp—l f“é-l' —I p, fi L”]‘ I'“'l ELIE |sn"arm. v:::m Cah-F-308 | Cang-Sod | CinS-S08
Re yexion zoox gt | L F o83 0A pe 2¢13-9-1 RC/9- 9134
VAN AT SAFRTY 'Av.'__'."_ |5 Sty > 10% s Parmer) > To Comtrol Circur?
I /3+43-41A covys B I T e L
; l % & WRT-A :t:.:‘- ©
ami e N
o5, C-§-s08
I [E i oV e 2;5:‘3;‘
E "a PLeRbuset-pa e l Az o2 ce
e e ey BRF4A =T ——— 1 . I I I
| Fr.mee.0 RC/3-13-7A € ML s
FLUX ANPLIPR il e Sk o5 Keid id /A
PATH LOFSEA Ti-veRE-A —— s, s | s it | e e | e s | e
(Rw-vaa s a) 1| 1] |—- )
£49 oIV gon
1 MEAY SA7ETY 2LEMENT (8) e, yasr ol p | 750 a » l
i 32 voe { :E"’ #0}": 3 ) R—‘: ifi:—b: 4 4 ‘ &‘J,.:;‘c‘;‘:};w ;
R — P ' . ’ e -<L e |
182 cua e ol swirenme DQAW c E ) 2 C r— I Gino,
e 1y i nere |, X NSCY-A LE5ET L = e [ ]
oy & m’vl‘m [vov &-psv] savacs -
oy vocr sew] | wcrace] |62 me crd-dos CM.T-!d "}‘ R95-H5C1- AS :
iy acisoig-il  |TFanzs. CNBeaey CNS I
I xfl’t lil—l:!’_'f' e | I_ — i ot e o 3y — —— — —. Sm—— —— w—-—-—-—— - '— I MaT CLoren
——
AOM.
L — — e .é. £00itep ey - SIMPLIEIED D/AGCRAM OF MO,
oy ! cwe ‘FJ ' VWA ' EHoNbaAl RVNRET-AY 13- usch nss NICWN e —(IJ
=Y :I:it-m it Do Mir v 101 OV 5 :
Q-2719 ( f'J .—k Re L-J lJ ®AY, l_' '.i - flzfi:;:‘ 83V LTC. Mad A',:.'.G:“.d = T ST T FranTes
N Coing 408 M/ P 1) Ao, ZPr) 548 #rmas] walld. WicLe iR uCAfe o
Y ’ vyl & EXC Mo, “ PonTion -
RR-HIED-A romido L} mm:: \ A RCa 18570 H2-9-13A H A RC/3-9-134 RC13-9-/5A | Sefety Sysfem Block Dizgram LCH-9- 51
B MBE AL AsYY '.'.__t_ » "- < 200V >1%6% >120 % >0 % ‘gm PamMT) " " Drower S-i O/ 3-9 56
CL3-/3-1iA ! I ) Zea- o w e " >3 o
oY v/ % J } £ WeRB-A :‘s::i
ST & gvol L Mtl—fl“‘ . ) " » ~ Sl -9 -384
4 4 SUsrLy | s as re08k - REFERENCE DRAWINGS DWaL NeL
b
L RCIS-9-7A CALE%%‘ET]QN 1 B s " | o sxzemnemantt EMNFRAY
e — ——— — — i— — — —— Lmst
& _[CHNGD, REF. DWG. Wo3. 700N @'s To RC 's. Vo667 igey) —T— = CREENT TEST ofi'm'é‘ AT aH '?‘u...... ! 113 5 MS.RE.
3 VAboen noTE S AT ", NIEN _ VOLTALE AN LUK AMPLITIER i\ )
| « (it Sley £ Goochs In Aoy Sy Somants :-':;'fl} t Oara’ cosean : wi l ad SAFETY SYSTEM
Canascrery £ Mg o aotrel (m-nsc i) .
3 lappED PERiC LABZAT 885 k32 CIrRCUIT DIAGRAM
ABDLY PARISD BARATY 4 SCRAW Sl N &)
? [ v T L6 | Zo | wores: A Sy | TR i SovTLE SR
L 1ADDES NOTE S L eslenr Lo L Reiay circuit i3 completed when fuel st pump motor 3 currents are gredier mg’IDGE‘NAflONAL LABORATORY
NQ. REVISIONS DATE APPD thon 35 amps. This reduces fiux amplifier gain = thus increasing scrém eI W‘ OV 8ot G / v
e T - ] point by three decades, 3ee control stir. ® N1, 29% ¢ M4 on dwy. DN 8- 57395 . tery UNON mw"’“m"' COMPANY
JCE Wawoowsn |250-6¢ |/ e ), H hnp frip open uM'll reactior esutlet Pemperature » rvoo k. - — ko
—— e ':}w — - ; ? f:: oot :“."“" . L, 2,3 14,‘00 dage. O-H¥-B- n;::fl:fz’sn. /7’7;& /s Growsy m—q e ed % n_r‘ 3
» | ; A Arc sugoressing diodes md indjice mp dcross relay coils oWy 1) rawa, Conmaclor Y
| | e | ] | é ot R s o et 'RC [/ 3-9-57 26
o A B 4
Fig. 2.5,7. Safety | ystem Circuit Diagram.
Yo -in.-OD STAINLESS
STEEL SHEATH Al,0q - |
INSULATED COAXIAL e
CABLES, 4 EACH-2 SIGNAL,

2 HIGH VOLTAGE

 

213

ORNL~-DWG 67-1104

THREADED RECEPTACLE FOR
PUSH ROD ATTACHMENT, MAT'L ;
HIGH PURITY Ni

 
   
 
 

MHYV CONNECTORS HIGH PURITY Ni QUTER

    
   

 

 

 

 

SIGNAL ~CABLE JACKS, 2 EACH CAN
HIGH VOLTAGE-CABLE PLUGS, 2 EACH
]
—— 1
LSENSITIVE __I
LENGTH 4Y4

 

 

 

 

45 ft - 64 in.

Fig. 2.5.8. MSRE Safety Chamber.

300 |

ORNL-DWG 67-1103

 

250

| l l |

I
T T I 1 T
/r 1.4x10'0 aV +~107 r/hr (GAMMA)

 

 

200 ‘

 

150 (- /

 

 

100

SIGNAL CURRENT (pA)

~5x10? nV +~10% r/hr (GAMMA)

 

50./
/ |

 

 

 

 

 

 

 

 

 

 

 

 

o 50

Fig. 2.5.9.

100 150 200 250 300 350 400 450 500

POSITIVE VOLTS

Saturation Curves — MSRE Safety Chamber.

o ot i ek

L, s e e

 

 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

    

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

214
£33
7K
s AN Poytin =&Y
ol
*¥7K
- VA~ # ASY
»VC%-'J"
a1 4 fl/ov
Of
o
5 > LA Efi?
0003 S0 o
K ..——.—-——1*—-—-———1
26 S J
2000 2 <
ey wac g
AMP 20/597-3 .y ) \
| .
¢ T TP3 H ARervoel 2
&ra. Koirchid 18 pse 3
SO0002
' e
{5 ' LO00uA
Ul e e — e T\ 4 AERIOD
7 - V4 20 1o ¥/ pc
!; Qs
N3
paEV [
3 <
e | Log Current r
? E: Aersod [
.'u LIy [ I8V :
S o Priafed Circuit Sowrd
fe (T - =I5V 7 ®
;7 Choasie & Shiske Grownd .
70 xwre insirymeewd, batweerr TP annd TPL, messurs
between 7y TRAE with Triplel? metar fa‘ oyval)y
: gl *Bal 1 ”wn?i/ veltege /o xere. MW Hreom .
; 7PL and TR y TPZ and , easwre wiiige
! ram 705 to TPS, Adjust ‘hla'mfil'm- /s mero. Eameve
. J’:wn’f. mh-zddmmrm: bt hm%mf
i ! duw axgjussting ~ un n? pane! paried meler
. indicates * ' »
% e 7 -5 FOR INFORMATION OMLY
i . - .y DO m UGI FOR
| e . . WAINTENANCE OR
l °2 COMSTRUCTION
i DETAILS 2655-T
i 42603 ADO-3 METAL PHOTO PANEL
PRWNTED CIREU\Y BOARD
l ASSEMBLN
| PARTS
\ REPERENCE DRMRINGS | owa wa.
E Nore et £ N FRAY
j ’ A resistors | Y Fgengiied corben excesy a¢ wolos! MODULAR BEACTOR TMSTRUMEN HTION
PERIOD SAFETY
- cirCcuIT
f ~ Xy I ]
1 Pl ‘ SRR AN GRNNELE
" REVSIONS DATE APTO , o ] ff .S wmmfi
Cosammas T Wl — 1 e o ORI [ o iE -
- a— [ S— - ! L34 | O |RUS =18 -11A - e
EmFadr oaef ; DATE |QREV m APPD. BY |
— _m—y - |= _—- , 1AS ISSUED FROM G- 2038 =/ L] 35/ eo

 

 

 

 

! Fig. 2.5.10.

Period Safety Circuit.
 

2 DA ST/ s n

 

 

 

 

 

 

    

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
   
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

o PERCENT POWER 7 P
§ ‘ TEIANWGE Shielded
38 "5V
| %0 v !
L8 50 e
200k - O (Front Fonel) I
9 R P
Imp. E0/597-3 2AI3) 200K _ __vey eta I
—AA—={ :)—h 2
Swre Py ANME
. - AAAA——— — "
Spne/ trpu# A R2 28Oue Zero contered ¥ ZERO .
‘ | 1500 (lasidha F7ant fonal) C2ANE Shret. e//o Covovd
Y Y
| @J o |
b FLUX AMP '
| INR's | wFERO " 4D Kow |
™ |
1 ne | f‘_’_z_i_ng Skl vg +25V
| 1 e Sea Mote 5 L E5B asey % |
I T '6023-4 7nt £40 “Vicloroen l
| SOMeg B ' >, Flox
l Gee Mote 2) BRI ; R nism
e Sz B oo
: S| Pusw 70 “zERO" g ' | Sr2ams Siotked|
This connection used when ¥ is z(—L— - ' ‘ "“"‘% >/
red 1o frip 9 externsl circuiF | (See Mare 3) cé ]
when Fhe module /s removed . C ZE0mF, 1OV
31 7oy . s OF thre D13, IN325S) |
4
l Grey) o ro0
£, |
. 77 —d K
-f;;':vgc: a8& l . r—=- r ISV : o 27 AOTES
- =z ' ! ‘ . I AN resistors erc Y2 watt, ) Ve deposited corban
o3 & ezs!; 1@ | £23 o k2e £28 o s unless. otherwise specified. ‘
NZBIEO P00 < Q0 Qi 2rooo  g/ro00 . sé"va ‘; AN
2V 2NMHEI ‘ & The finel volve of the Ffeedback resisfors will be
' ! selected for the desired curren? range of the
| i <X amplitier.
> 7 4 ) -
l 4;{3 2 a9 i 22015, 10V A | 3. Circuit board Las  provision for externel selection
0K & anit07 ! Q13 r=—=n ) 4 of & diFferent feedback rasisfor for large. chenges
' . alals ,J c3 ¢ i wrsor | ' I i1 renge or sccess fo Hie summing jonction.
2413 < = = ' —@ ) .
| l ] 2z "_(oaoo ;} < 4;3_&:’;-# E l 1 .0, | o, AFVer the exferns! wires ore sollered fo the
) sr6.8v ) = ae e d - 4 tronsformer ligs, & bead oF solder should ba '
l o¢ ;EEC r = tormed on Ihe end of the lws Ao asaurs good
S R/8 3 % oz S 825 cs | w29y UP2-7015. connection fo fhe internal wiras. ‘
23000 IN752A408 L 2400 g2/60 lnd = 50003 r . <
I S6V eo. % asv | T ! [ 7P3 &, Grovrd bus of Flux Amplifier prinfed erircwif boerd
i 227 Cer. : aoreE | 7/ (White J 73 saperors From the primary side of fha H.V.
| w"ww eu1sot = Trind TY-88 supply wnd Is connacted exfernally Wrough pm S and
2ov Bl 15€ 3‘;\'_‘; . i (Sea tote 4) he shields of pins 1,7 £ /3.
. AMETER FACE . -19-26'02"7
i ARTS L£/57 PEE5028)
o ASSEMBLY : @-2EOS]
LRINTED CXT. BCARD. PTEOL o
APETALPHOTO RPANEL @-2602-3
- LDETALLS P-2502-2
bend up ' o REFERENCE DRAWINGS | DWG. NO.
. cfcese) : "
Goain S LN S5 alh E( o £ vl A ogoa-7 OrF ] [ . 4. ANDERSON
Grre @ .g @ |58-6S| R& N miral rpcLedR JiA
- . . 2 L : $-145 | R4 |ReB=-9 -7A- fl* TiA MODULAR REAC’UE /MS‘IRUMEMHT/OIV
S _Ioale &8 chd R2.RT Add DIA BB |2.21c1| 714 Sesurce £ C C (case) : 4-4¢8 | REIRCH-TF-74 -0 | TLA
< _Chel £70, tezed 727 smesd TU | - s fs et s T ra—| cHamMBER HIGH voLTaGE SUPPLY
S e Bkt PR as QL Hhrw ot 12 o : Ler| Ry [Rensy oa Ry [ 7ea AND FLUX AMPLIFIER
2 |5, S e B T e T e (ro-se) (70-18) (vo-3) (ro-r0) | Tares| e Teoi-7 04 ek [ 77ea. | CIRCUIT
Qels OF, Rav. #5485, CE WA EAMMICONDLUCTO ‘ >-214b | RE {RXH~F2A - R3 A - i
Loltow notd &, A3 (isa 1) rovot TN vt m-Z6S| RI_(BCI3-9-TA-&) | Teh INSTRUMEIXATION 4D ol Ier3-LIVISION
| owTE Jaero | wero | DT 7OM YV/iews .. it RERCI-T7ARE | Tid OAK RIDGE NATIONAL LABORATORY
723743] 5. A Rmmare | pav-es : *2301R0_IRe13- 9= 24] |7 4. UMON CARBIDE NUCLEAR COMPANY
. Arreovee ar ) 7-23-¢3| RO | RCM:?A Tt A, Hewew [ T [P "
e r_‘gm JRIV [ STFIA DRAWINLG MO, | AVPD. BY '
—_— v e ‘
| | | | | |t wumnon o 2cpz -1 [ |Q-2602-1 s

 

 

 

 

 

Fig. 2.5.11. Chamber High-Voltage Supply and Flux Amplifier Circuit.

i«
 

k

 

216

ORNL-DWG &§7-6438

 

250

200 S~

 

T~
150 ' \

 

 

OUTPUT VOLTAGE

100 v

) /,//
L

0 10 20 30 40 50
LOAD CURRENT (ma)

 

 

 

 

 

 

 

 

, Filg. 2.5.12. Output Voltage vs Load Current for Chamber High-Voltage
Supply, Q-2602.

ORNL-DWG 67-6437

Ag>10°
TsionaL I,=0
—r

INPUT o p—mom——0 OUTPUT

——

Rin> 10'°0

I=1g6naL
= A \N—

R¢

 

 

Fig. 2.5.13, Amplifier Feedback Circuit.
 

 

217

ORNL-DWG 67-6436

FLUX AMPLIFIER

 

 

 

 

 

 

 

 

 

Q-2602 F—————- _]l
|
FLUX I\ | | | RESET FLUX
SIGNAL ° I/ | | °  OUTPUT
|
: : R6 |
Re l :
—— AN —7< |
| / @,
e v |
4 / |
e l
I | - /] |
| HEAT | I R? |
POWER 0———————#= : ‘ |
[ |INSTRUMENT
| SIGNAL ! SERVO 3-- | |
P ——
1 = |
| i___._._.__.._____.___.__l______’
| Q-2603 FLUX RESET |

 

 

 

Fig. 2.5.14. Amplifier Gain-Adjusting Circuit.

 

 

 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  
 
       
     

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

218
P8
AP EO/5IT T
- 12TV i L . r32y +22V
7 Al s
: - v aq’gn'm:: ::..':": —, Sy ,.’:‘fii
l ri ¥4 ;.«.A—n :.I:lm o ~8 :]:m P
This comecrion vsex! wherr hd l i £
it is reguired to trip e G' @D L G
axternw! cirevit whan | re I s Yeihar
modv/e /s remo I Gpussmnns & /e i ser ‘,,5:’ oV
I : e ‘ Q7 |fween) | (awe/ g€ Ao CrdE YT
. Js7e L ‘ 2636 daw Cuocs rcx 2m “earen”
| .'I"“ o1 as “aeIET "
| Fres 225 24
g #.8.00d. s > > 2MEIF
i . sodk SVA,L o '
s |
| f:'-:' ' | wra. |
| & '
' ‘ :&m " Pl
; cw
P —— T e e e e e T T T T T T I 5%« Vo A 2 2000
AW meeemeeed | &
l | “-‘ . “;l
=1 = | . z:ém [LA2A | eummasr,
L T 1 | = P a8 v
i 1L
A by v Y =
i i L B
| ) [ ' | 26
| [ | 5 KéA
P P | i |l wu i ‘ | l'—"‘—' /. All rasistors ara Ye W, /% depesited carbon, axcept 23 moted,
v ~ 1
: ; : : : surrn] | I | 2 &.% " indicates freat pansl identitications.
) || L-—==—- J — - 500,000 Meg. . 8 K5 & K6 are Elgin VRS/2C/E7S0-24 and pick up on
L-J L—d | i I 1 ' Hepe. KI & KE ara Clare CREM-1940 Reed lelags,
I : K3 & kKo are Clare CRM-/913 Kaed Kelays.
CHAMBER AND ARIPLIFTER ARECANSEMENT Jd |
b — e e e e T | L < @Dmoh:h‘yfi.qwlflyyrwnd.
l | W Dencbes 2OV battery ground.
| o
| | 5 0
s il r32Y : &7 -
| “AIEN* i! /S,
| ot
RATE "y
| vow=
| N A
I S&
o8
| = ron Iteasarion,
53 ‘ NO
I L | xs nmu:mg_e on
—2 I\ CONSTRUCTIO
| o 1
| CURRENT |/ Z8ze
YWISH o
| we
rciietll)  Qpmpmarrnce
' Se LV
Abre
e
4 <_-_J_ 7e L :' . NE RN EN.FRAY
| Té%al L A% WMODULAR REACTOR INSTRUMENTAT
SIE: we | SRE MOOULE
K70 on M.S.RE. TEST i
CURRENT .
“9 ‘i facare 2% CIRCUIT
’ 6 7 1" ‘ 1 Tl
5570 106 CALIBRATE JWITCHE ) 5 l % L _ _— A — 4N e o TR 0GOS e
- reamons ot w0 v 3 | \ YR 1 1QTHeit-d M prE | — OAK RIOGE NATION, LABORATORY
— { i i 98/ L@‘-’,.‘_".‘Q‘.’.. LR . VOEON CARNDE CONe.
EMmeosowin }I-12-68 - b _— . Chvasrs & Shinid . 348 o0 RQII-IT-s0A -RO - JiA
o Sasr 345" ! . CBATTT N NPIATIIW S NG | ARD. BY
] [ i v SEPIAS 1SSUED FROM Q- 2634~/ Q-2634( »:¢
. |
Fig. 2.5.15. MSRE Test Module Circuit.
r
| \
!
J
- N

 

 

R
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

     

 

 

 

 

 

 

 

 

 

 

 

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

 

 

 

 

 

 

 

 

 

 

 ——r—————— e -
|
i
N
]
219 ;
.‘
|
li
i
: w7z
T : AMP £O/359-3
fi. ‘% X} +/0v
)
| |
. | »(S5) sisv
P 7 > L/2 ‘ /75 2/8 L2/ o 222 |
£ SITE I oa"'flf oKk B FToe PN 3 pry )
1508 £z AAA — |
y, L0000
cnv‘. Zrimpot @ (7] PS l
4
f ; 4
“;."-T_ \a ——@ Vow22234 _2;"'@ 21279 |
I , - @3 I Sok
o1 2n2060 / |
~soe ‘T
v INESPA . i » l
' oS | J
S/ L2155 £/6 S 220 S £23 I
.: FL7 4 -.faoa q: 2S5k 1; SFOx 1:25K |
“TEIP TEST" |
SL !S
(Avwe! Becesred ) ' a |
26 ‘
~ <00 J & . 2 £ D | 3
s VWA € € T ’ | (€} -wv
Fr¥4 i |
LoV Aers L ) { | >(N) M@ Ground
I
This connection: vied when (¥ ’é:
7# A5 required fo #rip s exherrs! I : 4 I
cacan’? when Fhe module /s (e) : L} .
removed. | . I
l € ¢ == s i >(0) -32v )
eESET " mis79 Y £
I g L Sees 2275 s £28 (raar Aser) Spme SEMPICC |
L2nf T :;gg'o::x S7L f $800 252 2294 v esm 2 e mrec dpgz | Z - »(Y) K2 Close on trip
S . "m & - ‘e >
| a7k $ ATew 7000 L5510 $¥7e  |ni > (“V’j e Commen
#3 P hos__ s sefer—oh d > e o0 rie
| Shiakd £26 bfeos __Soe @9 T2 §
2300 , 5 SUIIZA| o TRIF |
l 3300 Q8 o '!wgoazm v |
‘ X y, 02 Q7 fad
| W w307 o 30208 ey sov 5332 234
_ 200457, -z2v |
’ I £ v, WV, b (2)
Connecs (@xrernelly) Vo () € AAA |
o &8 Fo fwrich elacrronc -~ -é\’.f 5 | { (¢) xs o I,
ocsowr (Sea soYe &) SOR 20V Bert £302 ! L1 wes on rrp (onnrc!(exferna ) o
. zwo‘r 2oV 8sers ¥ | (8) K/ Common pin b Fo %
; i (F) Kt Close on Frim Yronic o«#puf
o I sca rore
P < —— | (k)
‘@‘ ‘ 4 | () FOR INFORMATION OMLY
Tod * o (4) DO NOT USE FOR
~¢ T MAINTENANCE OR
G Mo Gd QS Meu Q9 ] Il CONSTRUCTION
) | ’
| ; W) 2oV Batt
EXTERNAL JUMPERS AND CONMECTIONS FOR YARIOUS TRIP FUNCTIONS : NHOTES f;: 7564 ;-5'7' 29-6
A or |POS. SIGNAL \NEG. SIGNAL |POS. SIGNAL TNEG. SIGNAL |TWO SIGNALS | TWO .mmu‘ 20V oty | ASSEMBL 2-2¢09- 5]
TERM NOAHIGH TRIP |Wi6K TRIP  |LOW TRIP — [tow TRip ~ |70W A(e)> BL)| TRIP BC) > A aA fe-fl”-'f’ o fim.f” £/ % deposited carbon (emay) PRINTED €7, BO. @-2605-4
~S/aWAL 3 oA '173»«. 1 excesl as e AMETALPHOTO PANEL 226035
A’ECT 7 & When pin b /8 comeched fo pin B for elecironic lafch, Mhe logic eas-2
M “remar 3 YERM, | TERM. L ZERLU. 1 ) ~Sie 8 -5i6 a outputs (pins A end ) will remain in tripped stote REFERENCE DRAWINGS oG, N0,
i after & frip wnts/ the reset butfen is sctueted.
L »oy -1ov -10v */0V +iov -rov e oy v L. ANDERSON
7 Pl & | A 7O P | SRS 75 i K | AR5 To P A | SR T8 P |
A 5w s ~ow Rl Ao sstns OF T | e oo MODULAR REACTOR INSTRUMENTATION
Term. 1 |G s D D }
OINA | NN | AN AL | PN A LD CONN. | WO CoNM. [Fooge] 2 |G 3eo9-s | orz FAST TRIP COMPARATOR
Torm, & -/0v - lov 4 s/0¥ NO Com, WO CONN. PMeS| 2 |WWTED Miied® | JiA CIRCLIT
3_[adt 05 Aweaviod O 1144 | 0% [ JAIPER TO | SRR T8 | JAMPER TO | JOMPTE 70 | JOMPER 70 | JORiPER T0 ;;-':-"I? 2 Teis-s-n1a &2 | 7i4
A7, Sow. £, O #B K s 499 N~ 20V 3 2 -4 % ¥ N _A e1-¢5] 2 laen-9-a-e2 104
/ oI /- OF o, S, ot b4 ._n%IT Ty S . -
ooy pri i K | pra oo ] A o 2t4eH] ! lecy-9-sa-R) | Tia INSTRUMENTATION AND COMTROLS DRVISION
g |[ee A E| A in-oeeg| 1 [Rev-9-13a. @) | Tud OAK RIDGE NATIONAL LABORATORY
. —a MO o POwieY A0V FESP| A0SR0 OV TEW LV MORY OF TRIP [0V MM W TN | 0-2-61] & [RC13-9-124-k0 | Ted oo
= F I8V 14 -/5V r/8v »/ 5V ~/EV -— For MM Aodch only 23] O 8CY -9 -/3A Lo | Tia e .
6»0 é z; connected ":xkjmlly | DATE |QREV] A obehiTNO | W60 B
= Jee no SPIAS ISSUED FAOM Q. 2609 -
= [@-2609-1 s
Fig. 2.5.16. Fast-Trip Comparator Circuit.
‘l
]

 

 

 

 
 

220

 

 

 

 

 

 

 

ORNL-DWG 66-11720 \-)
+32 v
Rl
500

Contacts in e -l ‘ -----2

Relay Safety I B _L C I. f 1_; o

Elements in = . -, B_} S

Channels A, B, L %

and C

<
R2 R3 R4 N,
100 | |
100 100 330 )
\N 17
Meter /{ | -
0 - 250 na B A ) . ) .
11;{32 v
R6 -=
8 k
~———— _ Console Meter
Fig. 2.5.17. MSRE Coincidence Matrix Monitor. J

 

 

 

 

 

e
 

221

2.6 SHIM AND REGULATING ROD CONTROL SYSTEM
2.6.1 Introduction

This section is concerned with the circuitry and circuit components
which are used routinely for operational control of the reactor. The rod
control system should be considered as & separate system from the rod
safety system described in Sect. 2.5. It is true that there is weak
coupling between the systems, but only to the extent that certain inter-
locks in the control system depend on information received from safety sys-
tem channels. Reverse coupling is not designed into the system; that is,
the rod control system circuits and components do not perform any safety
functions, either as input or output elements.

The design of the control rods and the drive units is described in
Sect. 2.7. The location of the rods with respect to the core, their
mounting and installation, rod worths, etc., are discussed in Sect. 2.7
and in refs. 1.

2.6.2 Rod Control Circuits

Figures 2.6.1 to 2.6.4 are block and elementary diagrams that pro-
vide the basic criteria for the design of the rod control system. Table
2.6.1 1ists the interlocks, safety actions, prohibitions, and permitted
actions governing control rod action.ls :

The reactor system is designed so that rod manipulation is either
a 100% manual operation or, optionally, an automatic rod control servo-
mechanism is used to maintain either constant flux or constant core out-
let temperature, depending on the power being generated in the core. The
rod servo is used to control one rod only; this rod is arbitrarily des-~
ignated Ycontrol rod 1" on MSRE design drawings and in the text and fig-
ures in this report. The rod drive units (see Sect. 2.7) are inter-
changesble, and individual rod worths (ref. 3, p. 58) do not differ
widely from thimble to thimble., Therefore, the control system is de-
signed so that any one of the three rods may be selected as the servo-
controlled rod (rod 1). From this it can be seen that, without supple-
mentary informgtion, the rod numbers used in design drawings, reports,
etc., cannot be used as the only information required to designate thimble

 

1s. E. Beall et al., MSRE Design and Qperations Report, Part V,
Reactor Safety Analysis, ORNL-TM-732 (August 1964).

?R. C. Robertson, MSRE Design and Operations Report, Part I, De-
scription of Reactor Design, ORNL-TM-728 (to be published).

3P, N. Haubenreich et al., MSRE Design and Operations Report, Part
IIT, Nuclear Analysis, ORNL-TM-730 (Feb. 3, 1964).

“Servomechanism Fundamentals, Philco Corporation, Technical Center
Staff, Library of Congress No. TJ2l4, p. 47.

SMSRE Project Staff, Molten-Salt Reactor Program Semiann. Progr.
Rept. Feb. 28, 1966, ORNL-3936.

 

 

 

 
Table 2.6.1. Control Rod Operation

 

Operational Mode

Conditions of Operation -~ Interlocks, Permissive
Actions, Prohibitions, Automatic Actions

References and Notes

 

2.

5.

Manual scram

Automatic scram

Individual insert
(manual)

Group insert
manual "Reverse")

Group insert

No restrictions; at discretlon of operator at control
console

When any two of the three rod scram safety channels
calle for "Scram." Each channel requests "Scram"
for inputs as follows:
a) Flux (reactor power) greater than 11.25 Mw;
see b below

b) Flux (reactor power) greater then 11.25 kw when
fuel sslt pump motor three-phase currents are
less than 35 amp

c) Positive reactor period is less than 1.0 sec

d) Reactor outlet temperature greater than 1300°F

e) Channel integrity monltor shows a malfunction

No restrictions other than lower limit
No restrictions other than lower limit

Automatically tekes place when:

a) Any two of three fuel salt outlet temperature
measurement channels indicates greater than
1275°F

b) Fuel salt level in the pump bowl exceeds 75%

¢) Any two of three flux measurement channels
indicate reactor power greater than 9.0 Mw

a) Any two of three flux measurement channels
indicate reactor power greater than 9.0 kw, and
the fuel pump motor is drawing less than 35 amp

e) Wnen reactor power (flux) exceeds 1.50 Mw and
control system is in Operate-Start mode

£) When positive reactor period is less than 5 sec
and control system is in Operate-~Start mode

g) Rod "Scram" takes place

The manual switch contacts are not sealed

See ref. 1, sect. 2.2.1, p. 58

Motor currents less than 35 amp imply that no
fuel salt is being circulated

See 2b, this table

Power and period information used to initiate
5e and 5f comes from either of the two wide-
range counting channels; see Sect. 2.3, ref.
1, Sect. 2.8, and Sect. 1.4

Applies motor torque in addition to gravity to
inltiate scram. If a rod will not fall
under action of gravity the motor will drive
rod in

e

 
Teble 2.6.1. (continued)

 

Operational Mode

Conditions of Operation — Interlocks, Permissive

Actions, Prohibitions, Automatic Actlons

References and Notes

 

6.

7.

Individual rod with-

drawal

Group withdrawal

 

6.

a)

b)

c)

Prohibited, with two exceptions, if the control
gsystem calls for "Insert.” All manual switches
and relasys are cross-interlocked so that "Insert"
mode (see preceding Nos. 3, 4, 5, this table)
takes precedence over "Withdraw" mode. The ex-
ceptions are:

1. The servo can withdraw rod 1 within the span
of the regulating rod limit switch, approxi-
mately 6 in., while rods 2 and 3 are being
inserted

2. By manually actuating two switches simulta-
neously, two rods can be withdrawn while the
third is being inserted

Prohibited during Operate-~Start control system

mode uniess one of the following conditions is

met

1) "Confidence" is established in one or more
wide-range counting chanmnels and the re-
actor period in the chanmnel(s) providing
"Confidence" is greater than +25 sec

2) Confidence is established in the BF3 count-
ing channel and the reactor vessel is less
than half full of fuel salt

3) Confidence is established in BF3; counting
channel and the drain tank selector switch
86 (F111) is in the FFT position; i.e., when
using flush salt in the reactor vessel, the
"alf-full" requirement (see preceding Par.
2) is bypassed

Permitted in Operate-Run mode without having

"Confidence" (see bl above) providing no "n-

sert" request exists. However, if "Confidence"

exists In one, or both channels, the reactor
period in channel(s) with "Confidence" must be
greater than +25 sec

Prohibited in Pre-Fill unless conditions per b

above are met

Prohibited if, for any reason, the control system
calls for "Insert" as in 6a above

—T. 2 8L e M sl a

™. d maea o . . . 2_ *_ N
orouailplLuc WLLCEE COLLLUL sybLCill 1o LIl Dt

mode

a1t sub-

Discussed in Sect. 2.6.2 and in ref. 5,
P. 44

€Ce

 
Table 2,6.1. (continued)

 

Conditions of Operation — Interlocks, Permissive
Operational Mode Actions, Prohibitions, Automatic Actions References and Notes

 

1) Control system must be in Operate-Start mode "Start" is a submode of the "Operate" mode
(Sect. 1.4); Start and Run are mutuslly ex-
clusive

2) Reactor drain valve (FV-103) must be frozen

3) Pump bowl must be filled

NOTE: Group withdrawael is only intended for use during startup and at powers less than 500 kw. Power limitation is by means
of a circuit interlock in the radiator door control circultry which requires that the reactor control system be in the "Operate-
Run" mode in order to raise the doors and thus demand power levels above 500 kw.

 

1 {44

 
 

225

locations in the core. The selection of "eontrol rod 1" as the servo-
operated regulating rod is administrative and is accomplished by making
the appropriaste interconnections between the rod drive units and the
control and servo system circuits. These interconnections are made in
Junction box 120, locabed in the north electrical service area. Control
rods 2 and 3, designated as shim rods, are always manually controlled.
Figures 2.6.5 to 2.6.7 show the contacts and relays which directly govern
control rod operation. Figures 2.6.5 and 2.6.6 are concerned only with
the control of rod 1, the regulating rod. The dynamic brake (Fig. 2.6.6)
is an addition to the design (see ref. 5, pp. 41—42), and while it does
not appear on Fig. 2.6.5, it is always used in the circuit controlling
rod 1. Because it is the servo-controlled rod, the circuitry is more com-
plex than that required by the manually operated shim rods 2 and 3. The
automatic rod control servo and the principles governing its design and
operation are described in Sect. 2.6.3.

Certain interlocks are common to all control rod "Withdraw' cir-
cuits. The contact arrangement of these interlocks is shown in the
upper left corner of Fig. 2.6.5. These interlocks are shown in block
disgram form in Fig. 2.6.8. The "Confidence," "No Confidence," and
"Reactor Period" interlocks originate in the BF3 counting channel and
the wide-range counting channels described in Sects. 2.2 and 2.3 of
this report.

The "Automatic Reverse" (group insertion of all rods) has been oub-
lined in detail in Table 2.6.l, and the circuitry is diagrammed in Fig.
2.6.9, The reactor operating modes are discussed in Sect. l.4.

The interlocks diagrammed in Figs. 2.6.5 and 2.6.8 meet the follow-
ing criteria:

1. Control rod withdrawal, during reactor start and at low powers
("Start" mode), is prevented unless at least one channel of the low-
level flux instrumentation is complete, is operating correctly, and
is on scale. This defines "Confidence." "Confidence" is established
by a wide-range channel when all the following conditions are met:

a) the indicated count rate is not less than 2 cps and not greater
than 50,000 cps,

b) +the selector switch on the model Q-2614 pulse amplifier and
logarithmic count rate meter module is in the "Operate" posi-
tion, ;

¢) all the Q-2609 fast-trip comparators (a total of eight — see
Fig. 2.3.3, Sect. 2.3) are plugged into their cabinet drawers
and the channel is selected by the operator.

"Confidence" is established by the BF3 counting channel when these re-
quirements are met:
d) the indicated count rate is not less than 10 cps and not greater
+than 10,000 cps,
e) the "Use-Calibrate" switch on the count rate meter is in the
- "Use" position.

2. Control rod withdrawal during the "Start" mode is prevented if the
reactor period, meassured by elther or both of the wide-range count-
ing channels in which there is "Confidence," is less than 25 sec.

 
 

 

226

3. Control rod withdrawal, either by the operator or by the servo con- :
troller, is prevented if an automatic "Reverse" is in force. W

4. Simultaneous withdrawal (group'withdrawal) of all rods is desirable
only during reactor start and at low powers and should be prohibited
as a means of shimming when the reactor is in the power range (the
Run mode).

5. Once the reactor is in the power region (the Run mode) and develop-
ing more than 1 Mw, the wide-range counting chemnel "Confidence"
interlocks in the Run mode circuitry (see Sect. 1.4) are bypassed
so that a loss of "Confidence" will not require a return to the
Start mode and consequent reduction in reactor power. This bypass-
ing requires that two of the three safety channels be in operation.
This bypassing is accomplished by control signals from the model
Q-2609 fast-trip comparators in the control rod safety system (see
Fig. 2.5.1, Sect. 2.5) and a seal contact on the Run mode relay. This
is done to permit long, sustained runs at power uninterrupted by mal-
functions in, or maintenance of, the wide-range counting channels.

The block diagram in Fig. 2.6.8 may be difficult to interpret at
first glance. It may be instructive to list and comment on the dif-
ferent conditions which produce continuity to point A in the diagram.

The conmbinations listed in Table 2.6.2 are consistent with the design
criteria and the characteristics of the instruments involved. Note

that if either one of the wide-range counting channel log count rate
meters is functioning correctly as defined by "confidence," but if the
reactor period is less than +25 sec, rod withdrawal is prevented re- o
gardless of whether the reactor system is in Start or Run mode. This kfij
may appear inconsistent with the criteria in paragraph 5 above and con-
dition 4 in Table 2.6.2. This arrangement recognizes that it is highly
desirable to have at least one wide-range channel in service at all
levels of reactor power and that when they are in service the interlocks
which they provide will be in force. For example, suppose that the MSRE
was in the middle of a long, sustained power run at, say, 5 Mv and that
wide-range counting channel 2 was out of service for routine maintenance,
This is condition 2 in Table 2.6.2. Now, suppose that a malfunction de-
velops in the ICRM in the remaining wide-range counting channel 1, re-
sulting in a loss of "Confidence" in this remaining channel., This is
condition 4; reactor operation may continue unaffected by the loss of
the remaining wide-range channel as long as power is above 1 Mw. Again,
suppose that a malfunction not in the ICRM develops which produces &
spurious, short (1ess than 25 sec) reactor period signal. This inhibits
rod withdrawsl, and the indication that a trip has taken place appears
on the panel of the Q-2609 fast-trip comparator (see Fig. 2.3.3, Sect.
2.3). If & thorough check shows conclusively that the period indication
is spurious, operation can be restored by manual selection of the other
channel with the switch on the console or by putting the switch on the
Q-2614 ICRM in the "Calibrate" position, thus going into "No Confidence"
on the offending chammel and establishing a signal path per condition 4.
Similarly, if it develops that, in this remaining channel, one of the
Q=-2609 fast-trip comparators requires removal for servicing, the loss

of "Confidence"” so produced will not inhibit reactor operation if power
is above 1 Mw. gi#;
Table 2.6.2
T = True; F = Falsge; NA = Not Applicahle

 

 

Reactor Drain
" 1
Situstion No "No " Reactor Reactor "oonfidence”  "Confidence! Control  Vessel "Confidence" Tank
or Confidence Confidence Perlod Period 1n WRCC in WRCC System Less in BF Selector Not
Condition in WRCC in WRCC >+25 Sec > +25 See Yo. 1 No. 2 in ‘than Chamei in FFT ®
No. Fo. 1 _Fo. 2 (WRCC No. 1)  (WRCC No. 2) ’ : “Run* Half o
Position
Full
1 F F T T T. T TorF F NA NA This is normal situation with the reactor
filled with fuel salt above "BF; Con-
fidence™ level and with both wide-range
counting channels in operation
2 T F TorF T F T TorP¥F ¥ NA NA Reactor situation same as 1 but only one
wide-range counting channel in opera-
tion
3 F T T TorF T F TorF F NA NA Reactor situation same as 1 but only one
wide-range counting channel in opera-
tion
4 T T T or F T or F F F 7 F NA NA Reactor is operating st power (flux)
greater than 1 Mw and neither wide-
* range counting channel is operating;
note that getting into "Run" mode can
only be accomplished via condition 1
or 2
5 T T TorF T or F F F r T T F This gituation cbtains during esrly part
: of a "Reactor Fili" with fuel salt and
before flux is sufficiently high to pro-
duce 2 cps in the wide-range counting
channels
6 T T TorPF TorF F F F F T T

Reactor beiu% filled from the flush
salt tank FFT); selection of FFT eli-
minates the requirements for "Confi-
dence" in either the BF; or the wide-
range counting chennels

 

LTT

 

 
 

228

"Reverse" is the insertion, in group, of all control rods. It
takes place when the instruments indicate that system conditions have
~ exceeded operating limits to the extent that rod insertion is the pru-
dent sction to be taken. The conditions or situations producing "Re-
verse" are listed in Table 2.6.1, and the circuitry which actuates the
"Reverse' relay is depicted in Fig. 2.6.9.

2.6.3 The Autamatic Rod Controller

The linear power channels (refer to Sect. 2.4) and automstic rod
controller of the MSRE are shown in block diagram in Fig. 2.6.,10. The
purpose of this system is to provide automatic control of the reactor
by the movement of one of the three shim rods in either of two controller
modes (refer to Sect. 1.4). There is also a provision for disabling,
through the servo "on-off" switch, the autamatic controller in either
mode to permit manusl operation of the rod by the operator. The other
two shim rods are always operated manually, as pointed out above.

One of the two automatic modes is called the flux mode and provides
automatic control of neutron flux at a level selected by the operator
when the reactor is in its "Start" mode of operation. The power range
in which this mode is used extends fraom about 10 w to 1 M¢., The second
mode is used to control the temperature of the fuel salt leaving the
core and is called the temperature mode. This mode is used when the
reactor is in the "Run" mode and is capsble of adjusting the neutron
flux to maintain the reactor outlet temperature at a set point estab-
lished by the operator. In this mode the steady-state reactor power 1is
a function only of the thermal load, which may be varied from about 1
to 10 Mw. The instantaneous power levels depend upon the thermal load
and any changes in system temperatures required to achieve the desired
outlet temperature. Switching between these two modes of controller
operation is automatically accomplished when the reactor operating mode
is changed. Reference 1, pages 104 to 108, is suggested for additional
reading to augment this paragraph.

Significant features of the controller and its auxiliaries will be
described below by referring to Fig. 2.6.10. The actual circuit dia-
gram is shown in Fig. 2.6.11.

2.6.3.1 Basic Rod Control Circuit

The output element of the rod controller (Fig. 2.6.10) is a pair
of pilot relays which operate as simple “on-off" switches to actuate
the "Insert" and "Withdrasw" relsys in the rod drive motor circuit of
control rod 1. These "Insert" and "Withdrew" relays must always be
actuated to produce controlled rod movement regardless of whether the
reactor is being operated manuslly or automatically. The pilot relay
contacts are identified in Fig. 2.6.5 as contacts R,SS-NARC-Al and A2
for "Withdrew" and "Insert" respectively. The power contactors which
they comtrol are relays K183 and K176, whose contacts are in the power
leads to the servo motor in the control rod drive selected as "control
rod 1." Amplifier 8 acts as a comparator with three inputs: (1) meas-
ured neutron flux, (2) flux demand, and (3) = sifinal proportional to rod
speed. The model Q-2627 synchronous demodulator® is used to convert
 

229

the ac signal from the tachometer to a de voltage with an amplitude pro-
portional to rod speed and a polarity that depends upon the direction
of rotation of the rod drive motor. This dc signal provides negative
feedback to optimize the response of the servo mechanism.

When the conmtroller is in the "flux" mode of operation, the operator
chooses the flux at which the reactor is to operate and at which the con-
troller output is zero by adjusting the demand potentiometer and the
range of the picoammeter in the channel selected as the control input
channel, This demand signal is ldentified as "¢ demand" in Fig. 2.6.10
and originates with the operator at the console. The "¢ demsnd" setting
determines the voltage from the picoammeter that is required to bring
the output of the comparator to zero (assuming no tachometer signal) and,
with the range selection, determines the value of neutron flux required
to produce that voltsge. As indicated in Fig. 2.6.10, the range and the
output voltage level of the picoammeters are recorded by the dats logger.

In addition, the range setting and level of the selected channel are re-
corded on a strip-chart power recorder located on the main control board.
Although not shown in Fig. 2.6.,10, there is an illuminated indicator on
the main board immediately above the recorder, which displays the range
of the selected channel.

In the "temperature control" mode the demand voltage is generated
by the rod controller complex, and the range of the picoammeters is
fixed., The way in which this is accomplished is described in the next
section.

2.6.3.2 Temperature Control

The control of reactor outlet temperature is achieved by continu-
ously compubing a flux set point so that the temperature rise of the
fuel salt through the core is just equal to the difference between the
outlet temperature set point [To]SP and the measured reactor inlet tem-

perature T;. Figure 2.6.12 is a diagram of the array of Q-2605 opera-
tional amplifiers that accomplish this computation.

The system is best explained by neglecting, for the moment, am-
plifier 5 and its connection to amplifier 6. Considering the other two
inputs to the summing amplifier 6, we note that, by proper choice of
polarity, the algebraic sum of these two inputs is equal to the differ-
ence between the desired outlet temperature [TOJSP'(selected by the

operstor through the model Q-2628 temperature servo demand drive unit)
and the measured inlet temperature'Ti. The output of amplifier 6 is
(still neglecting the third input) proportional to the desired tempera-
ture rise through the core and, at constant flow, is a measure of the
nuclear power required to achieve the desired outlet temperature. This
output, through a sign-changing amplifier 7 and limiting circuits not
included on Fig. 2.6.12, becames the flux demand or set-point signal

to amplifier 8. Because of the varying conditions, both in the relation-
ship of neutron flux to total heat generastion and possible sensor errors,
it is necessary to modify this set point if the measured outlet tempera-
ture is to be truly equal to the desired set-point value. The modifica~
tion of the set point is accomplished by use of amplifier 5, the reset

 
 

 

230

amplifier, to generate a correction term. The reset amplifier is an in-
tegrator which continuously compares the measured flux ¢, the measured
core differential temperature (TO -T-), and a correction term whose
value is a function of the sum of the other three inputs and slowly
alters the value of the correction term until the sum of the four in-
puts is zero, with the proper algebraic signs of the inputs considered.
Since the correction term, the output of amplifier 5, is forced by this
integration to be numerically equal to any discrepancy between measured
flux and measured differential tempersture, applying this same correc-
tion term with the proper polarity alters the flux demand as required
to assure that the steady-state value of the measured outlet temperature
is exactly equal to the set point. The response of the integrator is
purposely adjusted to be considerably slower than the response of the
other amplifiers on this computing system. Therefore, if either the
reactor flux or inlet temperature, or both, experience a rapid change
caused, for example, by & load transient or high rate of manual shimming,
the error signal computation will initially proceed as if the integrator
were not .present. The controller will respond immediately to the tran-
sient, as explained in the first part of this paragraph.

Because of the rapid response of flux demand, and therefore flux,
to a change in inlet temperature or outlet temperature set point, it is
desirable that neither of these be permitted to change rapidly under
normal operating conditions. Inlet temperature changes, assuming con-
trol of outlet temperature at a constant set point, are caused by load
changes. These load changes are not normally permitted at a rate that
exceeds the capability of the rod controller to hold the outlet tempera-
ture constant. The rate of change of outlet temperature set point is
limited by using a motor-driven potentiometer to determine the refer-
ence voltage. This rate is necessarily very slow to prevent undesirable
thermal gradients in the system when the controller is operating in the
temperature mode, and, since it is desirable to match the outlet temper-
ature set point to the actual outlet temperature prior to changing from
manual to automatic control, a faster rate of altering the set point is
avallable to the operator when the temperature is not being automatically
controlied.,

2.6.3.3 Flux Demand Limiting

Because components and devices do occasionally fail or malfunction
and may thereby cause an unscheduled lncrease or decresse in flux de-
mand in the temperature mode, a limiting circuit, block diagrammed in
Figs. 2.6.10 and 2.6.11, has been provided which prevents the flux de-
mand signal from departing appreciably outside its normal range. This
feature 1s also useful to mitigate the consequences of an operstor error
such as turning on the controller when the outlet temperature set point
is grossly different from the measured value.

In addition, & Q-2609 fast-trip comparator, shown in Fig. 2.6.10,
is used to provide an interlock (see Sect. 2.5, Fig. 2.5.8) to prevent
initiation of the Run mode of reactor operation while under automatic
control unless the computed flux demand is less than about 1 Mw. Since
the transfer from Start to Run must be made (by circuits not related to
the automatic rod controller) at a power level of about 1 Mw, this com-
parator assures that no significant power excursion will occur.
 

231

2.6.4 Regulating Rod Limit Switch Assembly, Q-2586

It is good practice to limit the reactivity change that can be pro-
duced by the autcmatic controller to an amount equal to or slightly less
than the effective delayed neutron fraction B_ro.. Since each rod in the
MSRE has a total full-stroke worth of approximately 2.2% in Ak/k (ref.

3, Sect. 4.3, Table 4.1, p. 58), the regulating rod limit switch as-
sembly, hereinafter referred to as RRLSA, is provided to limit the stroke
of No. 1 control rod to 6 in. when the automatic controller is in use.

Figure 2.6.13 is a simplified functional diagram of the RRLSA., This
disgram does not depict the actual configuration of the system. The rod
drive unit does not actually contain any intermediste movable limit switches
as implied by the diagram. The actual short stroke limit switching takes
place in the control room, and the mechanism which accomplishes this is
shown in Figs. 2.6.14 to 2.6.17. Figure 2.6.18 is a mechanical diagram
of the drive train, and Fig. 2.6.19 is & detailed block diagram of the
assembly.

An ac servomechanism is used to position the limit switch cam when
the automatic reactor controller is operating. This follows typical po-
sitioning servo practice4 when a synchro control transformer is used as
the position error sensor. The servo loop (Figs. 2.6.18 and 2.6.,19)
consists of a size 15 control transformer whose output goes to an ac
amplifier (Fig. 2.6.20), which drives the positioning servo motor. The
control transformer is mechanically coupled to the positioning servo
motor and is driven in a direction which reduces the error signal toward
zero. When the rod controller is "on," the electromechanic clutch is
engaged (the brake is off) and the cam is also commected, through speed
changing gears and the differential gear set, to the ac servo motor. The
shim-locating motor is also directly connected to the limit switch cam
vy gears and through the other input of the mechanical differential. Be-
cause the differential gear set is included in the drive train, both the
ac servo motor and the shim-locating motor may be used independently and
simultaneously to obtain cam motion. The net cam rotation is proportional
to the algebraic sum of these two input rotations. The electromechanical
clutch-brake in the output gear train hetween the shim-locating motor and
the differential (see Figs. 2.6.18 and 2.6.19) is a design modification
which does not appear in the photographs. It was added to eliminate the
undesirable effects of coastdown of the shim-locating motor and of back-
lash in the motort!s built-in gear reducer. Table 2.6.3 gives the rota-
tional characteristics of the various components in the system when the
reactor is in the sutomatically controlled mode and with the gear ratios
in accordsnce with Fig. 2.6.18.

When the reactor is in the "Manual Control" mode, the control cir-
cuitry (Fig. 2.6.5) causes the electromechanical clutch-brake to become
deenergized; the mechanical drive connection from the ac servo motor to
the cam is broken and the brake is applied. Control eircuit interlocks
also prevent applying power to the shim-locat motor. Because of the
very high built-in reduction gearing (2400 to 1) in this motor, it is
not susceptible to being driven by torque applied to the output shaft.
The brake prevents rotation of the other input to the differential.
Therefore, both inputs to the differential are locked, and the limit
switch cam is not free to rotate when torqued externally.

 
Table 2.6.3

 

RPM Outputs (Component Rotations in Q-2586,

Input Conditions Regulating Rod Limit Switch Assembly)

 

 

 

Limit Switch
ReguJ(.;:;g.‘n% )ROd' Limi'g aSgitch giifirfi AC Servo Cam and Size  Shim-Locating
P T Motor 31 Position Motor
ransformer
Transmitter
Withdrawing at 0.5 in./sec Stationary +0.42 +5.0 - +2.50 Zero
2. Inserting at 0.5 in./sec Stationary ~0.42 -5.0 —2.50 Zero
3. Stationary Withdrawing Zero Zero —2.25 -L.5
4. Stationary Inserting Zero Zero +2.25 +1.5
5. Withdrawing at 0.5 in./sec Withdrawing +0.42 +5.0 +0.25 -1.5
6. Withdrawing at 0.5 in./sec Inserting +0.42 +5.0 +4.75 +1.5
7. Inserting at 0.5 in./sec Withdrawing —0.42 5.0 —4.75 -1.5
8. Inserting at 0.5 in./sec Inserting —0.42 -5.0 -0.25 +1.5

 

A4

 
 

233

From Table 2.6.3 it is seen that the cam speed resulting from re-
locating the span of the limit switches with the shim-relocating motor
is slightly less than the cam speed produced by control rod motion. With
the gear ratios shown in Fig. 2.6.18, these speeds are 2.25 and 2.50 rpm
respectively (see Table 2.6.3). The cam is cut for a meximum of 180°
rotation between limits, which is equivalent to 6 in. rod motion. The
position of the 1imit switches is adjustable; hence, the effective span
TAVE] (Fig. 2.6.13) of the regulating rod may be adjusted within this maxi-
mum of 6 in. From Fig. 2.6.14, it can be seen that the gearing, clutch,
-motors, etc., are supported on movable mounts and hearing hangers. There~
fore, it is simple and inexpensive to change the cam speeds and the span.
A detailed description of the major components used in this unit is given
in Sect. 2.6.5. :

As noted sbove (see also Figs. 2.6.5 and 2.6.19), the net rotation
of the limit switch cam is the resultant of two components: (1) the
rotation produced by the balance motor and (2) the rotation of the
shim-locating motor. When the reactor is in the servo control mode
and if the operator is not relocating the position of the regulating

rod span, the balance motor, driving through the clutch (the brake is
disengaged) and the differential, rotates the limit switch cam through
an angle that is directly proportional to the linear motion of the servo-
controlled rod. Assume, for the sake of discussion, that the reactor is
being operated in steady state and that no fuel is being added. Burnup
and poisoning will cause slow withdrawal of rod 1, the servo-controlled
rod, unless the reactor is manually shimmed by the other two rods. If

no shimming takes place, the limit switch cam will continue to rotate
clockwisen%see Fig. 2.6.5), and, unless the shim-locating motor is ac-
tuated to produce counterclockwise cam rotation, the upper shim regulating
rod limit switch will be opened, its associated relay K240 will drop out,
and contact K240F will open. This will prevent the servo system "With-
draw" relay contact R, SS-NARC-Al from transmitting power to the rod with-
draw relay K176. Note that the servo system is not turned off and that
it continues to exert comtrol in the "Rod Insert" direction; that is, if
for any reason the servo calls for the insertion of negative reactivity
with the servo rod at the upper limit of the regulating rod span, the
rod insert requirement will be transmitted to relasy Ki83, which causes
the rod drive motor to insert the rod. This rod 1 insert relay, K183,
cross-interlocks the rod withdraw relay K176 so that an "Insert" request
from any source overrides all "Withdraw" requests. This cross interlock
is included in all rod drive circuits. The operator must now shim the
reactor. If he chooses to shim by using rod 1, the servo-controlled rod,
he does so by means of the individual rod control switch, S19, used for
manual operation., This closes contact S19A and energizes K175, the re-
lay which causes the shim-locating motor to turn the cam counterclock-
wise. The limit switch closes, contact K240F closes, and the servo is in
command of rod 1. The servo now withdraws rod 1 until the upper limit

is again reached or until shimming requirements are met. The shim-
relocating motor moves the cam at a slightly lower speed than does the
balance motor, and the actual withdrawal of rod 1 in these circumstances
is a series of start and stop movements until the span of the regulating
rod is relocated. The alternate method of shimming is to withdraw either
or both of the manually controlled rods 2 and 3 until the servo automati-
cally returns rod 1 to a suitable place within the regulating rod span.

 
 

 

 

234

Should the servo controller malfunction and ask for a continuous
out-of-control withdrawal of rod 1, the withdrawal will only persist
until the upper regulating rod limit is reached. The "on-off" power
amplifier relays in the servo controller do not exert direct control
of the rod drive motors (see Fig. 2.6.5); instead they control the
"Withdraw" and "Insert" relays K176 and K183, and a servo malfunction
has to be accompanied by failure of other control-grade interlocks to
become of consequence.

Should the regulating rod limit switch mechanism misoperate in con-
Junction with a servo controller malfunction so that the cam fails to
rotate as the rod is being withdrawn by the servo, the control system
interlocks may call for a "Reverse" (group insertion of all three rods)
if the failure produces any of the situations listed in Table 2.6.1.
"Reverse" by the control system is independent of the condition of the
servo controller and may also be invoked should the operator inadvert-
ently withdraw either shim rod so as to produce any of the listed con-
ditions. ' ~

If one of the shim regulating rod limit switches remains actuated
or if the cam fails to move off the mechanical stop, rod 1 is inhibited
from further motion in one direction only. The operator can provide con-
trol with rods 2 and 3 and can switch over to manual control until the
trouble is cleared.

A detailed step-by-step breakdown of the circuit and RRLSA responses
to various situations is included in Sect. 2.6.6.

2.6.4.1 Range Switching

The range switching circuits of the flux channels are extensive be=-
cause of the large number of operating conditions possible. Figure 2.6.21
shows these circuits, as well as those assoclated with the various reactor
and rod controller modes.

The first two stages of the operator's range switches are used to
connect the proper feedback resistors by energizing appropriate relays
in the picoammeters. Contacts K204A and K204B (Fig. 2.6.21) are used
to disconnect the range selector switches and to automatically connect
a feedback resistor corresponding to a full-scale range of 15 Mv when
a "range seal" condition exists. The "range seal" is described below.

Stages 3 and 4 of the range switch are used for proper switching
of the inputs to the range indicator light assembly. This range indi-
cator displays, in exponential form, the nominal full-scale range of
the selected channel in watts. The range switching is by alternate
steps of factors of 3 and 3-1/3. Stage 3 monitors the position of the
range switches and the console channel selector switch and causes one
of two multiplying factors (1.5 and 0.5) to be illuminated. In the
event that K205 (another "range seal" relay) is energized, the 1.5
light 1s operated regardless of the position of either range switch.
Stage 4 causes illumination of the proper exponent in the range indi-
cator, thereby completing the identification of the range. The range
seal condition causes a 7 to appear in the exponent position, indie
cating a range of 1.5 X 107, or 15 Mw, when the range seal condition
exists.
 

235

Stage 5 is a voltage divider used to provide range information to
the data logger and range recorder. K208B contacts are used to switch
the range recorder input to the selected channel range switeh. Again
K205 contacts disconnect the range selector switches and insert signals
corresponding to the 15-Mw condition when the range seal is energized.

Stage 6 is a permissive switch used to enforce the 1.5-Mw range
required to switch the operating mode of the reactor from Start to Run.

Stage 7 is used for the range seal function, which will now be de-
scribed.

2.6.4.2 Range Seal

The transfer from Start to Run or Run to Start in reactor operation
involves a number of distinct, but related, operations. To assure that
all these are performed and that no severe transients are introduced as
a result of such transfer, the range seal circuits have been developed.

The range seal, as the name may imply, is an electrical latching
circuit which is energized whenever the reactor operating mode is
switched by the operator from Start to Run. This transfer is restricted
to power levels in the vicinity of 1 Mw. Energizing the range seal,
represented in Fig. 2.6.21 by relays K203, K204, and K205, disconnects
the range selector switches and causes the range of each picoammeter to
become 15 Mw, as described above. Inasmuch as the range selector switches
are now totally ineffective, it is reasonable to assume that they may
be in any position during subsequent operations in the Run mode. It
should be noted that the Run mode may be terminated automatically under
certain conditions. Should this occur, the range seal circuits are used
to auvtomatically force the rod controller flux set point to about 1 Mw.
The operator can then assume control of flux set point by putting both
range selector switches in the 1.5-Mw position, at which time the flux
set point becomes 1.5 Mwv multiplied by the setting of the flux demand
potentiometer.

The above features are shown in Fig. 2.6.21 at the bottom of the
sheet. Relays K203 through K208 are operated in the following manner:

A contact from the Run relay in the rod control system operates K206,
called a run auxiliary relay. This relay in turn energizes K203, K204,
and 205. If either of the range selector switches is turned from its
1.5-Mw position, the relays are sealed in their energized condition
through S1 or S2 and K203A. Relay K207 is the relay which defines, for
the controller and for the reset of the control system, the temperature
mode of operation. Although it is clear that K204 should always be en-
ergized when K206 is energized, the interposition of K204C between K206
and K207 has a purpose. Inasmuch as the temperature control system
cannot function properly unless the picoammeter range is 15 Mw, it was
decided to initiate the temperature mode by the operation of the same re-
lay, K204, that switches range. K208 is the relay which selects either
channel 1 or ‘channel 2 signals to be the input to the controller at the
request of the operator.

At the bottom of Fig. 2.6.21 is also shown the switching circuit
for the servo amplifier demand input. As described earlier, in the
temperature mode the computed flux demand serves as a reference to be
compared with the measured flux level. K207A, normally open, serves

 
 

236

this function. If K207 is deenergized, as it will be whenever the "run" .
relay 1s deenergized, the controller will be in the flux mode, and a gui
flux demand voltage is supplied through a K203, or range seal, contact.
If K203 is energized, the picoammeters are on their 15-Mw ranges, and
the setting of the operator's demand potentiometer is in terms of per-
cent of full scale and could represent as much as 15 Mv if used as a
reference to the controller. Therefore, K203 is used to introduce a
demand of 1 Mw, based on a 15-Mw range, whenever the range seal is en-
ergized and the run relay deenergized, as described earlier.
The temperature reset amplifier, described earlier, compares flux
and temperatures to compute a correction term so that the reactor out-
let temperature is equal to its set point in steady state. Since the
flux signal into the controller depends upon the range of the picoam-
meter and the temperature signal does not, the reset mechanism would
be saturated during most operations at low power. To provide a means
for minimizing the error in the correction term at the time of transfer
from Start to Run, a fictitious signal representing a 1-My flux level
has been introduced whenever the range seal is deenerglzed. Since 1 Mw
corresponds to a differential temperature of 5°, the correction term
will at most be 5°, even if the power level is so low as to produce an
unmeasurable differential temperature. As the reactor power approaches
1l Mw, prior to initiating the Run mode, the reset amplifier begins to
operate properly. If the flux level is held actually at 1 Mw for a few
minutes prior to transfer to the Run mode, there should be no appreciable
change after transfer, since energizing K204 transfers the input to the
reset amplifier from a fictitious 1-Mw signal to a real 1-Mw signal com-
ing from the selected picoammeter. kiJ

2.6.5 Component Descriptions

2.6.5.1 BServo Motor

This is a two-phase, 60-hertz ac motor primsrily designed to be
the balancing pen drive motor in Minneapolis-Honeywell Company self-
balancing potentiometer~type strip-chart recorders. It contains integral
gear reduction such that it has a maximum no-locad speed of 27 rpm. It
is capable of operating at stalled torque continuously without damage.
Its electrical characteristics provide a good match to the amplifier de-
scribed below. The motor is designated by Minneapolis-Honeywell as their
part No. 76750-3.

2.6.5.2 Amplifier

This is a general-purpose instrument servo emplifier designed to
accept 60-hertz input signals in the millivolt range and to amplify them
to a power level capeble of driving the servo motor described above.
This amplifier (Fig. 2.6.20) is manufactured by Minneapolis-Honeywell
and modified in accordance with ORNL Instrumentation and Controls Di=-
vision Drawing No. RC-2-10-12.
 

237

2.6.5.3 Clutch-Brake

The clutch-brake is manufactured by Autotronics, Inc., Florissant
Missouri, and is identified as part No. MB-34-2. [Refer to UCNC (ORNL)
Requisition No. R-7674, April 4, 1963, and Purchase Order 63X47734.]
Its performance characteristics are outlined below.

Operating voltage 24 to 28 v de
Coil resistance, *10% 138 cohms
Clutch torque, min 80.0 oz-in.
Brake torque, min 100.0 oz-in.
Response time to energize 0.020 sec
at 28 v de
Maximum no-load torque
(drag)
When energized 0.20 oz-in.
When deenergized 0.50 oz-in.
Operating mode With coil energized the input

gear flange is free to rotate
and the output is braked to
the housing

2.6.5.4 Shim-Locating Motor

The shim-locating motor is a synchronous capacitor type with in-
tegral gear reducer. It is manufectured by Bodine Electric Company,
2504 West Bradley Place, Chicago, Illinois, and is identified by catalog
No. B8122E-1200C, frame KYCC22RC with K-45 capacitor. (Refer to UCNC
Purchase Order 63X-50673, June 10, 1963.) Its performance characteristics
are outlined below.

Input 115-v, 60-hertz, single-phase
Output speed 1.5 rpm

Output torque 105 oz-in.

Capacitor 0.85 uf

2.6.5.5 Mechanical Differential

The mechanical differential is a bevel gear type supplied by Reeves
Instrument Corporation, Roosevelt Field, Garden City, New York.

2.6.5.6 Size 15 Control Transformer

This transformer (U.S. Government type 15CT6b, Mil. Spec. S-20708)
is manufactured by the Bendix Corporation, Montrose Division, South
Montrose, Pennsylvania, and is identified by Bendix Catalog No. AY1501B-
11-B2, Dwg. 1501B-0, or equal. (Refer to UCNC Purchase Order 63X-47764,
April 29, 1963.) Specifications are given below. .

 
 

 

238

Voltage, primary/secondary 90/57.3, 60 hertz i
Current, mex (typical) 0.011 amp &si
Power, primary (typical) 0.13 w

Total voltage at null 90 mv

Fundamental voltage at null 60 mv

Electrical accuracy 6 min

Phase shift 20° lead

2.6.5.7 Size 31 Torque Transmitter®

The size 31 torque transmitter (U.S. Government type 31TX6b, Mil.
Spec. S-20709) is manufactured by the Bendix Corporation, Montrose Di-
vision, Montrose, Pennsylvania, and is identified by Bendix catalog No.
AY-3101B-12-E2, Bendix Dwg. 3010B-O, or equal. (Refer to UCNC Purchase
Order 63X-47764, April 29, 1963.) Specifications are given below.

Voltage, primary/seconda 115/90, 60 hertz
Current, primary (typical 0.395 amp
Power, primary (typical) 4.5 w
Electrical accuracy 10 min
Max total signal at null 125 mv
Max total signal, funda- 35 mv
mental at null
Phase shift 6.5° lead
Torque gradient 0.40 oz-in./deg
2.6.6 Operational Situations Involving the Regulating Rod tsJ

Limit Switch and the Regulating Rod Servo
(Refer to Figs. 2.6.5, 2.6.7, and 2.6.9)

I. Servo withdraws rod to upper limit of the RRLSA
A. This moves cam clockwise to upper limit switch; this actuates
(deenergizes) K240.
B. The active contact chain during "Withdraw," in servo, is:
1. BRyxSS-NARC — Al — K240F — KA170D — K228A — KR220A —
K183C — relay K176.
2. K240F opens and prevents further withdrawal by the servo.

IT. Regulating rod at upper limit of the RRLSA; operator acts to let
servo continue rod withdrawal

A, This requires that the circuit to relay K176 be restored to en-
ergize relay K240 (see A sbove).

B. This is permitted if the RRLSA is withdrawn so that its upper
limit switch 1s not actuated. This 1s accomplished by manual
operation of S19A to energize reley Ki75. The contact chain
in circuit 175 is: S19A — S20B — 8521B - KL70H — K241A — relay
175 energized.

 

SThis synchro was also designed for use as a control transmitter. { -
 

III.

IV.

c.

239

When relay 175 is energized, the RRLSA cam moves off the upper

limit and these actions follow:

1. K240F closes.

2. X176 is energized since, by hypothesis, the servo error
signal requesting withdraw rod 1 still exists and servo
relay contact RXSS-NARC-Al is still closed. The RRLSA cam
is now receiving motion from two sources:

a) Clockwise rotation produced by the actual withdrawal of
rod 1, which rotates the position synchro in the RRLSA,

b) Counterclockw1se rotation produced by the operator's
closure of the manual shim switch (S19), which operates
the shim-locating motor in the RRLSA.

c) Since the cam speed produced by withdrawing rod 1 is
slightly faster than the speed in the opposite direction
produced by the shim-locating motor, the net rotation
of the cam tends to be clockwise. Therefore, the motion
of rod 1 will tend to keep the cam at its upper limit,
while at the same time the operator is continuing to re-
verse the cam. Rod 1 will move up in steps as long as
the servo requests withdrawal.

d) When the servo error signal becomes zero:

1) R, SS-NARC-Al opens and relay K176 is deenergized.

2) If the operator continues to request withdrawal of
rod 1 by actuating S19A and energizing relay K175,
the cam continues to move counterclockwise. Pre-
sumably the operator will stop the cam so that it
is midway between limits. If the cam reaches the
lower limit and energizes relay K241, rod 1 is pre-
vented from responding to a servo error signal call-
ing for rod insertion.

Servo inserts regulating rod to lower limit of the RRISA

Control system response is same as in I, but in opposite directions.
Regulating rod at lower limit of the RRLSA; operator acts to let
servo continue rod insertion

Control system response is same as in 1T, bubt in opposite directions.
Manual insert of rod 1 (regulatlng rod) or manual or automstic re-
verse of all rods is requested

A.
B.

C.

Any one of contacts S22B, S19D, or K186F is closed.

Assume that rod 1 is between limits of the RRISA; then the

pertinent contact chain becomes: (S22B, S19D, or K186F) —

KAL70E — K240A — relay K182. |

The shim-locating motor rotates cam in the "Insert" direction.

Note: Rod 1 does not move during this step as the cam approaches

the upper limit switch in the RRLSA.

The upper limit switch is actuated by the cam and relay K240 is

deenergized.

1. Contact K240A opens and stops the shim-locating motor.

2. Contact K240C closes and the relevant contact chain be-
comes: (S22B, SL9D, or KL86F) — KA170E — KA240C —
K230A — K231A — relay K183,

Relay contact KL83A closes, causing the drive motor for rod 1

to insert the rod. The cam will be rotated opposite in direc-

 
 

240

tion to its original rotation per VC above, and this action \.J
will continue until it is backed away from the upper limit
switch in the RRISA. Relay K240 is energized, and the cycle,
starting with VB above, is repeated. The action is similar
to that described above in IIB.
F. Once rod 1 has reached either of the limit switches in the
RRISA, its speed is limited by the speed with which the posi-
tion of the RRLSA can be changed. This is approximately 10%
less than that of rod 1.

G. If, during a request for "insert" per VA above, the servo
also requests rod 1 insert, the resulting action is to im-
mediately insert rod 1 until the lower cam limit switch in
RRISA is reached. During this time the rotational speed of
the cam will be the absolute difference of two speeds; namely:
1. The speed, counterclockwise, of rod 1 reproduced by the

rod position synchro which drives the cam.
2. The speed, clockwise, of the RRLSA produced by the shim-
locating motor.

The shim-locating motor moves the cam at a slightly lower rate (approxi-
mately 10% less) than the position-transmitting synchro. The net speed
is the algebraic sum (absolute difference) of the two, thus (refer also
to Sect. 2.6.4 and Table 2.6.3):

Cam speed.

+ (speed produced by shim-locating motor)
- (speed produced by rod 1 motion)

+ 0.9 (rod speed) — (rod speed) Qfia

— 0.1 rod speed.

Therefore, in these circumstances, the cam will be turning, slowly in
a counterclockwise direction until the lower 1limit switch in the RRLSA
is actuated. As long as the servo is calling for rod 1 to insert, the
rod will be nudging the lower limit switch in the same manner as de-
scribed at the upper limit (see IIB).

H. If, during a reverse, the servo is requesting withdrawal of
rod 1, the reverse relay contact K186A (see Fig. 2.6.9) is
open and prevents energizing relays K174, K175, and K176.

This, in turn, prevents group withdraw of all rods, withdraw

RRISA, and individual withdraw of rod 1.

J. If the operator requests "insert rod 1" while the servo is re-
questing "withdraw," the result is, in terms of pertinent con-
tacts:

1. R, SS-NARC-Al — K240F — KA170D — D228A — K229A — K183C —
energize relay K176 — (withdraw, rod 1). Rod 1 withdraws,
and the position transmitter rotates the cam clockwise
toward the upper limit of the RRLSA. :

2. 819D —» KA170E — K240A — energize relay K182. The shim-
locating motor rotates the cam clockwise toward the upper
limit RRIS.

3. The net result of 1 and 2 above is to make the RRLSA cam
approach its upper limit switch at a rate nearly twice as
fest as normal; that is, net speed, the absolute sum of the (;Q
 

241

two speed components, instead of the difference as described

in VG,

4. When the upper limit switch of the RRLSA is actuated, the
| closed circuit, per 2 above, is broken because contacts
- K240A, K240F, and KA240C change their aspect. This ener-
gizes relay K183 and deenergizes K176, thus:
a) S19D — KAL70E — KA240C — K230A — K231A — ener-
- gize K183, This calls for "insert rod 1." Note that
K176 becomes deenergized for either of two reasons:

1)
2)

Energizing K183 opens K183C (see J1 above)
K240F opens.

In addition, contacts Ki83A and K183D appear in both "insert" and
~ "withdraw" power leads to the motor in rod drive 1, so that "insert"
‘overrides "withdraw." Note that, when the servo is controlling, this
overriding interlock is not in effect until the upper limit switch
in the RRLSA has heen actuated.

b) Rod 1 is inserted, and the RRLSA cam is rotated counter-
~ clockwise and away from the upper limit of the RRLSA.
¢) Insertion of rod 1 continues momentarily until the RRLSA
~ cam leaves its upper limit switch. |

1)
2)
3)
)

5)

6)

KA240C opens.

Relay K183 is deenergized.

Rod 1 stops inserting. -
K240A closes and the shim-locating motor drives. the

“cam clockwise toward the RRLSA upper limit.

K240F closes, K183 closes, and relay K176 is ener-
gized, causing rod 1 to withdraw. |
The RRLSA cam is also now being driven toward its
upper limit by the position transmitter.

d) This condition (4, 5, and 6 above) is the seme as that
originally postulated, assuming that the servo is still
requesting rod 1 withdraw and the operator is manually
calling for "insert."

 

 
 

 

ArmEE R meE T ' : MM, e Cote - C o . S et w i et e - e E o ames

 

 

 

    
    
 

 

OPERATE WO RN G&
AN

 

 

 

 

 

 

 

| PCOANMEIER 2 »
RANLE Yavicny asan saiecian

 

 

 

 

 

 

 

      
  
 

 

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

         

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  
 

 

 

     

  
  
   

  
     

 

 

 

   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   

 

 

 

 

 

nw:lu -h :!‘\“i"‘ ‘m* i
/ note*e \uore %%
,’ “evo o i
sRAL |
sERve uoDd | i
SWITCh I
NOLO" PaniTion ] [ [ ! UL Pt
- i “wxmcrow | ) [ weacon ] T AT
\ EAL Wet mor e mun | ] e mun ; vm
\\ RATABAARED moom | | MO ]
N l ‘
LRV MoDR ; Aite Rew
VTCH el W | coutmoL w
SHE* PatlieN | ; TEMP. MoDs
o~
. -
A0 N o7
coMTAn
SN0
M
/
N
R
B “ | /By
| = g - l
- " ’ * v < .
// soye®s N 4 I
“F ; . N M vavien 4910w :
i midwio i . !
j ' =| -y s o o v o o e . t curriean 2 P---—-fi—-——-——-—-- cnaMBAR, YE :
i *AuTpmarie” ’  IFnonayic” o s A
. 1 - - rE I g = .
[ -
1 ACIOAL %1 wivnoeawl 02 iuseer | [v2 aveat . WIRPRAW [*1 aciunten 71 AcrAten
EIT. SWITLH - SwhTen - TesT SwWiTcH TRT Bwire SIgNAL GMAL, PalitoH - Swita it -
| AcTuATa L OpF " ACTUATED AcTuATRD AR cops”
- { : ' X ‘ |
1 VNBARY | WITHDRAW "
SieidAL, S BAL
2 F19sien T nevien
U AMMER NoT
G LR I e L R
4
SARLYY SYITEM BLOGK DIAGEAM oww-a 51835
. EREERE YALYE Wl.OLK DihGaERM CWH-E - 3734
NMOTES'S ; AUR, PROCESE GONTROL SYETEME BAOLK DIAGEANIRIAJDHWE: 518481
.—-I—é-'_ : AUL. PROCESS CONTEOL STSTEMS BLOGK TIAGEAM(SKLALDWIS- 3T840
3. THE RAMGER AL 14 UALE TO AMRULA SMOITUITRAMAITION BHATWLEY TREWPERATURL SELY0 MDY AUR, PROCESS LONTEOL AYAYEME BLOLK DINEAM{MAI ATONWE- 51D 39

 

PAUR . SARVO OPLEATION WWLMW TWE RLACIOR % TAREL OUT OB TWE RUN MOOK. ARTER
TAR TEARSATION . TR FLUR DAMAND 15 MAVITRMLD ST . MROUT, 1 HRW et Twe OPLREMION CONTAINMENT SYSTEM BOLK TIMGEAM (SAZe$5) Jowms 315348
ALBUMES  CONTEOL OR THE DLMAND HY SWATCHING . BOTH RANGE . SWATCWRS TO WA O-1. 3 MW CONTAINMENT SYSTEM ILOLK DIAGEAM (4.l o488 >. DHWS- 5718537
S POSIHION, Wir CAL TWEN BALELT RAMGE AN PR CENT DAWMAND. FOE LOW. LINEL TLRYO OPREATAONRS o oo SALT $YETEM WLOCK DIhGEAM owwer 57836,

2. TWR RESET MECHANIGM 18 TRE AUTOMATIL ROD CONTROLLER CAN OPERATE. ) MASTRE COMTROL WLOGHK TIAGEAM ($W. % «f T) [OnWS+ 519
' | PROWERLY ONLY 1% THE WMICED MICED AMMEITER RAuGk 1S O-1F Mw. Wasw MASTAR, CONTREOL WLOLH DIAGRMACIN- a4 1) [OuwE- 51950
NOYT 1IN TRE RUN MODE A EIRED StavAl BLFLALES TWe VLUL S\GNAL YO Twe

REBET MECHAMIGM, PROVIDING A RESET WITH A MARMMUNM BLEOR Ow A . [£OD couTeon BLDCK Dieeam {insey 2 aft) _ fOuw e F1W8Y

 

 

 

 

 

 

 

rAW DEGRETS, ‘ REFERENCE DRAWINGS NO.
A, TRAMPERATURE DRMAND CHAWGNE CAN IS MADE ONLY AT A EINED RATE WY OAK RIDGE NATIONAL LABORATORY
MEANS OF A MOTORIGED POTENTIOMETER . OPERATED 8Y
, ’ [
4, REALTOR OPERATIG MODES ARL DERINED OW DEAWING * D -RW-the 51350 . UNioN CARBIDE NUCLEAR COMPANY ]
DIVISION OF UNION CARBIDE CORPORATION i
, 5 FIlaesiON CUAMEAR TEHT FWITOCALE AR LOLATED OW TWA . HULLLAR OAK KIDGE,

 

PAVRL 1N THR AVKALIARY WOOW -

 

 

MOLTEN SALT RRALTOR WAPLRIMLWMT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

"% |ved.¥ s0ey . v sv-esif{E Py . 4% E°0T ARE CAUBITRARY POMITIONS od RAMAR SELRGLOAE SiTel. RAMGE SWMACTOR UMITR ON DINCNZONS hLESS WALOCLK DI GRAM o 190%
b | cHAN GR NeTicl WP BOSO  Drresli{y T OITEN MAS 14 PiTient CevERING RANGRD FReM. G5 W . T0 LA MW I ATPREX: OTHERWISE $PECIFIED:
- Vi DECADS. APy { £ MArs PR DICATL) . ARG DG, ReiB: 12-. 84 .  RANMGE- SRSCTeR FRACTIONS + RO CONTROW

RO, : REVISIONS | DATE |APFD] APFD SWITLH . DOWS HOT _MLWDR A 15 WW FosiTien (S8 udte 74 AUD THAGRAN ELIT. Y BLOCK UIAGRAM

w77, hee-e BAT DATE: . ‘ DEGMALS £ . SHEET |\ o4 2

DESIGN DAT] APPROVED | DAT| ‘ ANOLES £ T""‘ W
5.3.9 A2 1, ke _ ’ : o mflru vy

.W' -M mu APPROVED . | DATE | APPROVED | -DATE : ’ S . i . _ . . SCALE: NONE. . : O-HHIB

 

 

 

 

 

 

 

 

 

12079¢

Fig. 2.6.1. MSRE Rod Control Block Diagram.

!
\
i
i

i

 
         

 

 

 

 

 

  

 

   
 

 
 

 

  

 

 

 

 

 

 

 

 

 

 

 

 

 

   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

  

 

 
 

 

 

  

 
 

 

 

    
  

 

   

      

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   

 

 

 

 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

 

 

 

 

 

 

 

 

 

 

 

   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

..... Rt " e o T T e A o ; T ol ¥
j
i
i
}
&
’ 1
} ¥
| :
4
§
i
\
0 3 ' . ‘ ! ’ | , 179
. o S 1511 1 ‘ 5 " e : Y 1 st
sy gvh. w0 " . . s e 9 ‘ 180 isi 209
d8VBe. 1P, l |f“ TN .
o it - . A
. KBISGD s e FEIOWN o KBI08A A CLOSR WwEw ‘
Nt PERIOD > 25 %%, : ; :
! O . : . i
‘ . e NCCT A i
xatoh o K226A ‘.;'.".K\\N-h oe L~ OPBN WUEYS WRIGHT s i :
T S Jyauw OR LALT (u RUALTOR 2 Y . :
W N -l;q.v.‘ub.> 1% sec. ( o0l tan. :E_,.r‘f_f_ : '
Q ; : ;
. - i . it I B4R ; :
IR ’ J_ _ .\L'fi, - 'Lse? ' ¥ e . ‘
o ALY =K REIDN G P——]_ b I I ! : !
c KivGe ! ; S YBISE T-KBIaB ZOKBISSA KBI76A :
f—— ' T L | T T T :
: . ) Y ’ ' : : :
. ::Z:'*A«-M?EKI'JEA xRN Frasen ; e :
N - it . .
'm.::".'gw‘ - RO -1 —— : + : 250V. _‘*‘ G
cel . NE ] 3 . . & 4 o e -
isone . n.a%ro' /Q l _I- ) ™ o T v
’ : : - . <
- - ok . > - >
© TKISSA.  TUKAIBGG oKIBeR fcLotE . ON SERVO. > 2 -
: : [“unm:tuu SIaNAL 3 <
) N L cra 4
: K - ~Eraisse s . ) . : ! )
1 1 : Fxassp Lo Zwnab. Awssp
S RATTGCE. -’..X_AIT‘D ¢ 1B . . o
SEKIAC | ITKAISBA Crarea SR _r\mn- S RAVEN
— SR NOTE -1
/V'-‘-_—._—.
t .
<4 —
K"‘.B‘bk
KinSC
L
&rn_. 8-.11;.
NS
ZNY ; . ! . : \ ‘ : : 20—
Looadlen A, e VVERLITE ARy A%, : { 10as, TN, o BT, T, MY o ToAB el
S feM2, 483 116,16 - ANE,AAT. . AN, (987 199,099 N ) e NABINYY 188, £33, Sl :
188, 100 ABNL1BN. 184, . 404, %9, 148 o o
S : _}l‘" G- S .
LSONRNOTeN  SERV0 1 FLUNL. EMERGITLI TS ENERGIE TO GROLE  ERGULATING | ®1 2o0 : S W won : T @R ECD | DYNAMIC BEAKE . IORURT  WITWORAW. L LvbRERT  WMWORAW
T AW MOTIE WIWEW. ' INCREASE DECREASE . WITHDRASAG:: gow AT Lo . — " .
- WHLRGIND | DERMRRGAETT QUTLET TIMR  SUTLKT TRMP, . CHWITLAL S S . : }
‘ R 4 RS1O . ST PONT SET POINY ) i . o o ’ L.
OEREAIRED. . (DBMAND) {oemant) . ) . " T BeD . n . e T omr eom
SLLVD 10 TR, : i ‘ — [ m————
- MODL. WINES . | . e ' '
. EWERMD : . S i
-4 KWAID . . . ) \ ) .
RERECINNG 5, ‘ — . s — : - e : - f
o e T CONTROL RO WITHDRAIAL WHAEN WMNERGIEED COUTROL MO "DRIVES MOTORS, - "
KOO SEEVO. A e it oR ' A IO DUTLEY " TEMPERATURE: DEMAN MY CH sHim mou vy AeTUarow swiyew SelELl
ST s 5 : Wy : - . A1 . ‘ _ : .
200 SERND MODE SELECIOR SWITCH RERCIOR: DUTLETY EMAND SWITCH. SHUA L BDE T ACTVATL : PUALE IPLITTING CAPALITER To Ww
A o - ORITION _(FTONT. View) - ] PORITION . { EEONY View ) B BOBRATION  (FEONT VikEw) .. OI-FIALLD PAPR-K AWD EATED. AY
R YR T U OFR]. . WoLty | JSERve- O] SOCMTIon | | ConNTACT I o ranen] .. orw . [mciumges] -OChTION S ROWTALT T TIMBERY ovr AITADERL | WOCRTIOR. 500 V.A.L.s  CAPACITOR TO MumT : ‘
AN DU WS . a ] (ewt mae)] HAGDAGR BT e tery. mall [ wanDLke . Hwo —w— - {ext. wa). CRAVIEEMRLTS orcfo:fl.oo;_go:, TG, ELEM. CONTROL INTRELOLE CIRLLITE: M Lat T BUWB-5102Y
sy Ity e . AN fatay ] oo oo Ve ALY G . : R L ovae i} ORive- Farve ™ AMB-FLATE .. LG, BLEM. BOD CORTROL CIRLOITS - 4W, To4l oww- 5. 51519
. Lletey | . Ana.. - w5 ] -~ =& ' . T s wt25] . o % . e ooovv REFERENCE DRAWINGS _ NO.
- T : : , e (8l - w1 s .
Che e T T e . . e . ——t e Oax RiDaE Nam“ummv
: ICAS = e e st g . i : ‘ ‘ ‘ - i
oLl ey e - — UNON CARBIDE NUCLEAR COMPANY
-3 Al - VLl 1-&-6b) ) . el . 220 '
ot e R T ey ewiv & - ~ ATO wI\TC i . HiM ROD. =2 TACTOMOR, ' DIVISION Woaflbflm%mflflmm. TioN ‘
C locns sidn . . | % , POSITION (FEOMNT Vitwi) . - LPOBITION (FRONT View) , MOLTER SALT REMCTOR TAPLRIMWWT mpa n
B8 lerANGE NOT. K] — v-scasilipn coONTALTS MLt orr . arinowiw | LOCATION CONTRCT I o lwer | onm_  |shinbeme | -oCRTIOW LIMITS ON DIMENSIONS Ungess | ™ ‘ ‘ A0S 50N,
A ) WAK - e - enT M) WANOLE  %ND Lewt. med OTHERWISE SPECIAED: - ‘
VAL | enAMGE uoTiCR® T 2917 4. 104/ d . RWOLE BN St 2y, Rt ) ) ’ - . et g B R, marefinsmsael). . . :
REVISIONS ALY ® 11s .1 |7 aewvy |- . S R T hl FRACTIONS £ e ENGINGSERING LEMENMTARKY
no, ! ‘ . | DATE. [APPD] APPD —— - - * ‘ " - CIMALS ' ROW " CORTROWL CQCIiRLUNIT=
. - - =T : T P e T EETR Tt e Dec . O vy - \ ! .
S S di biesees] - . c (3], % M 7 ) N R S s . : BT 1.3
Ly ] [ AFFrovED — | ota) x : TeE. ole | Al .1 .. . ANGLES & —1 <~ A - APPRONED
- DA, o . _ scaLe: e 0 D

 

 

 

 

 

 

 

e e —— . ‘ ; : 1 - - . 20 4T ED

Fig. 2.6.2., MSRE Rod '.C_ontrol Circuits.

'

b

 

 
 

 

 

244

 

 

 

s y NO LOUNT FENIOE

 

 

 

  

LOUNT
EATL METER
LOMIIDEL

e

|
~uoyg ¥

 

 

 

   
    

 
 

ELALYOR
| rcorm
< ¥y POULL

 

 

 

 

 
     

|flt R, &
“N‘P‘IT L]m *

 

 

 

 

!) 12 Mw
-t ct\muu.‘\

 

 

REACTAL SWTART
TUMS SR RTVAY
>80 b
Laanuts * )

 

 

   

 

   

 

[m.'s .mmm.'s.

 

L Mw ‘)l! aw

 

 

 

 

 

®00 L1
] semam BLRAM SCRAM
¢ HADLELS | HANUELESZ | uanaL®g
. ROD e © ROD
THCRAM . ".&IQM‘ " SCEAM .
: AVOEL YR cnhneL ¥ 8 CHANREL®S

 

o sug uo'ra.'gn

J WGH LEVEL
iy

Hod et

Bavi.

 

 

 

—

[

B i

 

srany Moye *1
RVT-T-Y S

e, o

=

 

 

REM T JOOT ... ..

“"."“:l : fi(fi'

 

 

 

a . .
B | CHANGE wolrc& * 5::5::
A [EHANGE NOTICE NO. 2787

cealtimi|
4204 e

 

 

 

SR

 

DATE [APPD| APPD
APPROVED | DATE:
APPROVED | DATE

 

 

 

 

 

PRLELL
MOOE

 

OPLEAT
wWoR R

 

ROD™TE

 

 

 

 

 

wneve

=00 “um;j

 

I TN
HOY W
UPPRR LT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ag xo
' wWOT W
LowaR LimiT

scnvo l AtTusoR
EVER LA 'ws:.l“" t WITLH WITOR Ruvaxie numa uurcn REVERSE
SN ‘waveER e ‘msclr.f ‘mevERSE S S ERY

 

 

 

 

 

AMSEET
.‘= xOOD

NOTES

1 SIART § RUM MODES ARE MUTUALLY BXCLWISWE , 1.E, ReEACTOR
CANNOL BE [H HIART ¢ BUN MODES AT THE BAWME TiWE,

(Het DWG, D-HH-T-51331)

1. THE CONTROL HYSTEM DOED NOT REQUIRE TWAT WIDE RiGeE:
COVNTING CHAMMELS Bt N OPERATIOM IN RUM KODE
HOWEVER , |F ONE OR BOTH CHANNELS ARE OPERATING
CORRECTLY (cou\'—mnuci ESTABLISHED) A PERIOD OF
!o slcouos ar Lts': mmbfls RoD wlTuDfl.AwAu.

wmw rFURL SALT IS cnzcumrmd » auve:se— OCLUKRS Ar
12MW AS SHOWA ., WHEN FuwiL SALT IS MOT CIRCULATING
THE FLUX AMPLIFIER GAINS ARE JNCEEASED BY. A

1000 AUD *RBVERSE " OCCURS AT 12 kKw,
Sk DHH E-5T73483 AND RC+IF-D-3-R} ,

FALTOR OB

4. EEFuR_ ro DEAWING . D:HH-B-57332 FOR.  COMDITIONS
Y ZRQuikeD TO ESTABLISH COMPDEMCE .

[

 

 

COMTREOL OO HLOLK DIAGKAM -~ SHEEY | oF 2

[O-HeeB- JISB L.

 

REFERENCE DRAWINGS

 

NO.

 

OAK RIDGE NATIONAL LABORATORY
OPERATED BY
UNION CARBIDE NUCLEAR COMPANY
DIVISION OF UNION CARBIDE CORPORATION
" OAK RIDGE, TENNESSEE .

 

 

LIMITS ON DIMENSIONS UNLESS
OTHERWISE SPECIFIED:

FRACTIONS £
mtfl
NGLES & e

 

MOLTEN SALT RIATOR BAPLEIMENT.
BLOCK A GRAM

T
L6 1303

 

 

SCALE:  wmoww

CONTROL ROD
BLOCK DODiAGRAM
SHEET __Z,_ o‘

 

 

 

 

 

 

 

Fig. 2.6.3.

MSRE Cq

 

ontrol Rod Block Diagram.

 

 

 
g —

s o —

 

245

 

 

e, (7= JISHS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

    

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

184 : i o
{ aseva. '8 4uq 18D ~ 155 : 186 189 188 suq.
J'st'l.b J--.‘nu ToNIsGE EuSS-HARC-AT 4—
. -l' g}os‘.‘:‘u‘r:::& _ e e J o //—-.VWW__. - T
™ i - - D.c. Ao
n *> 4 \ —=s1rcC g S X1 o KIBLG f:flzb ZIsnD ToKIBGD ;f‘.m.o'n-c 3_1:;&&5!05:. SRS e AL ::u‘c‘a-AsA ":R..s’umt-aa:'uzcz-nk pLYD < - BIPSA
. . ‘ . CLOSE WueY [CLDTh PERWDILLOSE WHRELE [CLO%% P“lfl.m M e e ‘_\‘—-
_I_ ' ’ ¥ o> nswmn | €10 o> .5 M | ¢ 10 suc.
o kAOR . R TeE i CRMTY cRM b2
| o]
H l ;:nm'\ot- t KBIOE L .
. T KZAGK Huzene y l
‘ _ i oKl G Kine Gr Frronn 2 KBk
]:; N N ; g o b
3 W
7~ j:\ /:E J ‘ T : _ l .
, . T=xamea . jfusu , ICRzRsA : (k@115 J=xis2n
TN Ekamim ; : “-x2as5n N _I_nzssa __]-
-
_,rnmuc. P
AN
. :J.:K\un jf.!(lszc j :
P e
:‘ TR
Akusa  Fuwse  Fowmae _
’ . i i
v -lL ‘4
J 4 L ‘ ]
—~ K240 ~¥X150A K150 ¢ ; _ — el -
7 ¥ ; |_c.\.u1c|-i-..b!AKE-_ i;mm MoToR bn\;}
! | i I w |
\, ~ s Nt N 1] Iesaoativg RoD | | REGULATING oD
’6:)1 &% | (— ,(D:—" , {;‘ | AT Switen || Lt swirek |
( ~ | B R | | Jol L MmeHARIsM || MackAuism
3“ Z &l& '&‘5 &‘ =D M BAYTT
&\u 183 Y ~ s B Biaiay™
ZMG - 289
189, . . VYV L . n:. 179 180, wé, 118, la
b . 179, 1 97,100 &) 1] 184, IAS
151,188 pE 2102 ne, e e
::gus‘._“m‘_u ‘ ) po *2 goo »npor ; WL ERY WHTHDRAM
Ay oo Z » . .
oy kB —tEoL —=re= - 1 ‘ ‘ ~ N s . ’
CONTEOL ROD IMSERTED WHEW EMEvRGILED LEONIROL  ROD REVELSE WHEW ENELGILED. REGULATING _ROGH _SHIM MoTor Brars
_ . ; LUMET _ Swsitowm OFEF_WHEWN ENERGIZRED.
: POSITIONING MOTOR
‘ I T
T ROD GROVTE ACTURATOR SWITOH LT
* ’ PORITION  (PRONT Views) ]
COMTALTS L evekhw]  HOLD |witnDrAw] -OCAtion
CHAKNDLE BNt o S =) LanT. wa)
AL L ' X 194 |
B (22 X 185 ), ELEM . CONTROL WMREWLK CIRLITE. $W. T o4 T [OWWS- 51010
(%) S X 184 WG, BEM, ROD CONTEOL GIEGUNT:+ M. | ag T DAwE- SIBT4
4 x 18
R4 2 REFERENCE DRAWINGS NO.
. OAX RIDGE NATIONAL LABORATORY
: OPERATED BY
. " L ‘ ] UNiON CARBIDE NUCLEAR COMPANY
d Yocu =zrid . . . . lezreH il pwir DIVISION OF UNION CARBIDE CORPORATION
3 |ocw ¥ 5740 = Pé-as e . OAK MDGE TENNESSER
: i OLTEN SALT REALTOR & APLR\MENT,
8 | cHANGE NoTicd NE_3047 _ |ssoesliin | oFly LTS O DIMENSIONS Uniess | ™ " 1son
N | CHANGE Motie& * 1411 B-r-&4 L7 {nl @3 - . -
- PRACTIONS & e EMGINEERING  BLEMENTARY.
NO. REVISIONS | DATE apPo| APPD | : ROD COMTROL CIRCUINTS
AT O EWITTED | DATE DATE: DECMALS % e SHERT 2 of B
AN W ' . — 4
ANGLES 2 =7 §UB
N DATE - DATE | APFROVED 1~ DATE - }U Mmi!i'
D TE DA APPROVED DATE SOME; rers et APPROVED

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fig. 2.6.4. MSRE Rod Control Circuits.

 

 

 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

     
  

 

 

 

 

 

 

 

 

 

 

 

 

246
f
! ORNL-DWG 64-6082R4
' SEE NOTE 2
_ 74, 175 7 182, 183 o 240 244 .
115-v AC—2H I -t { ¢ L
J_ Ki93A | RxS-NCC1-a4
A~ THESE CONTACTS LOCATED IN Q-2609 FAST TRIP COMPARATORS ‘
T\ IN WIDE RANGE COUNTING CHANNELS. CONTACTS OPEN IF REACTOR
PERIOD IS LESS THAN 25 sec, ( INHIBIT ROD WITHDRAWAL )
J_ K194 A 4 RxS‘NCCZ'A"
7(—
CLOSED IN THESE CONTACTS OPEN WHEN WIDE RANGE
OPERATE-RUN COUNTING CHANNEL "CONFIDENCE * ESTABLISHED
MOOE
OPEN WHEN DRAIN TANKS FDT-1 AND/OR 2
—[//I_ SHOW LOSS OF 4550 Ib OF FUEL SALT
WoS
1002 $65=CLOSED WHEN FLUSH SALT TANK
KBI396G _ KI93H |/ KI94H 22 B4 'S SELECTED
7T
K195C
I “CLOSED WHEN "CONFIDENCE"
/ 0 ESTABLISHED IN BFy CHANNEL
RELAY CONTACT
THESE CONTACTS Py SS-NARC-A2 LIN Q-2615
CLOSED WHEN WIDE SERVO CONTROLLER
RANGE COUNTING | T “INSERT" ROD NO.4 SHIM REG. ROD
CHANNEL “CONFIDENCE"| Ki86A . \ $228 ~l. 5190 Ji86F - 1 ASSEMBLY LIMIT
EsTABL]SHED _ffl OPENS ON AUTOMATIC REVERSE MANUAL - SHIM NO. § REVERSE , ' - UPPER SWITCHES LOWER
- "REVERSE" ACTUATE _ L T N sl L Ki75A \
INSERT" kae3a L. kairea . 7 < L xis2a T 'WITHDRAW
_ _lekeaie INSERT T WITHDRAW | “INSERT" Ri% I?gE‘ELS'M‘T
TO "ROD WITHDRAW" 77" OPENS WHEN SHIM REG. ROD NO.1 ROD NO.4 REG. ROD LIMIT "
_ CONTROL CONTACTS ROD LIMIT SWITCH SWITCHES Sf= K182C
CLOSED IN E2E 'F10. Rea- ane 3 ' ASSEMBLY CAM AT KA1B3D ;é
L I KI34E . RCS- ] LOWER LIMIT
foPERATE™ 4 == goseom S CLoseD wirH OPEN T I ol
KA136G LL™ Mo SERVO "ON" SERVO["ON"
° WITHDRAW INSERT e
L kaz40c _l/ks170€ | ROD NO.t | ROD NO.14
R CLOSED WHEN SHIM-REG. 71" cLoseo wiTH ' s
RELAY CONTACT ROD ASSEMBLY CAM AT "SERVO" ON
son | IN Q-2615 UPPER LIMIT 2 k240 | KeH °
SHIM NO. 1 RySS-NARC-Al _|  SERVO CONTROLLER I i f
L Ki3eA 1 KiT4A : ACTUATE T~ WITHDRAW ROD NO.1 } : ; Z .
CLOSED ONLY =T~ GROUP WITHDRAW  wITHDRAW INSERT [ WITHDRAW ' // INSERT WITHDRAW
IN"START 5208] SHIMS NO. 2 _|/ K240F _lek240a RIVE MOTOR | | | /s
MODE AND NO.3 77— OPENS WHEN SHIM 71— OPENS WHEN SHIM o ;oo i y SHIM LOCATING MOTOR
$218 | ACTUATE REG. ROD LIMIT SWITCH REG. ROD LIMIT . | ~
$22A CAM AT UPPER LIMIT SWITCH CAM AT L POSITION | C v
=1~ GROUP ROD —L UPPER LIMIT TRANSMITTER
WITHDRAW Lz kiron ‘_mg:&%lm _lz kar700 S \MECHANICAL DIFFERENTIAL
(MANUAL) >f— CLOSED WITH SERVO "ON" 7T~ CLOSED WiTH
SERVO “ON" SERVO "ON" CLUTCH-BRAKE
CLOSED WHEN NOTES
— Hi
S#- k2284 | RoD DRIVE UNIT SHIM LOCATING
2l (a9 [ NOT AT uPPER CAM ROTATION ROD NO. { MOTION
WL K241A T LMt | (cLockwisey | ™ | (witHDRAW) + | MOTOR ROTATION
71— OPENS WHEN SHIM REG. / kie3c (INSERT)
ROD LIMIT SWITCH CAM = 6PENS FOR R
AT LOWER LIMIT 7 SO_E,N ,NS%RT ob AND VICE VERSA FOR COUNTERCLOCKWISE CAM ROTATION
2. THIS DWG DOES NOT SHOW DYNAMIC BRAKE CIRCUITRY
KI5 K(76 K182 K183 FOR ROD NO. IN CIRCUIT NO.179
THIS RELAY, WHEN ENERGIZED, THIS RELAY, WHEN THIS RELAY, WHEN ENERGIZED, THIS RELAY, WHEN ENERGIZED,
< KiTa OPERATES SHIM LOCATING <, ENERGIZED, OPERATES OPERATES SHIM LOCATING OPERATES ROD DRIVE MOTOR 3. SWITCH AND RELAY CONTACT ASPECT (OPEN OR CLOSED) ON
MOTOR IN REG. ROD LIMIT ROD DRIVE MOTOR IN MOTOR IN LIMIT SWITCH INSERT IN "INSERT" DIRECTION|CAM THIS SKETCH IS FOR FOLLOWING CONDITIONS :
SWITCH. WITHDRAW DIRECTION ROD WITHDRAW DIRECTION, DIRECTION, CAM ROTATES ROTATES WITH SERVO 'JoN* O a. SERVO "ON", ZERO ERROR SIGNAL .
CAM ROTATES CAM ROTATES WITH n b. REACTOR SYSTEM IN "OPERATE-RUN" MODES
m SERVO “ON" O ¢. REGULATING ROD BETWEEN LIMITS
d. REACTOR IN STEADY-STATE
NEUTRAL ¢. "CONFIDENCE" ESTABLISHED IN BOTH WIDE
: RANGE COUNTING CHANNELS
GROUP ROD REG. ROD LIMIT ROD NO. 1 REG. ROD ROD NO. 1
WITHDRAW SWITCH ASSEMBLY WITHDRAW LIMIT SWITCH INSERT 4, ANY ONE OF THE THREE CONTROL RODS MAY BE DESIGNATED
WITHDRAW INSERT "ROD NO.1", THIS NUMBER HAS BEEN ASSIGNED TO THE ROD
WHICH IS INTERCONNECTED TO THE SERVO CONTROLLER
MSRE
Shim-Regulating Rog Control Circuits.
Fig. 2.6.5. MSRE Shim Regulatihg Rod Control Circuits.
-,

 

N —— |
 

247

ORNL~-DWG 66-5716

15V AC
= <

 

 

 

 

 

 

 

 

 

—J: KA1B3A £ KA183D
—HKAITE6A
KBIS3B KBIB3A | KBI7T6A
[: L L
Ak AN
[ KB!183C KAIT6C
L 1y \
Al Al -
300uf l KB183D KA{76D I
+_| " 280v ~ 2 I
SERVO
508 500 MOTOR
NEUTRAL
5 L

 

 

F

Fig. 2.6.6. Circuit Diagram for Regulating Rod Dynamic Brake.

 
 

 

LIMIT SWITCH CIRCUIT, TYPICAL
OF ALL LIMIT SWITCHING

ORNL~ DWG 66-9430

 

 

 

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CIRCUITS NO. 232 TO 239 CIRCUITS NO.
1uucn. , . 174 TO 178 INCL 184 185
C t ( !
_[ l MANUALJ—
——— —_— s522C "REVERSE"| 522D
conFIDENCE" W —_ f—
REACTOR PERIOD 'J."f»'«‘fl'fi’ A
"REVERSE" AND MODE | 5200 s 21D INSERT
INTERLOCK CONTACTS | —_— -
TO ROD NO.1 T
CIRCUITS K186 C Ki86 D
e LmiT swiTch, - INSTRUMENT
-4~ OPENS AT "REVERSE"
LIMIT
S21A
INDIVIDUAL
:[: I 1o L SHIM ROD ACTUATE 1840 | , K185D],
S SWITCH CONTACTS, A~ 7
SEE BELOW
_| K84A Ki85A
s20C _— —_—
KI7TA K178A
KI74D K1i74C _— -
GROUP
WITHDRAW K234 A
RELAY A K238A 1,
CONTACT 77— LOWER LIMIT
K 2354 SWITCH RELAY
K239A
Lz CONTACTS,
K232A K236A | opep vl = PHASE PHASE
| :[: LIMIT SWITCH SHIFTING SHIFTING
RELAY CONTACTS CAPACITOR CAPACITOR
K 233 A K 237 A | {
X
K 584 C K 185¢
OPENS FOR
ENERGIZE RELAYS ROD "INSERT ENERGIZE RELAYS
LIMIT SWITCH TO WITHDRAW TO INSERT
RELAY ™~ / T ;
K177 K178 K184 K 185 DRIVE DRIVE
MOTOR MOTOR
¢ { ¢ 12N9
ROD NO.2 ROD NO. 3 ROD NO.2 ROD NO.3 INSERT WITHDRAW INSERT WITHDRAW
. ' J L NO.2 NO.3 '
Y. v
WITHDRAW INSERT CONTROL ROD
SHIM RODS 2 AND 3 SHIM RODS 2 AND 3 DRIVE UNITS
INDIVIDUAL SHIM ROD ACTUATOR SWITCHES NO. $19, S20 AND S21. 22
MANUAL , ON CONSOLE GROUP SHIM ROD ACTUATOR SWITCH S
CONTACT POSITION CONTACT POSITION CIRCUIT
NUMBERS INSERT | "OFF" | wiITHDRAW NO. REVERSE(INSERT) | HOLD { WITHDRAW | NO.
S19A, S20A, S21A 0 o X S224 o o X
S198, 5208, S2iB 0 X o s228 X 0 0
S19C, 520C, S2iC 0 X 0 s22¢ X 0 0
S19D, 520D, $21D X 0 0 $22D X 0 0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fig. 2.6.7.

MSRE Control Rods 2 and 3. Circuits.

C

8¥C

 
o

 

 

 

 

 

O “CONFITENCE" REACTOR PERIOD
WRC CEANNEL { OREATER THAN 25 SFC,
. 1 (WRC CHANNEL MO. 1)

N "CONFIDENCE" REACTOR PERIOD
WRC CHANNEL JOREATER THAR 2 SEC.
2 (WRC CHAMMEL XO. 2)

 

 

 

—

 

 

 

 

 

 

 

 

 

[ eams A
| sELECTOR 1n

PFT FOSITION

 

 

 

 

 

 

 

"CONFIDENCE" "co! "
ESTABLISHED. 28 TARLIEHED
IN WRC IN WRC
CEANNEL #1 CHAKREL #2
A

 

NO AUTOMATIC "REVERGE"

 

REACTIOR SYSTEM IN
EITHER "OFFRATE"

OR "PREFILL" MOLES

FEMAINING CIRCUTT

GOVERNIIG
INDIVIDUAL CONTROL ROD

WITHIRAWAL

INDIVIDUAL
WITHIRAW

 

FAST TRIF COMPARATORS IN

ORNL-DWG 66-9074

 

48v-g¢ 193 194 195
L4 4h. »
— . Llsi3A L sise L com
SELECTOR "RILSE AN AND T CALIIRA WITe
TI0N 8 H
SWTICE RATE A on 100
- Q-261h "CALTHRATE-OFERATE " 1 RATE METFR TH
SHTICH, HSS-NCC)-A, i WISE" POSTTION
L_______J CICSED IN "OFERATE" 1
POSTTTON =
1
1
|
1
: CILOSED WHEN BF
CHANMNEL COURT RATE
THESE CONNECIORS USED TO
FIDG THDIVITUAL Q- | ICEELS 10 cps
UNITE INTO CONTROL SYSTEM i
AND CARRY ALL POWER AND 1
SIGHAL CORNRECTIORS IN ™IS CIRCULIT
ADDITION TO THE TIERTICAL 70
CONTINUITY LOOF SBOWH THAT OF WIDE
RANGE COUNT-

CLOSED IF COUNT RAYE
[ — EXCEFIS 2 cps
el

 

 

 

|
N\ —"(:l_ —- _‘.\_4 CLOSED IF COURT RATR

LESS THAN 50,000 cps

A WITE-RANGE COUNTING
CHANNEL, 8 TOTAL.

2.6.8.

ING CHANNEL
M. L (#193)

e -

 

Ki93e KI94B KI95B
Kig3 Ki94 K96
" vIE RAms WIIE RANGE momrTIVE S,
COUNTING CHANNEL #1 COUNTING CEANNBL #2  COUNTING CHANREL
— s

 

CONFIDENCE CIRCUITS

MSRE Control System Confidence Circuits.

 

6¥C

 

 

 
 

78% FULL SCALE

-

ORNL-DWS 88-3218

 

rempeRaTURE | 1557100A1-2 | THESE TEMPERATURE SWITCH CONTACTS
SwiTCHES | TSS-100A2-2 ¢ LOCATED IN FOXBORO MODEL 63 S. CON
TS5-100A3-2] DUAL SWITCHES RECEIPT OF A SCRAM SIGNAL.

 

 

T

% éKMOfiB % {KEO&B
¢

 

 

| A\

CONTACTS OPEN
WHEN REACTOR
OUTLET TEMPERATURE
EXCEEDS 1275° F

CONTACTS QPEN
WHEN REACTOR

3 )
C 1
lfifi-NSCi lRSS-NSCZ J_RSS-NSC3
A4 A4 A4

 

 

 

 

 

POWER { FLUX)
EXCEEDS
SEE NOTE 2
K248 K249 K250
K202
(—
REVERSE ROD "REVERSE" ON SCRAM
2 OUT OF 3 REACTOR FLUX AND TEMPERATURE INPUT DE-ENERGIZED WHEN ANY 2 OF 3 INPUT CIRCUT
CIRCUITS FOR CONTROL ROD "REVERSE REACTOR OUTLET TEMPERATURE
PUMP BOWL LEVEL INPUT INSTRUMENTS INDICATE
CIRCUIT TEMPERATURES GREATER THAN
1275°F
5 1
KS108C K207C _L* “J‘R‘S‘NCCPAB l‘ “lRIS'NCCZ'B
THIS CONTACT &  CLOSED WHEN NeR NCEDe
i CLOSED IF FUEL REACTOR OUTLET RyS-NCC1-A8 RyS-NCC2-28 " THESE RELAY CONTACTS, R,S-stc.,
K248A _[Kk248C _K24SC SALT LEVEL EXCEEDS TEMPERATURE IN Q-2609 FAST TRIP COMPARATORS IN WIDE RANGE
I I I 8% FULL SCALE ON EXCEEDS 1275°F COUNTING CHANNELS, SEE NOTE 1
K294 | k2504 | K250C LEVEL INSTRUMENT
Kig36 K 1940 NOTES : 1.{a) CONTACTS R,S-NCCi-A8 AND

CONTACT MATRIX TO

ANY 2 OF 3 CONTROL
RODS ARE SCRAMMED

 

PRODUCE "REVERSE" IF

  

CLOSED WHEN _*"
WIDE RANGE COUNTING
CHANNEL "CONFIDENCE"
EXISTS

      
   
 
    

K203A,

£ CLOSED WHEN
REACTOR POWER

{FLUX) EXCEEDS

12 MW (OR kW)

N

KB(3SC
THIS CONTACT
CLOSED IN "START"
MODE OF REACTOR
OPERATION

 

 

 

K186

 

CONTROL ROD “REVERSE" QUTPUT CIRCUIT

2.6.9. MSRE Control Rod "Reverse" Circuits.

ReS5-NCC2-A8 CLOSE WHEN
REACTOR POWER (FLUX) EXCEEDS
L5MwW

{b) CONTACTS RxS-NCCI-A3 AND
R.S-NCC2-A3 CLOSE WHEN
REACTOR PERIOD 1S LESS THAN
5sec

2. WHEN FUEL SALT PUMP MOTOR CURRENT
IS LESS THAN 55 AMPERES TRIP POINT
1$ REDUCED TO 9kw

0sT

 
 

     

251

ORNL-DWG 64-635

 

 

 

 

 

 

 

 

 

 

 

    
    
   
  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

DATA
LOGGER
RANGE l
CHANGER
POWER
SUPPLY
Q-995
COMPENSATED
ION CHAMBER
Q-1045
TO INLET
TEMPERATURE NOTE: Q-2605 IS OPERATIONAL
SENSOR AMPLIFIER
d TWO PEN
ROER
_/—' RECORDE FOXBORO
i RANGE | LEVEL E/1
CONSOLE CHANNEL
POWER Q-2605
SUPPLY SELECTOR SWITCH 2008
Q-995 AMPLIFIER
=] S =N
o ] S Q-2605 0-260
COMPENSATED ‘ NO RANGE —l/
ION CHAMBER M SEAL
Q-1045 FLUX
CLAMP FOXBORO
‘ £/1
TEMPERATURE
SERVO DEMAND
DRIVE UNIT
o oy CONSOLE
: . 10 QUTLET
COMPUTED - TEMPERATURE
FLUX OEMAND SENSOR
J

 

 

 

COMPARATOR |~ RUN PERMIT
Q-2609 $<iMw

oN
‘ RUN :
FLUX DEMAND |———4———0 R _1\ SERVO —°\___
LIMITING CRT, o + Q-2605 PILOT O TATOR AL,
FMwed<iimw NORUNO oo @ __I/ RELAYS OFF 9 TACHOMETER

NO RANGE SEAL
MANUAL
CONTROL SYNCHRONOUS MOTOR

DEMODULATOR

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

¢
DEMAND

RANGE SEAL
1-Mw - .
FLUX i

DEMAND

  
  

   

 

 

Fig, 2.6.10, Linear Power Channels and Automatic Rod Controller.

 

 

 
 

 

 

  
  
     

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

     
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  
    

 

  
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Lo Y ED
RUI DELMND
DOUTLET T&sdS, TER APLIN o FLR
OEAIAND AMETER Yryl-MARS AL " OMiAnd POT RA-MARL-AG
—]L — — ChAr-&-20d .
[_ oV — —'
2224 v out et suus semt pipa A VL RANEE SW (wiss 3rane 4)
I Jooo 4728 #3y Re APASC it AL BAEE BiFA LOCEER
A P Q| a4 %2 orwes 3. (srarae smar o)
wrze uu'./,.z -
oo - sV RC w2088
. Alre TH-MARL- A2 A T2 BAGL B, (ArPGR STASE $)
= ,i\_‘“" z :;::_;1-- _ A CAT AMPLIFIER * O wpA R Leves oane coasen
' Phwap ok et RowHARG-AY ARG . o
ek anered 35 50 e aasn S . AR DI e e Jaud s asce s (orrns rnsea &1
* t i ari s /2 - sav/pe 7 aseg RALATS SPRRATE &1 ~ bvwn
=TI i v Wv ACCLTIPLICR RANGE CISNTS
- £227 ) Frd
o.mv/,- % azes | o« ‘1 "”:‘g' 3 %";, \[.nuvj.. 5“ 7 . c iz
7o o AA I‘ | m‘ Y AA A & FVAC et I ¢
o esavfr ) M ctor 2k F < £eh ¥
T, SEaison oy e a:w as383 sa003 iy gois xeog | avmavewr mrnvaa cronrs
&c e Jccancm 1 | s Foo g & . | & #2058 &_—Idj )
Lo, - " - |
rI0d Ay e
"o %:r " i ‘ ns W‘—-—o—z-
Peu"l e v, cwesnr ‘36 | J e % Y werwvowaw coany
LEVEL & ~ Yy ] 3
oLy SYAXCHAO 2
:::f‘gl e [SE440D. mawc ot I
_e8iI00 b id RC/3-13-8A 3 ¥ INSERT coonT
- > v AR 2 tos il X AIODE LISHTS
xeaagn . f20/ L2803 Lot S ELY 2206 LES? arse
SO— KSOS5D (Com. ) ST Sy TK 22e9 274 S e 74 2V
Ti- WARC-AY n a ROOK wITNORA AMIERY AAN, ALUN. b
Re _r - MARE-
A208¢C (Com.) INCET 3 ourLer Feux wirnoraw
rearr. TRACH, D& AeAwD
nee’s uem-riee "k o-woe R »EV
e v 2208 Ral-WARC-Ad cvtnss| cuue| SELE
242 pry INSGRT
| /.4 Fr’ 4 7L
1 -32v
1)” ; g -E AL SEAL LroNy
“""“_"T P Pry
RANGE SWITCN ¢|‘ ‘
| i Tt | [~
! E i
oUN .s:wrr:#¢ w‘m——o—r v . }s:ur:rfp CNANMEL. LIGNT
‘ ‘ 2c
l fc K#os :
CAAINNEL SELECTOR SW. VOLTAGE ; rerrP. AOOE RELA
S 1 DISTRIBUTION . _ CMP. A v
1 BUSES :
I T PV o 4 .scat_ ; 7o ppud *2 1Suw
SecélTon od s AR 2OF HANCE RELAY
- g a8l 2 CAWCR R-2 ?4.0 - _I
RK'NAQC—' Al To pud "L /S
-22y ; LANEE RELAY
L00
¥
, - ' | MR 7 FOR INFORMATION ONLY
e “:.:... P — "—... — —— mmfl DO NOT USE FOR
r : | MAINTENANCE OR
l [ l CONSTRUCTION
I HEVAL/ OV & ~ov 45V E-Z5W wEY € WS
6.9 VAC WALT #66, VoL T, 65, VOLY. £€G. I
Mo EE. UG, INITEUMENT APPLCATION DikGy. oA ded T
TEANSF. RC[3-17-1 RCI3-16+1] RC/3-15/ .-mv: aul.u' yACH. 2 )
I R HALS- A RUARC- Y RuARY - A | [ EGEND Auto. Eod lontrodier Dwr. 28 l”nwy LLIAESH
| ] .3 Ao, Lod Controlier Owr. £/ Wairig LTS A
—_— -y — — —— .7_..__....__] 3 00 ORIV G Migh Qualify Ground Lo 2o Cow, Block D/
v e 1 REFERENCE DRAWINGS WA NO.
ORAWER _R-1 5 W OV beg. Ground
- NARC- A2 S Y EN.FRAY
”EC 232V W 2OV Batlery Grownd
4 [CrNGD. ATIYZAIA TeasTT 9% :n-; Py pe . ¢ Drower Conmecrtor AU T og;?ufrag/dcgg ; f(OL LER
R2we fA0m 3000 TO Fo0 CA "¥7 - ; ‘
3 |CcHNGD REF DG Nos. Ao &'s TD AC‘s)-27-47 i ¢, Extarnel! Connecler
| & |etoles Computod Fiur Dovopad Woder Oniont ey |
|_[2voo 220edzes acceo w288 kwvsleny |xeo | WNSTRUMENTATION ANO CONTHOLS DIVISION
NO. REVISIONS DATE Em APPD = OAK RIDGE NATIONA& LABORATORY
a— T P R — ] e ] m——
€ £ Macoomn 10-5-68 |\ F I } 215 ¢ ‘ ‘M_“wou CARBIDE NUCLEAR COMPANY
Wi [} ;'-'I .7.:-'. A it ) . St R amrnan L
Fig. 2.6.11. MSRE Automatic Rod Controller Circuit Diagram.
]
i
|

 

 

 
 

 

RESET
AMPLIFIER
- (INTEGRATOR)

 

 

 

 

 

 

 

 

 

 

 

253

ORNL- DWG 66-9304

SUMMING AMPLIFIERS:
OUTPUTS ARE NEGATIVE
SUM OF INPUTS

FLUX DEMAND
8 SIGNAL TO SERVO
PILOT RELAYS

 

 

COMPUTED
FLUX DEMAND

ROD DRIVE MOTOR

 

 

7 =FUEL SALT TEMF‘ERATURE. CORE INLET
L =FUEL SALT TEMPERATURE, CORE OUTLET

¢ =NEUTRON FLUX

SPEED SIGNAL
FROM TACHOMETER

[7‘;]5 = SET POINT, FUEL SALT OUTLET TEMPERATURE

0

Fig. 2.6.12., Diagram of Regulating Rod Servo Controller.

 
GEARBOX

LOWER
LIMIT SWITCH

RCD DRIVE MOTOR,
SERVO OR MANUALLY
CONTROLLE

 

 

 

CONTROL ROD—"]

=Y

o

 

 

 

 

U
T

 

SHIM LOCATING
MOTOR, OPERATOR
CONTROLLED

GEARBOX

NOTE: AS REDUCED TO PRACTICE THE
CONTROL ROD MOTION IS
REPROOUCED IN THE CONTROL RCOM
AND LIMIT SWITCHES ARE ACTUATED
BY THE REGULATING ROD LIMIT
SWITCH ASSEMBLY. SEE DIAGRAM.

e

 

 

 

 

REGULATING ROD
SPAN,Ay,

 

  
  

 

 

¥

  

~i
)
—_—

REGULATING ROD

0 LIMIT SWITCHES

 

 

 

 

 

SYNCHRO
POSITION
TRANSMITTERS

SCRAM
CLUTCH

   

GEAR
REDUCER

GEARBOX

ROD DRIVE MOTOR:

OPERATED BY ROD CONTROLLER
ONLY WHEN IN SERVO OPERATION
AND BY ROD ACTUATOR SWITCH
IN MANUAL OPERATION

 

 

ROD DRIVE UNIT

i
-

g
2l
A

ORNL-DWG 64-622R2

REGULATING RCD LIMIT SWITCH ASSEMBLY
IN INSTRUMENT CABINET

 

ROD POSITION
TRANSMITTER
r————erwy,

i
e
SYNCHRO

CONTROL BALANCE
TRANSFORMER MOTOR

CLUTCH-BRAKE:
0. IN SERVO OPERATION THE
CLUTCH 1S ENGAGED AND
THE CAM IS COUPLED TO
THE BALANCE MOTOR
b. IN MANUAL OPERATION
THE OUTPUT SHAFT IS
LOCKED AND THE
BALANCE MOTOR
DECOUPLED

UPPER REGULATING
ROD LIMIT SWITCH

WITH MECHANICAL STOP

 

CALIBRATICN

CAM AND LIMIT SWITCHE},

SHIM LOCATING MOTCR,
OPERATOR CONTROLLED
WITH CONTROL ROD ACTUATOR
SWITCH. USED DURING

SERVO OPERATION ONLY

   
  
  
  
  
    
 

MECHANICAL
OIFFERENTIAL

SLIP CLUTCH

GEAR BOX FOR
SPAN CHANGE GEARS

LOWER
REGULATING ROD
LIMIT SWITCH

REGULATING ROD
POSITION TRANSMITTER
{SYNCHRO}

 

 

 

|
|
{
|
|
I
|
|
|
|
|
|
|
|
|
l
|
I
I
{
!
i

 

 

 

 

] CLOCK CAM ROTATION
EQUIV. TO:
B4 0. WITHDRAW ROD NO.{ |
=% AVAILABLE TO SERVO b. INSERT LIMIT SWITCH
CONTROLLER WITH SPAN (DECREASE y,) |
ROD REG. ROD SWITCHES !
/ STROKE AT ¥, }
/‘z_ Jd 9 (-
A COARSE  FINE
Lz i _ REG. ROD POSITION
/‘ A1 SHIM ROD INDICATOR {RELATIVE
POSITION TO SPAN LIMIT
INDICATORS SWITCHES)
o -
Bk CONTROL CONSOLE
&

Fig. 2.6.13.

Regulating Rod Limit Switching = Operational Diagram.

vST

 
 

 

f
|
|
i
i
'
i
|

 

 

255

' PHOTQ 62304A

REGULATING ROD POSITION

TRANSMITTER {SYNCHRO

TR
SLIP CLUTCH TORQUE ANSMITTER SIZE 31)

SPAN CHANGE | SPIRAL BEVEL
» CAM DRIVE GEARS

 
 
   
   
   
  
  

 

SHIM LOCATING
MOTOR '

MECHANICAL
DIFFERENTIAL

SERVO , - } il B . 48 || ELECTRO-MECHANICAL
AMPLIFIER |~ | SEulmeuse) L TR B %4 CLUTCH-BRAKE
SEE NOTE ' , , o L = ) |

' ; . CALIBRATION
MOTOR DIAL '

BALANCE

 
 

 

 

 

 

 

256

 

Rod Limit Switch Assembly ~ Side View.

Regulating

015.

6

2

Fig.
      
 

 

 

 

PHOTO 62303

K
wn
~J

 

 

 
 

 

 

258

PHOTO 62305A

Fr

LIMIT SWITCH
(SEE NOTE 2)

 

NOTES:

{. REFER TO: MSRE DESIGN AND OPERATIONS REPORT, PART V,
REACTOR SAFETY ANALYSIS REPORT, ORNL-TM-732, AUG 1964,
PAGES 108 TO 113 INCLUSIVE FOR APPLICATION IN MSRE.

2. THIS ILLUSTRATION SHOWS FOUR (4) LIMIT SWITCHES SO THAT
INTERMEDIATE SWITCH POINTS BETWEEN EXTREME LIMITS CAN
BE PROVIDED. IN THE MSRE ONLY TWO (2) ARE USED

 

 

Fig. 2.6.17. Regulating Rod Limit Switch Assembly — Underside View.
 

259

ORNL-DWG 66-4105R

ELECTRO-MECHANICAL BRAKE TO REDUCE
EFFECTS OF GEAR BACKLASH AND COASTING

OF THE SYNCHRONOUS MOTOR, BRAKE RELEASES
WHEN SYNCHRONOUS MOTCR IS "ON"

CHANGE GEARS

 
   
 

961 B
SYNCHRONOUS MOTOR [ 48
{1.5rpm} -

  
 
  
   
  

  
    
 
 

    

  
  
  
  
  

  
    

    
   
    

SLIP
30+ mm} CLUTCH
LIP CLUTCH |
° =~ 721 MECHANICAL
(IDLER) 0 L = DIFFERENTIAL
- - §4
AC SERVO MOTOR Ty swiTCH

MAX SPEED 27 rpm '
[ T AR L T

  

 

        
 

     
   
 
      
     
 
 

1 40t 30° PER inch
- OF ROD
=3} 43 MOTION
N2
| o 8~ —ELECTRO Q4 P
MECHANICAL =
CLUTCH-
BRAKE \\\\\\\\\
5° PER inch NSl
OF ROD MOTION TN
szt LIMIT
SW|TCHES\® é
30° PER inch
OF ROD MOTION gggcm:fim

SYNCHRO TORQUE

SYNCHRO . TRANSMITTER
CONTROL SIZE 3t
TRANSFORMER
CALIBRATION DIAL SIZE 15

Fig. 2.6.18. MSRE Regulating Rod Limit Switch Assembly, Drive
Train Diagram.

 
1.5-rpm
SYNCHRONOQUS MOTOR
({DUMMY SHIM
LOCATING MOTOR}

TO MANUAL CONTROL SWITCH,
SHEM ROD NO.1, ON CONSOLE

—_—pm- MECHANICAL DRIVE CONNECTION

 

——wee——p= ELECTRICAL CONNECTION

 

 

 

 

  

 

 

 

 

 

 

 

 

 

Q INPUT _ g CALIBRATION
b —e=- SPEED CHANGE; oUTPUT - b DIAL
SLIP
2 CLUTCH
S —— <4
{
ELECTRO-MECHANICAL
CLUTCH-BRAKE
{
> -

 

 

 

 

 

 

 

   
   

SIZE 15 CONTROL
TRANSFORMER

 

 

 

 

 

      

CLUTCH ENGAGED

ERROR SIGNAL~——_ WHEN ROD SERVQ IS "ON"

AC SERVO
AMPLIFIER

 

 

 

 

 

TO
STATOR WINDINGS
OF SIZE 31 SYNCHRO
IN ROD DRIVE

 

Fig. 2.6.19. MSRE Regulating Rod Limit Switch

ELECTROMECHANICAL
BRAKE, RELEASED
WHEN DUMMY SHIM
MOTOR 1$ "ON"

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

/
T0
SYNCHRO RECEIVER

MECHANICAL
DIFFERENTIAL

CHANGE

ORNL-DWG 66-4104R

SLIP

 

 

2

.

 

 

 

1 1

/ GEARS \ CLUTCH
2

_.U

 

 

 

LIMIT
SWITCH CAM

SIZE 3
SYNCHRO
TORQUE

TRANSMITTER

{ REGULATING ROD POSITION)

ON CONSOLE

Assembly, Block Diagram.

09¢

 

 
 

 

261

GO MHa Lnput
Signal.

omfl. DWG. 67-1584

 

o £,

 

s v acd

 

 

 

 

 
   

 

 

 

 

 

 

 

 

  

 

 

 

‘ o~ 7o
788 I

NOTE THAT FIRST STAGE IS BY-PASSED.

Fig. 2.6.20. Modified Brown Amplifier (Unused Wiring not Shown]

 

 

 

 

 

 

 

 

 

 

 

o O X2 ? 275V | 2285y
p
>
22Mep. 22Mep.
f D;;:\:,—J b
: T a—— i 922
. / o
. - : -..-. :: 2 - :’-— 7
. 3 s 2 L
/ Meg. o ¢
X: Xz ¥ ¥ Y
/500

 

'E,

N

 

 

 

J/Jf Servo
- \ A7olor

N
/1

 

 

dz2pf
~

 

 

 
 

 

262

 

 

/(MQ](; S| (we-mci-a)  AND  S2 (wwwica-a)  ARE INPUT CHANMEL SELECTOD SWITCHES LOCATED ON COMNSOLE 6L CHWB 40068 41995 ¢ 41632

 

 

 

 

    

 

 

 

 

 

   

' ‘ . @.B VA, ‘ . * Qv )
' l ‘ l l.,_ J." 2.4 MODE PERMIT cuT. 4124 ROt SEAL CiRewT
' # T Fag - ‘ wion el . :iesu AL o MR- STMe { Doukh ATREL A B
AW T T e A ne -
Ko Al rl.‘l.o'. al ) K210% & Fnu.y ot E L vy et ;
S . . i
=S A e n i i
o) | SiacE 142 52 | viAue 142 ‘bi-"‘fihc.! 3 S| PAGE 4
’ o ° 1:0: e -
o % " ° 3
"-6 '1.-

 

gl

TR countcTion 1 iNTREC OuslcTion . AL CRHATORS AR VK
WIRIEG, WIRIN G

& e - e = o . °
MOLTIPLIBR, |- = —  jOF EXPOMENT ‘ |
SeLector SELECTOR _ | T

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

e e - - e
RANGY . ‘ Ktos & 7] Tue:a B2
DiICATD
“ WS : Y ¥
NPT ek 10 . WYt SN AL 19
OATA Lo&AR; DATA LOGGUE
Rhutal, MCOMAMATER *2

 

WANGE, Pluu--\q-u‘l

 

 

\-lum LOGE CLECUIT POR RAb&L wimm
PMI 0F KEITREY CO. MODRL 41D PICOAMMETE
TS DAAGERAM 1% FUNCTIONALLY mll‘ ONY »
/ WA rouTioun- EARGE TABULATION.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

AT,
WHEN RC K104 1% Dk FOR INFORMATION OMLY
£WERGIZED THE BAMGE \S DO NOT USE FOR
SELECTED AS FOWOWS ! ‘ , MAINTENANCE OR
SWiICH SEAECIED ‘ o FLUX SeNAL FROWM LUK WGNAL oM CONSTRUCTION
. . PILAAMMTIOR ) ProAMgTSR * T
postTION Bangt 'a.: zu‘u :1:"..‘ :-s:mfl:t: AUTR=ATIE ALY
b 1.5 MW SEAL 1D MAITAINED 1F LiTHRR RANGS ALIcTOR
:? _|-; :: -832 W ) RS AT 5.8 MW POUTION ) 1M Ay MODRS k- oo -:j..n -0V e V.AC-
. : X0 At
1 50, KW thaat «m« $LUZ DBMAuD PaY, 1 . ;““
’ Coul AATY GFIH T %
13 1%, Kw s fonTion 4 LB1M L -Nags:Aep ]
1 5. Kw " > - --‘:;:u“mq' e g TR AL Tk T e T T Fa TaeC ke ot ‘L :ie. et
- 2 . —_ —
B 1.5%w : LVIABLIANED . “ ?.':.“J:.‘\-':&" KD c"l“ R10IAL  |KT®1 A W“fi r nza ) tiohe %30 &I i Kisee”
1) o9 AW —o7 G L ve e e NG,
W7 V50, W - CLath® ne"Bun” of Lieb b Ve
18 50, W : ] £33 1
" 15 W . L ke " s s mw
1 5, W & - ““n e Licd FereT A
:; | -;J U:l “.a. ..., ook
WHEN RC K204 1% e b1t
ENERGIIRD THE 1% MW LA Lem hR wosd :E 100 & EE LLes gr1e eHe sn R133
RANGE 1% SBLECTED. i A ARALRD e ot V. ”e ’c e ® nx e mw
i . *1. Saav Aoo®,
e i [ee lee |ae < 7 ) saox K701 - X202 wmomans Y ey vy wn o2
$17 SERVO FLUX CHAMMEL SELECTOR (&b 3oM) K1os L PR {""‘ kios kod Samdnp et proetindid L Hen vent o
PosiTion e Al e fe0r *1 fre-fen ot ' e eaTs
cONTAC \ 1] - .
o o Jewz | 9SO naey Q‘/” waew  wmee  Sues ateensem gy SR \/ Nasy
oo oo () bl S, Mrat P M e utepe &tm“ :.“-..::Q‘. ey JEMP. ne uter h RG uNSL A
(b » B, BTAGE 4 SEECIOR M_L_ _AUX. MoDE PR Y e cie1n HANT. BLER. + HUSLBAR WAT. GECWTET ST o] [eumeesran
3 ()} w “PARG ' GHAL: SLEM. ¢ ROD cHTRSL CRANITY: .1 ® 8 -t - 47924
ko othe 4 (v) n SPARG ‘ MUCLEAR WAVTEVMRUT APPLILATI®N DIAGRAM [0-488.4091%
o oipo :t‘:; : ::., :::: L ' AVIOHMALIC B9 CHITEALAR - CIRGUT DIAGEAM  (RE3-18-89
. REFERENCE DRAWINGS OWG. NO.
oibo oqpo |1 X ne Kios TP CKT.* v To cxt. "\l O oxr, 183
& (W) X SP AN ; att sSeE Bee O-HW-B- §7D2S e —
i Diuk-©-91324 D-Wi-B-37334 : MOLTEN BALT RPACTOR wXPGRIMENT
-M. _ AUTOMATIC T €
| 7 We e0* Y e LoD * 7 M 1' EOD COM QOLL R
HIGK QUALITY GROUND . CANGE SWITCHING AND
& RCI3-3-104 WiAS & -260, ail
_I_|A0DED CowsolE NerirT el oml W 2 ov tte. atound RANGE SEAL ClRCuLITS
. INSTRUMENTATION AND CONTROLS DIWMISION
NQ, APPD ! A
e e R W2 ov sATTERY GROUMD OAX RIDGE NATIONAL LABORATORY
TWEIS (5-4-0d : ommrED Y
X UNION CARBIDE NUCLEAR COMPANY

T — |

—

r-—'_—'—fi‘“‘ ‘
r‘-T-—_t-_ : e

T

 

 

 

 

 

 

 

 

 

 

 

Fig. 2.6.21. Automatic Rod Controll|r Range Switching and Range Seal Circuits.

 

 

 

 
 

263

2.7 CONTROL RODS AND ROD DRIVES

2.7.1 General Arrangement

The control rod drive unit and its housing are shown in Figs. 2.7.1
to 2.7.3. Figure 2.7.4 is a simplified electromechanical diagram which
shows the functional location of the essential elements which comprise
the drive train. The gearing and the clutches are inside a cast-alu-
minum gear box. The drive motor, the two position-transmititing synchros,
and the position-indicating potentiometer are mounted on and outside the
gear box with thelr shafts carrying their drive gears projecting inside
the box so as to mesh with the appropriate gears in the drive train
(Fig. 2.7.2).

The gear box subassembly, which includes the position transmitters
and the clutches, is located at the upper end of the drive unit in an
effort to keep the radiation-sensitive components (electrical insulation
and lubricant) as far from the reactor as feasible. Figure 2.7.5 is a
diagram of the gear train and the clutches. The worm and gear set is
of somewhsat unorthodox design, if compared with typical standard prac-
tice for this type of gearing (see Sect. 2.7.9.10). The other gears
are conventional.

The rod is scrammed by interrupting current to the electromechanical
clutch. During scram, the driven element of the overrunning clutch is
free to rotate and, except for a small amount of friction and inertia,
does not interfere with rotation of the output sprocket in the "rod
insert" direction.

The electromechanical clutch and the overrunning clutch provide
parallel power transmission paths between the motor and the output
sprocket, The arrangement is such that the overrunning clutch transmits
motor torque in the "rod insert" direction only and can be used to ap-
ply motor torque to the drive sprocket in the event that a rod sticks
or binds following a scram. If external torgue is applied to the output
sprocket in the "rod withdraw" direction of rotation, the overrunning
clutch provides a solid mechanical coupling between the drive sprocket
and the input side of the drive train. The worm and gear set are in-
herently self-locking with respect to torque in either direction origi-
nating at the output sprocket. This combination of overrunning clutch
and worm and gear set prevents rod withdrawals by upward forces applied
to the control rod or by a torque applied to the drive sprocket.

The drive unit housing, with the drive unit secured thereto, is
atbached to the control rod thimble by means of a flange welded to the
bottom of the housing. Figure 2.7.6 is a photograph of the rod thimble,
vhich extends into the core wvessel, and shows the mating flange. The
radial slots in the rim of the thimble flange mate with pins in the
housing flange and are required to ease the problem of orientation dur-
ing remote maintenance operations., The milled slot in the face of the
flange accepts the T-shaped flange fitting, which is cap-screwed to the
rod drive tow block (see Figs. 2.7.19, 2.7.20 and 2.7.14). It prevents
the rod from twisting when it is being detached from the tow block dur-
ing remote maintensnce. Figure 2.7.7 is a photograph of the subassenmbly
formed by the thimbles and the graphite sampler taken before installation

 
 

264

on the reactor vessel. This illustration also affords a good view of
the lower, stationary halves of typical thermocouple disconnects de-
signed for remote handling., Figure 2.7.8 shows this subassembly mounted
on the reactor vessel; Fig. 2.7.9 is a line drawing of the control rod
drives and rod thimbles on the reactor vessel. The rod drives are off-
set radially to make room for the graphite sampler tube (not shown on
this sketch), which occupies space on the vertical center line through
the core vessel., Flgure 2.7.10 shows the top of the control rod drives
installed on the reactor. This picture was taken looking down through
the access hole in the top of the secondary containment cell. The
electrical jumper cables and cooling air hoses with their disconnects
are visible in this picture. ZElectrical interconnections between drive
units and junction boxes on the wall of the reactor cell are made with
flexible jumper cables. Each drive unit has its individual cable as-
sembly, which is designed for remote handling. The wires making up the
cable are designed for high temperatures and use radiation-resistant
insulation (see Sect. 2.7.9). The wires are tightly bundled by means
of heat-shrinkable plastic tubing. This wire bundle is sheathed in a
loose-fitting, spirally wound stainless steel hose to give mechanical
protection. The fittings at each end use ceramic pin and socket inserts
of standard pattern in shells and receptacles which have been designed
to meet remote handling requirements. The interconnection cabling and
junction boxes are described in Sect. 2.1.

2.7.2 Position Indication

Continuous indication of rod position is provided by two synchro
torque transmitter-receiver pairs, one "fine" and one "coarse." The
location of the transmitters on the gear box is shown in Fig. 2.7.2.

The "coarse" rod position transmitter rotates 5° per inch of rod
travel., Since this is less than one full turn for the maximum rod
travel of 60 in., the indication is unambiguous. The "coarse" position
receivers, one for each rod, are located on the main control board.

The "coarse" transmitter slso supplies the ac error signal to the synchro
control transformer in the torque amplifying rod position follower.

This unit (see Fig. 2.6.20) drives the potentiometer which provides the
rod position input signal to the logger. On rod 1, the same ac signal

is used as the input to the Honeywell servo amplifier in the Instru-
mentation and Controls drawing Q-2586 shim regulating rod limit switch
assembly. This device is discussed in Sect., 2.6, The "fine" trans-
mitter rotates 60° per inch of rod travel and is expected to be capable
of resolving incremental sprocket chain motions to within +0,050 in,

Since both the "coarse" and "fine" synchro transmitters are geared
to the sprocket shaft, they indicate sprocket shaft rotation and do not
take into account changes in rod length caused by thermal expansion,
stretching, etec. In order to locate the control rod as accurately as
possible with respect to the reactor core, a single-point, pneumatically
operated, position device is employed. The position sensor consists of
an air nozzle at the bottom of the control rod which carries the flow
of rod cooling air from the hollow inside of the rod to the thimble.
When the rod is at the bottom of its normal stroke the nozzle is op-
 

265

posite a flow restrictor built into the thimble, The increase in pres-
sure drop caused by the restriction is the position indication. The
nozzle and restrictor are shown in Fig. 2.7.11l, and the schematic dia-
gram of the pressure measuring instrumentation is shown in Fig. 2.7.12.
This device is manually opersated and is used to check the zero readings
of the position-indicating synchros and, inferentially, provides in-
formation on how temperatures and stresses produce small changes in the
relative position of the rod with respect to the thimble.

2.7.3 Shock Absorber

The shock absorber is a development of the Vard Division of Royal
Industries, who built the drive units. It uses the general principle
of a typical hydraulic shock absorber but differs in that the working
"fluid" consists of 3/32-in.-diam steel balls, Figure 2.7.13 is a
vertical cross-section view of the shock absorber installed in the drive
unit. Referring to this figure, the piston is the knob, which is an
integral part of the plunger. The latter is a tubular rod which is
threaded into the carriage and which commects the control rod tow block
to the carriage. The closed cylinder, partially filled with steel balls,
travels with the carriage and is positioned relative to the carriage
(and the plunger) by the buffer return spring. At the end of a scram
the bottom face of the cylinder strikes the stationary steel blocks
which are bolted to the housing flange. The plunger continues to move
downward and is decelerated by the forces developed by the springs and
by the flow of the steel balls around the knob on the plunger.

Shock=-absorbing characteristics are adjusted by changing either
the spring constants or the preloading of the buffer return and ball
reset springs, or both, by changing the quantity and size of the steel
balls, and by sizing the knob on the plunger. A stroke of from 2.75 to
4,00 in. is considered satisfactory. During testsl of the prototype,
the shock absorber performed consistently and provided a stroke of 3.4 *
0.2 in, following rod scrams from a height of 51 in. This produced an
average deceleration of 6.2 g.

2.7.4 Cooling Air Flow and Temperature Monitoring

The drive is provided with two separate flows of cooling air. The
first is conducted into the thimble by means of a thin-walled tube that
projects into the stainless steel hose which supports the poison ele-
ments of the rod. This flow of air exits through the nozzle at the
lower end of the rod (see Fig. 2.7.11) and returns up through the an-
nilus formed by the outside of the rod and the inside of the thimble.
The second air stream is admitted st the top of the rod drive housing
and flows downward within the housing. ThlS air flow is counter to the
first flow and prevents heated air from the thimble from rising into
the drive unit. Both streams are dlscharged into the reactor cell at
the upper end of the thimble,

~ Two bimetallic thermostatic switches are mounted on the support
colum of the drive unit approximately 8 in. above the lower sprocket.

 

AMSR-64-7, Feb. 10, 1964 (internal memorandum).

 
 

266

Their contacts are in series for redundancy and are set to open at
200°F. Switch actuation is annunciated in the control room; no control
action results.

These switches (Fig. 2.7.14) were added to the drive units after
they had seen service during the initial critical tests and low=-power
runs of the reactor; hence they do not appear in the photographs of the
drive unit assembly. Their purpose is to signal the control room that
the drive unit is in danger of being subjected to damaging temperatures,
a condition which could result from loss of air flow into the housing,
excessive thimble temperatures, stoppage of the exhaust line, or ex-
cessively high ambient cell atmosphere temperature., The switches are
described in Sect. 2.7.9.9.

A second, or backup, method of checking temperatures within the
rod drive is shown in Fig. 2.7.15. This method uses the temperature
coefficient of resistance of the cooling fan motor windings (part of
the rod drive motor assembly) to measure the temperature within the rod
drive unit housings. The fan motor field windings typically have room-
temperature resistances of 520 ohms. Copper has a temperature coef-
ficient of resistance of 2.18 X 107> ohm/ohm-°F over the temperature
range of interest. The slightly more than 10% change in resistance for
a 50°F change in winding temperature provides more than ample sensitivity.
Periodic measurements made during reactor operation showed that the de
resistance of these windings gave a good linear correlation in following
in-cell air temperature. The duty cycle of the rod drive motors is ex-
ceedingly light; for example, the servo motor was "on" for a total of
51 sec in a 2-1/2-hr period with the reactor at an intermediate power
level and in servo control of the outlet temperatures. Manual shimming
is an infrequent operation and requires only a few seconds to accomplish.
In addition, the servo motors operate at a fraction of their rated ca-
pacity. The light load and duty cycle permit shutting off the fan long
enough to measure the dc resistance of one of the fan motor field wind-
ings. It is likely that the motor cooling fans are not needed in the
MSRE. As can be seen from Fig. 2.7.1l5, the fan motor being checked for
temperature is turned off temporarily by energizing the selector-switched
relays, and the temperature is indicated on the meter in the output cir-
cuit of the regulated voltage supply. The diodes across the motor wind-
ings prevent insulation damage by preventing high-voltage switching
transients caused by opening the highly inductive field winding.

2.7.5 Limit Switches

Limit switches and their actuators are a frequent problem area in
devices of this type. The MSRE rod drive unit was no exception; during
the first critical tests, the actuator became stuck at the lower limit,
This was caused by excessive wear and galling of soft steel sliding
bearing surfaces in the switch actuator guide. The design was altered
by providing hardened-steel, spring-loaded, floating bearing pads to
replace the galled bearing surfaces. Tae revised design is shown in
Fig. 2.7.16. The slide assembly is lubricated with Neolube (see Sect.
2.7.3.8). Figures 2.7.17 and 2.7.18 are photographs of the limit
switches and actuators installed on the drive unit.
 

267

2.7.6 Control Rods

Figure 2.7.19 is a photograph of the upper end of a display model
of the MSRE control rod with the poison elements® removed. The poison
elements? are shown in Fig. 2.7.11. There are three control rods, which
are identical in construction, each weighing approximately 11.2 1b.

The rod lengths are slightly different because of the required offset
of the control rod thimbles. The rod lengths are: rod 1, 11 ft 9-7/16
in.; rod 2, 11 £t 9 in.; and rod 3, 11 ft 7-3/16 in.

The control rod is attached to the control rod drive by means of a
two=-bolt (3/8 in. X 16 thread) flange or tow block made of 304 stainless
steel, The drive mechanism contains a matching flange containing the
captive bolts, The assembly is designed to permit attachment of the
control rod drive flange to the control rod flange through an access
hatch in the drive unit case using a remote, manually operated extension
wrench.

The upper hose consists of a length (~6-1/2 ft) of 0.850-in.-0D by
1/2 in.-ID annularly corrugated, 321 stainless steel, flexible metal
hose with a single exterior layer of wire braid. The corrugated hose
provides a leaktight passage for the low-pressure (~8 psig, ~5 scfm)
rod cooling air to reach the poison elements. The wire mesh serves the
purpose of protecting the hose from abrasion, minimizes stretching of
the hose, and acts as an emergency retainer in the event of hose failure.
The 1/2-in. inside diameter of the hose permits passage of the 7/16-in.-
OD stationary cooling ailr tube which is attached to the upper drive
mechanism. When the rod is in motion, the corrugated hose and tow block
move up and down over the air tube.

The weld adapter serves to align the two types of metal hose used
in the rod construction. It also serves as the upper anchor point for
a 1/8-in.-0D INOR-8 retaining rod, which is located inside the lower
hose.

The lower hose is 5 ft 2 in. long, Inconel 600, fully interlocked,
unpacked, strip-wound flexible metal hose 47/64 in. OD and 5/8 in. ID.
The 38 Inconel-clad poison elements, detailed in Fig. 2.7.11, are beaded
over the strip-wound hose, as shown in Fig. 2.7.20,

The lower end of the strip-wound hose is welded to the air exhaust
nozzle, which acts as the element retainer and lower anchor point for
the 1/8-in. retaining rod. The rod supports a portion of the weight of
the poison elements, contains the stretching of the strip-wound hose,
and acts as safety retainer in the event of hose failure.

During the two years of rod testing, there have been three inci-
dents of rod failure, Two failures were due to misoperation of the
equipment, and one incident was due to misslignment of 7/16-in.-OD air
tube in the cCrrugatedfupper hose. The upper hose was worn by the air
tube rubbing the inside surface of the hose so that when the rod was

 

23, E. Beall et al., MSRE Design and Operations Report, Part V,
Reactor Safety Analysis, ORNL-TM-732 (August 1964); G. M. Tolson and
A, Taboada, MSRE Control Elements: Manufacture, Inspection, Drawings,
and Specifications, ORNL-4123 (July 1967).

 

 
 

268

released in scram, the hose broke away from the tow block when it hit
the mechanical stop in the shock absorber mechanism.

A bronze bushing was installed in the tow block to assure alignment
of the air tube and hose. Subsequent examination revealed only minor
wear at this point. ,

2.7.7 Rod Drop Timer

Routine operation of the MSRE®? requires that the drop time for
each rod be checked each time before filling the reactor with fuel salt.
Figure 2.7.21 diagrams the timing circuitry used to measure drop times.
The timer consists of a continuously rumning synchronous motor connected,
via gearing, to a fast-acting electromechanical clutch~brake whose out-
put shaft drives an indicating pointer. The elapsed time indicated by
the pointer, therefore, is the time during which the clutch is engaged.
The drop time is easily measured. The rod is scrammed using the manual
scram switch on the console. This closes relsy contact K29A, and the
timer clutch is engaged and remains engaged until a lower rod limit
switch is actuated by the rod at the end of the drop.

2.7.8 Performance Characteristics

This list of performance characteristics is derived from prototype
test data:

1. Rod speed with either 25- or 10-w motor running continuously at
rated voltage (115 v ac, 60 cps), 0.53 in./sec. Note: The change
in speed in going from "Up" to "Down" is approximately 1%.

2. Rod speed with the 25-w motor in "inching" mode (1/2 sec "On," 1/2
sec "Off," etc.), motor at rated voltage, 0.22 in./sec.

3. Motor speed as a function of applied voltage, see Fig. 2.7.22.
Note: Rod speed (in./sec) = 1.53 X 10™ X rpm of motor.

4., Scram performancel

a) Elapsed time to drop 51 in., 0.80 sec (see Fig. 2.7.23).

b) Average acceleration during scram for a 51-in, drop, 13.2
ft/sec? = 0.4lg.

c) Clutch release time, inferred from a curve of the square root
of distance vs elapsed time (see Fig. 2.7.24), 0.012 sec.

d) Figure 2.7.25 compares actual and required reactivity insertions
during scram. These curves are calculated from curves "A" and
"B" on Fig. 2.7.23 and the calculated percent of total rod worth
vs distance curve, Fig. 1.19, p 59, ref. 2, and a total worth
of 4.1% Ak/k. This value of total worth approximstes the total
reactivity inserted by scramming any two of the three rods.
The initial height prior to scram was taken as 51 in.,

 

3S. E. Beall and R. H. Guymon, MSRE Design and Operations Report,
Part VI, Operating Safety Limits for the Molten Salt Reactor Experiment,
ORNL-TM-733 (Rev. 2) (Sept. 19, 1966).
 

269

2.7.9 Component Descriptions and Specifications
2.7.9.1 Rod Drive Motor Assembly

General Description

The drive motor is a 115-v ac, 60-hertz, two-pole, two-phase servo
motor rated at 25 w maximum output.* As used in the MSRE, the input
power is single-phase 115-v ac, and phase splitting is obtained with a
10- to 12~pf capacitor in series with one of the field windings. An ac
tachometer is mounted integrally on the motor shaft. The tachometer
output 1s used as a feedback signal to stabilize the servo controller,
Tachometer output is 6 v per 1000 rpm. A small blower is included as
part of the assembly. The blower is powered by a separate, capacitor-
type two-phase motor and runs continuously whether the servo motor is on
or off, These three units (motor, tachometer, and blower) are incorpo-
rated into a single unit supplied by the Diehl Electrical Division of the
Singer Manufacturing Company. The unit specified for the MSRE is sim-
ilar in shape, size, and performance to a standard Diehl 25-w motor No.
FPF 49-91-1. They are special in that they call for class H radiation=-
resistant electrical insulation and use radistion-resistant grease.
Performance data are given in Figs. 2.7.26 and 2.7.27.

Procurement Information

Procurement specifications are contained in Vard Specification No.
114096, modified by ORNL, and dated April 12, 1964, and in ORNL Purchase
Order No. 63Y-76819.

2.7.9.2 Electromechanical Clutch

This clutch is of the single-disk type with a stationary field
coil. It is supplied by the Electroid Corporation, Union, New Jersey,
their Drawing Z2EC-6CC-8-8. Characteristics and specifications are as
follows:

Rated static torque : 75 in.=1lb

Rated coil voltage 32 de

Coil current at 32 v dec 0.24 amp

Nominal size (clutch disk diam) 2-5/8 in,
Engagement time™ 0.0075 sec or less
Release time Not available
Electrical insulation - Class H -

Friction torque (max) 0.5 in.-oz

"This number from Electroid catalog for this size
clutch with both 24- and 90-v de coils.

 

A 10-w motor, identical in all respects but power rating, may be
substituted for the 25-w motor.

 
 

270

Detailed procurement information is on Vard Corporation Drawing No.
114701.

2.7.9.3 Overrunning Clutch

The overrunning clutch is a standard, commercially available device
manufactured by the Formsprag Company, 23601 Hoover Road, Warren, Michi-
gan. It is a Formsprag model. FS-05 in which the Oilite sintered bronze
bushing normally used has been replaced with a bronze bushing and which
has been packed with California Research Corporation type NRRG-159 or
Shell type APL grease. The manufacturer states it meets performance
requirements as follows: normal running torque, 3 1b-ft at 8 rpm; and
stall torque, 20 1b-ft at 8 rpm., Additional specification-type infor-
mation is contained in a letter dated February 1, 1963, from W. T.
Cherry, Formsprag Company, 609 West Lincoln Avenue, Anaheim, California,
to P. Butkys, Vard Division of Royal Industries.

2.7.9.4 Position-Indicating Synchros

The synchro torque transmitters, both "Fine" (size 18) and "Coarse"
(size 31), meet military standard (Mil. S-20708) design requirements
with respect to size, shape, mounting dimensions, and performance
characteristics. They are nonstandard in that the electrical insulation
and lubricant are for a high-radiation environmment. The torque trans-
mitters in the prototype rod drive unit were supplied by the Vernitron
Corporation, 1742 Crenshaw Boulevard, Torrance, California. Additional
specification data for these transmitters are as follows:

 

Ttem size 31° Size 18°
Primary winding Rotor Rotor
Primary voltage, 115 115

nominal
Frequency 60 cps 60 cps
Input current, max 462 ma, 105 ma
Input power, max 6.6 W 4,0 w
Transformation ratio 0.783 = 24 0,783 £ 2%
Phase shift, max 6.5° lead 18.0°
Electrical error, max 10 min 6 min
Torque gradient 0.40 oz-in./deg. 0.05 oz-in./deg.
Null voltage 125 mv

(total), max
Null voltage 35 mv

(fundamental), max

®Yernitron Corp. No. VIX31-6Rl, Vernitron Dwg, OD10581.
bVernitron Corp. No. VIX18-6Rl, Vernitron Dwg. OD10582.
 

271

2.7.9.5 Position~Indicating Potentiometer

The specifications for the position-indicating potentiometer, a
Beckman Company type 6200 series potentiometer with ball bearings lub-
ricated as described in Sect. 2.7.9.8, are as follows:

Type Infinite resolution, cermet re-
sistance element, continuous
rotation with no stops, metal
housing, 1-1/16 in. diam X 5/8
in, long with standard servo
mounting dimensions, ball bear-

ings
Resistance 1000 ohms * 5% at 150°F
Linearity 0.5%
Electrical rotation 350 £ 5°
Power rating 5 w at 185°F derated to zero at
300°F

Refer to UCNC Purchase Order 5651446, Item 1 (Requisition 1.-8824),
January 29, 1965,

2.7.9,6 ILimit Switches

Limit switches are Micro Switch type V3-130l, a high-temperature
nuclear-radiation-resistant design, manufactured by Micro Switch Di-
vision, Minneapolis-Honeywell Regulator Company, Freeport, Illinois,
Catalog information describing this switch is supplemented by two let-
ters written by V. J. Brown, Los Angeles 22, California, to Povilas
Butkys, Vard Corporation. The letters are dated December 20, 1962, and
January 9, 1963,

2.7.9.7 ZElectrical Wiring

Internal wiring within the rod drive wmit from the terminals on the
disconnect to the various components is of high-temperature, radiation-
resistant hookup wire., The prototype used Supertemp type MGT, manu-
factured by American Super-Temperature Wires, Inc., 50 West Canal Street,
Winooski, Vermont.

Micatemp, & similar type of wire manufactured by Rockbestos Wire
and Cable Company, Division of Aero Corporation, Nicoll and Conner
Streets, New Haven, Connecticut, is equally acceptable.

2.7.9.8 Iubrication | |

The gears, overrunning clutch, and the bearings in the gearbox,
motor, synchros, etc., are lubricated with a nuclear-radistion-resistant
grease: Shell Corporation type APL or California Research Corporation
type NBRG-159. This latter grease®?® is composed of "Cp¢_jg-alkylbi-

 

3 James G. Carroll et al., "Field Tests on a Radiation Resistant
Grease," Lubrication Engineering (February 1962).

6WADC-TR-57-299, Pt. II, p. 9 (report refers to NRRG-159).

 
 

272

phenyl fluid inhibited with didodecyl selenide and gelled with a sodium
terephthalamate.”" The sprocket chain and the limit switch actuator are
coated with Neolube, & film of colloidal graphite deposited as a dis-
persion of graphite in a volatile carrier (isopropsnol). Neolube is
manufactured by Huron Industries, Post Office Box 104, Port Huron,
Michigan.

2.7.9.9 Thermostatic Switches

The thermostats are small bimetal-type units with the bimetal
mounted in a ceramic tube. Sample switches were tested well beyond
destruction by heating to over 1200°F, and no release of solder or
other low-temperature melting point material was observed.

Technical data on these switches, based on the seller's catalog,
are as follows:

Electrical rating 50 w at 115 to 230 v ac, non-
inductive load
Qperatigg temperature Adjustable, by means of a screw,
range to 300°F.
Physical appearance 1/4 in. dism, 1-1/8 in. long;

terminal at each end with a 2-56
tapped hole for making electrical
connection

Contact operation To open on rising temperature

Yhe range specified for the MSRE was 150 to 200°F.

The thermostats were purchased from the George Ulanet Company,
413415 Market Street, Newark, New Jersey, their model No. 17-L13.
Refer to UCNC Purchase Order 59Y-17341, Requisition No. L-9682 dated
August 10, 1965.

2.,7.9.10 Gears

All gears are of carbon steel or stainless steel. The 24 diametral-~
pitch gears in the power train between the motor and the output sprocket
are of steel and designed particularly for the drive unit. The 32 di-
ametral-pitch gears which drive the synchros and the position potentiom-
eter are commercially available components with minor modifications
where required for mounting, etec.

The worm and gear set is the end product of test stand experience
with the prototype unit. The original design specified an aluminum
bronze worm wheel mating with a steel worm. The worm had a hardness of
38 to 42 on the Rockwell C scale and a surface finish of 64 pin., maxi-
mum roughness. These gears failed at a rapid rate by abrasive wear.

The final design of this gear pair, based on additional test stand ex-~
perimentation and life testing with the prototype unit specified type
440C stainless steel, hardened to R, 55 or better, for both the worm

and gear, The worm thread was ground and had a surface finish of ap-
 

 

273

proximately 20 pin. The gears were lapped to form selectively fitted
pairs., Gear sets of other hardenable steels were tried in the proto-
type, and it was concluded that the determining factor for the steels
used in this service is probably surface hardness a.nd finish, not any
particular type or alloy. :

 
 

 
 

i
i

s
e
S
v

COARSE" AND "FINE" §

 

SYNCHRO POSITION
TRANSMITTERS
GEARBOX

i aanliad o

 

 

 

SERVO MOTOR
WITH INTEGRAL
AC TACHOMETER
AND COOLING FAN

 

 

3;&

e

e

o

LIMIT SWITCH
ACTUATOR ROD

gt

SPROCKET
CHAIN

e

TEMPERATURE

 

SWITCHES
(THERMOSTATS)

g

ETTR

 

 

ing.

and Hous

MSRE Control Rod Drive Unit

.ll

7

2

Fig.

 

 

 
 

275

 

PHOTO 62055

-
Q
w
Z
=
Q
Q
®
o
=z
a.
1
M~
0

 

a
o
=
<
Q
o
z
!
z
S
=
o
o
o

&

SYNCHROS

 

DRIVE SPROCKET

D

GEAR REDUCTION AN

CLUTCH UNIT

CHAIN DRIVE

 

LIMIT SWITCHES

 

25-w AC LOW INERTIA

SERVO MOTOR

SHOCK ABSORBER AND

 

TOW BLOCK

 

Unit — Upper End Showing Gear

ive

MSRE Control Rod Dr

2.
Box and Servo Motor.

7

2

Fig.

 
 

PHOTO 39975

 

 

 

 

 

 

 

UPPER AND

LOWER LIMIT
SWITCHES

 

 

MSRE Control Rod Dr

 

ion

Locat

ive Unit - Upper End Show

Fig. 2.7.3.
of Iimit Switches.

1ng

 
 

Lo 277

 

ORNL-DOWG 63-8391R

INPUT SIGNAL TO SIZE 18 SYNCHRO
CONTROL TRANSFCORMER, PART OF
TORQUE AMPLIFYING ROD POSITION | = —)
TRANSMITTER IN SHIM REGULATING
ROD LIMIT SWITCH ASSEMBLY

INPUT SIGNAL TO Q-2560 TORQUE
AMPLIFIED ROD POSITION POTEN-
TIOMETER DRIVES IN LOGGER-
COMPUTER ROOM

 

~-s—— FINE

 

  
  
    
   

TO POSITION READOUTS

SYNCRO NO.2
IN CONTROL ROOM -— COARSE

60° PER {NCH
OF ROD MOTION

POSITION
POTENTIOMETER
ROD POSITION
INPUT TO SAFETY SYSTEM

 

 

 

 

 

 

 

 

 

TO SAFETY
SYSTEM REDUCTION
GEARING
FAN SYNCHRO NO.1
MOTOR 5° PER INCH
OF ROD MOTICN
TACH
SERVO
MOTOR
DRIVE
ELECTROMECHANICAL SPROCKET
CLUTCH

 

 

 

 

REDUCTION { ”’ Le— SPROCKET

e~ 1-TO-1 GEARS

 
 
 
 

 

 

 

GEARING CHAIN
INCLUDES !
REVERSE T I
LOCKING )
AIR FLOW
VERR Nu\/
© EELLLJ;'II}JCH ¢ TO COOL ROD

FLEXIBLE
TUBULAR

ROD
SUPPORT——/

o — — - —

»
Yy

 

V=0.5in./sec I

 

 

POISON ELEMENTS !

[T [P

HORIZONTAL

GRAPHITE BARS — GRID PLATE

 

CORE VESSEL —

 

Fig. 2.7.4. Electromechanical Diagram of Control Rod Drive Train.

 

 
 

SPROCKET
CHAIN
41 PITCH

SPROCKET, 69T

PITCH CIRCUMFERENCE \
O

¢.00 /NCHES

DIEHL €O, MOTOR
BASIC ASSY.
N FPF 49-9/-1

Fig. 2.7.5.

278

ORNL-Dwg. 66-3915

RATIOS:
FINE SYNCHRO ROTATION _ 40°
£OD TRAVEL N

COARSE SYNCHRO ROTATION _ 5°
ROD TRAVEL T IN

POT. ROTATION _ 5°

527, 320P RoD TRAVEL = iN

( F-POTENTIOMETER
307, 82DP \ SINGLE TURN
4 jooon.
527, 320P .fe A

787, 32DP L COARSE " SYNCHRO

Q(e\ S/ZE 31
267, 3EbP
R
267, 320° ; ;
V (@( e\.

LEINE " SYNCHRO
N e
N
26T, 32DP

  

S/ZE /8

ELECTROMAGNETIC
CLUTCH, 32V.DC.,

0:28 AMR, ELECTROID CO.
NE 2EC-26CC-8-8

]
]
1
]
]

  
  
 

WORM WHEEL
527 290P

OVERRUNNING CLUTCH \\

FORMSPRAG TYPE FS/05~
WORM, 24DF, SINGLE THREAD
QIT, 24DP

547, 24DF

147, 240P . qor, 240P
(VB

\# (4T, 249DP

SERVD Momef_ 15V,

o ¢Ps, 25 WATT, 2 # — ‘

AC TACNOMETER —

 

 

BLOWER — "]

 

MSRE Control Rod Drive Unit Power Transmission Diagram.
               

 

PHOTO 39863

N
~J
O

 

Fig. 2.7.6. MSRE Control Rod Thimble.

 

 
 

 

 

 

280

PHOTO 71111 A

FLANGE, MATES WITH LOWER
END OF CONTROL ROD
DRIVE HOUSING

CONTROL ROD
GUIDE ROLLER
TYPICAL

TYPICAL
THERMOCOUPLE
DISCONNECT

LOWER ENDS OF
CONTROL ROD
THIMBLES

NOTE: REFER TO

FIGURES 5.4 AND 5.5,

IN TM-728 FOR LR CONTROL ROD
INSTALLATION OF i THIMBLES AND GRAPHITE
THIS SUB-ASSEMBLY SAMPLE TUBE

INTO CORE VESSEL. _- SUB-ASSEMBLY

Fig. 2.7.7.
Sample Tube.

 

MSRE Subassembly of Control Rod Thimbles and Graphite
 

 

281

-
-
~
o
-
Q
X
a.

 

 

  
 
 
 

 

 

 

 

7.7) Mounted on Reactor Vessel.

2

Subassembly (Fig.

Fig. 2.7.8.
 

282

i ORNL-DWG 64-6083

 

 

\REACTOR GCELL ROOF PLUGS

CONTROL ROD DRIVE
MOTOR HOUSING

,—;CONTROL ROD DRIVE HOUSING

 

 

CONTROL ROD L

THIMBLE NO. 3 —
CONTROL. ROD
THIMBLE NC. 2

~=——CONTROL ROD THIMBLE NO 1.

REACTOR ACCESS
PLUG FLANGE —=—

SALT QUTLET TO
CIRCULATING PUMP
REACTOR ACCESS NOZZLE=~

C )

 

 

 

 

 

 

 

  
   
   
 
 

 

 

 

 

 

b CORE

 
 

=—GRAPHITE
LATTICE BARS

REACTOR
VESSEL =

 

 

~~—FILL AND DRAIN LINE

Pig. 2.7.9. Diagram of Control Rods, as Installed.

 

 
 

B PHOTO 81373A

 

L

AIR HOSE, INLET

AlR TO ROD DRIVE
HOUSING AIR HOSE DISCONNECT,

TYPICAL -

AIR HOSE, INLET AIR
TO CONTROL ROD. HOSE
SHOWN REMOVED FROM
DISCONNECT.

ROD DRIVE
HOUSING

 

FLANGE ON
ACCESS OPENING
TO CONTROL
ROD DRIVES

 

{
i
i
i
i

ACCESS STANDPIPE
TO GRAPHITE
SAMPLES

i
{
|
|

 

 

Fig. 2.7.10. MSRE View Looking Down Through Access Opening in Sec-
ondary Contaimment Cell Showing Control Rod Drives as Installed.

 
 

284

ORNL-DWG 63~8394 R3

POISON SLUG

 

 
 

9% in. /\/ -
LOCATION OF FIDUCIAL ZERO
vw%u\/jl X,

&-in. OIAM HASTELLOY N / SEE DETAIL
{INOR-8) WIRE (TYPICAL)

     
 
 

 

 

   

AIR FLOW

 

 

 

 

 

 

 

 

) )

 
 
 

 

       

 

 

AIR FLOW
il L2 2 Ll L L L. 1-_\i“\\
\——_/
END FITTING WITH P
I RESTRICTOR
INTEGRAL AIR NOZZLE THIMBLE
OUTER TUBE
UPPER SEALING Gd, O3 - Al, O3 BUSHINGS
RING LOWER SEALING
-I \ ; - \ /
3 N N Y N Sl LN
]
POISON SLUG
INNER TUBE /TWICE SIZE
0.790-in,
LD.

1.140-in.
oD.

 

 

 

AT 2Tl L

NS G AALLLLGATKILLN

1.560 in, ———————— =

 

 

 

 

 

 

2.7.11. MSRE Lower End of Control Rod.
DIFFERENTIAL
PRESSURE
INDICATOR

DIFFERENTIAL
PRESSURE
SENSOR,
RANGE 0-20in. Hy0

NOTE:

MANUAL CONTROL
STATION,
HIC-915-A

     

 

 

HAND VALVES

 

 

OPENED (ONE AT o
A TIME ) ONLY

 

WHEN CHECKING
ROD ZERO POSTION

 

 

B

 

 
   
  
   
 

X

THROTTLING ‘{
VALVES — 7

 

 

TO

etc.

|

REMOTELY
OPERATED, MANUALLY
— REACTOR CONTROLLED REACTOR
7 CELL WALL VALVE, HCV-915-At CELL WALL ==
% o SEE NOTE NOA _ \ _
b /A‘
~ o U
7

20.7-psia
/ HEADER, R

 

 

 

989-A

VALVE ASPECT IS THAT
REQUIRED TO CHECK .
ZERO POSITION OF

ROD NO.4

 

 

L
{1

   

 
  
 

g

 

—BIFFERENTIAL
PRESSURE
INDICATING
CONTROLLER,

 

ADJUSTABL
RESTRICTORS
B #
P
L—"'5 ROD DRIVE
THIMBLE HOUSING
®
[+]
a0,
VENT TO
CELL
ROD
3 55-gal
TANK
Ps
S

 

 

 

 

Fig. 2.7‘12'

 

A RIC-960A

 

 

T T IiN

DN

™

 

 

/

v
COMPONENT
COOLING
PUMPS

™~ SECONDARY
CONTAINMENT
PRESSURE -12.7 psio

 

AN

ORNL-DWG 84-4001R 2

  
   

RESTRICTOR, ADJUSTS
FLOW TO CONTROL
ROD THIMBLE

    
   

DIFFERENTIAL
PRESSURE

. TRANSDUCER

989 A N

       
 

COMPONENT R
COOLING
PUMP

R

  

NOZZLE - FLOW
" RESTRICTOR; PARTS
OF CONTROL ROD
\‘ AND ROD THIMBLE
~ROD
MOTION

 

REACTOR
CELL

R - PRESSURE IN MAIN SUPPLY HEADER, APPROX 20.7 psio
P, - PRESSURE IN SUPPLY LINE NO. 95 TO ROD DRIVES

Py -~ PRESSURE AT INLET TO ROD DRIVES

P, - ADJUST TO EQUAL Py WHEN NOZZLE |S NOT IN THROAT OF RESTRICTOR

Fy - EXHAUST PRESSURE { REACTOR CELL PRESSURE}, APPROX . $2.7 psio

 

NOTE:

t. THIS VALVE 1S ALSO A SAFETY SYSTEM
BLOCK VALVE. CLOSES IF RM 565 BOR C
INDICATES EXCESS RADIOACTIVITY.

Diagram of Instrumentation Used to Locate Rods at Fiducial Zero Position.

98¢

 

 
 

286

ORNL-DWG 64-983

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

J T
[ \
]
]
N | N
N 7'"'\: M
CARRIAGE ] N
: SN
I
i N
AR INLET TUBE-——____ ] R
1 N
: .
I
N | \
N | N
7| — N
\ 3
\ Ny
e\ }
¥ I \
] |
BUFFER RETURN SPRING-—_ [ )
: .
N I
\ I
|
|
|
N |
BALL RESET SPRING ——_N !
\ |
CYUINDER——— | |
»
N
PLUNGER - —————— | \
¥, -in-DIAM \
/52 in-D ) | t
STEEL BALLS———— ) | N
E | | E
\ | ' A
\ ol
CARRIAGE TRACK \ N | |
\ T ] i ]
N N R
N b \
ROD DRIVE HOUSING ——__]] A
) H N ]
N
L] N
\ N
\ N
\ N
N
N
N
M
Tow BLOCK~—___ [}
+
N N
N ‘\\ \ N
RN N
N N
\ N
\\\\\ §§§> \
- ) \ 2 \
\% / ; 7//////‘
N > /
\‘ //< ! : /\
Y N
N i
” 1
THIMBLE e
POISON ELEMENT
w

 

 

Fig. 2.7.13. Cross Section of MSRE Control Rod Drive Shock Absorber.
 

i
i
§
i

 

 

 

 

 

SHOCK ABSORBER!

 

 

 

 

 

 

 

 

CAPTIVE CAP SCREW :
USED TO ATTACH
CONTROL ROD TO
THE ROD DRIVE
ASSEMBLY. NOTE

THE CUP WELDED

TO SOCKET HEAD

TO GUIDE REMOTELY
HANDLED WRENCH

 

PHOTO- 73175A

 

'WO THERMOSTATIC
EMPERATURE SWITCHES
ENEATH COVER

Flg 2.7.14. MSRE Shock Absorber and Thermostatic Temperature

Switches.

 
115 V_AC

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Q@ {
OF F o o OFF
' 3 AMMETER(/) AMMETER AMMETER
P2
c: [ -
BECMLATED KA KA KB KBI KC KC
YoLTAGE |97AT |97e:[' usn:[' 1973'[ 197AT 1978T
M?
g : ”, o
09V kAl [ kBl ke 1
1970 1970 _ 1970
T FAN MOTOR T + FAN_MOTOR T T FAN MOTOR
ROD N% | ROD N22 RODN23
KA LkB Lkec + L4 . + +
KA 197 BIS7 KCI
*) *) o7 'I‘mc 'rs?c. ‘[mc
NOTE: REGULATED SUPPLY IS ZENER DIODE TYPE DESIGNED

 

TO REPLACE STANDARD CELLS IN POTENTIOMETERS

Fig. 2.7.15.

MSRE Rod Drive Temperature Indicator.

88¢C

 
 

ORML-Dwg. 86-4186

) SPACERS, ADJUST TOTAL
THICKNESS TO O8TAIN

   
     

 

    

 

  

 

 

 

  

 

 

 

 

 

 

 

 

. SPRING RETAINER PROPER SPRING LOADING |
' ' LEAR SPRING (STERL) HARD (Re 58-60) sresL SPRING LOADED
) 'rwcé aPPeeAuu‘;;Tsmmas _ o A BEARING PAD, 2 RED'D, 5 SWITCH ADJUSTER
SHOWN ACTUATED \ _
PIVOTAL AXIS : ) . _ _ 0O SWITCH - AU-TWO LOWER LIMIT SWITCHES _
OF SWITCN — i ) RETAINER : CSHOWN AOT ACWATED) MOUNTING PLATE
........... Ayt [ B2 N _
- s . N
Swren e _ T Ny N i | o /Iflf-illl
ot L ,
Keruor S T TN e \[7
g L= N 3 NI |
‘ % Sy oTIg 20T SWITCN ACTUATOR
OPERATED BY CONTROL ROD " DE. i
O / TOW BLOCK AT ENDS OF STROKE §UIDES (SOFT Y
seerion A-A

 

 

 

MSRE Rod Drive Unit, Switch Actuator—Guide Bearing Assembly.

Fig. 2.7.16.

68¢

 

 

 
 

 

 

PHOTO 73176 A
AIR TUBE TO

S

(i

=~

 

 

 

UPPER AND
LOWER LIMIT
SWITCHES

 

 

 
 
 

 

o e e
LA g

 

 

 

xR

 

Showing Inlet Air Tube

for Control Rod Cooling Air and Side View of Upper and Lower Position

Limit Switches.

2

Upper End of Rod Drive Unit

Fig. 2.7.17.

 
 

 

291

PHOTO 73177A

 
 

LIMIT SWITCHES
AND ACTUATOR

 
 

 

 

 

ition ILimit

Pos

ing

Show

2

t

Uni

ive

Upper End of Rod Dri

.18.

7

Fig. 2

Switches.

 
 

   

 

 

 

BLED ELEMENT .-

 

c6¢

 

ettt i T Ly AR ' AR R *“' 4 e '
y 3 3 LY, AR TIPS __ N b e e . 'i;H IRELES .'.‘?:fi\???}u? n.*_ e ¥,
; ! Y s ? ALY X g " & .4 3 P T e 4 e e

5 i

SE

 

 

Fig. 2.7.19. MSRE Control Rod with Poison Elements Shown Removed from Supporting Structure.

 

 
 

 

Fig. 2.7.20.

 

MSRE Control Rods, Assembled.

 

 

€6C

 
 

 

294

ORNL-DWG 66-11377

SO kVA, 1SV AC

~~

 

 

 

 

 SUPPLY
48v DC > - ' 2
THIS CONTACT IS CLOSED
BY MANUAL ROD SCRAM
K29A SWITCH, S-1. :
ROD DRIVE ROD DRIVE ROD DRIVE
S 120 ‘ NO. 1 | NO.2 NO.3
TOGGLE SWITCH o |
ON CONSOLE ' |
1 A4
T Ke308 K234B -~ K238B ) 1iesE CONTACTS
OPEN WHEN
| CONTROL RODS AT
== K231D K235D —= K239D LOWER LIMIT
Vv V% JACKS MOUNTED
ON CONSOLE
PLUG

 

 

 

 

 

 

 

 

 

CLUTCH

 

 

 

NEUTRAL

INDICATING DIAL
0.001-sec GRAD.

r————_———————— [ ———— —
| cLuTeH coil—
GROUND , I T
| =
| L—_
| 3
| ,é,ps ELECTROMECHANICAL
|
|

PORTABLE TIMER, |_
STD ELECTRICAL o -_———— =
TIME CO, TYPE MSHOO'/_

Fig. 2.7.21L. MSRE Rod Drop Timer Circuitry.
 

SERVO MOTOR (rpm)

295

ORNL-DWG 66—10180

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

g8
T L jour 1 —
i I | T/ ) 5 SPROCKET
m
60 cps g
CONTROL ROD
DIEHL NO. 49-91-1 /
SERVO MOTOR,25  STROKE TOTAL SUSPENDED
watts RATED OUTPUT n.. WEIGHT = 18.0 1bs
4000
3500 /DOWN
r  ————— 3
L ® __—-—-."t
"’\kup
3000
FROM TESTS OF MARCH 9,1964
SYSTEM CONTINUOUSLY CYCLING
5500 FOR FULL STROKE.NOT IN "INCHING
MODE.
- —
0
50 60 70 80 90 100 1O

Em (AC volts)

Fig. 2.7.22. MSRE Control Rod Drive Motor Speed vs Voltage.

 
 

DISTANCE (in.)

CURVE A-REFERENCE CURVE OF SATISFACTORY SCRAM PERFORMANCE;
BASED ON ACCELERATION OF 5 ft/sec® AND RELEASE TIME OF 0400 sec

10

20

30

40

50

60

296

ORNL—DWG €4—{4109R

 

 

 

 

 

 

 

 

 

 

 

 

 

 

™~
\ X
NN
\,
\ \
\
\

\

X
\

\,
0.25 0.50 0.75 1.00 1.25

ELAPSED TIME (sec)

CURVE B-—SCRAM PERFORMANCE FROM TESTS OF JAN. 27-28,1964

Fig. 2.7.23.

MSRE Control Rod Height vs Time During Scram.

.50
 

297

ORNL-DWG 66—-1018!¢

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

@
/
6 ¥
| .,0
’
5 o
7|
A
S S
- ./‘
£ L
/ .
e THIS CURVE USED TO
o2 ESTIMATE RELEASE
| INTERCEPT AT &7 TIME. POINTS TAKEN
> 1 ootz sec A L FROM CURVE B, MSR
| /T MEMO 64 -27. CLUTCH
; - // 0 VOLTAGE -- 23 v dc.
I
I
l /
N
|
0 010 020 030 040 050 060 070 080

- {ELAPSED TIME (sec)

Fig. 2.7.24. MSRE Scrain Performance Tests (Jan. 2728, 1964).

 
 

0.01

O
O
N

Ak/k INSERTED
O
@)
(1

O
o
B

0.05

298

ORNL-DWG 64-2146

 

™~

ADEQUATE PERFORMANCE

—J REFERENCE CURVE PROVIDING
KNug:eme SCRAM

 

N

 

\<CALCULATED PERFORM-
ANCE BASED ON ROD

 

 

 

 

 

TOTAL ROD WORTH:

0.041 Akfk |

51 in.

— INITIAL WITHDRAWAL :

\DROP TESTS OF PROTO-
TYPE SYSTEM AND CAL-

\CULATED ROD WORTH DATA

N

 

N

N

 

 

 

 

 

SN

 

 

 

 

 

 

 

Fig. 2.7.25.

0.2 0.3

0.4

0.5 0.6 0.7 0.8

ELAPSED TIME AFTER SCRAM SIGNAL (sec)

0.9

MSRE Control Rod Performance During Scram.

1.0
8 o4-nf

»Momol>»

% :

 

ORNL DWG. 67-2414

 

 

 

 

 

 

 

 

 

 

ERFORMANCE DATA TACHOMETER ELECTRICAL DATA 60 cyc.t
25 WATTS OUTPUT. A YOLTS + 60 CYCLES. 2 POLES 2 PHASE :
PHASE 1
POLES 2
EXCITATION | INPUT CURRENT (MA.) 50
PHASE (115v.) | INPUD POWER (WATTS) 5.0
*QUTPUT VOLTAGE /1000 RPM 6
OUTPUT
LINEARTTY.% at 3000 RPM 1.0
PHASE
RESIDUAL RMS (Mv.) 110
100 VOLTAGE VARIATION (Mv.) 55

 

 

 

 

 

1.
80
&
g
o0 &
TOTAL WATTS INPUT .
5
EFF A
°
20
0

TOAQUE OZ N

*May vary *10%.
Based on tach. load of 0.l megohms.

Fig. 2.7.26. Performance Curves, 25-w Servo Motor.

 

66C

 
 

V=~ =

3

Lmoamol>

30

10 WATT MAX. OUTPUT « 115415 VOLTS » 60 CYCLES « 2 POLES - 2 PHASE

300

MOTOR PERFORMANCE DATA

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R.
-3
M
3
‘\\\\\
Y
3200
<,R.p.m
2000 N
\\
AN ,
2400
N /
2000 \\\\\\‘ )//,
%00
VvV
200 TOTAL WATTS mu-r-7/ \ 6
/ AMPERES #lpm Pm:szj/\ w %
o Yo
"/ ] L~
1;4// — *”><:\\\ \ 30
4 ///7' ’/_”“ - §k \ 20
/ // WATTS OUTPUT/ \\\ .
0 2 4 6 8 10 12
TORQUE-0Z. IN.

Fig. 2.7.27.

Performance Curves, 10-w Servo Motor.

EFFICIENCY - PERCENT
 

 

301

2.8 LOAD CONTROL SYSTEM

The reactor loading system in the MSRE has been described in detail
in ORNL-TM-728.1 Some design changes to improve the effectiveness of
the air seals and the annulus cooling air flow have been made since the
publication of TM-728, but the basic design remains unaltered. Briefly,
the nuclear power generated by the reactor is finally dissipated by a
coolant-salt-to-air radiator and discharged to the atmosphere via a
stack 70 ft high and 10 ft in diameter. Air flow through the radiator
is supplied by two large, 250-hp (nominal), axial flow fans., The ra-
diator consists of a bundle of 120 thin-walled tubes (0.750 in. diam,
0.072-in, wall, 30 ft long) bent in the shape of a zee (Fig. 2.8.1).
The radistor 1s enclosed by two vertically sliding doors which act, to
a degree, as air flow control elements. Additional control of air flow
is obtained with a bypass damper and by selecting either one or both
fans. When the doors are fully lowered, cams on the guide roller track
force the gasketed door against a flat sealing surface to prevent the
entry of air to the radlator. Figure 2.8.2 shows the radiator, the
doors and their drive mechanism, and the coolant salt pump as they are
installed in the duct. Figure 2.8.3 is a simplified drawing of the
door drive mechanism, Note the flywheel which reduces the door ac-
celeration during a load scram when the clutch and brake are released.
The flywheel is connected to the shaft by an overrunning clutch so that
it continues to coast after the door reaches the lower limit,

The coolant salt experiences a calculated temperature drop (subject
to small changes caused by slight variations in flow) in the radiator
of 56°F at full power of 7.5 Mw. When ambient inlet air temperature is
in the 40°F region, typical operating parameters at the radiator are as
follows:

Coolant salt inlet temperature 1015°F
Coolant salt outlet temperature 1073°F
Air inlet temperature 42°F
Air outlet temperature 151°F
Air flow 200,000 cfm

Coolant salt freezes at 850°F, and the operating margin above the freez-
ing point is therefore 165°F. This margin will be less on cold days,
when the ambient temperature 1s reduced.

The remainder of this section is concerned with the instrumentaticnm,
control, and protection of the complex of equipment that is used to re-
ject the reactor's energy output to the atmosphere.

Tt has been pointed out in ref. 2 (pp. 107 and 140) that the MSRE
is a load-following reactor and is inherently self-regulating when de-
veloping any appreciable power. In any realistic power reactor system,

 

1R. C. Robertson, MSRE Design and Operations Report, Part I, De-
scription of Reactor Design, ORNL-TM-728 (to be published),

2MSRE Project Staff, Molten-Salt Reactor Program Semiann. Progr.
Rept. July 31, 1964, ORNL-3708,

 
 

302

the operators have little or no direct control over the public'!s demand
for power. There was, therefore, no incentive to control closely the
load on the reactor. The only requirement in the MSRE is that the op-
erators he able to establish and adjust the load about a point in any
region within the operating range, up to 7.5 Mw, of the reactor and to
do so in an orderly fashion. It can be seen from Fig. 2.8.4 that the
reactor load (the heat rejection at the radiator) is determined by five
independently variable elements, namely: (1) inlet radiator door, (2)
outlet radiator door, (3) main blower 1, (4) main blower 3, and (5) by-
pass damper, Over a considerable portion of the range, the same value
of load can he obtained by two or more different operating configurations
of the above equipment. It follows that load changing and adjusting, if
done strictly by manually manipulating these five different components,
may add considerably to the duties of the operator at a time when he
least needs such additional responsibility and, in addition, may produce
unnecessarily high thermal shocks with accompanying high stresses.

In view of the foregoing, the adjustment of the thermal load of
the reactor has been designed for either manual or programmed control.
With programmed control, load changes are accomplished by means of a
single control at the console (Fig. 2.8.5) when the selector switch
(8-23) is in the "Auto" position.

2.8.1 Blower Operation

The main blowers, 1 and 3, are axial flow propeller-type fans.
They are driven by direct-comnected, 250-hp, 1750-rpm, three-phase,
440-v ac wound rotor induction motors. High rotor resistance starting
is incorporated in the power circuits to limit starting currents to ac-
ceptable values. During start, the motor windings are connected in
series to external resistances. As the motor accelerates, the external
resistance in each winding is successively reduced by timer-controlled
switching. This requires approximately 30 sec., After attaining full
speed, when all external resistances have been disconnected, the motors
operate as typical squirrel-cage induction motors. This startup cir-
cuitry operates automatically when a motor circuit bresker is closed to
start a blower and, in the following discussion, is not included as a
part of the reactor control system. The control system relays control
the blowers by operating the "Close®” and "Trip" coils in these circuit
breakers.

2.8.2 Door Operation

Figure 2.8.6 is a diagram of the door drives. A single gear-reduced
motor provides power to raise both doors; individusl door control is ob-
tained by means of clutches and brakes located on the separate sheave
drive shafts. Operating conditions of the elements governing door move-
ment in different situations are shown in Table 2.8.1.
 

303

Table 2.8.1

 

 

‘ Brake Brake
. . Clutch, o Clutch, ?
Situation Motor Inlet Door Inlet Outlet Door Outlet
Door Door
1. Normal, raise On Engaged off Engaged off
or lower both
doors simul-
taneously
2. Normal, raise On Engaged Off Disengaged On

or lower in-
let door only

3. Normel, raise On Disengaged On Engaged Off
or lower out-
let door only

4. Load scram On or Disengaged off Disengaged Off
Off

 

Door position is indicated on the control console (Fig. 2.8.5) by
synchro position receivers driven by synchro transmitters. The trans-
mitters are mechanically connected, through gear reducers, to the sheave
drive shafts, The intermediate 11m1t switches (Fig. 2.8. 7) used as
control interlocks, are actuated by cams on the transmlttlng synchro
drives., The position of these switches is adjustable over a wide range.
The upper and lower limit switches are in redundant pairs and are ac-
tuated directly by the doors. These limit switches are an integral part
of the control system used during normal operation., Additional switches
used solely to protect the doors and the drive mechanism from overtravel
and overload are provided. These are described in Sect. 2.8.6.

The bypass damper is positioned by an air cylinder with a built-in
positioner, as diagrammed in Fig. 2.8.6. Cylinder position, directly
proportional to cylinder pressure, is controlled either directly and
manually or with a pneumatic servo, The servo positions the bypass
damper to maintain the differential pressure drop AP across the damper
equal to the set-point value AP

Direct manual control of damper position may be obtained by man-
ually adjusting the inlet pressure to the air cylinder with a pressure
regulator in the manual control station mounted on the main control
board., A three-way valve transfers cylinder alr supply from the servo
to the pressure regulator.

~ Assuming that one or both blowers are on, servo control of AP
across the damper is accomplished from the console by operator adjust-
ment of OP sp with the switch labeled DP Demand (see Figs. 2.8.5 and

2.8, 6) - This switch operates an electric-motor-driven pressure regu-
lator, PdX-ADZ-Al, whose output APSP goes to the pneumatic servo. If

the condition of other elements in the system (doors and blowers) is not

 
 

304

altered, a request for an increase (decrease) in APSP will cause the

bypass damper to close (open). If, however, the doors are moved or
blowers are turned on or off, the damper will also respond to maintain
AP equal to APSP.

When load control is being automatically programmed, the adjust-
ment of APSP is included in the program and is not directly manipulated

by the operator. In either control mode the values of AP and AP and
the damper position are indicated on the console.

2.8.3 Automatic Load Programming

As the reactor system is brought from zeroc to full power, the
various elements (as stated previously) governing reactor load are pro-
grammed in accordance with Fig. 2.8.8. This diagram is based on tests
conducted on January 31, 1967. The dashed portion of the door position
curve merely connects the end-point values of power obtained by moving
the doors from the fully closed to fully open positions. The curves
will shift slightly with changes in ambient temperature.

The programmed control system was designed with these fairly ob-
vious assumptions:

1. When the radiator is presenting a constant frontal area to the air
stream, heat transfer therefrdm is closely related to static pres-
gure drop across the radiator.?

2. Heat transfer from the radiator increases as the doors are raised
as long as the operating condition of the other flow elements
(blowers and bypass damper) remains unaltered. The tests referred
to above and in Fig. 2.8.8 indicate that the last 2 or 3 ft of door
travel exerts little influence on the load; that is, the doors are
most effective during the early stages of thelr movement.

3. The static pressure drop measured across the bypass damper (see
Fig. 2.8.6) differs only slightly from the static pressure across
the radiator; that is, the pressure drop in the branching ducts to
and from the radistor doors and the bypass damper, respectively, is
small compared with the pressure drop across the radiator tubes.

The programming control system diagrammed in Fig. 2.8.6 uses the
air flow differential pressure AP across the bypass damper and the limit
switches (Fig. 2.8.7) to program the sequence in which the doors are
raised, the blowers are turned on, and the bypass damper is opened or
closed. Control system pressure and limit switches also provide re=-
strictive and permissive interlock signals. Figures 2.8.9 to 2.8.11
are, respectively, the block diagram and the relsy circuits which im-
Plement the block diagram. The operation of the load control system
when the programmed load control ("Auto" control) is in use is best ex-
Plained by tracing the sequence of events and operations which take
place as a particular pover level is established following a reactor
start.

 

3W. M. Kays and A. L. London, Compact Heat Exchangers, McGraw-Hill,
New York, 1958,

 
 

 

305

Suppose that operation at 7.5 Mw is required and the operator will
establish this value of reactor load using the programmed or automatic
load control mode of operation. Procedure and system actions are out-
lined below (refer to Figs. 2.8.5 to 2.8.11 in following the discussion):

Actuate the load control selector S23 to the "Auto" position. This
switch 1s spring-returned to the "Hold," or center, position; but, if
the conditions required to establish automatic operation have been met,
automatic load control is in force. These conditions are (see circuit
150, Fig. 2.8.10):4

1. reagtor system in "Operate" mode, contact KAL36F closed (see Sect.
1.4);

2. salt level in the fuel-pump bowl above 43% of full-scale level,
contact K97C closed;

. fuel-salt pump speed greater than 1000 rpm, contact K96D closed;

. drain valve FV-103 frozen, contact K659D closed;

. static air pressure drop AP across the radiator equal to the oper-
ator-established set point APSP in the bypass damper controller

(Fig. 2.8.6), contact K211A closed.

3

4. coolant-salt pump speed greater than 1400 rpm, contact KLOE closed;
5

6

Alternate conditions to 6 above are:

7. system not in Run, contact KA139C closed;
8. bypass damper 100% "Open," contact K214A closed;

9. operator-established set-point signal AP _ to the bypass damper
controller set at zero. Sp

With the automatic load control mode established and, in the case
under discussion, the conditions listed above obtaining, reactor power
is increased from near zero to approximately 1.0 Mw by the operator
turning on main blower 1 or 3 and requesting the load increase with the
load demand switch S24. Assume that it is decided to begin the ascent
to 100% power (7.5 Mw) using main blower 1. The operator will actuate
the main blower 1 Start switch S29, and, if system conditions are not
producing preventive interlocks, the following conditions prevail (refer
to the)block diagram in Fig. 2.8.9 and the circuits in Figs. 2.8.10 and
2.8.11): L

1. The bypass damper is being held 100% open (APSP = Q),
2. both radiator doors are closed,
3. main blower 1 is "On,"

4, main blower 3 is “Off,"

 

“Conditions 1 to 5 must be met at all times to maintain automatic
load control; that is, they are not sealed. The remaining conditions
are required only to enter automatic load control but are not required
to stay in this mode.

 
 

306

5. main blower 3 has been selected to turn on gutomatically when the
load demand cannot be met by a single blower. Had the operator
elected to start with main blower 3, he would then have selected
main blower 1 to turn on automatically when the load demand requires
both blowers.

After main blower 1 is turned "On," the operator starts to load the re-
actor by actuating load demand switch S24. This causes the radiator
doors to start opening and, as long as S24 is actuated, they will con-
tinue to do so without restriction until the lower intermediate limit
is reached. The operator follows the course of reactor power by ob-
serving either the linear power recorder on the main control board or
the two indicators, RI-~NLC1-Al and RI-NLC2-A2, on the console. The
doors will continue to rise until the lower intermediate limit is
reached and the system power level is approximately 1 Mw. The doors
may be stopped at any point before this if it is desired to operate at
povwers less than 1 Mw.

When the doors have been raised to the lower intermediate limit,

system conditions are:

1. main blower 1 is "On,"
2. bypass damper is being held 100% open (APSP = 0),

3. reactor power is approximately 1 Mw,

The 1-Mw level is the transition point from "Operate-Start™ mode to
"Operate-Run," and further increases in power level require that the
Run mode of system operation be established. This has been discussed
in Sects. 1.4 and 4.2.

Once the system is in "Run" mode the operator can again request
additional load, using S24 as before. This can be seen by referring to
circuits 162 and 164, in which "Run" relay contacts KA139G and KB139D
bypass the intermediate limit relay contacts K219A and K223A respectively.
Note that if the automatic rod controller has been used during the pre-
ceding operations, it has been in the "Flux" control mode during "Start.”
Going from "Start" to "Run" automatically puts the automatic controller
into the "Outlet Temperature” mode (see Sects. 1.4 and 2.6). As the
operator continues to request more load, the doors continue to rise
until fully open. As the doors are going from the partially raised,
intermediate limit, position to the upper limit position, the bypass
damper remains fully open since the control system, by means of contact
S24A in circuit 151, Fig. 2.8.10, is keeping APSP = 0. The load is in-

creasing because of the increasing exposure of the radiator to the flow-
ing air stream. Once both doors reach their upper limits, the bypass
damper must start closing to divert more air through the radiator and
thus increase heat rejection. This is accomplished in circuit 153,

Fig. 2.8.10, by switch contact S24C. Closure of this contact turns on

the motor which drives the APSP device, PdX-ADZ-Al, in Fig. 2.8.6;

APSP is increased, and the bypass damper controller PdC-ADZ-A closes the

damper to satisfy the requirement for increased AP; more air is diverted
307

through the fully exposed radiator and more heat is exbtracted from the
system. Reactor power rises to meet this increased load., As before,
the operator continues to request increased load with 824 and to follow
the power by watching the linear channel instruments on the console and
the main board. Any power level in this region can be established by
the operator. This type of system response continues until the bypass

damper is fully closed and the entire output of main blower 1 is flow-
ing through the radiator. A sumary of system conditions is:

1. main blower 1 "On,"
2. main blower 3 "Off,"
3. bypass damper 100% closed,
o APSP at intermediate value,

5. power level at approximately 5 Mw.

The only way now remaining to increase heat rejection (load) by
the radistor is to turn on the second blower, main blower 3 in this
discussion. Note, in Fig. 2.8.10, circuits 153 and 154, that when the
bypass damper is fully closed, the following circuit actions tske place:
(1) contact K215A in circuit 153 opens, preventing further increases in

APSP, and (2) contact KR215F in circuit 154 closes and permits energizing
of relay 154, which will turn on the second main blower. At this point,
the value of APSP is established and is equal to or greater than the

actual AP across the radiator. With the radiator presenting a constant
frontal area to the air stream, as it will when the doors are fixed at
their upper limits, the heat rejection is related to the AP across the
radiator. Now, when the operator asks for more load via the ILoad Demand
switch, S24, the circuitry (see action 2 above) is such that relay Ki54
is energized; this initiates the start of main blower 3. As this
blower picks up speed, it delivers additional air through the radiator,
thus raising AP above APSP, and the bypass desmper will open an amount

sufficient to bypass some or all of the additional air flow produced by
main blower 3, depending on whether or not AP and APSP were or were not

exactly equal when main blower 3 was turned on. The load may change
slightly when main blower 3 1s turned on. This is attributed to the
large duct and the nonuniform shape of the radiator, which permits
slight changes in air flow which are not measured by the single probe
in the center of the duct. -

After the second main blower (3) is turned on, the bypass demper
is open, and the control circuit configuration (circuits 153 and 154)
is as it was Jjust before the damper was completely closed with only
one blower running; that is, (1) contact K215A in circuit 153 (Fig.
2.8.10) is closed, permitting changes in.APsp‘by energizing relay 153,

and (2) contact K215F is open, and main blower 3, once "on," is sealed
and is no longer controlled by relay 154. '

With both blowers "On" and with the bypass damper partially open,
the heat rejection (load) is increased, as before, by actuating Load

 
 

308

Demand switch S24. This causes AP to increase, and the automatic

damper controller (Fig. 2.8.6) closes the bypass damper to divert more
air through the radiator. This mode of operation continues until the
bypass damper is from 75 to 100% closed® and the load, somevwhat de-
pendent on ambient temperature, is in the 7- to 8-Mw region.

Reduction in load under automatic load control proceeds in the
reverse direction.

2.8.4 Msanual Control

When the reactor load is in the Manual Control mode, the separate
components governing heat rejection (see earlier part of this section)
are treated as independent units and are controlled separately. Refer-
ring to Figs. 2.8.5, 2.8.10, and 2.8.11, it can be noted that each
door, Inlet and Outlet, has its own "Raise" and "Lower" switch and that
bypass damper position is controlled by a AP demand switch. The blowers
are not cross-interlocked with each other or controlled by door position
as they are during Automatic Load Control. The selection of a partic-
wlar operating configuration of these components and the operational
path required to arrive at the desired configuration are entirely at
the operator's discretion. :

2.8.5 Interlocks

In either control mode the reactor loading system is subject to a
nunber of interlocks and control actions whose primary purpose is to
prevent or reduce the possibility that the coolant salt will freeze in
the radiator. These interlocks and control actions and their purpose
are listed and described in Table 2.8.2 and, in some cases, amplified
in subsequent paragraphs of this section.

2.8.6 Load Scram

Load scram (or emergency closure of the radiator doors) is pro-
vided to prevent freezing of coolant salt in the radiator tubes. A
pessimistic, worst case, calculation® showed that salt freezing can
take place is less than a minute. Operating experience tends to con-
firm this calculation.

Figure 2.8.12 is a diagram of the instrument system used to provide
load scram, and Figs. 2.8.13 and 2.8.14 are elementary diagrams of the as-
sociated control circuits. The primary input information is coolant
salt temperature at the radiator outlet. Three independent temperature
measuring channels are used so that if any two of the three indicate
an asbnormally low temperature, the clutches and brakes in the door drive
mechanism are automatically deenergized and the doors drop to the closed
position.

 

5finel damper position is adjusted to keep system temperatures at
reasonable values,

63, J. Ball, “"Freezing Times for Stagnsnt Salt in MSRE Radiator
Tubes, " private commmication (Apr. 9, 1963).
Table 2.8.2. Load Control System Protective Interlocks

 

Initiating Condition(s) or

 

Interlock or Control Action System Response Situstion(s) Supplemental and Explanatory Notes
I. Load scram 1, Radiator doors are dropped 1. Abnormally low (980°F)a' coolant 1. Low salt temperature is the primary indi-
to closed position salt temperature in radiator cation that freezing is imminent
outlet pipe, line 202
2. Both main blowers, MB-1 2. Abnormally low {less than 700 2 and 3, A loss or substén’qial reduction of
and MB-3, are shut down gpm) flow rate of coolant salt salt flow through the radiator is the pre-

lude to a freeze; particularly true when

1
3. Abnormally low speed of coolant system is developing full pover

salt pump

4, Control rod scram 4, Power generation ceases with a rod scram.
Unless heat rejection Wy the radiator is
reduced, a freeze 1s inevitable, Note
(refer to Sect. 2.5) that when the reactor
is developing power, a rod scram will be
produced by an electrical power system
failure, a loss of fuel salt level in the
punp bowl, or any other condition which
reduces input current to the fuel salt
pump motor

These are safety-grade interlocks with addi-

tional deseription in Sect. 2.8.6.

II. First upper limits Prevents doors from being Door(s) at normal, fully open, 1. These are typical limit-switching controls
raised - position actuate limit switches, of the type ususlly associated with mech-
two each per door anisms having limited motion. They are not
the final limits whose sole purpose is to
prevent demage to the system (see inter-
lock No. III) '

2. Redundsancy:

a) Two switches per door. Actuation of
either switch is capable of releasing
the door drive clutch and applying
the brake

b) When doors are being raised one at a
time (manual control), limit switch
actuation opens the "Raise" circuit
in the door drive motor starter

60¢

 

 

 

 

 
Table 2.8.2. (continued)

 

III.

Final (maximum) upper
limits

Shuts off door drive motor Door(s) raised sbove normal fully

Disengages door drive
clutches

Applies brakes in door
drive mechanism

open position by epproximately 8 in.

For detalls refer to:
a) Limit switch circults 216, 220, 224,
and 225, Fig. 2.8.7

b) "Raise" circuits 162 snd 164, Fig.
2.8'11

¢) Clutch and breke circuits 13 to 16,
Figl 2.8.13

d) Motor starter circuit 568, Fig. 2.8.16

These switches also used in the automatic
load control clrcults

Actuation of these limit switches indi-
cates an sbnormel situation which, if
continued, will demage the drive mech-
anism or the doors. If the damage in-
cludes a jammed door or snarled cable,

it may prevent lowering the doors, elther
normally or by a load scram, and hence
cause a radiator freeze

Reliability:
a) Two switches per door

b) Two independent relay circults with
both releys actuated if either door
at the final limit

c¢) Either chammel (relay circuit) will
produce the actions tabulated in the
"System Response" column

1] §3

d) Interconnection wiring carried in
separate, individual conduits to
control room

In genersal, safety system criteria
(Sect. 1.55 were used wherever possible
in design of this interlock

For detalls, refer to:
a) Limit switch circults 255 and 256,
Fign 2.8.7

b) Clutch and brake circuits 13 to 16,
Fig. 2.8.13

c) Motor starter circult 568, Fig. 2.8.16

 
Table 2.8.2. (continued)

 

VI.

Motor overload

Manual emergency
bypass of coolant
punmp control circult

Lower limits

Same as IITI above

Maintains forced circu-
lation of coolant salt

Drops door(s)

Motor current in one phase indicates 1.
that docr drive motor is overloaded

Variable and at discretion of re- 1.
actor operator

2.
3.
1. Door(s) being lowered and 1.
2. At Mower 1imit" position
{see Fig. 2.8.7)
2.
3.

Thie augments III above. Except that
only one excess current relay is used,
it has same degree of reliability and
redundancy. The excess current relay
has its contacts in series with the
final upper limit switches and hence
the output actions are identical

This consists of a manually operated
switch with contacts in the control
power circuits of bresker K, This
circult bresker controls ac power to
the coolant salt pump

This switch bypasses all the interlocks

in elrcuit 142, which controls the coolant
salt pump (refer to Sects, 3.3 and 4.2.3).
It is used only for short periods, when

it is absolutely mandatory, regardless of
other considerations, that the coolant
pump be operated to prevent a radiator
freeze.® This switch does not bypass the
overcurrent protection which is built into
the circuit bresker. Coolant pump cpera-
tion by this switch is annuneisted

Refer to Fig. 2.8.17 for circuit details

| §£3

This is not & true lower limit (Sect. VII,
this table). These switches are actuated
approximstely 8 in. above the fully closed,
or sealed, position. The doors then fall
freely as in losd scram and acquire suf-
ficient veloecity to ensure an effective

seal against leakage air flow across the
radiator (door sealing is described in

ref. 1, p. 298)

Redundancy: Two switches for each door

‘with contacts in series connected to cne

relay

For details refer to:
8) Limit switch circuits 217 and 221,
Fig. 2.8.7

b) "Lower" door(s) circuits 163 and 165,
Fig. 2.8.11

¢} Door clutch and brake circuits 13 to
16, Fig. 2.8.13

 

 

e e e TECTT——
Table 2.8.2. (continued)

 

VII. "Seal” limits 1. Stops doors at fully
sealed (fully closed)

position

a) Disengages clutch(es)
if not disengaged by
VI

b) Applies brake(s)
providing door(ss are
belng lowered

¢) Shuts off door drive
motor

1. Door(s) at fully closed position
actuate 1imit swltches

The seal limit is the true lower limit

door position.

At this location the

door(s) has been self-cammed by its own

weight agasinst the sealing gaskets which
prevent excesslve air leakage across the
radiator

Reliability:
a) Two switches per door

b) Any one of following outpute based on
switch actuation will stop door{s):

1}

2)

3)

4)

5)

6)

Clutch disengagement via elther of
limit switch contacts in each clutch
circuit; refer to eireuits 13 and 15,
Fig. 2.8.13

Clutch disengagement by either of
two 1limit switch contacts which de-
energize "lower door™ relay(s).
Refer to circuits 163 and 165, Fig.
2.8.11

Drive motor shutdown by either of
two limit switch contacts which de-
energize "lower" contactor in the
motor starter. Refer to circult
568, Fig. 2.8.13

Drive motor shutdown by contact on
"lower door" relay, which de-
energizes the "lower" contactor in
the motor starter. Refer to circuit
568, Fig. 2.8.,16

Brake actuation by elther of two
limit switch contactz in circuits 14
and 16 (refer to Fig. 2.8.13)

If, because of malfunction, drive
motor is "On" when a door (or doors)
1s sealed and brake is engaged, the
excess motor current relsy (see IV,
this table) will shut motor off

c1e

 
 

313

Figure 2,8.15 depicts a typical temperature input signal channel.
Note that this is virtually identical to the temperature instrumentation
used to provide rod scram (Sect. 2 5) except that the polarity of the
thermocouple in the test assembly’ is reversed; therefore, the appli-

cation of heat and the resulting temperature increase of this test
thermocouple appear as a reduction in temperature to the rest of the
instruments. Each temperature input chasnnel can be tested by turning
on the heater in the test assembly and dbserving the response of the
relays, which are controlled by the Foxboro temperature switches. The
equivalent drop in temperature produced during the test procedure can
be observed on a meter by the person conducting the test.

A Joss of coolant salt flow will inevitably produce freez1ng if
the doors are open and there is any appreciable air flow through the
radiator. Therefore, the doors are also closed automatically by com-
binations of signals from the flowmeters on the radiastor outlet line
and from the coolant salt pump speed monitors. These signal combina~
tions are tabulated in Fig. 2.8.12.

The pump speed measuring instrumentation is discussed in Sect. 6.
A "loss of speed" input signal to one of the speed monitors is simulated,
for testing purposes, by means of the calibration switch built into the
speed monitor. Output relay action indicates whether or not the sys-
tem is responding properly.

The instrumentation used to measure coolant salt flow rate is de-
scribed in Sect. 6. For test purposes, a simulated loss of flow signal
may be produced in each channel by shunting a leg of the resistance
bridge in the differential pressure cell, Observation of the output
relays gives an indication of input channel response.

Redundant door travel limit switches (Fig. 2.8.16) are employed
to protect the ability of the doors to drop when the safety system
calls for a load scram., Door limit switching has been described in
Table 2.8.2, but it is worth while to emphasize here that the primary
purpose of this redundancy is to prevent jamming of the doors or the
drive mechanism which, in turn, is likely to compromise their ability
to drop. An excess current relay in the motor circuit (Fig. 2.8.16) is
used to detect an overload caused by a jammed door, snarled cable, or
similar malfunction if it occurs either in the normal motion span of
the doors or at the limits. The action of both of these limiting cir-
cuits is to stop the drive motor by deenergizing the relays in the motor
starter. Manual reset (refer to circuits 255 and 256, Fig. 2.8.16) is
required before restarting the drive motor.

Insofar as possible the limit switch design and installation follow
the recommended safety-system practices outlined in Sect. 1.5.

The predominant requirement in controlling and operating the load
control system is to prevent a frozen radiator., To this end the cir-
cuitry diagrammed in Fig. 2.8.17 was added. The time required to freeze
the salt in the radiator is extended if circulation is maintained with

 

"Molten-Salt Reactor Program Semiann. Progr. Rept. Jan. 31, 1964,
ORNL-3626, p. 44.

 
 

314

the coolant pump. The coolant pump control circuit (see Sect. 4) con-
tains interlocks which stop the pump if it experiences a loss of motor-
cooling water or lube oil. The salt pumps cannot run for any appreciable
length of time without oil or cooling water, but no harm will come to
either pump or motor during the first minute or so following a loss of
either. The manual switch, S127, located on the main control board,
overrides these interlocks which are capable of stopping the coolant
pump. It does not bypass the overload protection in the coolant pump
circuit breaker. Use of this overriding switch is controlled adminis-
tratively and is only permitted if the pump stops and a frozen radisator
is imminent.
 

315

ORNL DWG 64-8826

9" 0.D. INLET 5" SCHD. 40,
HEADER LINE 201

 
 
  
      

L

2-7/16" 1.D.
MANIFOLDS (10)

120 S-SHAPED
3/4" 0.D. TUBES

T
1

9" 0.0. OUTLET
HEADER

vl

 

Y

S" SCHD. 40,
LINE 202

l._—_fi,'gg"

Fig. 2.8.1. Rediator Coil Configuration.

 
ORNL-LR-DWG 55841R2

 

PENTHOUSE

MAGNETIC CLUTCH '

 

AIR OUTLET DUCT

  
 

 

316

 

            

 

FIRST FLOOR

(ELEV. 852 ft-0in)

SUPPORTING STEEL

BLDG. 7503,

 

-
R

/
/

AIR INLET DUCT

/

i
|
\}
/" AR DUCT FLANGE
|
|
MAIN A
/
/

/

 

 

 

 

Radiator Coil and Enclosure.

Fig. 2.8.2.
 

317

ORNL-DWG 63-8390R

 

ELECTRO-
ELECTRO- MECHANICAL BRAKE
MECHANICAL OVER-RUNNING
CLUTCH

 

 

I I I I CLUTCH
_ / « SHEAVES — FLYWHEEL

VL T -
)| == =

    
 

 

 

 

 

I

 

ORIVE MOTOR WITH ‘
GEAR REDUCER. SINGLE
MOTOR USED TO DRIVE
BOTH DOORS—

 

 

 

 

 

 

0

 

 

 

 

 

 

 

 

 

 

   
  

SPRING SHOCK
ABSORBERS

A
¥yl

 

 

 

 

 

 

 

NOTE:
THIS ARRANGEMENT IS
TYPICAL AND IS USED FOR

RADIATOR DOOR
BOTH DOORS '

 
 

' Fig. 2.8.3. Diagram of Radiator Door Drive.

ORNL-DWG 66-10633

 

5|

 

MAIN BLOWERS

&
]
Conlle )

 

 

 

 

 

 

 

 

Fig. 2.8.4. Diagram of Radiator Air Flow System.

 
 

318

 

PHOTO 68582

 

 

 

Fig. 2.8.5. Load Controls Located on Operator's Console.

 
SYNCHRZo

TRANGMITTER ]
INTEZMEDIATE
\.\N\T SWITeH
CAMS

o

GEAR Esnucaw/_

 

 

orRive SPROCKRET
“oxgs CHAIMNS
rnouN?lKSHAh‘l‘
w
ekt ewt i SHRAVRS cwt\s  cktrie

 

 

 

[rawarinsmmmei

DAMPER &
Mhik BLOWERS

PrEsSURE L

PRESfuUme
ERQULATOR

    
  

SBRAKER
/ RADIATOR

A R e Lo F s

 

 

 

 
 

 

 

®TATIC

PROBEY S

<

COMSTANY

PuEUMATIC
SARVO

HEO: ADRA

nigy PRELIUES
CED 5. hin AIRD) ?

 

 

Roow

 

 

 

 

 

 

SYNEHRo

TRANS MITIE 2
/ —~rer
LM
S AMNG
o
w

CLUTCH

Lc,a arR Repucer

—_— P TO STAGK

STATIC DIFFERENTIAL
PRESIUR B~

 

 

 

AP =

MEDIATE
LSwWIteH

EUMATIC SiaNAl PEOPORTIOMA
O _STATIL \EF, PrE

 

 

 

 

 

 

PdM-AD2- M;fl

 

 

 

POSITIONER

 

 

< -~ R

 

 

 

 

-pht

Auvte

ManN .,

TWO PosiTioN S PonT
UANUAL vALVE

  

 

2o Psig suePLy-S

 

 

CONTROL STATION ON MAIN ZOARD NP 4 FOR

SPFTioMalb Manual conTrol of By-Pass
Damper

Fig. 2.8.6.

3

 

 

 

A ey PURUMATIC
£ TRLAY
{ bl e m-AD2. A
DikmmgENTIAL f r
PREASURE % s
TRANSOVE SR z
PaT-ADT-A el | i PMRUMATHC
: L F RELAY
QU\AL ‘Puissuu.t | 5y e ADE- AB

 

 

   
 

 

 

 

 

 

(P Y

 

 

Pye-ADZ- A

i Sl o 3
RORBORO |77 il
M-S0
CONTROLLER

el gl
iy W

R gy
iy

 

Y
M

 

 

 

A

Ny

2 B i
o

 

PR ESSUR&
SwiTCHRS

 

Pys5-AD2-A3

Pys5-AD2- A

P53 -AD2-A4

  

ORNL-DWG 66-11719

CONTALT OFmM
WHEN AP LESS
THAN AP ., CiRculY M+ 2)|

CONTALT oPmp
WHEM AP EXCEEDS
APg; CIRCuUIT Me 20l

CONTALT oP&wL
WHEN APy, = O ;CIRCUT 212

  
   

CONTALT OPmM
WHEN AP, m (0O

CIRCUIT Me 218 LEEGEND

g PNEUMATIC

 

 

BYRAIN GAGE

PRALLUR S

TRAWRDULARR

M ADY- A4

£OLTEOL Line

AP INPuY BTCiS P0G,

SIGNAL T
DATA LOGGER

 

e

- ee wm == MECH. DRIVE-

 

 

 

 

 

 

W

~Pressur e Pegulatonr
FoR MAMUALLY ADJIVSTING
TAMPER PoSITIOM

kfisp

-l ik,
.

7

=PNEUMATIC
" SIQHN L !

FEOROS

2L
1 >

 

l"""""!

PRESSURE
REQULATOR

= F_‘x.'i':bz-hl

o

PROGRAMMED
LOAD CONTRODL,

=13

MHJUAL

 

 

COMTROL

 

ONAL.

 

TO SEYT POIT LOEMmMAND

DHEFERENT 1AL

PRESS

O RE

Load Control System Bypass Damper Servo.

61¢

 

 
 

 

 

   
  

 

 

 

 

 

     
  

 

 

 

 

 

 

 

 

 

 

 

 

ORNL-DWG 67-950

 

 

 

 

" U2 218 T4 2% e 217 e 214 220 azt
- inY . a . e & 3
RYA.
Pyis Pyss: 8 &% B 1!'- s RS
ADL ADT ‘Dl 1D 10- 10 10- 00
'|‘\ AL Al A at < ot T\ai L <t
| SFW wiaw | orau wiay | oFaw waen | @3- as- ‘ \ A1 ws. g
RADIATER RADIATOR RADVATOR - ADT ADY i —_— 0 oD
I AP AR, APLL,80 APy, = 100N AL Al . {' 8l ey
P‘s!- OPFEY WaRH orgu i.g . .- oPEM wugH OPRM wWHls
o1 or.-oam oY PASS Ite 10 vy our
AS canras 1 | oamesn 13 €z 'I\(Dt 2ACIATOR | mAmATOR -
100% P | 100 cipeep BOOE ATRIRSY | Deom AT b
:'III‘:::II OFeN Wil OPN wuls OPEN Fflll‘ OFPEM wulh wwhaR L Lowak LiMiT ' f-
¢ 1-1} A
|
ar > an, RADIATOR RAD IATOR RADIATOR RapiareR L !
R AT AITAT R AY Doo, oseR FiINAL yPrPre IMIT - i
u’v.v:c .\‘\'mv ::u L un.’n woweR Fa-10-33% B b D i
TR MADIATS ¢ b
wnr |
POSITION NoRMAL LPPER LlMlT_h =pp" | :
M xuz xus w4 Ky 26 KAty %218 a8 KN 20 8 k2t B-10-ul b2 t |
o) ord) ' '
TN 3 ] ,
o < - - o & g * > > . 1
1590, 130, 158, 139,13 199,470 15, 148, 188,79 ;::.1 190, &;. ‘o | |
2481 58 182,164 &b "W »
& s ihige gt ub e 2t ’ UPPER INTER MEDIATE -
$ 820 re2 ;14 168 LM "
~ . . PR » —” ES-10D-A2
€
AP__SITPQ!NT LIMITS aY- n:’“ DAMPLR RADIAYOW DOOR LMY SWITCHES : Ifl’ gc;osz'I:NQEAL e S
'POMITION ) LowetR MTERMEDIATE 0 S
222 123 114 213 246 47 LINMIT 1
o L] _ _ " wn 29 _ . - A |
< sy 4 Z2S-1D AL |
'G’ 9 1 |
KA. _j_ KVA . I
13- Laws2 LT ) p oo my i
o1 £5-10-c1 je-2 : 1l
7773 i 7 >
A e - 17
oD - 10 T8 - . .
-y Doar Ssalso L _ . 4__Luy
! . L-nbt - o zs-lo,; ol Qb-e} h= o y
_ng oreN wuaw wusy | orsu wians oPaN WHEM | ofEl wien -
- OO JuLey ouTLuY INL 7
\bt ::.:.n :QI. :;:;::::fl unm‘:f:‘:.r RADIATOR rRADIATOR THESE QWITCHES OPERATER
opan wasl L uPFER LT | UFFRR LIMIT UPPER urePRR By CaM3I ON SYNCHRO
OUT\EY INTSRMEDIATE INYERMEDIATE | INTOEMADIATE TRANSWMITTER DRWE AND
RAGIATOR Limir d :;"‘;?N Po";’:wou ARE CAPARBLE OF W\DER
' 1
DOOR SEARD | POSITION ‘ » n ADJUSTMENT
212 K228 2223 Kitle K249
on )
P L] . oINS <
4 & m- & * 2 2 - 5
199,19 . 181 162 156 104 168, I8,
468,18 a3, 6 488, s
368, a3, i s

2

RADIATOR DOOR LIMIT SWITCHES

Fig. 2.8.7.

Radiator Door Control System Limit Switches.

 
 

 

 

 

321

-MSRE-

RADIATOR SYSTEM PERFORMANCE

BOTH BLOWERS

o_.._u/

ORNL DWG 674645

INLET AIR TEMP 40°F

ONE BLOWER ON

" BOTH BLOWERS
NN

 

 

 

 

Dy > o
< o o

n
(=

DAMPER POSITION - % CLOSED

100

80

60

40

DOOR POSITION=- o OPEN

20

A

0 2

NOTE:

 

 

4

Lt

Program of Reactor Power ILoading.

Fig. 2.8.8.

PRESSURE DROP ACROSS RADIATOR,
AP-INCHES H20

6 8

* HEAT BALANCE POWER - MW

DASHED PART OF AP CURVE. “A* TO"B"
TO “C" IS ESTIMATED. .

 
 

     

 

|
l | | 322
|

 

 

      
   
  
   
  
 
   
     
   
   
   

gf2

   
    
  

L7 ALY e
o bl

   

 

O fumnn -l-ut\.r
ST

‘b N.uulc. "4 . uu

C e -
I- LA

!tfluu.v ] znul-.
TD— ow

l-m. b

it

=1
p

 

 

 

 

    

DooORY "
yrEiR vt

RARLTOR,
Hnor N

 

      
    

  
  

RADATOR b
- Aty

 

 

 

 

 

WeRALS BYPTALS

 

 

 

 

 

 

 

 

 

WO AR C!.Ult‘l‘
AL STRLT ARY
¥ BLOWER [®3 sn. D) &

WA

 

 

 

 

 

 

 

 

[ MO RAQURLT
comysoL | Dauns g LOwAR
raure Al ou_LP

1wk DooR

 

 

       
   
   

 

  

 
  

I weao F“uo -ouu'r eut olo‘g
1 WITRO!
———— m‘s"'c' tore An- PR S

 
 

NLEY DOOR
BELOW PINAL
VEPER LUMT

 

- — - . e e - =

- More W -

 

N o o = = ——— -

 

S e e e e o A v o e

 

 

   
  
           
 

 

 

 

 

 

 

 

   
     

  

AT
LONTROL
AMUTOMAT G

 

 

 

 

 

 

tawrsalt i
PCLITI0N
2 WAL YA

FOR INFORMATION ONLY

 

   

 
   
   
 
  
  
 

 

 

 

    
  
 

   
  
    
 
   
  
 

   
   

 

 

   
   
 

 

 

                

   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

e . DO NOT USE FOR ‘
oromanE. vy Soou] e MAINTENANCE OR
roipead seg goi CONSTRUCTION
“LEY DOBR AT DeRN S o . » ]
:::::' :.I:‘:L ::’w:; :::\-.-: AvE 1.;* S fi-. ..cn-n ol VIB4L |
| 1! u gqune. ., n-- [ PRI T YT TS ORI SR LI LT ,'-m
‘.“';5: qu:‘. :::,':;::" aut, tnc.\n. LonIRn ‘u-n-nl B Ginwr ‘qu t i [Cmam 9-\.0
i L_”P‘ } LMY L1y LOWBE LW T LomTeAL  BYITIAL GUDLK LaAwAY .= i ) |Tewe ""\.'\__
< AMEY ‘ wLOCK DiaERAL g T a13) °~§‘-'-"?5
t,nu\mu-\un FERIMM  BALCM S mtaithm L § e B Teal SRR
‘-m coCLANT tacy ’v;f‘m _BAOLN TramuEas L e . |
\ SRRErY B¥ETAV ;.ev.n Ok kst josun ‘-“.'_..
BT L WTLYE WOl TiALERWA (WL TY) TuNE l‘\},
‘!-'IJ CAMTE . RLOLW TIBGRAM {gum | 41D Cavl U831
i ‘Middle Limit Position will be preset to correspond to L M power with ona blower O, pover. Full power (10 J8f operation) will be resched vhen the bypass damper is fully. DAL GONTIO. WOLR Siaemam tweroc) prme I
2 uuo Comrol loonm in a8 follows: i ) closed . ARLTRE COMTRS. BLOLW D imdasbm (1w 3 ad L] punl. 1420
Start reactor and take power to approximste . . K1} 'T™e above s stopped st any point by returning the Losd Demand switch
Place Bypass Damper Coutrol im Autamatic Poeitiom to 1ts noutral (lou) pouuon and way te reverssd (decressing pover) by turning losd REFERENCE DRAMVINGS NO.
Lower AP sstpoint to(uro dewand svitch to 1ts "Decromse” positiom.
Start either blower ¢ damper will sutcmatically move t0 full opon position and bnce Automatic ioed comtrol oparation is atteined, the reactor pover can be 1ad betvesn
the other blower wiil sutomtioslly be selscted for sutomstic operstica) ) 1 and 10 M by operstion of the losd dsmand switoh. var v OAX RIDGE NATIONAL LABORATORY
. Switch Losd Control Mode switch to "Automstic™ positica {loed cootrol vill seal in ) rae both bloyers ars ON" the selectica of the "Autcmatic” blover may be changed by OPERATED &Y
to sutcmatic positioa) pushing the "ON" button of the dasired blowar. UnNiON CARBIDE NUCLEAR COMPANY
b - 1 - P s m e (f) Turn Losd Demand switch to “Increase Losd” position. Doors will raise until stopped (5) [he load may be increased manually and then evitched to mutomstic control by edjusting
4 |0csn = 1270 e by mg-linis. {Pouer should incresse (o spproximtely 1 W) P setpoint 1o Mtch the wxisting o2 aad svitahing loud costrol mcde svitch to Sreatier ) DIVISION OF UNION CARBIDE CORPORATION
8 [ oen = 5067 AETIYIPR LR (g} Push "Pun Node CB” run mode elrcuits Eel Load 3ot back produces same Sction &é decrease losd, OAX RIDGE, TENNESSER
- 7Y ‘ M’,“e T ETEs s 47as |, 0 will ';1:::1:’:“1..1': conu-ol from flux t.o ulwut.m servo nnl permitting Load screm drops rediator doors and stops fane. TS Oh D MOLTEN SALT REAGIOR GEAPERIMELNT —
A I CHANGE NOTICE NO. 2'757 - "; '!a"x"].m (b) Turn Losd Demand switch to "Increase Load” position, Doors will ralse and po\nr wiil OTHERWSE SPECIFIED: Bl DK OV A GaR A N0
| . -_'(Ah. increase. Iypass damper will remain opes since AP setpoint is gzero. Whon door € Rewmoved Rev 4
N REVISIONS DATE [aPrp| APPD rouch Ugper Liait, the aF setpoime vill Biicasticully incresse (ribe). Vhem the o7 ¢ A FRACTIONS & oo |RADIATOR LOAD CONTROL SYSTEM
- oquals setpoint the bypass demper will start to closs. Continmued request for load BLOLK D AGRAM
APPROVED e inerense vill cause further Lacresse 1o AP setpoint. The dasper vill be positioned to DECMALS +
[ R A snintain AF at setpoint and will closs as the setpoint incressss. Reactor pover will . —————
oD T ATl increase 48 the AP incremdes. When the dANper redches its closed positicm, the sscond  (9) |Sam D-wu-6: ST/ ROR OPANATIN OF BLowaR BACK ALow DAMPEES . ANGLES £
e e iy v "A_’I . blower will start sutomstioal 1;. hthbla-r-udlmmu,thow-d-p-ruu ! T —— b
e encioce antomatically open to maistain the AP at set d request far losd increass
e : APPROVED | DA APPROVED | DA : will roswlt in further l.lu-u in AP setpolnt with & Tesultant increass in rosctor SCALE: NONE
¢ Vyrig 3

 

 

 

 

 

 

 

Fig. 2.8.9. BRadiator|Load Control System, Block Diagram.

 

 

           

 

     

 
 

 

323

L s

 

 

 

 

  
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

el B 17171

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2% LA tua-"" 152 % 9 o 154 158 N 11 197 158 2
lkmlb - 5246 ls'nn B TAW
[nq'u. = KAWE ;'—'KI!‘C - xAiSON ;tKI‘?A Ktidc ;fimnc ;"_‘ KeisoH FKIe6A ..l-nzmn
"D 24 Frmsoc ;_‘:nmson-
[ . -
wow O O
[ Lgaa Hazien EeaTTe® > J_ Y
‘ SSRGS T KAl A gy
X T 1
! E 4 ’ _ = KAVZE. KAI2Gy
wn.tsA raTzoA Al Eyazrom _,_ntlilr
;"nm“v. I NG C\ . J
SEBA . [SY.18
: I wew srom
RAISON ST ;"\u\#h :d -
d Q .“,.~ s - —31rac ';“ .29
Fxrn L 4 T
RGASOM g N1 1 - I
]: :d 234 . ' 1 ngd
Ku STHM b —————— —— e e - = - —— fudod
3on . ~ -il- AN “‘d—+‘ . oW [ g
L K
. Sawln KiG70 %FK'“D
Catat . .
.‘ Zrkie Lwmson Friset  Fxaisom -—’(/\
o
1.
[
KiSBA ;[-.\ssc fomRIS4A TKisec
r- \®'_.4; s ,.__33): ,__‘d :
7~ N oran ‘:L.—’ % {5 ’ ‘:‘(
A WP g ‘
T orgu oy S s ~, ,
AT . 4 ") ‘@
TRWEL LT ,& rtf _@\ /C:j\ 4
b= { N1 %18 E‘: TKEISSL
®Asy nisy, Kiss <-|\tmss i. 8535 2&!5« 8&\9‘! ;[v.msa KIS
i
2S5 i 2N &
180, 150,151 150, ", . TSN, 53, CONTACT 18 JuLs. } CONTRGY \h WWGE. 136 , {onthcr 1 twak. COWTALT 1% Rt .
LeF A58 131,053 162,002 —22 xpve Lowaw 22 Be. oS e ext. : TRIP COIL CRY., i35 . e, {u?q.'u‘a‘a“:;'u. ey roor per e Y.,
48T, 450 15).133 164, 16e TR T TO L ‘ s . an :
16D, 158 155,158 1o%, &S sseraie 16 =t B Rt Yo wugnoie 1O k nl.l.n:!l.!".l- vo m. LoD ‘:s‘l; tuAcTan rox fpuozoaw To nu.u:‘.gl“ Te
- : . ~ - — - e - AR GRS AR - o,
" & AP SLTPOIWY COMTROL, ENARG\LE: _‘L__ MEh-1 BLOWER CONTROL, AUTOMATIC % SLECTO ME-8 BLOWER COMTEDL
AUTOMATIC ZRGVEST SIART : !
WHREN ERERGIALD AIOMATIC !
i BLOWER,
3 FOR MPORBXTTON UMY
i 89 NOT USE POR
Sk el ; MAWITENANCE OR
LOAD  COMIROL MOBE, SSLECTOR. SwWITCW ALOAD OEMAND  RELECTOR, SWiYoW |
TAYCTION
PORITION (ErouT viEw) - PO ITION (weowy Vikw) LOGATION ’
COMNTACTS LOCATION CONTMET o T Een e
HANELE D [IANOAL MOLE  |ATOMATIC (CKT. wa) MABLE Bun (orcRRRL Sus2 < Cewy. vad
e %, Rt} Qe 5 R = fe—— ) ‘ e
~ 1) - S0 Ta ) Ty T feramusts O, u w.vd{@m Ao Loh“.ol- TRLAY & [oNnC-4iN e
&:2) * T T 150 s (2) * r 15 WKW Dikathwm TYA wob t,pgg o MK c- a1V
c (™) . ) (5% W, ELAM. CONTROL INTREAD LK, CIRLUITS - 4W. 2 e d oW B 51N
o(a) n b 159 MG, AL, TADIATOR LOAD CORTROL BYRTEM - 0. Lo 0-MA- - 51321
* (5) n % 138 REFERENCE DRAWINGS NO.
- (o) R a2
PYTT T Ton mmnatlu\m"umm
T T T |l OPERATED
221 MBI L R e , RBIDE NUCLEAR COMPANY
- gADIAID POINT RDUURTING  SWITLW s R T ies | m%‘ e, CLEAR LOMPANY
gi:’: - 3!7:'? CONTACT % POLITION _(rmont vitw) LOCATION - { OAX RO JEMENNeL
ST 31BL MR OLE  *WD _ltowex H::D  RAVWE (CKT. WR) R _DENOILES CLOSED GONTALTS ‘-'. LIWITS ON DIMENSIONS UNLESS MOLITRW SALT ERALTOR EIPQ.—HME!JT%“_"os
G B t
CHANGE Belicw ¥ 2411 O x = 4 OTHERWISE SFECIPED:
ot L et e . FRACTIONS + NG I\NEETRING  SLEMERTARY
REVISIONS a0 e 4 * 33 { . RADIATOR LOAD CONTROL SYSTEM
' ' DECMALS [ SHEET 1 o4 2
3.8, Iee P -
o [ e o Y] =
| i - O Au|[Bis1822| D] ]

 

 

Fig. 2.8.10.

Radiator Load

Control System.

]
J
1
|
i
1
i

5

e s,

 

 

 
 

 

 

 

324

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TS WAA. 159 248 led Gl 1 6% 164 165 1 Caln 16" o8 a9 218
[ R T LFEa wums -} l l -]_
BEWAKE-K SEEAAL \ STA- TESISA KCISD G STNG Flln ;:nusm.
orau | . oren |,
(mealorn) S8 (wni-essm 2 |
P SR ., KTisD
smp| TS Smen H U{
AUR LONBLY AUk, CONTALT, ‘ K50 ‘ ‘ R RiISOe w
‘W HWaw, W WA
et 'P,N{'}_n!- - L. . | I oyt s
) 43 - =
’ f""b B e - Wik conTaty | Aun ConTAst
CLOSED WHEW [CLOSED WMWY ~ N Skl - Swat
BRETAKEE BRUATIE TREAKST BehAgin
ard ooy ’ ~ mose | ovem ==
(MBI ORE) MOJ ORR) [ ' .
TKieew KiaTE LR KiGTIR K&i5oM sas | wienvar : !
. T Zwnisen T Zunisor ] cuottn | caten
, Df 1T T I
L ~ ;-KZMF SLL ) |
i 1
: 1
‘ Q—' - e - —
L@ ==xtia KA @ = Ki23A SKEI  ReIA
N f‘ : N
LI_I S RETAM
‘ KATIBA s KAZZZA
I I -
; KB 2/8A KB2ZZA i |
. i
] #KIe3D vd | :
:(I [ ,
' Exieso S | |
:(}‘__",_____-L Yy | |
= KB224A b ———— -
";?.:'o’.')h (re.0> z21-0D-
i~ N, s i
1 (:E—-»
£ ~ ~ /@
Ly -y
%‘.‘: :2' : KAIGT N&i1et Kish Kibt KALT
1
25 5 ZNB
OPRLATES OPRRATRYL S8 , 13 s68, 13 368, o 0, 198, 189 1GA, 189
WO “MReih - WLO- MDA i 14,19 i, 18 1%, ek 16, 6] i;’i.nb ighy , LB
Lk% , 1% o8 % 168, il 1T, "4
W
TNAE G ki TR G TRt R ENARGiE LT oLTILET
M-l mMe-B TO Whih~ TO LOWEW TG WAlS S o LOWER \
w) = 13 CHA IASIN ) = LOMNTED DUTLEY WOOR COMIROL RADIATOR DUOR, POSiTION SHINCHROS
FOR MFORMATION ONLY
*25 Tt 00 NOT UGE FOR
TADIATOR IMAEYT DOOR DRIWE SBuwWiTw RADIATOR] OUTLEY HOOR VRIVE Switiw MAINTENANCE OR
PORITION  (FEonT vigw ) PORITION {(MMONT view)
COMTALT W Lowan WOLD Rapa | LOLATION COMTALT B LOWRR HOLD ®ague | LOCATION ConsTRUCTION
HAMDLL BND {ewr, oa) HANDLE ¥uD CLMT. wa)
msmmnoengns. %, R, v s . [~ e L A )
A L) X &1 wn (1) n L od R G BLAM, CONTROL 'MTERLOCK CILLITH - 4W. 24T  Pwrn-ST3LY
wi{l) A B L 1w B (1) x 1S G RLM, CONIRGL WMTEELRLW CIRLNITS - 34, § o4 T [DMHE- 37T
d o e e — — REFERENCE DRAWINGS NO.
A TRWOTRS CLORRD  CORTALY OaK RIDGE NATIONAL LABORATORY
OPERATED BY
S |ocu. #3240 3/768 ; UNioN CARBIDE NUCLEAR COMPANY
© [oen. * 297 i % 5738 57739 DIVGION OF UNION CARBIOE CORPORATION
T [Cuavaw Wericw = 8734 ) ‘L"'fi" BLOWER OISCHARGE DANFEE SWITCH MB-3 BLONER DISCHARGE DAMPER SWITCH T T T T e e e e s
CHAN, L 50 - POSINOG _(FEOUT VIEW) POSITION (FIONT VIEW) LIATS ON DIMENSIONS UMEIS | o o »ALT RRALY FPARIMENT A g 08,
A [CHANGE MOTICE ® T4 Fred CoNTMLTS o <0380 LOCATION CoONTALTS —on cloSmD ;OCATIO*; OTWERWISE SPECLRIED: MO,
v
N KT, Ne, HANDLE mwp) V. NOy
- e aTe o I‘“‘“’" B8O ¢ ) FANCTIONS & ENGIMEBERING %TLEMENTARY
| A SPARE A SPALE DECIMALS & RATDTIATOR LOAD LONTROL SYSTEW
3.3, J1r-a-g Py = SPARS . Sraza me— DHEET T o4 2
" APPROVED i ¢ X isg | T X /S8 ANGLES o
NPROVED o x 59 D X 160 ;
4 AL “HH [BIS132%IB ]|

 

 

Fig. 2.8.11. R

 

pdiator Load Control System.

 

 
 

 

 

 

 

 

SAFETY
CIRCUITRY

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ORNL~ DWG 63-8389

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

COOLANT
PUMP
MOTOR
MAGNETIC PICKUPS PUMP SPEED| S4 5y OR Sz Sy OR Sz
INSTALLED )7 | " MeNITOR
SPARE. (el 3 INDEPENDENT COINCIDENCE
] oyl P ; Srow ]| ey
. {o}2 FLOW — MATRIX
PUMP SPEED | Sp ks (b) SPEED F
MONITOR — —_— >
MOTOR TO PUMP
SHAFT GOUPLING VENTURI | e ooy
HEAT DIFFERENTIAL
PUMP BOWL EXCHANGER PRESSURE TRANSMITTERS
TI
AT~ | 3 INCGEPENDENT [ —F, " fzo'OUNCT”:)":F"g)E
Y '\ TEMPERATURE —_——
SIGNALS T3 __| ReLAv
RADIATOR MATRIX
THERMOCOUPLE
CIRCUITRY
NOTE:
EMERGENCY CLOSURE PRODUGED BY INPUT
SIGNAL COMBINATIONS AS FOLLOWS:
{a) §, OR S, +F,
{b) S, OR S+ Fp
CURRENT {e} Fy+ Fp
THERMOCOUPLES ACTUATED
—_ SWITCHES (d) ANY TWO OF THE THREE TEMPERATURE
INPUT SIGNALS

LINE 202

 

 

 

 

 

 

 

Fig. 2.8.12.

  

 

EMF TO CURRENT

ALARM
o I—‘ TO READOUTS

LOGGER ETC.

 

CONVERTERS

 

   

    

Diagram of Load Scram System.

 

CLUTCH
UPSTREAM DOOR

GLUTCH

E
’

BRAKE

 

v
BRAKE

DOWNSTREAM DOOR

ste

 

 
—_

 

 

 

 

 

 

 

 

 

 

ORNL-DWG 67-913

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  
  
 
   

 

  

 

 

13 14
1", 12
48V 0C § ) {15) (16) ,
OPEN IN "RAISE"
OTHER DOOR
I } MANUAL ROD SCRAM CLOSED iN KAI64B l
"RAISE DOOR" {KA162B)
I REQUEST -~— _ . KAI62C L KBI62C
L az ’T{(KAIS‘!C) f"’(KB|54C)
I MANUAL LOAD SCRAM KA162D _Tkaazgg) —
(Kmsm):: KB'64233 ,OPEN ™
KA2{8D (KB162B) "RAISE AT
{KA2228) DOOR"REQUEST CLOSED
CLOSED IN L N , | MAXIMUM UPPER
" ; A ~~————I—OPEN IN "LOWER" | LIMIT OR FOR
RESET K AA RAISE DOOR KI65B OTHER EXCESSIVE METER
S REQUEST {Ki1638B) DOOR CURRENT
KBHA | K120
sio08 SEALS T (KB164D) K255C
“A'ZA 4 Kmva Je(K2258) "
KBiZA K|65F “‘22‘3) A
" (Hres F, (K256G)
CLOSED IN OPEN A ’CLOSED WHEN
"LOWER LOWER DOOR 1S SEALED
DOOR" REQUEST LimiT SHUT
KA4 K5C TWO-0UT-OF THREE K4 K&C 42
CONTACT MATRIX. H OPEN AT MAXIMUM 558
- k2604 KAGA CONTACTS OPEN WHEN KAEC - k2624 KAZlBD
COOLANT SALT TEMP s 262 UPPER LIMIT OR FOR k2568 2(KA222D) 2 k82160
LESS THAN 980°F EXCESSIVE MOTOR T = (XB2220)
KAGG K5D KABD CURRENT / K2170
r OPEN AT (K221D) .
LOWER KIG3C e L OPEN IN
LIMIT (K185C) "LOWER DOOR" w
SAFETY
GRADE KAl24E OPEN FOR A CONTROL KBi2ac REQUEST ~
JUMPERS ROD SCRAM SAFETY GRADE o
KB{124A KA{24F JUMPERS = KA{IH KAIIC
I(KAHD) OPEN I(KAHE)
L kaszn Ff‘)n LOAD SCR::: KA12C
(kat2D) | (AND ROD SCRAM) (KA1Z E)
K 2614 LOSS OF FLOW K7C K8C - K263A CL%TEH BRAKE COIL:
AND PUMP SPEED =
CONTACTS. K7 AND KB ks =
I CONTACTS OPEN WHEN K7D I T0 REVERSING
COOLANT SALT FLOW KioC STARTER, CKT 568 2
1S LESS THAN 700 gpm;
K9 AND K10 CONTACTS K9D
OPEN WHEN PUMP k8o |
SPEED IS LESS THAN
1400 rpm

 

GND }

 

KBiiB

 

 

 
   

DOQR DRIVE MOTOR

Tt

KB12

 

 

 

 

 

14,11,13,14,15
16,155,158

", g
499, 1082

1,12 ,13,14
45,16, 155,158

Y’
LOAD SCRAM WHEN DE-ENERGIZED

Fig.

2.8.13.

12,12
499, 1082 COLS DE-ENERGIZED TO RELEASE BRAKE AND DISENGAGE CLUTCH
NOTE: INLET AND OUTLET DOOR CiRCUITS ARE IDENTICAL.

NOS. IN PARENTHESES REFER TO OUTLET DCOR
CONTROL CIRCUITS

_/

Load Scram Output Circuits.

C

)
T

 
 

 

 

ORNL-DWG 67-912

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

tsvac 24 5 8 ,
TVA-DIESEL’ —
115V AC .
50 kVA SUPPLY !
48v 0C
— 5 1 ssscpet | sss-cpe2
TEMPERATURE SWITCHES, l T T
| Tss-202-02 CONTACTS OPEN WHEN RADIATOR FSS201-A | FSS-2018
- | Tss02-82 QUTLET TEMPERATURE IS LESS - FLOW SWITCHES SPEED SWITCHES,
o TSS-202-C2 THAN 9B0O°F ' CONTACTS OPEN WHEN
CONTACTS OPEN WHEN
COOLANT PUMP SPEED
COOLANT SALT FLOW 1S LESS THAN 700 rom
IS LESS THAN 700gpm P
2 K4 (\' K5
KT K8
NEUT $d—uo KAS KB6 S K9 K10
NEUT piiod — 4 NEUT
GND } -
50kVA
SUPPLY 115V AC ' 5
TVA DIESEL Lo
HsvaC ! 5 8
48V DC F— 5 5 —
CONTACT K5-1 CONTACT K5-1 CONTACT K5-1
- IN RELAY —= IN RELAY = IN RELAY [KA125 | KBI125 | [ka1260 | KB125D | kci2s50
SAFETY ELEMENT, | SAFETY ELEMENT,! SAFETY ELEMENT, A A KC125A
RSS-NSCI-A4, - RSS-NSC2-A4, RSS-NSC3-A4 IKE‘C*Zf’ Tketes T KA125C Ixerese Jxatess kawse
CHANNEL NO.1 CHANNEL NO.2 CHANNEL NO.3 T - € T T
\TWO-OUT-OF-THREE
CONTACT MATRICES
(ROD SCRAM)
= KB1258 ‘g KA1248 KB t24 B
KA (25 KB125 KC 125 KAf24 KB 124
GND &—
1,12, 147,148 11,12, 124
NEUT 119, 124
NEUT
- J e J
Y Y

 

THESE RELAYS DE-ENERGIZED WHEN NUCLEAR
SAFETY SYSTEM PRODUCES A CONTROL ROD SCRAM

Fig. 2.8.14. Load

 

RADIATOR DOORS SCRAM WHEN
EITHER OF THESE RELAYS IS DE-ENERGIZED

Scram Input Circuits.
 

 

328

ORNL-DWG 66-11424

  
 

 

 

 

 

 

 

 

 

 

 

 

 

 

    
 
    

 

 

 

 

 

 

 

 

 

 

 

CURRENT
ACTUATED SWITCH
Y2 OF

TEST ASSEMBLY: FOXBORO DUAL

a. ELECTRICAL TO SAFETY SWITCH, TYPE 63 ALARM
r " HEATER SYSTEM

INPUT NO. 10
| b. TEST THERMO- I:sl; 2'(")'2 :;”” o,
COUPLE -202- LOGOER

| v |
I+ CURRENT
| ! FOXBORO CO. I_I FI ACTUATED | I“J
l— | —|——1J TvpPE 693 SWITCH, FOXBORO \

3 9 TYPE 63 :
MEASURING e o 11’ ISOLATION L3 |
THERMOCOUPLE CONVERTER AMPLIFIER | 150 0

o > FOXBORO CO
+ O .
= o ° 4008 | MODEL 63 PV OR
° o 3 [ 10-50 ma MODEL 65 PH
- 10 TO 50 ma FOXBORO CO. METER
PART N111 LF

 

« CHANNEL NO.2

SAME AS ABOVE
CHANNEL NO.3

<
C SPARE
D\J\\

 

RADIATOR
OUTLET PIPE, LINE 202

Fig. 2.8.15. Temperature Measuring Equipment Used to Provide Load
Scram.
RADIATOR DOOR

 

 

 

 

 

 

 

 

 

DRIVE MQTCR
34 48y DC
480V el —
q-2 0
CURRENT SEAL BREAK CONTACTS
TRANSFORMER IN DOOR DRIVE MOTOR
. STARTER RELAYS
CLOSED IN
"RAISE DOORS"
f l
CCA ccB
-[ S6BE T 568E
"CLOSED IN
"LOWER DOORS"
r__ ——— & e ———
| SEAL |
I [
| u‘L’
|
[

1

: |

. ]

|

/l_ _________ o -
OVERCURRENT

RELAY, GE NO.1AC K5638

   

GROUND
255,256
RELAY ENERGIZED WHEN
MOTOR IS OVERLOADED

 

 

 

 

. 255 256 3
E;S-DDt-At |, _—OPEN WHEN MOTOR - 1; E;S-D01-A2
{(K569A) 71 CURRENT INDICATES DOOR DRIVE - (K569C)
MOTOR IS OVERLOADED
OR STALLED
in. L a—OPEN WHEN INLET DOOR AT FINAL .
Z5-1D-B38 UPPER LIMIT—— o A~ Z5-1D-B4B
ke s —OPEN WHEN OUTLET DCOR AT an-
Z5-00-B38 FINAL UPPER LIMIT ——— - £5-00-84B
MANUAL .
RESET . 51264
SWITCH MANUAL
K-2554 RESET >—| K-256 A
51254 SWITCH
K-255 . K-256
— - —f
255,13,44,15 256,13 ,14,15
1097,16, 568 097,16, 568

/

Y

FINAL MAXIMUM TRAVEL LIMIT SWITCHES

Fig. 2.8.16.

568

 

T2X

480V flg 120

 

1
1

K255H

K 256H

ORNL=-DWG 67-91)

OPEN WHEN EITHER OUTLET OR
INLET DOOR AT MAXIMUM
UPPER LIMIT OR WHEN DRIVE
MOTOR CURRENT AT QVERLOAD
VALUE
THESE CONTACTS
OPEN WHEN QUTLET

 

DOOR IS SEALED

SHUT
THESE CONTACTS N
..;k?:g.?lmfl KA(62A KA164 A OPEN WHEN KAz'BE\ KazzzE
INLET DOOR IS
DOOR SEALED SHUT KB218E I KB 222E
KBI62A KBI64A
K163A KIE5A
——fl [ ] cLosep In
\\ "LOWER"
CLOSED IN "RAISE" OUTLET DOOR
OUTLET DOOR
'JCCB ROS ~—~< CCA
Z 5680‘____1 s lNTERLO(iK’S R
cca =
568 - . \__\\2 ccB
52.@?'&%@ ~_TRESE RELAYS PART OF 3 PHASE g:?ERGEZE 10
REVERSING MOTOR STARTER WHICH COWER DOORS

CONTROLS DOOR DRIVE MOTOR

 

 

 

I

THERMAL MOTOR \ 7=

OVERLOAD cowmc1‘s/‘£
{

}
\T/

Radiator Door Drive Motor Control Overtravel and Overload Interlocks.

6C€

 

 
 

 

ORNL-DWG 67-685

 

 

240V AC 250 v DC
— > z b <
30 amp iSamp

 

 

_— MOTOR STOPS IN NORMAL
CONTROL WHEN CLOSED.
| KA 142 A l S127 A KB142A

~ s127¢
l___ ~——CLOSED, MOMENTARILY,

TO START MOTOR
L. X | X IN NORMAL CONTROL

]l
i
III

   
 

-~ S1298B

 

 

TRIP COIL IN
CKT BK'R "K".
STOPS MOTOR
WHEN ENERGIZED

 

 

CLOSING, "
{START), COIL "%" RELAY a" THIS CONTACT
IN CKT BK'R IN CKT BK'R ‘ CLOSED WHEN
ne" " BREAKER IS

K CLOSED

 

€ £
¥

 

REFER TO IV-9,7 FOR TYPICAL MOTOR
S127, EMERGENCY START SWITCH,LOCATED CONTROL CIRCUITS
ON MAIN CONTROL BOARD

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CONTACT POSITION
NO. STOP | NORM | RUN [ START
S127A X CONTACT
S1276 X % DEVELOPMENT
$127C X
S$270 X
S127E* X
S127F*® X
*ANNUNCIATOR o-——0
CONTACTS SPRING RETURN

Fig. 2.8.17. Normsl and Emergency Control of Circuit Breaker "K" Which Operates Coolant Pump Motor.

¢ C C

oce

 
 

331
2.9 HEAITH PHYSICS MONITORING
2.2.1 Introduction

The purpose of the Health Physics Monitoring Systeml is to provide
personnel protection at the reactor site from radiation hazards due to
airborne and fixed source activity. The monitors composing this system
are placed at strategically located points throughout the reactor build-
ing. Those monitors which measure area activity and airborne activity
make up the Facility Radiation and Contamination Systeml'3 and produce
signals which are transmitted to a central annunciator panel located in
the reactor auxiliary control room and to the laboratory Emergency Con-
trol Center in Building 2500. The Facility Radiation and Contamination
System also produces a building evacuation signal based upon finding a
coincidence of at least two monitors in an alarmed state. The other
monitors composing the general system are mainly for personal survey and
include such items as beta-gamma survey meters, & hand-and-foot counter,
and smear counters for use by Health Physics personnel.

2.9.2 Facility Radiation and Cohtamination System

2.9.2.1 Introduction

A Facility Radiation and Contamination System was installed in the
Molten-Salt Reactor Experiment Building 7503 to continuously and auto-
matically monitor gamma radiation (by seven gamms monitrons) and air
contamination (by seven beta-gamme air monitors) in the entire facility.
These instruments and other components in the network provide health
physics monitoring information, sound local alarms when abnormal con-
ditions occur, and indicate the abnormal conditions on a central panel-
board and at the laboratory Emergency Control Center in Building 2500.

Operating personnel are first given warning when a "caution level”
of 7.5 mr/hr or 1000 counts/min is detected by a monitron or beta-gamma
air monitor respectively. A second warning is given when a "high level"
is detected, that is, 23 mr/hr by & monitron or 4000 counts/min by &
beta-gamma air monitor.

The building evacuation system operates automatlcally when two or
more monitrons or two or more air monitors from a specific group of
instruments detect a "high level" of radiation or air contamination. An

 

lThe system is further described in ORNL-TM-1127, Description of
Facility Radiation Contamination System Installed in the Molten-Salt
Reactor Experiment Building 7503, May 13, 1965, by J. A. Russell and
D. J. Knowles. Parts of this report have been extracted verbatim from
T™-1127«

2D, J. Knowles et al., Instrumentation and Controls Div. Ann. Progr.
Rept. Sept. 1, 1963, ORNI-3578, pp. 37—40.

 

3L. F. lLieber, "Radiation-Monitoring and Warning System at ORNL,"
Nucl. Safety 6(4), 414-20 (Summer 1965).

 

 
 

332

audible alarm in the building will be actuated, warning lights outside
the building will flash, and an alarm signal will be transmitted to the
Laboratory Emergency Control Center, Building 2500.

2.9.2.2 System Description

The gamma radiation level is monitored by seven monitrons located
throughout the building (Table 2.9.1). Air is monitored for beta-gamma-
emitting particles by seven constent air monitors located throughout the
building. ©See Figs. 2.9.1 and 2.9.2 for the location of all the instru-
ments.

Table 2.9.1. Radiation and Contamination Monitors Installed
in Building 7503

 

Location Monitor No.

 

1. Facility radiation monitors®’P

Control room 1 RE-7011
High bay, south 2 RE-7012
High bay, west 3 RE-7013
Basement, north 4 RE-7014
Transmitter room 5 RE-7015
Basement center 6 RE-7016
2. Radiation monitors with control room
alarm only®
Service tunnel 7 RE-7017
3. Facility contaminationm.onitorsb’c
Offices 3 RE-7002
Basement, north 4 RE-7003
Transmitter room 5 RE-7004
Service tunnel 6 RE-7005
4. Contamination monitors with control
room alarm only®
High bay, west 1 RE-7000
High bay, south 2 RE-7001
5. Mobile air monitor 7 RE-7006

 

gAll monitrons are Q-1154B-13.

bCoincidence of any two high-level alarms in the group causes
automatic evacuation.

cORNI.model Q-2240B«4 constant air monitor.
 

333

Since none of the health physics functions originally designed into
the monitrons and air monitors were altered, each instrument is an in-
dependent unit that retains all its local alarm features. FEach instru-
ment, however, is connected to an individual indicator module on the
monitoring panel located in the Auxiliary Control Room, Nuclear Board 3.
By means of three colored lamps, which normally give a dim light, an
indicator module indicates the condition of the instrument to which 1t
is connected; that is, a white lamp burns at full intensity if the in-
strument is inoperative, an amber lamp burns at full intensity if the
"eaution alarm level" (7.5 mr/hr for a monitron and 1000 counts/min for
a beta-gamma air monitor) is reached, and a red lamp burns at full in-
tensity if the "high level" (23 mr/hr for a monitron and 4000 counts/min
for a beta-gamma air monitor) is reached (Table 2.9.2). Any change in
the intensity of any lamp, that is, from dim to bright, is announced by
the sounding of a buzzer at the monitoring panel and by annunciation cn
the main board.

The high-level alarm outputs of six selected monitron indicator
modules are connected to a coincidence module, and the high-level alarm
outputs of four selected constant air monitors are connected to & coinci-
dence module. If a coincidence module receives a high-level alarm signal
from any two or more constant air monitors or monitrons in a group, the
building evacuation system is actuated (see Teble 2.9.1). See Fig.
2.9.3 for a block diagram of the system and Fig. 2.9.4 for the control
schematic.

Table 2.9.2. Central Control Panel Alarm Indications for
Monitrons and Air Monitors

 

Lamp Intensity

 

Instrument Condition

 

Red Amber White
Normal operation Dim Dim : Dim
Caution level® Dim | Bright Dim
High levelP o Bright Bright Dim
Instrument inoperative Dim Dim Bright

Instrument removed® , 'Bright Bright Bright

 

aCautipn level for a beta-gamma air monitor is 1000 counts/min and
for a monitron is 7.5 mr/hr. No caution level alarms are available on
constant alpha air monitors.

bHigh level for a beta-gamma air monitor is 4000 counts/min and for
s monitron is 23 mr/hr.

c - - s - - - - . -
Lamp intensities remain bright until a maintenance connection is
made giving "inoperative” indication.

 
 

334

2.9.2.3 Components

Panelboard

The central panelboard for the entire system, located in the Auxil-
iary Control Room on Nuclear Panel 5, consists of two l2-module racks,
one central control chassis, and one dc power supply (Fig. 2.9.2). The
12-module racks contain one indicating module for each instrument, coin-
cidence modules for the beta-gamma radiation alarm system and the con-
tamination alarm system, a remote alarm module, a buzzer module, and a
manual evacuation module. The remote alarm module transmits a signal to
a single annunciator on the main control panel. The racks and modules
are made of anodized aluminum. The modules have anodized Metalphoto
front panels. A Metalphoto text strip is provided at the top of each
rack for instrument identification. The central control chassis contains
menual switches, timers, relsys, and monitoring equipment which are parts
of the system but not located in modules. For circuit details on the
central control chassis, see Fig. 2.9.5.

Monitron

The remote monitron (ORNL model Q-1154B) is an ac-powered, null-type
radiation detection instrument for monitoring gamma radiation. The
monitron consists of two basic units: (1) a control chassis, which con-
tains the power supply, the main amplifier, a radiation-level indicating
meter, and the controls; and (2) a preamplifier and lon-chamber detector
assembly. The detector assenbly can be located remotely 50 ft or more
from the control chassis. A 0O-to-10-mv recorder or a O-to-1l-ma meter Qul
can be connected to the monitron. The range of the meter is O to 25
mr/hr, and the calibrated accuracy of the meter is within 3% for gamma
radiation. The zero setting may be checked by means of a push button.

When the set point of an alarm circuit in the main chassis is
exceeded, a bell is rung and a red lamp on the instrument is lighted.

A connection on the instrument for an external alarm is used to operate
the caution-level alarm for the system. In addition to these standard
features, the monitrons installed in Building 7503 have two other
features: (1) warmup time delay relays installed on the main chassis
and (2) a high-level alerm meter relay installed on an accessory chassis.

The instrument and alarms operate as follows:

1. A power failure or a disconnected power cord will cause the white
lamp on the central control panel to burn brightly. After power is
restored and a l-min delay for warmup, the white lamp resets itself.
During this l-min delay, caution and high-level alarms at the instru-
ment might sound, but the same alarms on the central pasnel are locked
out and will not sound.

2. If the caution level of 7.5 mr/hr is exceeded, an electronic alarm
circuit causes the yellow lamp on the central psnel to burn brightly
and the bell at the instrument to ring. The alarms are automatically
reset at the instrument when the radiation level decreases below 7.5
mr/hr, but they must be reset manually at the central panel.

3. The O-to-l-ma meter output terminals are connected to the accessory
meter relay, which is set to operate when the 23 mr/hr (high-level) C
 

335

alarm set point is exceeded. At 23 mr/hr the bell at the instrument
will be ringing, since it started at 7.5 mr/hr and the red lamp on
the central panel will burn brightly. When the radiation level de-
creases to less than 23 mr/hr, the high-level alarm at the instrument
is automatically reset by a signal interrupter. (allows a reset every
30 sec) from the central panel. The central panel alarm is reset
manually.

Beta-Gamma Constant Air Monitor

 

This monitor consists of &n aspirating system, a paper-tape filter,
a halogen-type Geiger-Mueller tube detector, a linear count-rate meter,

a recorder, and visible and audible alarms. Air is drawn through the
filter by a Roots blower. A sample containing beta-gamma-emitting parti-
cles is collected on the paper-tape filter (collected sample size of

11X 2- 1/2 in.). The sample tape is advanced automatically every 24 hr.
The tape may be advanced manually at any time by the operator. The de-
tector counts the sample as it is being collected. The count-rate meter
is a linear duty-cycle type utilizing a single range and having an in-
ternal high-voltage supply. The normal range is O to 5000 counts/min,
and ranges of 0 to 250, O to 1000, O to 10,000, and O to 25,000 counts/min
at full scale may be obtalned by various 1nterconnect10ns of two Jjumper
wires under the chassis. The input voltage sensitivity of the rate meter
is 200 mv. The overall accuracy of the rate meter, including the effect
of long-term drift, is within 5%. The corona-regulated high-voltage
supply is nominally 900 v with +150 v adjustment. The maximum load cur-
rent is 20 pa.

The rate meter has adjustable high-level and caution alarms and
puts out a l-ma full-scale signal to drive an integrally mounted Rustrack
recorder. The caution alarm is adjustable over the range of approximately
2 to 58% of full scale, and the high-level alarm is adjustable from the
caution-alarm set point to full scale. The caution alarm is an electronic
circuit which employs a dual triode and plate relay with potentiometer
adjustment. The relay is energized below the trip point and is deenergized
by current transfer from one triode to the other by a diode that couples
the cathode circuits. Hysteresis is approximately 4% of full scale. The
high-level trip is accomplished by the high contact on a contact-making
meter which energizes the high-level trip relay.

When the set point is reached, the meter contacts and relay are
locked in; these are released by depressing the reset push button. A
low-level pointer on the panel meter has no contacts and is used only as
a visual indicator. The pointer should be set at the level corresponding
to the caution-alarm set point.

The instrument has an alarm panel with four lights, a bell and a
buzzer. When the caution set point is reached, an amber lamp is 11ghted
and the buzzer is energized. There is no switch to silence the buzzer,
and the operator is expected to advance the tape when this point is
reached. When the high-level trip point is reached, a red lamp is
lighted and the bell rings. The bell can be silenced by a toggle switch,
and when this is done, an amber neon indicator is lighted.

When the filter tape breaks, a red neon indicator is energized and
the caution circuit is energized through a flasher. The amber neon bulb

 
 

336

burns continuously, and the caution light and the buzzer come on inter-
mittently. If a tape breaks and, the caution alarm sounds at this same
time, the tape-break neon light, the caution light, and the buzzer will
be on continuously. A test push button permits checking the alarm panel
by simultaneously simulating tape break and high-level alarm signals.

In addition to these standard festures, all air monitors at Building
7503 have an accessory "instrument-inoperative' chassis containing a
meter relay. The instrument and alarms operate as follows:

1. An accessory meter relay connected to the O-to-l-ma output of
the count-rate meter will cause the white "inoperative" light on the
central panel to burn brightly whenever the meter pointer drops to zero,
indicating no signal from the instrument. After power is restored and
a 60-sec delay, this alarm clears itself. During the 60-sec delay,
local caution and high-level alarms do not sound since they are locked
out.

2. At the caution level of 1000 counts/min, an electronic alarm
circuit will cause the yellow lamp in the control room to burn brightly.
With an ORNL model Q-2240 air monitor, a buzzer will sound at the instru-
ment. The alarm is automatically reset when the filter is changed.

3. At the high level of 4000 counts/min, the panel meter relay on
the instrument causes the red lamp in the control room to burn brightly.
Also, the bell sounds. These alarms are reset by advancing the filter
and by pressing the manual reset button on the monitor.

Indicator Module

The indicator module (ORNL model Q-2563-1) consists of three inde-
pendent transistorized channels, each operating an indicator lemp and
providing a dec voltage shift signal for alarm or control purposes and a
voltage pulse signal for operating the buzzer module. The three lamps
and a push button are on the front panel. Each module is 35.8 mm wide,
120 mm high, and 125.8 mm deep. All connections are made on printed
strip connections at the rear edge of the plug-in module.

When the instrument connected to an indicator module is operating
normally, all lamps on that module are dim (Table 2.9.2). When the
module receives a signal that the primary instrument is operating ab-
normally or that the caution or the high-level alarm values have been
exceeded, the lamps burn at full intensity: white for inoperative in-
strument, yellow for caution level, and red for high level. A signal
is also generated by the module which causes a buzzer to sound. The
white lamp indication will remain until the condition causing the salarm
is cleared, at which time the lamp will return to the dim condition.
The red and amber lights will remain bright until they are manually reset
by a push button on the indicator module. If the indicator module is
reset when the alarm or abnormal condition still exists, the lamps will
momentarily become dim when the reset button is depressed and then will
become bright and the buzzer will sound again when the reset button is
released.

Al]l indicator modules are identical and can be interchanged or re-
placed without alteration (see Fig. 2.9.6 for circuit details).

 
 

337

Coincidence Module

The coincidence module (ORNL model Q-2563~2) consists of one tran-
sistorized circuit which accepts a dc shift voltage alarm signal from
as many as sixX indicator modules. The circuit can be adjusted by in-
ternal Jjumper connections to operate a relay for alarm or control pur-
poses on any combination of one to six input signals. All coincidence
modules at Building 7503 are arranged to operate the relay when there
is a coincidence of any two alarms from & selected group of instruments.
Each module is 35.8 mm wide, 120 mm high, and 125.8 mm deep. All con-
nections are made on printed strip connections at the rear edge of the
plug-in module.

Four selected air-monitor indlcator modules are connected to a
coincidence module. Six selected monitron indicator modules are con-
nected to a separate coincidence module. When two or more monitron
indicator modules or two or more air-monitor indicator modules receive
high-level alarm signals, the associated coincidence module will actuate
the building warning and evacuation equipment and will transmit a signal
to the Emergency Control Center, Building 2500. A red lemp on the af-
fected coincidence module will indicate which set of instruments has de-
tected an abnormal condition.

When the indicator modules showing an abnormal condition are reset
manually, the coincidence module will also be reset.

All coincidence modules are identical and can be interchanged or
replaced without alteration, except for an internal jumper connection
which determines the number of coincidental input signals required for
an output signal (see Fig. 2.9.7 for the circuit schematic).

Relay Module

To alert the reactor operator, a relay in the relay module operates
an annunciator at the main control panel whenever the buzzer module
operates; that is, any alarm at the auxiliary panel also annunciates at
the operating position. The annunciator at the main control panel op-
erates in the same manner as all other Tigerman annunciators at that
point. To reset the annunciator, the operator must first silence the
buzzer at the auxiliary control panel.

Buzzer Mbdule z

The buzzer module (ORNI,model Q—2563 4) consists of a transistorized
trigger circuit that operates a silicon controlled rectifier to actuate a
buzzer when a voltage shift pulse is received from an indicator module.
The buzzer module is the same size as all other modules and is interchange-
able with other buzzer modules (see Fig. 2.9.8 for the circuit schematic).

The buzzer module gives audible notice that an indicator module has
received any one of" three input signals. The buzzer module, which serves
all indicator modules, is reset by a push.button at the front of the
module.

After belng reset, the buzzer will sound again whenever an input
signal is received by one of the indlcator modules. For example, a
change from a normal condition to a "caution alarm level" at some location
will start the buzzer. After it is reset, a change to "high alarm level"
or to "inoperative instrument" will start the buzzer again.

 
 

338

Air Whistle and Beacon lLights

When a coincidence module has heen energized by two or more monitrons
or air monitors, four air whistles are activated by nitrogen gas bottles
(one for each whistle) to notify the building occupents to leave the
building. The air whistle, a "Clarion whistle" by Westinghouse Air Brake
Company, will sound from 2 to 4 min on one filled gas bottle. A control
box for each whistle contains a pressure valve, pressure switches which
monitor tank and regulated pressures, and a solenoid valve that is opened
by an electrical signal from the coincidence module. A momentary signal
will open the solenoid valve, and the valve will remain open until it is
closed manually by pressing the mushroom head of the valve stem inward.
See Fig. 2.9.1 for the location of the whistles and Fig. 2.9.9 for the
control circuit schematic.

The normal gas pressures for proper operation of the whistles are
not less than 1000 psig tank pressure and 80 to 120 psig line pressure
to the solenoid valve. Abnormal pressures are indicated by red lamps
(labeled "horn trouble") on the central control panelboard, one lamp for
each whistle. A dim lamp indicates normal pressures, and a bright lamp
indicates abnormal pressures. Inspection of the gages will indicate
whether the tank pressure or the line pressure is abnormal.

Federal Sign and Signal Corporation model 27S 110-v beacons with
magenta-colored lenses are installed at 15 locations (Fig. 2.9.2) in
and around the reactor building complex and the office building to warn
personnel to evacuate the building. These beacons are actuated simul-
taneously with the air whistles by a signal from a coincidence module,
and they are automatically stopped when the coincidence module has re-
turned to a normal condition.

A key-operated switch, labeled "normal-disable," on the central
control panelboard may be used to disconnect the air whistles and beacons
during maintenance or abnormal operation periods. Since the Emergency
Control Center receives an alarm signal when the switch is moved to the
"disable" position, the Control Center should be notified before the
switch is set at this position.

A large red push button located on a module in the central control
panel, labeled "manual evacuate," actuates the air whistles and beacons
and transmits an alarm signal to the Emergency Control Center (if the
Center has not already received an alarm). Remote manual evacuation
switches are provided on the reactor control console and in the mainte-
nance control room. If one of the manual evacuation push buttons has
been used, the system may be restored to the normal condition by pressing
the "reset" push button on the "manual evacuate" module.

Power Supplies

The main power for the system is 120 v, 60 hertz, supplied from
instrument power panel 5 in Building 7503 to the 24-v dc power supply
and the monitoring instruments.

The 24-v dc transistorized power supply is a regulated voltage and
current unit. A green "power on" lamp on the control chassis and a neon
lamp on the power supply panel will be brightly lighted to indicate that
the power supplies are operating. Also a "dec failure relay" is used
which triggers an annunciator on the main control panel should the dc
power supply fail.

-
 

339

Drawings
The Facility Radlation and Contamination System is described in the
following ORNL Instrumentation and Controls and Reactor Division drawings.
1. Q-2354-1 to -7, instrumentation location and wiring diasgrams.
2. Q-2563-1 to -4, and Q-2563-16B, -17, and -19B, plug-in modules.
3. Q-2358-7, horn control box.
4. Q-1154B-1 to -14, monitron.
5. Q-2359-12, monitron high-level alarm.
6. Q-2240-1 to -23, constant air monitor.
7. @Q-2311B, constant air monitor instrument failure box.
g. D-HH-Z-40641, instrument placement plot.

Operating Manual
See ORNL-TM-1127 (Revised)! for operating and checkout procedures.

 

2.9.3 General System

2:.92.3.1 Introduction

This part of the Health Physics Monitoring System consists of all
the instruments used for health physics purposes which are not included
in the Facility Radiation and Contamination System. In general, these
instruments are for use by the area health physicists and for operating
personnel in conducting personal surveys of their bodies and clothes.
Inciuded in this system are seven beta-gamma survey-type monitors, a
beta-gamma sample counter, an alpha sample counter, and a hand-and-foot
monitor. See Fig. 2.9.1 for location of these instruments.

2.9.3.2 Beta-Gamma Monitors, Q-2091

The beta-gamma monitors are mostly placed in contamingtion-free
areas to provide a means of personal survey of clothing and body. How-
ever, when not used for this purpose, they are left operatlng and serve
as backup monitors for the monitrons. In four places (the cooling-water
equipment room, the hallway between. Buildings 7503 and 7509, the instru-
ment shop, and the venthouse) their primary purpose is area monltorlng.
They are used instead of the monitron because of the lower unit cost and
low ares background expected. They provide a local aural alarm only
and are not tied to any central alarm systen.

The Q-2091 monitor consists of a G-M tube and a count-rate meter
with integral power supply. The G-M tube has an adjustable beta shield
and is attached to the rate meter by a 3- £t length of coax cable.

 

 
 

 

340

The count rate meter (Q-2091) is of the duty-cycle, linear-scale
type. It includes an amplifier designed to accept the G-M beta-gamma
tube input. A high-voltage power supply, a high-level alarm circuit,
an aural monitor with volume control, and a l-ma full-scale output for
recorder or telemeter are included features. The unit weighs 19 1b and
is enclosed in a cabinet approximately 8 in. wide, 9 in. high, and 12
in. deep. It operates from 115 v, 60 hertz ac.

Performance Specifications

 

Performance specifications are given below.

Input sensitivity 200 mv

Circuit linearity 2.5%; overall accuracy, in-
cluding drift, 5%

Amplifier gain control None

High voltage 900 + 150 v, corona-regulated,
20 pa

Range selector 250, 1000, 2500, 10,000, and
25,000 counts/min

Integrator time constants 1, 11, and 21 sec

Alarm Adjustable, zero to full scale

on any range for high level
only, manual reset

Recorder output O to 1 ma output, 50,000-ohm
impedance

Aural monitor Gated relaxation oscillator and
power amplifier with volume
control

2.9.3.3 Hand-and-Foot Beta-Gamma Monitor, Q-1939-B

The hand-and-foot monitor is located in an area which serves as the
main entrance and exit from the reactor building (7503).

This instrument is an ac-powered four-channel monitor for beta-gamma
radiation with a channel for each hand, a channel for the shoes (feet),
and a channel with & movable probe. The probe is mounted approximately
waist high in order to monitor the front of clothes when not used for
special monitoring. Three channels are identical modular-constructed
units, actuated by a halogen-quenched stainless-wall G-M tube. The count-
ing rate is indicated by glow transfer scaler tubes and electrical reset
registers. The fourth channel, the survey probe, is an aural channel.
The count in this channel is not totalized. Maximum counting rate in the
probe channel is approximetely 5000 counts/sec. To start the instrument,
a manual push button is depressed which energizes a timer, after which
the operation is automatic. The instrument resets itself, and there is
a S5-sec walting period before the counting cycle starts, to give the user
 

341

time to get both hands in position for monitoring. The actual counting
period is 23 sec. The total cycle is 30 sec. The maximum count rate
per channel is approximetely 250 counts/sec, and the input resolving
time per channel is approximately 200 usec. The instrument is contained
in a rack cebinet 68-3/8 in. high, 21-1/16 in. wide, and 220 in. deep.

A detachable base, 4 In. high, 18 in. long, and 21 in. wide, contains
the foot-monitoring assembly. The power requirements are 115 * 10 v,

60 hertz, 75 w, 0.7 amp. Operating temperature limits are 0 to

135°F. -

2.9.3.4 Beta and Alpha Sémple Counters

The beta and alpha sample counters are located in the health physics
counting room at the north end of the reactor building.

Beta Sample Counting System, Q-2344-1

The Q-2344 beta counting system includes a Tracerlsb end-window G-M
tube mounted in a vertical lead shield (ORNI-Q-2089). The lead shield
also contains a card sample holder. Attached to the shield is a pre-
amplifier and cable. The preamplifier signal is transmitted via this
cdble to a decade scaler containing the high-voltage power supply (ORNL-
Q-2188-1), A timer is also included in this unit. The complete assembly
is usually mounted on a table or a laboratory bench.

Alpha Scintillation Counting System, Q-2345-1

This system uses a scintillation detector composed of a 2 x 2 Nal
crystal and a 2-in. photomultiplier tube (ORNL-Q-2287). The tube and
crystal are mounted in & housing which is attached to a2 smear or slide
sample holder. The system uses a preamplifier and the combined power
supply unit used for the beta sample counter (Q-2188). This system,

‘like the beta system, is mounted on a table or a laboratory bench.

 

 

 
 

S T T T T S AT L s s e e+

 

 

342

 

 

 

 

-
r__’(l')

 

 

 

 

 

 

 

 

 

0 RI-TOZIAS

 

o

 

@

 

 

 

?

RI-02IA1L Q

    
  
 
      
     

 
  

R
1302347
le
Hegay
‘QQE

RE=TOZY

 

 
    
      
  

 

 

 

 

 

 

 

 

 

 

    
  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   
 

 

 

 

 

 

 

 

 

 

 

 

 

 

   

 

 

   

 

 

 

    

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

-
G-
©-

RACIAFION MONITORING NSTRUMENTS WO 1703

 

3
o
a EH ~
: g 3
3 o & | S5a O
" 8 o . x9 ~ = =
4 § l‘.“ X . A .. g 3 mnl )
o 8 <A | ®- £ ge05| JL..
®— i 3 Q& $;‘\ R
i 2 4 ' e efa
" & §3 ) O
i o . LEGEND
“ X u ? o 2 .
N I 9 fly Hus N . ‘
W vl - R StuG e
i 9 { o Illm oS R d [ — momne vmir-a-2240——---- -~ I-rRE@D
ol : 4 d T o8 | M~ o | -
i ; RI_ | 2 . _ 402 .
in ! + :, E‘HEE L % N é i ¥ " At E‘é i E:] —_— AR MONI[OR ~@m2240 === == === - 2FQ'0
] g3 R . 3l :
sl iy , : oy ~
§ T { / ~! \I t ;Eg;‘, 2 1O — MONITEON -Q- 1154 -~ ————smon - 1. REQD
, : $ 5 , . i 9 .
o & — -« —me e o
w g U i “ § .5 o o CRM (BETA § GAMIAY-8-2091 = == 8- REQ'D
* O . o o n
@~ 4 ¥ ' i %—: $e ) B — #ano ¢ roor moniror -@-1939--1-rea'o
W (g i% o ) N
3 ‘ . 3 3: 9 < 5 (2) B~ BVACUATION HORN == == = -e:!.-'l.l:fl.‘o
8 3 .- ¥y © 1 peinirss -3 x ) .
¢ he - 3y S 38yl 2= e 2 < ALARM BEACON LIGNT— _ — - J5°REWD,
2 : 8 ~ o £ g )
) s g 5,‘ § o 2 U ,
- & B
~ o
v 4 , . NOTES:
1 I i paww : " {. COMTRAL CONIROL MND ANNUNCIATOR PANEL
5 1 X m " Q rze‘.:f‘zg.ca{e,;? N AUXILTARY CONFROL RODM
n 0 ol w (Y .
] 0 N
ke N 8 N ‘ —w J{ : ~ 2. SINGLE ANNUNCIATOR FOR ALL ALARMS IN
LY ; & ~ 2 v Y 7 Masw couiroL KGOM.
: : ~ wd -/ 8 / AN - 3. OuS MODEL Q2217 PATE METER AD ALPHA PROSE
Rk N n v usz 2 AT ZOZATED 1t HOT CHANGE HOUSE
NS = 2 i X M = &, FOR INSTRUIMENT JUNSIICN BOA LOCATIONS AND
e L a Ly 0 CONDUIT ROUTING , SBE D-KK-C §5I115, $511%-,
A4 ? 0 o3 o RADIATION ACAEM SYEFEM.
jQ N ~ “y b
¥ V) - : v D
‘Q: - \&:- b
hn X 0
§§' X ENRS o Q&
N 9 E w 9
& e L&y
e TR SRCT IR '6' g.,‘ -
v ] ] SY v
&« @ Y | &t ,
iV el [ 4 : .
o 3 : -
: \ : E s 8
3 I+ - %
. ', ' @ NG
d 8 U w N
B v o %3
oy | ' 438
B8 T T L e F s S ey o ;,L y :
it x .
&1 B s :
=] §
fl.l.l.m.l. B
< : NMULLEME CONTEOL, PRURL®E * LANDUY O-0n A 1 BTY|
5 x! WUCLEAE COMRSL PAURL™ B- Wikl UIRGELM  jBHth: Y,
g t 5 WLOA. V30N ZATIATION § COUTAMIMATAN MIATING $¥4 Q- LS4l
: '(’ ~ ‘! fl gg ms LB, 1T CONTULT ROUTIMG [OWK.C- 33N &
< § '&‘ v P, ST CLOUUNT EOUTIN'S WK C- G510
L 1 — - 8 . o,
(ib g]fi! ' MOLTEN SALT REACIOR #APERIMENDE
!
'

 

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

 

 

Q INSTRUMENT PLACEMENT PLOT
I % EIXED HEALTH PHYSICS INSTRUMENTS
S | bonFI74 3 T3 AT O ‘° RACIATION MONITORING SYSTEM
B A Pa% Cnanac & Z9TE oy R N LTS N, SN UMLESS OAK RIDGE NATIONAL LABORATORY
B | At PAR twniacats = Tisled. 318641/ 1] EAB) ) ShRR rcon areaTEs o o
NO. REVSIONS DATE {AppD | APPO rasemonn £ : UNION Cmm?f“Nucmn OMPANY
o~ OAR RIDGE, TENNESSES
e ) MGEIPTIO oy APIROVLD
/] /u}y ] i . . ’ -t Jlfil’:';'?-'}f'%“ ;‘;'h' M’r” (iijfi’
) - : : woun 85" s 120" VoAD-HH-2- 40641

 

 

 

 

 

 

 

 

 

 

 

Py

207T44KH 043D 3

Fig. 2.9.1. Location of Fixed Health Physics Monitoring Instruments.

 

 

 

 

 
 

 

 

 

 

 

 

343 ‘t

 

 

 

 

 

 

 

 

 

 

 

 

 

  
    
  

 

 
  
 

 

          
  
    

 

 

    

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

fl N . . ) ‘ | A
1 S : — : - - N
1 : L '#M"fi,fi,".g B3BAY5 CS‘H»&L;! kLo !“grflbogn wrwotat_| -xmios ;:nr:;mm | Boitoge
. At
—8— 0]0/0/0]0]0,]0, w0
‘ s e © whouas
T e ofl of of of on O e
- SO 7T, < ';I_‘,' conzammation | CAUTION ’ :
l‘fficr 7 ® . T ALAtM @
any_ _ Maintensnce sermce || f‘f’?’;f’\ s T msg) O O O Spase Nymbers #ssigned -
Shop ervice < o~ . : L RESET Air Momrtors - 7006 7o VO
= ' © Roem o ‘ iy Momrtors
o O - O O ! O O O O Moenitrons - 7018 to 7020
| R ’ 6‘.:@/0: ‘ & e ® ® © ® @)
' «9 A } RE 7005 . RESET ‘
o oo ~. |
N me RS arror Q2505 £ 1 oy 1 z 1] z 2 4] o |aesesare | vipren
— iTh RoOM | A G T AR,
l o + BT [ A It TS (M (B e (R e | s
e Speciat ( N ® & O & O & i ¢ o : )
Equipment MCIATION -~ fm~ o -
. Room ALARM (‘ T:\ : O i O @ O 7 O - O
Mafg:elr;ann X REACTOR sl | svsTEM T | 24
- £ ceee L - «“ O ‘ : : - ~ O : ‘ l-— —-I
l ' : BLANK <
f% ! 4 ' W ) L\ —T'
. . _ 1
Cell. - or 2021 (:) © P g O “ Lo YA C & o O e, O ® s-mcaxza;g:_l"ron 3 |
- Ef i L
[ i
£170224-14 o _L g2563-¢ R 1 4 I3 ! 1 2 2 s 3 Ll bl
r y T T )
RIOEAIS . = |
| |
L E
¥ i
Blower , -le i |
House 0 o rM 7023

S
—J‘

   

   

- STACK MONTOR,
f CENTRAL ALARM CHASSIS @20y
Dsesel i

 

 

 

 

 

 

 

 

 

 

 

 

 

 

a

|

X

8

“
o

 

 

 

 

 

 

 

 

 

   
 

   
   
    

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
 

 

 

 

 

 

 

 

 

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   

 

 

 

 

 

 

 

 

 

 

 

' B Q-23159-10 ‘ . oe "";fi"fl'"}
R P23A T 023412 y ‘
. Wes# end of Roorm : P D D
. 1 . "
BUILDING 7503 ELEVATION 840'-0% LEVEL b |
LEVEL b X T024 i : ]
RATOZRA- & i N
W w2509 a2 / POWER SUPPLY :
) ‘ L Rroozaac T By 7502 B ke to b . 0-35v p.C. NUCLEAR BOARD 1S
- : W O5A NJE RVC-36-5
Y - <
o i ra AMCIr b e ;
. . , & . !
: Nealth Pysiedl Doerafine  ||Goerafon O,aerarm f
Offl'fl??fl Féerflv Crew Chief ||~ Crew v _3:_ ey gy Instrumenty Instrament ‘
o = Snhop Sforage v
& ) E Main :
[ mxrO2S _ fl";g::-; f?bange inst Engl . e e R e e e NOFES:
fod = oo = com —_—
- b U ‘ . Accepfs a/arm 5tgnaf5 from mon:/'mns & continvous 1. Central control snd annunciator panel fo be
- ‘g‘a’:':;” Room e, ’ 1 ;_g?gg‘: / i ,fifi%fi:fl'jflm air monitors, Alarm outeut on Wi level” indication, located in aynf,ary control room (cemmon)
: Dots Nota#2H " ;r ‘” - RE 7028 " . eset each module by switch on unit. =/3 reg'd. on Nucleer Rarnel*5
" Room ore see ik | ! — eee /e P Accepts alarm 5;gnals From 3s meny as 6 model @«2563+ 2. Single annurcigtor for ol slerms in mérn
: Moin 'L — - Bl 58 o0 2 | Mo ‘g;.z g,’b :, Jule | Odules. Output signal if 2 or more are alorming- con frol room.
Controt Room @lamm & 7o I = | @25 ANO Modvle | soir peset, 2 - reqd. ) 3. Reacon &1 7023A% islocated af New affice Bldly.
A FA T02 281 K1 70234 -7 : Accepts @larm signal from alf Model Q-2563-] modules.
Moanle 1 9102 adove 3 Q".‘:‘;’%’f, A,’{f;"g,f;f *or{ Buzzer sounds ar? each sucessive alarm.
€ 4 Silence buzzer by switch on panel. |regd.
Blank . )
: 4 | Modute 4 reg'd,
e vecy) @ Front .
Rela Relay coil paralie/ed wi ' bugzer in Bype 3 unit operates 8pole, double
. 5 gggg ;k;’ Madcz'e { M.ro"{v relay contacts when actuated. ( @ 2563-17 ) I Req .
: i -'L" Maintenance fi [arm Monitors_on Contammaltion Alarm System _ Conduit Routing ‘ DIHE §3118
2 . Control Room vent house (Zoufof 4 cause aférm] Condui'} Routing 554
o _fl- RTIANTI Fley 8621 -0 i A Control Peorm REFERENCE DRAWINGS oW, N0
L m e | : Basement - North . - -
i . c2i-on LEVEL . RI 702341 AJerw'ce Tunnel winin wwommert J, A, Russel! ‘
Lo ' BUILoING7503 " ELEVATION 63¢ O  Transmitrer Room , BL06. 7503 FACILITY RADIATIGN & o:\b/err.t.ug\«mJ
N Fele 7 " = ” g Monitrons on Radiation Aidrm System WARNING SYS TFM
—_— Modute s 4 wes offiieare  l52347/40f2 ) Teoul of G Alarm combindfons)
5 M«;{gkzmttm»mm-n 23] ] LEGENDpr > | Contro/ Room " MSRE INS TEUMENTLOCAT}OMS
28 ,wg’ . ;-wg:a-u Yo I4 6-29-¢4 SYMBOL DESCRIPTION : Hish Bay - Sout
18 L Ada RITO2IAY fo 41O 22245 » Herm High Bay - west & CENTRAL PA NEL
TET AT B M. Pailare Medude A | % Basement- North - FRONTV’EW
Yo PATORIA3 £- 8, ade RTRO2IATH M43 A | 8/co. Central Panel (Nucicar Boarg’s) | © Basemant - Center INSTRUMENTATION AND
=t =L Counf Kafe Mefer, (Bets & Gamms) Transmit ter Room %
e e [ Constanr Al menifor - @228~ | | OAK RIDGE NATIONAL LA mm
N Ierae T ° 1 Signal light : ‘
v L Remots Monitron - G-1158, :
i - il Mobria Unit - a-2240
i B - | Hand & oot Counter — ¢ 0‘/33.9 .

 

 

 

 

 

 

 

 

 

 

 

Fig. 2.9.2. Instrument Panel and Health Physics Instruments Locations.

 
 

Controf Room Wigh Bay-Sowth Hgh &

 

344

ORNL-DWG 67-7830

Constant AlF Mopiters
Q@-2290 with Inst. Failure Bones Q-23:/8
A

 

 

 

 

anr; rom 2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Basement-Mer’h  Troasmitier Am. Sasement-Conter Service-Tontl "yt Koy -West Wi Bay- Soulk oFfices 2asemeant- North  Transmitier Moom* Service Timmwel! Modiie Uni?
Monitron Monitran \Monitron Monifron CAM CAM CAM CAM CAM
¢ 5 4 7 2 ¢ 5 5 7
u 0 2y 1008 & 2004 e, g0
Neot trod fo

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1402 20t 20105 2] M Yovi Nz 2 947
Tl i Indicater] Indicetor Ined) ¢
Input fw‘ Inpus Input r’l":;‘l;‘fm
Mo Module u%c Module
o o] o o A
y ' £ ' Z 2 '
‘ ' € ‘1 & ‘ A" -
w f 1
1 10258 1 1
MIRE ety
25631
1 2-n
o F.R.§C
F? 4
Indicatys Module Algrm Merrin o‘,::::c Lo
Tocatioh in recks T ——e s Meduie Rainy
‘ : A
I Purin
JoMmmy L4
- Contras
Algren
Chagais .
1 dIss-10 Shacik Aon/?) -t
Sytem
ogw
Mlay
Contamination l
Alarm T A . Me.
{Tol ckA te didp 2500) e
‘ QoooooouLLoLoon
Fon A

Fig. 2

 

 

Rodie arm
(Foh <kt 10 iy 2500) Building Alerm Beacens
Heorne RITORIA-1 TetS
A 2043 A e AG

.9.3. Functional Block Diagram of MSRE Health Physics Monitoring System.

 

 

 

System

 

 

o~
 

 

 

 

 

 

 

 

 

     
   
  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  
 

 

 

 

    
   

 

 

 

   

 

 

 

 

 

 

 

 

 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
 

 

 

 

 

 

 

 

 

   

 

 

 

 

 

 

 

 

 

¥ i
r 1
)
o - Evic. Modules Min. Evar. - 84T A3 . &- Horn Boxes i ' 072 -0
——f 06! - ‘ - . =
. ] w28 Consale Mirn?. 64 4870 k 311 YL 3ot-to
f &12+15 d L Test &ec 3 b s I?
b 1-8-15 k&35 5 0’ 2 e" X H3 fu43 'L} i |
. ki-8-5 k29-¢  pey i2e " Y | Tonk Low i ' t
- Hg ki
3 e
) h A K 1-12445 | _nYa el oo Low ‘ N . ' .
. : , ! " tal. Yrons,
- Ruset = | - - . .
‘ Fad 1 c“’_‘"é: _“ “}T I ro0®Hiss, I ‘_j =K s ]. 3128 & 1 .
Ki-d4 (294 bomeg L 1’ T ' { ] ]_ !
- 3-i-19 i . ’
v ms fory l’:,“::: » x| ] 5 T KAL-A HA-B s1ef .
Q. et D24 g ? . - |wass &, ————— soke o
~ K:G;‘lfi grs | - Ke ‘ e E“E 812 | 5.8 39 sm | 2u2 it 2 037
T Exka s e 23 — . e
i :l Ane g37oe3 L o < A AGS RSS A4 B Q7 85 €11 (29 e €45 DM Dt of ‘ fl » 2‘ 069 241, 54 ¢ miaze ks g
' Morme/ & (31 I R I T Vool : el s Evac, Beadons (15Total) | Pur supm] e |, o &
‘ 2 ) & d
1e flrasle o 56 EIR 24V, D¢ Interruppedtwice per minllo Manilors for - Reset " C : x » 9t !jfl — % on®
D e K 3 “ - "
. - - : : 3124 ‘ -
8o : LU LU L L 8 feso oo foe Los 5y s U re7023A} teRTT023A 15 £ ' Relng Module
G 2con’ KA-L & K tg] 27 K3 & 8 s=ix ez P )
2 : ool PS4 gegd 3 a2y 64 220 BB TAd BT pees 2d4 " 563-!?
i Ds2 ! 1 D‘.ff
‘ 312 2 \2et kst I o o
1mh2=1 A | pee s+-5 b2
=) 1 . ‘ S . :
Sz | . o% _ ] :
oy - . v _ : B D70
514 8-y D26 297 H )
Canfamimd?ion . Radiation pss . i
e AHrm 3.9.¢  Alarm _ »
+ s pes . 1188 .
¢e9
BT Stack Mamfilnn_q
e ys 7023 20153 w3 7028 T ey 2374
O Norrmal O Normal D3s
-————— . csy .
Disable Disable :
————ma gt "' 5
k 340417 Ty KeA= rryc. Jg.s’km. |
i ity Q232458
28 §C54 ) (\
. D3¢ Lo
x 1-12: 6 C s l
'ie AK-C O-C Farlure Alerm ;
@ To Annunc, Ne. :
k127 Main Control Board
\
si4 k B2o 1 xcf5e i "
‘I i
. REFERENCE DRAWINGS -DWaA. NO.."
Contamimation Alorm Radration Alarm M.
Telaphone Line fo Telaphone Line to : o scwemmny o A. Russel! Jr:
o Blade. 2500 Blde 2500 ; F'ACH.ITY ?D’AWONIC’ONTAMINATI@N :
e , RNIN TEM ;
3. | Add Pr. Crt mos. 5 22844 YR - ,4
"'4" -eontaet moved #up k-1 16296 . o
P YT _*"“%a ; ELECTRICAL CONTROL .SCHEMAEIQ R
"Ad‘? D¢ mlavldrm mlé-fl ’”?ll‘*"‘lf : e
[ 3t 5 415 torn, mnwauon o2 PHTREL ™ : :
L [ app0 | APPD ; INSTRUMENTATION AND CONTROLS DIVISION
e L | OAX RIDGE NATIONAL LABORATORY
.- —id Lo m mmnuemu COMPANY
bl 8 : : : iy . AR
Lt . e

 

 

 

 

 

Fig. 2.9.4. Electrical Schematic Diagram of Health Physics Monitoring System.

 

 
 

346

ORNL IWG. 67-7843

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

— e ——— — — —— — — —
- < nmmm
_ —_— Ifl.z*
o), :
T o~ o~ ~N oy
LY >
| P |
— N— P2 S L]
- 2H —f €2 _ S
e by
— 12 1 v
—fTA 02 ¢
o
—] &l — S
1025 27 _
—A 7 1 3] Q
R o |1 w.—R =
—i $7 _7 O.J
-1 P! ! 5
Lz_luw..l £/ m
e/ M N
N =i H R
H— 0/ ~
m— z
-2i-g M _ nrcu
e S - 2
~— O - .w- _
—_— '

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3-1 [~|~

 

 

 

 

— — —— o—

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

r |||.ll.|.|
\n
rlllz “ ¥
—— 53— 5|8
I~ti.|_ ! 4f-.w”'-
= Yiqj3(
¥ ~ SP
| Sladfy
9 Ny
Z R4W=J
6 Q
fl'\l&l ol
"
=

 

 

m————

 

|
|
|
_

 

Central Alarm Panel Wiring Diagram.

Fig. 2.9.5.

3

~

 

 

 

 
 

347

ORNL DWG. 67-7842

 

M/-LEVEL
MPUT " pip I

 

 

 

 

 
  
 
 
 

 

> Fin /5
o8
—»—> P /4
e

o—> Lin 13
o7
—»—> Ln s2

 

 

I?
3z7 RED
- LEVEL
I EATOR

 

Y

Note . 2 #4

 

CAUTION
WNPUT - Pin 6

 

 

Prrr 8

Prry 7

 

 

 

CH_rinn
JALOICATOR

 

 

 

 

 

 

 

 

 

 

   

 

 

L > n 1
Notes 14 [
>— > FPrn 9
# Prp 10
211
&80
Yew
e
2Naé3
IN::!;ATIVF
NPy Prrn & o¢
“‘”—') Ay 5
o5
I E > »W—> ~re
Dé
= J > 2 3
o

lf"t? _IT

FOR NON-LATCHING OPERATION <~
USE A CONDENSER INSTEAD OF
A JUMPER FROM A2 TO B2

 

 
 
 

j

Lz

ICT WarTE
NOFERATIVE
INDICAYOR

 

Nore < 2¢ 4

Fig. 2.9.6., Indicator Module.

 
 

348

ORNL -DWG &7-7834

 

     

 

 

  

 

 

 

 

 

reev 5 £y 15
THIS JUMPER PROVIDES I T >
2, 20 2, 12 £73 T !
TWO-OUT-OF -SIX ACTUATION éa.%a éz?: Tix  Ssico Skévo SEice g 342260
OF RELAY K-1 i
1 P &
I & & e o - H’g"”‘ i Priz 7
s | F ] Pir &
P I €  AAN—— fi" P &
) «— -’W\p———lfiz Q2 <t L ee For &
v 13 es [ ‘,‘j\;" Saret ¥ IR0 Cort —> P 3
Pra 18 &——AN—1e ar Loce
e 1 P4 €6 - o3
Forr [ €E—— N—d \ SNEIE
£
P S . —
£E 27 £9 ALre "~
Prr .9 € Vv 300 o s8¢ 'gzaw
Godd P f
~

 

Fig. 2.9.7. Coincidence Module Circuit Diagram.
ORNL DWG. 67-7832

 

   

1 ey —> Lo S5
Prry 13 C€——— L7
coo Pin @
FPn 18 K&—————— ISV A, VI
sxolafion Crarrsforrrer
Frr W E— ¢ Sercre
"

“on 1O E&——m—y 5 Pin i4 To operate remofe &larm reldy (@ 25e3-17 )

D7

 

 

 

 

Pn 9 % Jplrcorn
geo Sfecs
oy o,

P 8 &——rdy | Sl 57a

iy €
. ) £
Porn 7 & &2oo 1000
Pn & e———;——.
Fl
Porn & e} YO n.
S o

z
BUZTEL

lr d @ e———y LE€S€7 o
Pn 3 g

%e;
oL
P I <«

 

 

 

 

 

Fig. 2.9.8. Buzzer Module Circuit Diagram.

 

6ve

 
 

 

350

ORNL IWG. 67-7836

WESTING HOUSE
CLARION WHISTLE

 

 

 

 

 

 

 

 

 

N\

-
-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

( 7 )
H—-
— &, i
O-z C;/ 3 Test Pecept- \
M E-q-:n IO~ !
4 19 =¢ m_““tp'; i
3 7 ]
—0— o— 4 1
9:} } o ) J::i—g g S
o—! o t o—a ;’ B
2§ o83 i
— 4 —AF—1_ 9 Hpt—
& s 10—
RA 7023A] % i H-t
V2 ’g IN3253
HORN BOX-|¥ Froor # =

 

@2358-7

2\

T
$

 

Ne Na

 

 

 

 

 

 

Fig. 2.9.9. Air Whistle Schematic Diagram.
 

351

2.10 PROCESS RADIATION MONITORS

2.10.1 Introduction

The process radiation monitoring system monitors radiocactivity
levels in process pipelines, vessels, and operating components. This
system is distinct from the Health Physics Monitoring System, Sect. 2.9,
which is designed to warn personnel throughout the reactor area. Signals
from the process monitoring system detectors located on or near pipes and
components are used to produce alarm control signals and safety system
input signals when activity levels indicate abnormel conditions. These
monitors also provide information which indicates operating conditions of
various parts of the reactor system.

2.10.2 System Description

Two kinds of detectors are used in the process monitors, ion chambers
and Geiger-Mueller (G-M) tubes. The G-M tubes are used to monitor levels
up to 100 mr/hr. Three types of ion chambers are used. One is a stand-
ard, commercial Reuter-Stokes chamber (Fig. 2.10.1) used to cover a range
of 30 mr/hr to 300 r/hr. The second (Fig. 2.10.2) is an ORNL model Q-2818
and is used to cover a range of 100 mr/hr to 5 x 10% r/hr. The third
(Fig. 2.10.3) is a special high-level ion chamber used to cover a range
of 10% to 107 r/hr. This chamber is of special design to withstand the
high radiation intensity and temperature present in the reactor and drain-
tank cells during reactor power operation. It also has mineral-insulated
cables sheathed with stainless steel to satisfy the cell containment re-
quirements.

A typical G-M tube monitoring channell consists of an Anton 106C
G-M tube supplying the input signal to an ORNL model Q-1916 logarithmic
response gamma radiation monitor. This model Q-1916 instrument was de-
veloped to meet the requirements of most gamma radiation monitoring of
reactors and in-pile loop systems. It has been in use at ORNL since
1958. The G-M tube (Fig. 2.10.4) is enclosed in a stainless steel housing
less than 1 in. in diameter and 8 in. long, and it can be located up to
500 ft from the electronics. No preamplifier is used. The scale indica-
tion on the monitor is proportional to the logarithm of the radiation
level over a three-decade span.. Full-scale indication is normally 100
mr/hr, but it can be ‘increased to 1 r/hr by use of a different G-M tube
and by appropriate changes in the electronics. While the unit has a
normal range of 100 mr/hr, it can handle levels in excess of 100 r/hr
without impairing its alarm and control functions. The monitor provides
an upscale electronic alarm. The alarm level may be set at any point
over the readout range, and the alarm point may be read on the meter
while the setting is being made without tripping the alarm circuit. A
relay which is energized during normal in-limit operation provides the
alarm and control signels.

 

0RNL Instrumentation and Controls Div. Ann. Progr. Rept. July 1,
1958, ORNL-2647-

 
 

 

352

Figure 2.10.5 is a block diagram of & typical Q-1916 monitor, with
circuit details shown in Fig. 2.10.6. The G-M tube detector is operated
at 900 v, and the radiation level indicated is determined from the average
current through the tube rather than from the pulse rate. Radiation in-
tensity causes the tube to conduct. The voltage drop across a resistor
in series with the G-M tube provides the input signal to the averaging
filter. The filter's output, an analog signal, is fed to & dc amplifier
having a logarithmic response. The amplifier is used to drive the alarm
limit detector, panel meter, and recorder. The alarm limit detector
drives a DPDT relay which is used for alarm and control signals.

The monitor is fabricated using modular construction; the Q-1916
monitor assembly contains three plug-in modules (Fig. 2.10.7), each of
which is a complete monitor. A single power supply (Fig. 2.10.8) for all
three modules is located along the back of the chassis. A single-channel
unit with integral power supply is also availsble. The Q-1916 monitor
was chosen because of its operating simplicity, availability, small de-
tector size, ease of monitor replacement, fast response, and fail-safe
features.

An E-H Research laboratories model 202 electrometer is used to
measure and indicate the signal produced by the ion chambers. This
electrometer incorporates a 5889 low-leakage input tube and double feed-
back. Negative feedback reduces the effect of cable and source capaci-
tance, thereby improving transient response; positive feedback reduces
the input capacitance at low frequencies and further extends electrometer
response. The seven input resistors from 10%® ohms to 3 X 1012 ohms,
selectable in seven steps, provide a wide operating range. The elec-
trometer has an adjustable alarm set point on the front-panel meter. An
alarm reset button is provided to reset the instrument after an alarmed
condition has cleared. It contains a DPDT relay to provide alarm and
control signals and it produces an output signal scaled to drive a O-to-
10-mv recorder. A 150-v power supply is provided for chamber polarization.
Figures 2.10.9 and 2.10.10 are a front panel view of the electrometer and
the circuit schematic respectively.

Excluding the Chemical Processing Plant a total of 16 G-M tube
monitors and 12 ion chamber detectors are used for process monitoring at
the MSRE. A list of these monitors, their function, and their location
is shown in Table 2.10.1.

The column in Table 2.10.1 labeled "Number of Units and Type of
Coincidence Circuit" describes the number of complete monitor channels
at one location and how they are used to increase reliability. In a
one-of-two circuit, either monitor reaching the alarm set point initiates
the desired alarm or control action. If either monitor fails, the other
unit is still available to monitor the system and produce the required
action should it be required. With but one exception & failure of the
monitor power supply produces control and alarm signals as does any other
failure which causes the monitor response to appear like that caused by
a high radiocactive level (see sect. 1.5). The one-of-two system is used
in those applications where the output control action can be tolerated
during an on-line test.

In the two-out-of-three coincidence systems, two monitors are re-
quired to produce an alarm or control action. This arrangement allows
Teble 2.10.1.

 

 

Process or . Radiation level Number of Units
Instrument Detector _—-ms & o and Type of Control or
ggmfggizg - No. Detector Iocation® Background Alarm- Set, Coincidence Alarm Function® Monitoring Function
" : Point Circuit
Fuel pump bubbler RE#596A, B, C G-M tube Eagt of < 7 mr/hr 20 mr/nhr 3 Alarm; close To prevent fission gas backup
inlet lines ‘ transmitter Two of three bubbler inlet in fuel pump and pump over-
room at 840- valves flow tank bubbler helium sup-
£t level ply lines and ensure contain-
ment validity
Coolant pump sweep RE-528B, C G-M tube Vent house < 7 mr/or® 20 mr/hr 2 Alarm; emergency To monitor coolant salt for
gas One of two fuel drain; fuel in leskage through
fuel pump off break in heat exchanger
Helium supply line RE-500D G~-M tube Water room < 5 mr/hr 20 mr/hr 1 Alarm only To monitor for fission gas
One of one backup in helium supply
' header
Fuel sample box RE-675A, B G-M tube High bay < 7 mr/ar® 10 mr/hr 2 Alarm; close To indicate and comtrol
exhaust Cne of two valves in line amount of fission gas geing
‘ to filter pit to stack
Fuel pump oil RE-0T1B G-M tube Service < 7 mr/nr 20 mr/hr 1 Alarm only To indicate activity buildup
tenk. tunnel One of one in cil
Coolant pump oil RE-OT2B G-M tube Service < 7 mr/hr 20 mr/hr 1 Alarm only To indicate activity buildup
tank tunnel One of one in oil
Reactor cell con- RE-565B, ¢ G-M tube Vent house < 7 mr/nr¢ 20 mr/hr 2 Alarm; emergency To indicate fuel leak into
tainment air One of two fuel drain; conteinment ares and prevent
close valve excessive amounts from dis- w
. HCV-565A1 charging to stack &B
Off-gas sampler RE-524, 528 G-M tube Sempler box < 7 mr/hr 100 mr/hr 2 Alarm only To indicate leaks in the off-
at vent One of two gas sampler system
house
Charcoal bed dis- RE-5574, B G-M tube Vent house < 7 mr/br® 20 mr/hr 2 Alarm; close To check operation of charcoal
charge - One of two fuel and cool- filters and prevent excess
ant system activity discharge to stack
vent valves; and pump lube oil systems
close off-gas
vent valve
Fuel sampler vec-  RE-678C, D Ion chamber High bay < 7 mr/hr¢ 25 r/hr 2 Alarm only To indicate when sample ex-
uum line One of two change area is free of fission
gas
Reactor cell space RE-827A, B, C Ion chamber Blower house < 5 mr/hr® 50 mr/hr 3 Alarm; cloge To indicate break in the water
coolers 1 and 2, Two of three valves 1in lines in the cells and prevent
drain-tank cell water supply activity from escaping the con-
space cooler, and lines tainment area
fuel pump cool-
ant water return
line header
Reactor cell RE-6000-1, 2, 3 TIon chamber . Resctor cell 3 Indication only Indicate operating levels in the
‘ No slarm circuit cell
Drain-tank cell RE-600C-4, 5, 6 Ion chamber Drain-tank 3 Indication onily  TIndicate operating levels in
cell No alarm circuit the cell
Radistor pit RE-6010 Ton chamber Radiator pit 1 Indication only  Indicate operating levels in
No alarm circuit the radiator pit

 

83ce Dwgs. E-HH-A-55588 and D-HH-B-41668.
bSee instrument flow dlagrams for controlled element.
cAfter shielding detector.

 

 

 
 

 

 

354

the monitors to be tested, channel by channel, without actuating the -
final alarm and control or safety circuits. Each monitoring channel o/
can be tested completely up to and including the alarm light and the

alarm and control relay in the module. The two-out-of-three coincidence

arrangement is used where maintenance and on-line testing of any single

channel must be accomplished without producing control action and where

false output control action caused by a failure or malfunction of a

single channel is highly undesirable.

All the detectors, except the high-level ones in the reactor and
drain-tank cells and the radiator pit, are capable of being tested with
a radiation source. A %0Co source is used to test each location.

In areas where substantial background radiation exists, the low-
level detectors are provided with lead shields (Fig. 2.10.11). Shielding
reduces the background and improves the signal-to-noise ratio, thus pre-
venting spurious slarms from a rise in activity level at another lo-
cation. These shields consist of lead sheet formed into the required
shape or of concentric lead-filled pipes. The shields are designed2 to
facilitate the replacement of detectors and are huilt with access holes
to accept a radiation source for calibrating and testing the monitors.

No shields or test sources are provided for the high-level ion
chambers since their operating range is in the neighborhood of 10° r/hr.
The high-level chambers are mounted at selected locations in the reactor
and drain-tank cells. Three chambers are located near the wall of the
reactor cell, one at elevation 844.5 ft, one at elevation 838.5 ft, and
one directly over the reactor to measure control rod drive dose. Two
of the three chambers in the drain-tank cells are mounted on the walls,
and a third is mounted between the two fuel tanks on the thermocouple gig
tray.

The chambers are filled with nitrogen, employ alumina insulators,
and are built with mineral-insulated signal and high-voltage cables.

The chamber is 7-7/8 in. long and 1-1/16 in. in diemeter. The chamber
sensitivity is 4 X 10712 amp r~! hr; 98% saturation is obtained in a
field of 107 r/hr with 350 v applied.

Only one chamber is monitored at a time. This is done by using a
single electrometer and a six-position selector switch. The selector
switch connects the signal from any selected chamber to the electrometer.
Two high-voltage power supplies are used, each supplying 350 v to three
chambers.

All the process monitoring electronic instruments except those used
with the sampler-enricher system and the pump lube oil tanks are mounted
in nuclear boards 4 and 5.2 The other detectors are mounted in panels
associated with their respective systems. To obtain the required
reliability for the monitoring system, the ac input power to the monitors
is obtained from the 25-kva emergency power system. In addition, in the

 

2
Process line detector shields, ORNL Reactor Division Drawings

D-HH-B-41527, 41528, 40551, and 40552.
3
Nuclear control board panels 4 and 5 layout, ORNL Reactor Division
Drawings D-HH~A-41532 and 41533. kaJ
 

355

one-out-of-two monitor system, each channel has its own separate power
bus, providing added éperating relisbility.

With the exception of the six high-level, in-cell monitors, all
monitor outputs are transmitted to the data system for alarm detection
and logging. FEach monitor is provided with an individual alarm indica-
tion. In addition, the alarm signal from each monitor station is trans-
mitted to annunciators in the auxiliary control room. These annunciator

signals are interconnected and transmitted to a single annunciator in
the main control room, labeled "Process Radiation Monitors."

 
 

356

 

,3
™
H.
o
O
-
o
I
o

 

Stokes Standard Ion Chamber.

Reuter-

.10.1.

2

 

Fig.

 

 

 

 

 

 
   

 

 

Fig. 2‘10.2'

 

ORNL Model

 

Q-2818 Ion

 

 

Chamber.

LSE

 

 
 

 

 

 

 

 

 

. Fig. 2.10.3.

 

MSRE Special High-Level Gamma Ion Chamber.

PHOTO 89246

 

8S€

 
 

     

Fig. 2.10.4. G-M Tube Assembly.

PHOTO 89243

 

 

6S€

 

 
 

 

 

 

 

 

360

 

 

 

 

 

Rgg:“AT'IAON AVERAGING LOGARITHMIC

DETECTOR FILTER AMPLIFIER
GM _ - >

. T [B]

 

 

 

 

 

 

STRIP CHART
RECORDER OR
DATA LOGGER

 

 

 

 

 

 

 

UP TO 500 ft OF 3- CONDUCTOR
SHIELDED CABLE

Fig. 2.10.5.

 

 

UPPER
LIMIT

DETECTOR

ORNL-LR-DWG 3M{66AR

ALARM
INDICATOR

 

TO
RELAY ®-CONTROL CIRCUITS

 

 

 

 

- PANEL

 

o METER

 

 

 

 

 

——

CONTACTS TO
— ANNUNCIATORS

 

 

 

ALARM
SET POINT

Block Diagram of Q-1916 Radiation Monitor.
 

   

 

 

 

 

 
    

 

 

 

 

 

 

 

 

 

 

 

 

 

 

    

  

 

 

- 124
@ J R/
: frey dw
ol
e CAL
Ras o it anr)—Lu - < R
100 e R9 ° Y)Y
1% Im : c' Imeg /% *l
m L ; ‘ i "PTI-tDng"f-' 34?'4'
A R WA
170 i K0 i
;fivb 4. femez| 3
- - S RH T \tl‘f’ 2
. : Fmeg | 20 S/
1 rxf - A e e
; | ‘,‘”_”,' Treo %ue
. Amp. 3 0., ‘
. Y
. ~/150¥ l--A
3 :
| |
i -
! 7
: ADJ.
- {72
e e e e e e ey Scx
[ - Al Aty
. ‘ . 3 r
1 | A\ !— ‘ A - A
’ | s | "
T ts il 2 -
! - Feeabsck . . e
3 _ Nefwark fer Y te AR -1 A {
; (See 5160 ] ¢ Ay 1 Cnéa r3e
: '  ) 2 T 17:5:7 | Amph 106805

 

 

  

+250V

 

 

 

 

 

3 0¢ L@M@dfi! THMIC FEEDBACK
METWORK* ClIRCYUIT .
CRI thry CR7. INESIA

l ' R3IE thiu £49, 3W, 1% a’eposrfedr;rban.

 

   

R3

 

- e - - — o eem m e e ae o

Q Al grourd._ marked thus
must s Fr. chassrs af &

'Cammo- pornf

  

 

S 390K
iw

 

 

 

 

 

~ Vigwh - Pnt vy

 

 

 

 

 

-150V
cs |
L5 T
‘ Rwary fionel_“-
M:flru/

Epoxy Fiberghass, MICF-A77 groe SEE, Bu5 dritind

with #33 (.//2) holes spaced ,{ Mount @-900-13/ de? #/

sl termina! fugs with slofs a? 90° wifh
1-; /s of ferm. bd ir sit heles excapt
those marked 8,
® Enlirge with #27 (. /44 dm’/ and mowunt
SYvds 0.900-/42 d&’f */.

Fig. 2.10.6. Radiation Monitor Single-Module Circuit.

 

 
   

 

 

th
)
k2

t4)

($)

ORNL-DWG 67-7516

ALl regysiors 1 watl 30t 1wy heted, All resistnrs 5% excejt us noted.
Ba denptes Stenap cathen Jilx resistor, TI Jdeautes Terar Inetrument Co,

cur film I‘Pll‘il(‘l

After uM)awing instrunen? 10 ware uy n“roum- ely tan wanpter, adjuse

the Yobtarr wi the wager o1 the ‘Rotirence” 1ot ta 30 nv bith resject te
grouvgd. Thar reajing shouls be wure with o capite) or diffeisrtinl velimeter.
Sitrtoke *Catilente  -v:itel, M), depressed, adjust the ‘Colilrate’ got. te
wrveln metor rorcinn ot 0.3 MU/HR Ber 14 100 MR srade ar 3.0 MRAE for

the 1000 MEME wu!y

For smstew . vte busang weters nerbed 1o 100 AL, opply o 8 sott a0,

srgnal Lo the arpat wrs «at the slore adjuat pot, R208 1o pive o meteyp |
reading al 3 VP MR, Futr anetrurents Laving meteis washes 1o (OO0 W /WP,
ap1ly » 3 valy e, wipus! to the injut end set the slope s gece st R20a,
tO #¥ve 5 netel fruane ol 300 VR/AE,

Revint cteps {3 st 1 4).

NOTE.: This reproduced t‘rampareflcy of
I& C Dwg. R-19/6-/ was made
of Pev. 5 (Current as of Aprf/ &5)
for M.S. R.E. ONL)’

 

Aosg, wo - Blgnken * . m
.b__l,__h e : : e £ 9-¢

/el
f

{

BES |
+_ ' 4"«-?-":1 22k RemrcommnrTY
v500) 4.1 1. 2.26. 20 250021 W'M

£
L oee
Pir ER
v
”Qf:a,fi,k(—.‘ . '.;'—-‘T - o
ClagArme, Jiwa: 5
; Ipzt. ROC wa: 370 °,
[ oo |R2CS AT o Ness
m“.é S oL oy dded Do n f” "‘"“‘w" \-‘ {

 

R waz 8. o,
K-6wors 2mes ke ;
wes Imes Kitwie

Cotipanior Lrawipdy.

| ‘zz;xi‘;'::‘: In 2L et e Praver Oty ry,
R we AT ] J3:16-3 1 " . v

i

was 2 TOR re: ocate- 11,
A r: mov, L4 L3d Pda
CR1, & wer IN&ED

S-S F(.'r : | P PR
IR -t Al % oy ces

 

)y -3‘\l\

 

Term @ 9¢C- 18! 3
Ws CTC-£5- ok !

Stud £ 9C u‘e ' ‘

witr T K4 96 ‘ s

: ,‘\/ )

X M ifard

 

3

 

NPT AWE to K7 ST,

  

s’ ALrT, 0t o Wobs Oax Rwaoe NatonaL LasoraTORy
ownhe |5t e bog '
I o P'v -

4.

 

8 RaTeSe ALl L

o NSTRUMENTATION AND CONTROLS DIViSON -
Pty i T

 

 

 

 

 

 

 

   

 

I — RApiaTion MoNITOR
. SINGLE MoDULE
' . Crarcurr

 

 

 

 
 

 

            

e

" ‘
T
[
! .
~
.
,
. .

     

 

 

 

 

362

 

| I -4

 

Fig. 2.10.7. Three-Module Q-1916 Radiation Monitor.

 

 

    

     

 

 

 

   
 

 

 

 

 

 

&M Sho-dlo

AN -
cni /'f 13v o~ "'

78 {' re .
A Slo £l

. .

y Py o 774
C o L Perr =

v
LML Spec, G-580-5/
A\tores #06.982 5060

  
 
 
 
 

Shsrey POE-838-1667

+ 350

 

  
  
 

31206 TO8-838-15¢7
e~ S

 

   

I
270K
i w -

W
~

RELAY 1o
Srgaea Rerav
4240 100006 S/t
Connection Diegream

&,

¢

 

 

 

 

-— i e o —— —t— —‘j

 

 

 

 

orricron
BROAE

 

7

 

=\

 

 

 

 

r=—

 

RG-1282 )0 -

  

 

 

 

_'
-

 

 

 

v

 

e
| ;g

 

 

 

 

 

 

 

¥

—

 

 

When IR probe (Q-/9/6-22) #is'y. /s used,
V! G0 must ba chronped Ffo SIE2,
£S5 changad fo [1Emeg W IEC-MVX,
This cHABNgE reguired w1 ASsE (Aerrels
wheh have IR probes snd no other.

 

\
4
4 N

] e o | e e e e o . —— e
Ny oy

—

— — — m— -

 

 

 

 

 

 

e - — — -

 

 

 

 

 

 

CARRs e e

2263 gru e o

Te

f
|
|
|
!

. . - v o s m——
- e A N 0 M
=2 s ——:..z@ RECOR ]
e A 4

I Ry e

N

d
639/

|
Fe s

N G

, g 1 L Ber e climp 10 12 e p0g -
A = A J wEL I NIIO2AOSU-AP %8S, "E o5 e
. _ . '
<2 -—_,.L . res
7 ook
VI-;A N 1...,...3""

Li 42
(c/“c I7-917%68 - 145.
<« Lerdi clong 13510014

BT YA - 105, 1516 29) Arvpp, :

ISC629) Aorpty

Vidisg vid/ aAfm . )¢

L

a0 l,',-:“',,/ VP4 E 5,
9 etk o, Pikrr.,

   

WOTE: This ?eprada:ed transparericy of
" I1& C 0

wa . QIREE na: made

of Rev. (Cnr.rt. . JriJan '64;

Fowr

I

T ]

bay Sweey- 2Ty
wad SN 22v. !
IS was 250 T
RTwaswon, c2m2anics L Fan s
sfPlWes 2.2z,

 

M S k£ ONZY

'.urefi-..' L
AR Y i.oaa

 

 

 

 

 

 

 

 

 

T T
| sowonty ./ Liepd Lk

Y Ribedmore” b+ TAMES gl e

NS5, TR-2,3 werm

{06 wa s

L008-1.6KY,lr. &

o W02,

- I.‘l_" Feln 6 na

VELLETA '
R K e bumen FesroremuLrey_ - & B0 - e L b

[ R TTT T R Y -
! T Loy o Oax Rivor NanonaL Lamomatomy
o 2f S A2 e e, g'( :
lsrs . L g ¥ e ‘ IIETRUMENTATION AND CONTROLS DivImOn
sl 7y wdu
24 2 VB papiaTicn MiniTos

vk JF Mooute Fower Surrty

- omulie orRmrmwe SrcHS C/p, ur’r

 

4, v oAg.

 

 

 

 

 

 

 

() omd /g e
L 'P-38 ] ), A ,
&.J g e 3 0 /9/6M 2&

 

 

Fig.

2.10.8. Three-Module Radiation Monitor.

 

 

 

 

 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

E-H Research Laboratories Model 202 Electrometer.

.10.9,

2

Fig.

 

 

 

 

 

 

 

£
{

 

 

 

 
V-9
" A
whyy

365

Fig. 2.10.10.

 

Ry
INEe

*stasneze’

R ®

LE LY 4]
L3 71 [-1]

(0 racrony aosust ror zemo
) racTomy a0JUST FOR 1LOVOLTS ACROSS 3009 FILAMENT
3 UMLESS SPECIFIED ALL CAPACITORS 1N uf
| UNLESS SPECIFIED ALL MESISTORS Ypw-3%
woTES

Blectrometer Model 202 Circuit.

 

st e T S e

 

LS
M3 NOZA-OSL-4P
Ay
[
wuy

API 4a%IC
O304

 

e
WO -14%-13

———
»

St BEAARCH LASORATONES, 8L
Gosbsh Cossemas

SCHEMATIC

7 | ELECTROMVET
AMPLIFIER /202
0 T A

 

 

 

A e i A 1 - 4 A

 

 
 

 

 

ST IR TR TR R R g T R T TR T TR TR R PR DR e e S e el

 

366

 

 

 

 

 

 

 

 

 

 

 

Vo Paine-

   

B

mm
SII0 T PeAeAd Qhet YHIRND

 

~ChARYE

 

 

 

 

 

 
 
 
 
  

 

  
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

  

 

DHIELD ASSEMBLY - TYPICAL -

W31 orwe

S SHIELDS

MLV, THMLLY

TME: 4 FACRY, Do SuR Phitdh
MAT4H PRI LD ww e Py

o - Lo o e ',\4%- rm s et
e e e ':,\',,,,-. ——
i 102 ) /fl- .
. ! )
e | sovlch Piva | . - | ol ) W3y medts.
ok SHIELD DRwansl ; ! J.:-s ML por - e nrnmm‘
1 I .! - | CHORS: -
-MR2 withu ) jote m antuens
] e
Yl N w0
Bou? § HAT WALRAR
AT S I atew.
ALK
SHIELD / / |
Y 1,. .v‘tmm” "t RApATien DilactioR r‘& st :11 .
| GAMEE - WULLLR Tk} o |G ]
um- ltu'l ) ) 1 | ¢ L kae'? L. 1. el %) ’ \\ —:nv !
A
‘( =1 - _1 !
- Ceant L R 8 {'.‘;’» !
HAL - [ - 5. "‘
F— kLD Plocevs & i
| L s T
P
{ o
AP AGCESS WolSd £ / <! |
M WMAAD BRunibg
Pt -
. L e
4 oo 1 gt ' \heuu Fua(tee)
.. E ;-F.’.... - ' 11 - 2 teo'n
1" @ LY BT Y Lok
b:\._‘;f}i\-fi;%;gm :l:..w‘::l‘:ug :::::& upiI.
e peTAL T = IDE N/ tw

—ERS

 

 

 

 

_DEIML €

TIE _CuimPin TeptlD
LA R6Q'D. (4 TR suet)

Y4 T CoLD BRLLP STats

     
    

Py
SoUREE FLukr
. “".“?M '_AH.(“O

  
 

 

[ Dllll-‘fil tuut‘l

n-w.- At 10
elten o rtechas e

 

 

 

  

 

 

 

 

B2

RAASTON_BLACKST. % EAR'D.
.E_"_MM o8, 519 547

it

\.-_-!!!e!__'.'-_‘:!.fh_

     
 
   
 
     

 
 

   
 

=:£=l‘;.._
L||‘I"|‘i"| -!"
DEaL __DEIAIL B

g_'v._t__s_';on wEAeEL] i RLed. -PAISE1OR BRALNR] ) Wg'D
Lok _PRecuws ey “\,:l“‘“s,“j

m:“w-m vaTacToR’ nmu
bl M - y - -
PAYL. K, e su-lu" wun..m 4y ) u’i " 0»\:\-‘\3

     
   

\luu.l o )
. .um\nou Aanens

  

 

B

1SR PLecesds Liwas 675, 684

icouct oo
#uPhusion AwiueRs
- CLAMP M, BANDS

 

.!.‘llf-\ot “n“t h
wiLe to 5011”\ or
rescw um-bbA

 

   
   
 

 

 

 

- nr Wes. |n ut-ufl-& — S _
- SHIELD ASSE EMD VIEW = SHIEL L _EMND VIEW - SHIELD ASSEMBbL
-Jypich. _FOR. . PROCE . PROCESS LINES
PCEDS LINES SO0, 528, 557 912 G ] .
VAL TTPL LA BeD fu ’ . VAL TT7R 1A 69D pioas VAL 1T % 1 aND PLuks
WOTED 1. FUSE GLITS SHALL BE 100 AWE FERRULL TYPE CAZTRIDGE v £
A0P3 WITH BALGLITE Rasl . TaTAL ™ RLOD.
o] CLiP) SN PATACTOR WEALLLT wiin w3 [ UvTs Bukuin @ !
,4", -
)T EST Ao AL T
TR e )
s . ( . . . -3,
| tJ e i l £ 5 | ‘v kel e ! By sonl ol k. i
_.".’_.. ’ Y :_-:'--«:.tv':h.. _& i o Toitd Yiae - # ‘:'- ::-:: ::"-
! L luNIa, v i “up Nowuab J10A
: 0" AueanY = n ek
i el tom Yy' 8.1 Pty i
: |
’ !
1. ST = VAT T
}-- PP "S- l---——— s
~7—

g

 

 

 

 

 

 

 

b\’(\fifol AR TP 1 = DaTAwY —r
INEFERENCE DRAWINGS ’ DWa. NO.
l.nl"n(—vll] .t DAY 1O 83 ~ -‘.7505
'u - -
HBuie-LD 1Y Pe
LANSE
mewat A4 UNION CARBIDE Nww Gy
2 . gsoy: oo 4t 2OV M&mlwum.u ‘ -y

 

 

 

AP TF W

 

 

 

 

- YU p-aw-n- 40957

 

Fig. 2.

10.11

 

L  Typical Process Monitor Lead Shield.

 

 

 
 

367

2.11 STACK MONITORING SYSTEM
2.11.1 Introduction

The MSRE stack monitoring system monitors the MSRE off-gas for ab-
normally high radiation levels in the 100-ft-high off-gas stack. The
level of activity of the gas emitted from the stack is recorded on in-
struments located in the reactor auxiliary control room and by the com-
puter data logger. Abnormally high levels of activity generate an aural
and visual alarm in the reactor control room and in the Laboratory Waste
Monitoring Control Center located in Building 3105.

All hot-cell ventilation, some building ventilation, and all waste
gas (off-gas from process vessels and experiments) at ORNL are monitored
and discharged through one of several stacks. This section describes the
principal features of the MSRE stack monitoring system. This stack is
the main disposal facility for gaseous waste at the MSRE.' Cell ventila-
tion air (high flow, low contamination) makes up the bulk of the air flow;
reactor off-gas (Low flow, high contamination) is also disposed through
this facility. Filtering equipment consisting of multilayer fiber glass
roughing and absolute filters (see Fig. 1.5.10) is also located near the
stack. These filters are, in general, a second line of defense, since
all air and gas 1is cleaned near its source by the use of particle traps
and charcoal beds before entering the roughing filters.l

All continuous waste effluent monitoring systems at ORNL feed in-
formation to panelboards at the Waste Monitoring Control Center located
in Building 3105.2 The information is displayed by signal lights indi-
cating alarm conditions or by records on single-point or multipoint
strip-chart recorders.

2.11.2 ©System Description

The basic concept of stack monitoring installations divides the
channels of information into two functional parts. One part provides
day-to-day information necessary to arrive at monthly and quarterly in-
ventories of radionuclides emitted from the stack. The other part pro-
vides a continuous surveillance of the minute-to-minute condition of the
stack inventory in order to sound an alarm if an unusual burst of activity
occurs.

The function of this second part of the system, in addition to pro-
viding an early warning of unusual conditions, is to provide gross in-
formation about the incident useful in locating the source and in assisting
all emergency groups involved to evaluate the extent of the incident. At
present there are five channels of information available from the MSRE
stack to meet these requirements. All the primary instrumentation for

 

IR. C. Robertson, MSRE Design and Operations Report, Part I, De-
scription of Reactor Design, ORNL-TM-728 (to be issued).

®L. F. Lieber, "Radiation-Monitoring and Warning System at ORNL,"
Nucl. Safety 9(4), 41420 (Summer 1965).

 
 

 

368

these channels is located on a balcony 40 ft up the stack, with the in-
dicating instruments located in the reactor building (Fig. 2.,11.1).
These information channels are given below.

2.11.2.1 Flow Channel FT-S1

A Pitot tube in the stack at the 40-ft level continuously measures
the total flow of air in the stack (approximately 18,000 cfm). This
measurement provides surveillance to detect unusual changes in alr flow.
The flow data are also required, to calculate the average concentrations
of material passing through the stack. The stack flow rate is recorded
by the data-logger and printed on the hourly log.

2.11.2.2 In-Stack Sampler

An in-stack sampler is located at the 40-ft level. This sampler col-
lects a sample from the air stream by means of a cartridge with an inte-
gral filter and a charcoal trap (Fig. 2.11.2). Isokinetic sampling is
attempted, and the cartridge is removed once a day routinely for counting
room analysis and would be removed and replaced as often as necessary
during an incident or any unusual situation.

2.11.2.3 Particulate Monitors

Beta-Gamma Monitor, RE-S1A

 

A sample is continuously withdrawn from the stack stream at the 40-
ft level and passed through a filter paper which is monitored by a G-M
tube. The buildup of beta-gamma-emitting particulates provides the first
clue as to the physical form and characteristic radiation of contamination.
Exit gas from this monitor is sent to the 13'I monitor (refer to 2.11.2.4
below).

Alpha Monitor, RE-S1B

 

. A similar device monitors the stack stream for alpha activity. Exit
gas from the alpha monitor is returned to the stack.

2.11.2.4 Todine Monitor, RE-S1C (Fig. 2.11.3)

After passing through the paper filter of the beta-gamms monitor
(Sect. 2.11.2.3), the gaseous sample passes through a charcoal trap at
embient temperature; here it is monitored by G-M tubes. The charcoal
bed receives the sample free of particulates and detects iodine and
other materials, such as tellurium, in volatile gaseous form. These
gases are poorly trapped by the preceding filter; 1317 is the contaminant
usually detected, thus explaining the name, iodine monitor. A second
clue as to the physical form and identification of stack gas material
is, therefore, provided by this channel.

A sample of stack air is constantly pumped through the beta-gamma
monitor RE-S1A at 2 cfm by a Roots blower. A 2-1/2- by l-in. section
 

369

of filter-paper tape catches better than 90% of the particulate matter
of greater than 0.3 p size which passes, and any radiation of sufficient
energy is detected by a G-M tube. The paper used is Whatman No. 4 and
is in rolls 3 in. wide and 145 ft long. No regulation of air flow is
provided. Since the filter is changed at least every 8 hr, the air flow
remains reasonably constant at the blower-rated flow of 2 cfm. A pres-
gsure switch in the intake air line is held closed during operation and
sounds an alarm in Building 3105 if there is a blower failure. The sample
is collected inside a stainless steel shield that provides approximately
2 in. of metal in all directions except where an opening is necessary

to admit air and tape. A mica end-window G-M tube (Lionel Electronic
Laboratories tzpe 210T) is used as the detector. Window thickness is
1.4 to 2 mg/bm nominal and will pass beta particles of energies down

to 35 kev. BSince stack gas may contain practically any isotope, good
energy sensitivity is required.

Details of the assembled filter, detector, and shield are on In-
strumentation and Controls Division Dwg. Q-2325-5. The design of this
assenbly allows the filter tape to be advanced by a 24-v dc signal from
the control center in Building 3105 and also includes broken tape detec-
tion before and after the shield. If the filter-paper tape breaks or
runs out, it cannot be advanced, and an alarm signal is sounded in Build-
ing 3105. A method of calibration is described in ref. 3. The tape as-
sembly is based on the ORNL Q-2118 design used in the standard Q-2240
constant air monitors except that the intake portion has been altered
to allow easier disassembly for decontamination (see Instrumentation and
Controls Division Dwg. Q-2218-1 for details). Also, the air intake di-
ameter has been altered to match the sample probe and to reduce the number
of diameter changes in the sampling line.

At the time of installation, isokinetic sampling conditions were ap-
proximated by estimating the flow, assuming 2-cfm sample volume and sizing
the sample pipe accordingly. In addition, the end of the pipe was sharp-
ened, placed close to the center of the stack, and headed into the air
stream. The number of degrees of turn between the pipe entry and the
filter were minimized, and all pipe bends were at the maximum allowable
radius. All piping is of stainless steel except for a small section of
plastic tubing where flexibility is needed. The sample is taken approxi-
mately ten diameters downstream from the input to the stack.

The G-M tube is connected with RG59/U coaxial directly to the indi-
cating instrument located in Building 7503. The cable runs are in con-
duit, and lengths are typically 100 to- 250 ft. The indicating instrument
(RI-S1A) is a Q-2313 count rate meter with a current-sensitive input and
is located in nuclear panel board 5 (NB5) in the auxiliary control room.
The current-sensitive input allows the signal and high voltage for the
G-M tube to be put on the coaxial cable without using preamplifier at the
G-M tube. The count-rate meter chassis also holds the +HV supply, an
audio output, a Rustrak recorder, and a panel meter. Range and time
constant switchings are manual. The count-rate meter ranges are 0250,

 

3E. D. Gupton, W. L. Ohnesorge, and N. M. Butler, Calibration of
ORNIL Model Q-2240 Continuous Air Monitor, ORNL-TM-864 (May 14, 1964).

 
 

 

370

0-500, 010,000, and 0—25,000 counts/min. Damping time constants are 1,
11, and 22 sec. In addition to display by the rate meter and recorder,
the beta-gamma level is also checked for alarms recorded by the computer-
logger and output once a shift on the 8-hr log. The signal to the logger
is O to 10 mv and is obtained from the output of the ratemeter.

The alpha monitor (RI-S1B) is similar to the beta-gamma particulate
monitor. The stack-gas sample is withdrawn by means of a separate sample
pipe at the 40-ft level. The 2-cfm sample is drawn through a filter tape
deck, as with the beta-gamms monitor, by a Roots blower. In this monitor,
however, the radiation detector is a thallium-actuated zinc sulfide screen
(see Instrumentation and Comtrols Division Dwg. Q-2218-5 for details).
The area viewed is 1-5/8-in. in diameter (2 in.?), and the detector is on
the top (inteke) side of the filter tape to avoid absorption of alpha
particles by the filter paper. No shielding is necessary owing to the
low sensitivity of the screen to beta-gamma radiation. The indicating
instrument, a Q-2313 count rate meter labeled RE-S1B, is located in the
same panel as the beta-gamma rate meter. The alpha level is also moni-
tored for alarm condition, recorded by the logger-computer, and output
on the 8-hr log.

After leaving the beta-gamms particulate monitor, the gas is passed
through the model Q-2725 iodine monitor detector RE-S1C (Fig. 2.11.3) and
returned to the stack. A charcoal trap, made of a disposable plastic
bottle and containing 6—14 mesh coconut charcoal about 3 in. in depth,
is used to trap *3'I (and other materials such as tellurium that adsorb
on charcoal). The trap, placed within a standard 2-in.-thick lead shield
(Q-1907-15), is monitored by four Lionel 106C G-M tubes. The air flow
is 2 cfm, and the measured cross-sectional flow area of the charcoal bed
is 5.41 in.?. From curves given in ORNL-2872, the pressure drop is ap-
proximated at 2 in. H20 or less, and the air velocity is 55 fpm. The
decontamination factor is estimated from the above report to be 103 or
better. As a rough rule of thumb, 6—14 mesh charcoal will collect 90%
of 1311 per inch, so that the high concentration is at the upstream face
of the charcoal. Data presented in the report are for velocities of 200
fpm and less. Actually the charcoal is easily recoverable and can be
used for analysis since the trap is easily replaced. When sensitivity
is too great, the number of G-M tubes can be reduced. About 75 g of
charcoal is used in each trap.

The output of the G-M tubes (operated in parallel) is connected by
RG59/U coaxial cable to the input of a Q-231l3 count-rate meter (RI-S1C)
located in NB5 in the auwxiliary control room. The 10-mv output of the
rate meter is transmitted to the data-logger, which prints out the iodine
level on the 8-hr log.

The collected material is monitored by a halogen-filled G-M tube
(Lionel 106C) which has = 30—mg/cm2‘wall that excludes all beta energies
below about 300 kev. The G-M tube also sees inert and volatile gases
which are not collected by the filter paper. These show as only a rise
in count rate on the recorder for the time of their passage through the
monitor. Jodine-131 will collect on the filter paper but with very low
efficiency, depending on the stack conditions and the physical form of
the iodine.

Inert gas such as 85Kr will be seen in both the particulate and
1317 channels for the duration of its presence in the stack flow. It
 

371

will not collect to any extent on the filter or the charcoal. While
some adsorption on the charcoal has been noted, collection and retenticn
are very poor at ambient temperatures.

As can be seen, particulate matter is immediately identifiable since
it is collected by the beta-gamma monitor filter before it reaches the
iodine monitor.

Todine-131 will cause a long-term (8-day half-life) buildup on the
charcoal; inert gas can be identified since it shows on both chamnels
in a transient rather than an integrated manner.

As stated previously, the indicating instruments for the stack
monitors are located in NB5 in the auxiliary control room (Fig. 2.11.1).
The indicating instruments consist of the three rate meters with the
integral recorders for the three monitor channels, beta-gamma, alpha,
and iodine, plus the alarm detection and display circuitry for the three
channels. The alarm detection equipment provides a local annunciation
of the alarm from any of the detection channels and transmits the alarm
signal to the Waste Monitoring Control Center in Building 3105. Figure
2.11.4 is the functional block diagram of the system.

The alarm-detection equipment consists of three transistorized
switches which operate two alarm relays, a buzzer, and a lamp, all pow-
ered by a 24-v dc power supply. The equipment, except for the power
supply, is mounted on modular cards located in an integral panel (Fig.
2.11.53. The modular card panels are slightly modified, but the ecircuits
are identical with those used in the Health Physics Monitoring System
(Sect. 2.9). The three alarm switches are actuated from signals derived
from the three rate meters. See Fig. 2.9.6, Sect. 2.9, for a schematic
of the switch circuit. Any channel in an alarmed condition will cause
the appropriate alarm switch to trip, which turns the alarm lamp "On"
on the switch, turns on a local buzzer (Fig. 2.9.8, Sect. 2.9), actuates
a local annunciator, turns on a local alarm lamp, and actuates a relay
all through the action of the alarm module (Fig. 2.9.7, Sect. 2.9), which
also trips the stack monitor alarm in the Waste Monitoring Control Center
also. The alarm for each channel is set by the contact meter on each
rate meter. Once a channel is in the alarmed state, the alarm will con-
tinue until the signal has decreased below the alarm set point, the in-
dividual alarm switch 1is reset, and the common buzzer is reset. There
is an additional module, called the remote alarm relay module (Fig. 2.11.5),
which trips an annunciator in the main control room should the 24-v dec
power supply fail. See the ORNL Q-2563 series of drawings listed in Sect.
2.11.3 for details on the transistorized alarm circuitry. See Fig. 2.11.6
for the operational schematic and elementary diagram of the beta-gamma,
alpha, and iodine monitors.

 
 

 

372

2.11.3 ORNL Drawing List for the MSRE Stack Monitoring System

Q-2370-1 ~ Stack Sampler Location and Control Alarm Panel Assembly
Q-2370-2 — Functional Block Diagram

Q-2370-3 — Operational Block Diagram

Q-2370-4 — Power Wiring at Stack

Q-2370-5 — Interconnection Diagram

Q-2370-6 — Alarm Panels Rear View Wiring

Q-2370-7 — Beta-Gamma Monitor, Operational Schematic and Elementary Dia-
gram

Q-2370-8 — In-Stack Sampler Assembly

Q-2370-9 — In-Stack Sampler Details

Q-2370-1.0 — In-Stack Sampler Probe Details
Q-2370-13 — Tape Deck Cabinet Assembly and Details
Q-2370-14 — Sampling Cabinet Assembly and Details
Q-2563-1A — Hi-Level Module, Schematic

Q-2563-2A —~ Alarm Module, Schematic

Q-2563-4C — Reset Module, Schematic

Q~-2563-19B ~ Remote Alarm Relay, Schematic
Q-2328-13 — Alpha Monitor

Q-2325-5 — Filter and Shield

Q-2313-15 — Countrate Meter Schemsatic

Q-2218-5 — Iodine Detector

Q-2118 — Tape Assembly
 

 

 

 

 

 

 

 

 

 

 

 

 

      
 

 

 

 

 

 

 

 

 

 

 

 

 

  
  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

J‘)l
; ‘
';‘ |___e _..' ——— e e e —— e e
- T E z ¢
%?m :Ii?l:'?mfi‘ EA%T::OR oot opc PADIATION  BUZZER
1 MSRE HIGH LEVEL [ricH JEVEL THIGH LEVEL | REOTE Aam]  ALARM ] -
; STACK . reLar
! MONITORING
o4 |INSTRAMENTERON
| | eps.7s0s
RESET név REser RESET
S Q2370 |
4 -2 +3 -4 X i-e - -8 i3 110 reit t12
PUiIG D256NIG Q256G Q2503-198 Qsex-2o  Q2scr 4C
f‘ BLDG. 7503- ALARM PANEL
! STACK SAMPLER]
! See 923706
Steck Prdlform tayoul - Phia u
Scate: bl ii e
____ '{ |
~
f ¥ 54
g ‘ i ' 1o G :
] ' Pane) Cutouts for Bldy. 1503
: — £lse Panc/ $8-Q1378-27 Re /tam 3
T . Fanal SD- @ 1378-27 R4+ /tam 20
o ‘,;”;Q%M‘f 8/:;5 5;03
, 43 Tl ’
Sway ligh! Y = Bidg. Monitor Panel
2 > 9 2358
. L
U
= .
v - Sc
_“.!I s i v -”——-
7 & l——— : 3
™8 ‘-
- ) i —_— Count Rate Meler
: TAPE OECK : \‘_"‘““— [_ 8ela.Gomme
. > I « I ' .
fodive £ vy Xp | - i — | @4313:7
:} SAM’““ . Count Rate Meler
. Patform !‘ i | s Alphd
e - ~-- = ey [y — g2313-¢
T Counl Rate Meter
i ledrne
) L ‘ smwex |——" L gesiz-e
(:rc - ™ ok Ep
ae ., +
-6 720 | ¢
e P Y% Tubny r3rey.) !
JB 3O }
. To !
» . STAC K i
-~ . : | } -éw
- xS TEEA m cebimer |
m. e
. O © *14 apure C 0237014 —— e —
| aerio Beta- Gamma T
Y| a-en == — e - =
34 m - Ce ——
- . N, 5. ) Dhsiid-da 3784
! r‘ '”.;v‘ U2 cantrom { Aimha ! 4 luclear Control Ranel *5- De tail Layout ryn"wl
Sux Cont. Pal. - == : CENTRAL ALARM PANEL-RB-5 i e
8idy.7508 - - —— v e Vet —mwemaa /M. Molliday
| Steex ! 3 Sease: o
- Lo o L ‘E MSRE STACK MONITORING SYSTEM
- £ : |
Stack Plattorm ¢ Founddlion Lagoul - Developed ‘ STACK SAMPLER LOCATION ¢
| o \Sedle: None I+ WOV Nemd W.P Reces. - Cuplen CENTRAL ALAKM PANEL ASSY.
< Add VY Power Failure Moo -0 8314 e I way Switch
1 | A surlt 3-40-6: 3 Condulet “T" INSTRUMENTATION AND CONTROLS DIVISION ]
wo. — pare. [ero [seve | 47 LoV Lamp with globes umire OAK RIDGE NATIONAL LABORATORY
T < . ; otmn oy
N-F.-E.. s Sce D304 for wiring ; UNION CARBIDE MUCLEAR COMPANY
i R R L ] : Mt "/ e "
| J HH ! «*&—"’—L_{!,{ £?é ‘ 3 aras aaskiond
= Q23701 &
Fig. 2.11l.1. MSRE Stack Monitoring System, Showing Stack Sampler Location and Central Alarm Panel Assenbly.
%

 

 

 
 

374

ORNL-DWG 67-696

N1

m|@

-

 

 

 

 

 

 

 

-‘—-—-—a-—-—-—-—-—-w—-
————L STACK GAS
FLOW
@ FILTER
| REQ'D
CUT FROM WHATMAN NO. 41 ol lald
FILTER PAPER Y-12 STORES O INCH LOAD CARTRIDGE WITH 6-14
ITEM NO. 15-157-4450 ACTIVATED COCOANUT CHARCOAL
ASSEMBLY NO. 269 FISHER SCIENTIFIC CO.
CATALOG NO. 61 OR EQUAL
+ 4
3 | "33
~ 1-mm WALL |‘—1§“‘—"
| ! >
sg o
F:I_.‘Q - ?Q
END PLUG @ HOUSING @ STRAINER
MAT'L. CUT TO PROPER WIDTH MAT'L. CELLULOID- MAKE MAT'L 40-mesh
FROM {-0z POLYETHYLENE FROM 32-mm 0.D. CENTRIFUGE  SST SCREEN WIRE
BOTTLE, ORNL STORES ITEM TUBE ORNL STORES ITEM NO 2 REQ'D.
NO. 15-014-9602 15-242- 2483
2 REQ'D. 1 REQ'D

Fig. 2.11.2. Charcoal Cartridge for In-Stack Sampler.

 
w

75

ORNL-DWG 64-1200

—

L W Y SS9 Ny

//////

 

 

S
\

 

|_— SHIELD

S NA\ST T F

 

 

 

 

|_— GM TUBES

N N S \\IIIII

=
\/\\///\/‘\ S S

S S S, N S Sy

 

|- PLASTIC CENTRIFUGE

 

 

N,

=~ 7~ TUBE WITH PERFOR-
f.:-,-:: /| ATEDEND
/ \f /—— CHARCOAL TRAP
) %

= Sy Sy

////////////////

,
7

A— B-oz PLASTIG,WIDE-
* MOUTH BOTTLE WITH -
PERFORATED CAP

ke
S

7

 

 

—==— 0~RINGS

 

 

 

 

TN = <<

 

 

 

 

 

 

 

 

 

 

¢ : [
A
g
:\ N "
AN !
TS ‘ Ll \‘(
N
) T )
N I
_ Py
A N
\
N N
2
hy N
X
N N
™ R
I
\ .
e "

 

 

 

 

 

Fig. 2.11.3. TIodine Monitor Detector.

 

 

 

 

 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   

 

 

 

 

 

 

 

 

 

 
 
 
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

; 376
'
ORNL~-DWG 67-7515
B4 va3or
Rll-.tm'u ]
fa- Gami i Tos TA 20/ RI-SIA DA RA- 51 CRS-S1
Tapc Dack -y tad
- 'ad
Rt SiA- 1A High 128, .
) s Suszer """’.___.l::l Tigerman
' -t 12 i ‘
At Gawma cem l
Detector é-r _——_T
RE-3IA :}4-:::'414 - A See Dwg
24 T A o2354-2
[ ]
Aipha | 78 202 RM:JI‘-JA
Tape Decx > Todoz TN > -~ 2L -3/8 -3A
RM-518- 1A
:
Aiphd ! CRM )
Detector 3 a
RE - | RM-518-2A
8 . R 310-24
STACK )
PLATEFORM ‘ .
Joddine 78 203 RM -SXC-3A
Ortector =‘ Todine - RI-Sic-3A
RE-31¢ | High
{
3 L
CRM _r -
s —-‘ prid Todine
—_— M- SIC- 27
Sample R $ic-2A
Pump \
GP-SI1A [
—_—— 8L 2 3
JB 2ol
" 78-210
Alphd
Sempie
Puinp |
GP-S18
1 E Y T - l - &
In Stack - | - i | | V- MRS 1
e | — ’ | T;-m I | wigh | | twapd ¢ | joume Tape Tape | | chM ! saen| !
Aup yBwy | T8 r fad| [mad | || [mem | [amen|  paeiane) i Range ™ e | !
gr:- 3¢ oK | lawrs] |aam| | 1 lawm]| [awm]  swwca| ind. b | qaem] !
LAsE of JTACK =7l l_....t ] _—— - - J RR-i02 RI-i0f | L J
Tigerman
—dmy === -1 :__-0.-‘.._‘
|
t
———{EE Pump| | Tase Tape | | Rad. Cam t fi‘f |
a Inap. Broex Advwnce| | Rec Aenge i |
Alrm|  warm| | swins| | « Ind. i ]! | Nuciear 84 75 - Biock Diagrom Q23562
= ] AR-103 AI-103 { L= ...-J | Rlarm Panel- wiring Qe370-6
inferconnaction Oidgram Qarw-s
Operational Block Diagrem Pasro-3
| Sampter focation £ Riwm Papel . . 23701,
REFERENCE DRAWING” nwe o,
e ey PAEI
Teperman o mweenrt J, M, Hollaolay
- A Sl Wy e = b e - - .
r~1-2s "1" "‘l MSRE STACK MONITORING SYSTEM
| [se o A e emmes = te + mtn e n ermee]
755 | | fhee| e ! | |
2ehe | |aarm| | aaem| teding| | ndl. FUNCTIONAL BLOCK DIAGRAM
3 T/ad D.C Purfattars Med 1-10__|4¥% == __Re-loy RI-iey > - . o —
t | A1 buitt Jés P INSTRUMENTATION ANt Ll iB, iy et
- —— DATE PO s OAK RIDGE NATIONAL LABURATORY
TR | - ’———@i ; ) Sample| UNION CARBIOE NUCLEAR COMPANY
wkq loses] T Janpie Al 8LDG. 3/05 : P, oy ‘ ’
s - — - - ' I mep, I 14 I/Md . ‘L,
H W o) i 1 B / )
A et — | r Qe 370
e e mm—— ,

 

 

 

 

 

 

 

 

 

 

Fig. 2.11.4. Functional Block Diagram of MSRE

 

h

Stack Monitoring System.

 
 

377

1,064

-,625% 375~

 

713 *—;-,
-

 

 

 

Keyway |

L—/
2.437
3.875

  
  

Cl'“d'

  
   

 

1
OYgDia

\0 -

 

Etched Board - |
Kes5¢c3-16C

8

Pig. 2.11.5. Remote Alarm Relay Schematic.

 

 

 

 
 

 

 

378

 

 

 

ot

ME BED b 13

 

       
 
 

L

 
    
    
 
 

2 MC
Suppiy

 

 

 

 

 

WX pntod in reto -~ 48 ~ather i
To Central Moxk: Gaiiig dnserfrim g1 .l
Finel v JE 201 I Coutacror [
923705
caiy

@

FILTER TAPE
DORIVE ConTROL
@ 20707

(21 ]

"Il.fffl TAPE DRIVE
P LIS - s Erprgn]
Q@ I8 Apna, -

|
a4 ¢ .

. N-0)

- - e e

Car-7

-~ . -
:x.*oo’.-(_,-)-—’--rl-—————l— )
T i »
O] RATE METER (3) fq‘)r-r r8008

   

 

KIB 281" 6Aghae loding
Q23137 .o 8-r

TAT .
Su'?c-f—

 

i

12PENTRAL MONITORING PNL
! @ 23701
i

J

    
    
  

  

  

@ 3106 8- 1054-35
péo, 2w -—'j s

 

 

 

   

 

 

) Maple {28 Sypan
i 'tl- - e} rdring”T
! dofnr ne e el _, 1 sock s m"‘
o Xy, e b, } | Moo & Jd
\_--"i A
A «j &
'&m" = uluruz
ry Yy I Miapie Sevy §rd ten Svtscor
#af= 80 Beducny 1f-eB: Fhvmeus? Mana 75 tong
“L8 Rgper Kabdn
PICAL FOR MONITOR - § 232813 v
A Jeg 7 :
P==Stree: £if
. I Zaml veem Sfrack

 

=)

”e
l',on.f Llets
AP £8P

Cad
Y20

et 7 Rlarons f Racorders *
— ‘z,f:;. o8 “

OPERATIONAL SCHEMAT/C

 

NEG

| it v f
rd --.‘ r
1h b it 3

 

 

 

 

AM=] Ruhess? to Fload

 

 

 

 

 

 

 

P2370-13
for Fping Delails

  
 

Siae of Cabin
9.237¢0-13
- Tbeth

Aaf Stdc

——

 

 

of

Cabimet
base

 

 

 

 

 

 

 

 

 

 

 

  

 

_!M
d I
Nir 3 1
x5 ......-\ P - *-Tyua,
y _‘ 56 v ‘ @ Sange
f ot ' . > - ir dioafer
 eve S Iroper > e veve 1
< 4 S e gror f-d,.rvw_: ;
Cande Y Car0 Mo | _:,:a;:-. o L
d s Central Alarm ; ';
Ke Pana! ‘ | !
8/dy. 1503 J | !
21 n B
) , ridc
7 Cormnetan g P Dotowrgr oo
L EMENTARY O/ A 1on7) £ |
Remeli Aldrm
Eiae 7203
Central Alrm
NOTES:

 

 

 

 

 

 

 

 

 

 

cae
T 24
i -\ ]
i #ro
3 224
| i
z 1
: G
'
orm 1 . (1
(<]
: + Sryont
cn 9 II5e
Sryant 2 :
70 ,
i '
~~ o
JA

 

 

 

 

 

 

ré
SH

prne
A 20100008 311,

Tepe Broax Moskile

 
    
  
 

See 23702

    
 

 

 

 

 

 

1= Aglyusl series resister 3¢ Thal Range Indicarer
reads 25K whan count-mife mater is 3a7 e
25K range. This requires apprea. 480 K of rus,

2~ This Dwge. derived from @2325-2°

 

3 For inslaliation of Tape Drwve’ see Dy oenwj

 

 

Interconnaction Diagram

92’”fl

 

 

 

 

 

 

Functrona! Block Diagram @30-
Foter 'upe T .ve rertbre “hoes:s 3857
MnGE DA DR MO,

 

— bl /. //, M olladRy

 

MSRE Stacw MoniTomING SYSTEMS.

 

BeTa- GAMMA
OreLrATIONAL SCHEMATIC -ELEMENTARY
DisarAam Pump Fiutee Tares Daive

 

 

 

 

Fig. 2.11.6.

 

 

Pump, Filter Ta

e =z

Drive Control, and Alarm Panel Circuits.

 

 

 
 

379
2.12 DATA LOGGER-COMPUTER

2.12.1 Introduction

A digital data collecting and compubting system is used on the MSRE
to augment the conventional instrumentation system (Figs. 2.12.1 and
2.12.2). It is designed to collect and process 350 analog and 112 on-
off contact signals (at present it processes only 291 analog signals).
The remaining signals can be added by merely wiring in the signal leads
and altering the system program. Signal processing includes conversion
of the analog signals to digital values in engineering units; alarm
monitoring by comparing the signals against preset upper and lower
alarm limits; and calculations to provide heat balances, total pover,
reactivity, and other operational and analytical information. These
digital values may be logged on typewriters, displayed by a digital
lamp unit, or recorded on magnetic tape, at the system operator's option.

2.12.2 Basic System Equipment Description

The system consists of a Bunker-Ramo model 340 digital computer,
operating console, analog and digital input-output cabinets, typewriters,
x-y plotter, digital display lamp bank, and two magnetic tape unitst
(Fig. 2.12.3).

The analog input-output equipment is housed in three 23- by 84-in.
cabinets (Fig. 2.12.4). These cabinets contain four dec amplifiers, an
input signal multiplexer composed of mercury wetted contact relays, an
analog-to-digital converter, a thermocouple reference unit, power
supplies, and the input-output terminals with associated filters and
signal conditioning circuits., The dc amplifiers and the converter were
manufactured by the Redcor Corporation, Canoga Park, California. The
analog signals from the process instruments are transmitted by signal
leads to the first two cabinets, where they are scanned by the multi-
plexer, then amplified, digitized, and transmitted to the computer
memory.

I%fie analog input system is designed to handle analog input signals
ranging from millivolts de to 220 v dec or ac.1??2 The lower-level sig-
nals are amplified to 10 v dec, while the higher-level dc signals are
attenuated to the 10-v range and ac signals are rectified before at-
tenuation. '

The anslog input signals are transmitted to the input terminals
and then through 60-cycle noise filters before reaching the input

 

13, F. Pierce and D. C. Shattuck, Instrumentation and Controls Div.

o 2E, N, Fray and J. T. DeLorenzo, Instrumentation and Controls Div.
Amn. Progr. Rept. Sept. 1, 1963, ORNL-3578, p. 107. Note: Figure 9.4.1,
this reference, contains an error. The lower block, labeled "Linear
Count Rate Meter," should read "Logarithimic Count Rate Meter."

 

 

 
 

380

multiplexer., These filters have a manually set variable 60-cycle re-
jection of from 6 to 50 db. They are mounted on plug-in cards in the \_J
two analog input cabinets, In addition, digital filtering (integration)

is applied to selected input signals, most of which are thermocouple

signals used in precise calculations. The analog-to-digital converter

operates on a O- to 10-v dc range. All analog signsls are converted to

digital values on this basis, with the proper scaling done under program

control. Digital signals are compared with preset alarm limits and can

be selectively transmitted to digital-to-analog converters to produce

up to 36 analog signals for recorders, oscillographs, an x-y plotter,

or for control.

Three cabinets, indicated as I/O Nos. 1 to 3 in Fig. 2.12.4, house
the digital input/output equipment. This equipment handles the contact
input signals from relays, typewriters, and the input keyboard and
contains the control units for all the output devices., The contact in-
put signals are transmitted to the arithmetic and control unit of the
computer to perform operations under computer program control. The
digital output signals from the arithmetic and control unit are trans-
mitted through the digital input-output unit to operate relays, type-
writers, and the digital lamp display unit.

The computer consists of the basic digital computer, the master
input/output control unit, and the memory units. The computer con-
taining the basic electronics is housed in three labeled cabinets,
central processor, core memory, and drum memory (Fig. 2.12.4). Input/out-
put is housed in one cabinet labeled Master I/O.

The basic 340 computer has all-solid-state circuitry with the fol-

lowing specifications. ( |

Core memory 12,288 words, expandable to 16,384,
in blocks of 2048

Drum memory 28,672 words, expandable to 49,152,
in blocks of 4096

Machine cycle time 6.0 msec

Data word length 28 bits including sign plus one
parity bit on all memory operations

Instruction format Two fields: a l4-bit operation field
and a l4-bit operand field

Addressing Direct addressing of up to 16,384

words, single level indirect, and
immediate operand addressing

Number system 2's complement binary

Operation Arithmetic, control, and core memory
circuits: parallel; magnetic drum
memory circuits: serial

Clock frequency Arithmetic, control, and core memory
circuits: 478 kc; magnetic drum
memory circuits: 239 ke
Registers

Environmmental conditions

Software

Input-output subsystems

Priority interrupt

381

Three major arithmetic registers,
three index registers, and addi-
tional registers for peripheral
-equipment

Standard operation to 85°F cabinet
. temperature., The power consump-
tion at 115-v single-phase, 60~
hertz is 2000 w, The total sys-
tem power consumption is approxi-
mately 7000 w, including the two
tape drives which operate on
208 v, three phase

An integrated package designed for
process control; includes real
time executive, utility package,
assembler, and FORTRAN IT com-
piler, and library of subroutines

350 analog inputs, expandable to
over 2000; 32 digital outputs,
expandable to over 1000

Handles over 100 levels of program
priority (program operating time
schedule)

2.12.3 Peripheral Equipment Description

Aside from the computer itself and the analog input and output
subsystems, there are a number of peripheral devices which provide
communication between the operators and the machine. The devices are
listed below and can be seen in Fig. 2.12.1.

Four typewriters:

two with 30-in. carriage

and two with 16-in. carriage

Tfio magnetic-tape units

Paper-tape punch reader

Input keyboard
- x=y plotter

Console: function matrix and digital display

In normal operation, four IBM typewriters are used to provide
hard-copy records of reactor data (see Fig. 2.12.4 for location of the
typewriters). Two 30-in.-carriage typewriters are used to record es-
sentially all logs and calculation results. The periodically appearing
results are all typed on one device on preprinted forms; results of
demanded operations are typed on the second typewriter. One of the two
16-in.-carriage typewriters is installed in the reactor control room to

 
 

382

record alarm conditions associated with analog signals and calculation
results, The second 16-in. typewriter (console) records all operations
performed at the computer console.

The principal depository for reactor data is magnetic tape. The
values of all the analog signals are stored on magnetic tape every 5
min, In addition, all intermediate and final calculation results are
stored on tape. (The typeout of calculation results is generally less
frequent and more limited in extent.) Two tape drives (IBM model 729-2)
are available, with the second unit normally in standby. However, the
second unit can be used for off-line functions such as data processing
or program development while the first unit is on line,

The paper-tape punch and reader (Teletype model BPRE-2 and Digi-
tronics model 2500 respectively) are used primarily in connection with
programming functions, for example, assembly and compiling. There is
normally no input or output of reactor information through these devices.

The input keyboard (Invac model PK-164) operates in conjunction
with the on-line program development package (OLPD) in the computer.
From the standpoint of reactor operation, it is the means of entering
data for the trend logging and plotting functions.

The x-y plotter (Moseley type 2D2) is capable of plotting any
input variable as a function of time or of any other input varisble.
Parameters for both coordinate axes must be entered by the operator.

The computer console is the focal point for use of the computer by
the reactor operators. It contains the function matrix as well as the
digital switches for the selection of the various request functions.
The console also houses the panel for digital display of signal values
(Fig. 2.12.5).

2.12.4 System Operation

2.12.4,1 Collection and Processing of Analog and Digital Input Signals

At the present time there are 291 analog signals from the reactor
system connected to the computer. The types and numbers of signals
are sumarized in Table 2,12.1.32?% See Fig. 2.12.6 for a complete list
of all input signals. These signals are arranged in a scan table that
contains 350 entries. Under normal conditions the raw analog signals
for all 350 points are scanned, compared with high and low alarm limits,
and stored in core once each 5 sec.

In order to provide a more frequent loock at selected variables,
some analog signals appear at several points in the table. For instance,
the outputs of the three neutron safety channels are arranged so that
one of the signals is read every 200 msec. Another reason for multiple
entry in the scan table is to permit integration (digital filtering

 

3Ronald Nutt, Instrumentation and Controls Div, Ann, Progr. Rept.

4R. C. Robertson, MSRE Design and Operations Repdrt, Part I,
Description of Reactor Design, ORNL-TM-728 (to be published).

 
 

383

Table 2.12.1. Analog Input Signals

 

Number
Type of Signals

Thermocouple

Conventional 169

Integrated 17
Pressure 20
Flow 13
Amplifier gain

4
Weight 5
Power and voltage 4
Liquid level 11
Punp speed and tachometer 6

7

Position

Nuclear 13

Process radiation 23
Total 292

 

over 1/60 sec) of the signal for greater accuracy and resolution. Tem~
peratures that are used in calculations are integrated and converted to
the nearest 0.1°F in the range from 900 to 1300°F. Thus, the signal
must appear a second time, unintegrated, to provide information over
the entire operating range. As a result of these multiple appearing
signals, the 350-entry scan table contains 346 actual analog signals
with four spare locations.

Realistic high»and/or low process limits are imposed on most of
the analog signals. In the remaining cases the limits are set at the
instrument extremes. The normal computer response to an out-of-limits
condition is to actuate the logger annunciator in the main control room
and to print a message on the control-room typewriter identifying the
variable, its value, and the time. BSuch a message is typed in red when
the variable first goes out of limits and in black when it returns
within limits. No other information (except for a 4-hr out-of-limits
log) is typed while the signal is either out of or within limits.

There is one group of 65 analog signals (type 2) that is recorded
on magnetic tape, in engineering units, each 5 sec while any one of the
signals is out of limits. The typed messages for this group of wvariables
are similar to those for the other signals. The recording function can
be inhibited by operator request on any or all of the signals that will
produce this action. _ : ,

An out-of-limits condition on any one of another group of 22 analog
signals (for instance, neutron flux) switches the computer to a "fast
scan" mode of operation. In this mode the scan table is reduced to 64

 
 

384

important variables and all 64 are scanned, converted to engineering
units, and stored on magnetic tape once each 1/4 sec. This mode of
operation continues for 1 min, without 1limit checking, after its ini-
tiation. At the end of that minute the normal scan is resumed until
another signal to start "fast scan" is detected. The "fast scan" mode
of operation can also be inhibited by operator request on any or all
of the signals that will produce it.

Once each 5 min, regardless of the scanning mode, all 350 signals
are read, converted to engineering units, and stored on magnetic tape.

2.12.4.,2 TLogging Functions

The computer generates and types out a number of periodic logs,
which are tabulated below:

1-hr log (54 analog signals)

8-hr log (175 analog signals)
Daily report (21 parameters)
Out-of-limits log (once every 4 hr)
Calculation results

The 1- and 8-hr logs simply present the values of selected analog sig-
nals to record the status of the system. In both cases the values that
are printed are the same as those that were recorded on magnetic tape
during the last 5-min taping operation. The daily report summarizes a
number of operating parameters such as integrated power, time at tem-
perature, and numbers of thermal cycles on important components. The
out-of-limits log is an hourly summary of all analog signals (up to 40)
that are out of limits at that time along with their current values,
Selected results of some calculations, such as the average reactor in-
let and outlet temperature, are also typed on the log sheet periodically.

2.12.4.3 Calculations

Aside from the routine functions, such as units conversion, the
computer performs a number of on-line calculations using current reactor
data.%™® Many of these calculations include alarm functions to call at-
tention to abnormal conditions. The calculations are normally performed
on a periodic basis with the results being printed usually less fre-
quently. Many of the calculations can be performed at nonscheduled
times on operator demand; results of nonscheduled calculations are al-
ways printed.

Table 2.12.2 summarizes the schedule for some of the major calcu-
lations.

 

5G. W. Allin and H. J. Stripling, Jr., Instrumentation and Controls

6J. L. Anderson et al., Instrumentation and Controls Div. Ann.
Progr. Rept. Sept. 1, 1963, ORNL-3578, p. 100,

 
 

385

Table 2.12.2. Major Routine Calculations

 

 

. Normal Printout Demandable
Calculation Tnterval Interval ?
Reactivity balance 5 min 1 hr Yes
Average reactor inlet and 1 hr 1l hr Yes
outlet temperature
Reactor-vessel temperature 10 min 1 hr No
difference
Cell-atmosphere average 1 hr 8 hr Yes
temperature
Heat balance 4 hr 4 hr Yes
Salt inventory 8 hr g hr Yes

 

2.12.4.4 Miscellaneous Functions

Some of the miscellaneous functions that are, or can be, performed
by the computer are listed below.

Trend log (up to 26 variables)
Trend plot |

Digital display

Contact and analog outputs
On-line program development (OLFD)
Data retrieval and processing

General-purpose computing

The first three items, trend log, trend plot, and digital display,

are means of providing visual information for operator guidance. The
variables to which these functions are applied can be selected at will
by the operators. The last three items in this list are all related in
that they are nominally off-line functions ‘that can be performed with
the computer on line. The system program requires only about 30% of the
capability of the computer under normal . circumstances, this utilization
increases to about 40% in the "fast scan" mode of operation. In ad-
dition, the system.program requires only about two-thirds of the core
memory. Thus, there is ample capabllity for background processing of
off-line material.,

The purpose of the computer is to provide close surveillance,
rapid processing, and compact storage of large amounts of reactor data.
Since it is associated with a reactor experiment, it is not possible to
define all the data and calculations that are required for a complete
analysis of the system. Therefore a great deal of data are being col-
lected which may be used much later or which may never be used,

 

 

 

 
 

386

2.12.5 References and ORNL Drawings

For more details on all parts of the system, refer to the documents
and drawings listed. For details on the operation of the system from
the reactor operator's viewpoint, refer to item 11 in the Reference List,
Computer Manual for MSRE Operators.

1Interim Report to Oak Ridge National Laboratory Relating to a
Digital Data Acquisition System for Use with the Homogeneous Reactor
Test Facility, CF-60-3-159, R. K. Adams et al. (Mar. 29, 1960).

2Final Report to Osk Ridge National Laboratory Relating to s
Digital Data Collecting and Computing System for the EGCR Test Loop
Facility, R. K. Adams et al. (June 22, 1960).

3MSRE Data Collecting and Handling Requirements, A Study Report,
MSR-61-112, G. H. Burger (Aug. 15, 1961).

4Specification for a Digital Data Collecting and Computing System
for the Molten Salt Reactor Experiment Located at Oak Ridge National
Laborstory, Oak Ridge, Tennessee, JS-81-170 (May 1, 1962).

5Use of On-Line Computer in MSRE Operation, CF-62-3-26, P. N.
Haubenreich and J. R. Engel (Mar. 6, 1962).

6Toward Closed Loop Control in Nuclear Plants, Nucleonics, 71
(June 1962).

7High Speed Monitor for Closed Loop Control, Colin G. Lennox and
Albert Pearson, Nucleonics, 73 (June 1962).

8Input Signal Functional Tabulation, SC-I&C-EGM-6230.

MSRE Digital Data Collecting and Computer System Calculations,
May 17, 1963,

10TRWC Proposal for a TRW-340 Digital Data Collecting and Computing
System, TRWC-63 157.

1loomputer Manual for MSRE Operators.

120ross Reference Listing of MSRE Instrumentation and Control
System Drawings, CF-63-2-2, R. L. Moore.

 

13MSRE Data Logger Signal Intercomnection Wiring, ORNL Drawings
D-HH-B-57456, 57457, 57458, 57459, 57460, and 57461.
 

 

Fig. 2.12.1,

   

Bunker-Ramo 340 Computer Input-Output Equipment.

 

PHOTO 80019

 

 

L8¢€

 

 
 

 

Fig. 2.12.2.

 

Bunker-Ramo 340 Computer Central Processor.

C

PHOTO 80412

 

83¢

 
 

389

ORNL-DWG 64-64E1AR

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

INPUT
KEYBOARD
ANALOG SIGNALS TO REMOTE £y 3 LOGGING OPERATOR CONSOLE
INDICATORS, CONTROLLER'S, ETC. | TLOTTER TYPEWRITERS
‘ ’ ! r I PROGRAM CONTROL , PAPER-TAPE UT
i INDICATING LIGHTS, PUNCH INPUT-
| AND AND OUTPUT
i ALARMS READER TYPEWRITER
f N\
i 36 ANALOG
32 DIGITIZED OUTPUTS CONTROL
3 OUTPUTS AND
| PROGRAM
|
'——-'l INPUT-0QUTPUT INSTRUCTIONS
o | 350 ANALOG EQUIPMENT AND CONTROL. A
= INPUT SIGNALS DIGITAL
, REACTOR i DIGITAL INPUT COMPUTER
\ ) SYSTEM [ . (MULTIPLEXER,
INSTRUMENTS VOLTAGE DIVIDERS, |  DIGITAL OUTPUT
———:1 112 "ON-OFF" FILTERS, l |
T [~ SIGNALS AND AMPLIFIERS) CONTROLDIGITAL

 

 

 

rerrrr————-

 

 

 

Fig. 2.12.3.

Computer System.

i INFORMA'i’ION

 

2 MAGNETIC
TAPE UNITS

 

 

 

Block Diagram of MSRE Digital Data Collecting and

 
 

®

390

ORNL-DWG 64-628R

 

AL A

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

©
M
N
] N j _ - - }
| tl \ SPARE PARTS ' S
N STORAGE TABLE DESK N
N N
T~ \
Y POWER PANEL P
' N £
N = 1
N - N
N = N
N N
\ 3
\
N N
N
N |
N ANALOG TO 1/0 NO. Y N
§ ANALOG [ANp’th'o? DIGITAL 170 170 & §.
N SIGNAL | 1N CONVERSION| NO.3 | NO. 2 | POWER N
N INPUT | OUTPUT " gysTEmM SUPPLIES N
N \ N
N N
N w ¢ N
N o £
CR E w © §
N *
N o 2 ~ N
§ = N
N w2 N
N Zo
N 3 MASTER | CENTRAL | CORE DRUM POWER i
| /0 | PROCESSOR [ MEMORY | MEMORY | SUPPLIES N
\ \
\ \
N N
N\
'\
- MAGNETIC N
TAPE N
N R
RN
MAGNETIC 30in. = 30in. '
| TAPE {LOGGER LOGGER
\ \
Uy pLOTTER
PAPER TAPE
PUNCH AND
READER |
N
r COMPUTER _ I N
CONSOLE
T m
I N
CONSOLE ~—KEY BOARD S
TYPEWRITER N
N
N
DESK N
N
\
ESNSNSSN
1
~=——16 in. LOGGER ‘

 

 

 

 

 

 
    

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

&

 

 

 

 

 

 

 

 

Fig. 2.12.4.

 

 

 

 

 

 

Layout of Data Room.,

 

 

 

 

=
 

 

391

Fig. 2.12.5.

 

 

 

FREEZE [CONNECT

 

 

 

 

ALARM UNASS_IGNED

PUTPUTSIOUTPUTS l

CANCEL

 

REQUEST]

 

 

57 S-6 S-5 5S4 S-3

CONTROL SWITCHES

Computer Operator Console.

S-2

8.1

 

 

- ORNL DW(G, 67-1821

 

 

 

 

s

 

 

 

 

 
 

Ly , . e SR R

 

 

 

 

 

 

 

 

 

 

 

 

 

   
    
  
 
 
 
 
 
  

  

 

 

 

 

  

 

     

 

 

 

 

 

 

 

 

 

     

 

 

 

 

 

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

 

 

 

 

    
  
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   

 

 

 

 

 

      
 

 
  

    

 

 

 

 

 

 

 

 

 

 

 

 

 

   

 

 

 

 

 

 

 

   

 

 

 

 

 

    

 

 

 

 

 

 
 

 

 

 

 

       

 

 

 

 

  

 

 

 

 

 

 

    
   

 

 

 

 

 

 

 

    

   
  

 

 

 

 

 

    

 

 

 

 

 

   

 

 

 

 

 

 

 

    

 

 

 

 

 

 

 

              

   

 

 

 

 

 

 

 

   

 

 

 

 

 

 

 

 

 

   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  
  
 
  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

b
. ' : ' ' 392
REACTOR HXATHM OATA LOGGA G RGACTON H(TEM DATA LOGaEL: RAALTIOR 4¥4TUM  PAIA OO GRR TWEACTOR 4YATRM DATA LOG GER, RUACTOR SYSTRM OATA LOGLGER RAACTOR HrPTIeM OMTA LoawaR
- e = e —_— 3 et e e mn i :
1]l el w1« | wl e 19 l ¥ l l g 1% | |
SiaAl b 3|4 g p ;_;§ Seiihl » % 'é' ‘3' o E? SIGMAL o .f, "é é o 5’5' SIGHAL ¥ s % 3 o 5k G AL v 3 % 310 |35% SlGMAL ¥ 5 g § i i 5%
Fl8| 418§ |3k BERERERERLL rl 83! |3 Fle| 8§39 |48 e $1 8% !4z irtgl3alstads
A TURE! Tt e e Tep T | [meaccs lye jwewfren: a 1oy jaey =50 o] | ececiricac [Poy ‘ e
X TheTelt AT ey e TRl i SR TIT T el \d tiTm T w W [T . T Ir__-‘_
v el w B i A veemeno 1 : 2! [Pn-ue- A Fe [ wes fM-CP- 0 1T e h i d
. ™ 101 ¢ By L4 n-un " PH- Re- AT ;& it 204 . L
4 “'""b“'; Ve {wep|aw | D e g 0e eoten PH- 500" A1 S o W e
A e Las Lok o S VOO S T 5000 . AU P 0 s O T oty PM- 510 A lect. Jorz A | € | 21 100 - e
- R ISA et l e rer it 19-_»«-_»:0_5_,__ TM-I. o 1oy [ ws [ I8-Ote- 4 M- G-t jaet. 1y | ALl | & 1% M POSITY o
n-u-mn ; AL e | ed i3] Al B eV ud e Dt PM- 5107 "gel  tay [Au | & N et -1o- A T
e R-Toh ] | A eI A e an || o | U [ Ta oo P B AY wexr oy [t 6 T Taes '_:n-oé-i“'l"t; o
Teewoonl e e Tl W TN, Feekon | T[T b [o% |hie | tect01 10 P 51T AL 861wt “x 2 M-WRE AV _‘1' ¥ )
seemanh D DT e e e Ta-cr- 86 | y e 1o il PM- %21-A2 L 1§ | ® 43
yerwrzedl T TR T @3 T TRe T e rer NrseTveen o e W . P58 A2 “eed ey A3y |
[Je-g 2 b oY (31 (fyeswedin- e ) aw B e | e 14!!_5}9)‘ el 1ms :
[ te-R-28h 4 ! wotre IPARE. TET T/c resm. o v ! up 1 - u._j: N3 nr
 Tecmeah L b e leow & { Seans- Vo7 l";“'l"* ST 1"151-'!A o1
Te-R-%0h: ' AL € " " eeiedds, | f AL B |0 15 T8 e
LCLR S 1T YO W £ renut ; ML LB 2 TIneedt Fa
Y6 AA ! . f Yoot . o r/e Teprl ALt | 0 L el |us v
Te-R- 444" -] Taevioh- bJ_'_f..r Ang ] bt | ™ T A2 'Z \!U\-H\.t:l a
Te-R- A% | rE Y=l Tl yerp] ML | © ot |16 L 2,5 HLCI-A
ve-w-mo (L L re-398:) v/ lvepef At | B u e [ RM-WLet-A
Ye-wesl | ___E_ WO I b et | ABT B A ae P Re%-MLC-A &
TR-WX- TN a2 To.vr=1 _ Hyje irerp o 13 as __g BM-MECk N,
L ;'\__ T wiel: 1B v} o n V =L RM-Mcct- AT,
TerwxeTA 1T [ Yewvoran] | L 5 | w e o FM- DA - weCi A4S ® 3 PR
R-wx- AN U At | Tevvien- 3o v e | W im o Trw Tma | M- - A T NG £ i T o
Te-200-200, | AL ;€ Yewish 1| "z D st g” e M- 201- A2 | M- HEC » " w7 o v T Ty T
TR0 1D J Al e Tacvied- 18 o o [ Tsy | - . 0 a4 | FM- 201: 82 W MEC 2 qu . 7 |4 " ) .
NIRRT s o e[ ns Wwewi T e T ey | T e R0t uyct W Jecee. B eV Tea ] Ao L
g A e epwov s | L] B P e Jeset s s [FM- 516wt s . [RR-NSCE- A aeae. Ll R et A e .
Il | an]e v Twoever e, | S T e Fey e A Pe et iTs PV %7481 'I____‘ Ay ® e Ru-03C3 A weae. | WBL [ AL "B T3 T a4 Ty
. M e 1w o ee vepnesc3el L g lave 1w [ .8 L= | wy | A siecalaet uay { Akl 1 (e zed [ o Ty e e
o 1T [kt [ |7 | & W 16| B 1 & Jah o |0 | ne i o1 | b #9763 At €3, w8A | Ak | k[ S5 o - F
0 | ¥ ia | e | [4ae faermerze] & VTV T o e iy ST e [FM- 104 AT [ec.t wea [hin [o |01 an e
J L [ av [ e v e wpme-de| o ! 3 ML o s lee oy .1k [EM: 193 A2 et mmy | ML [ F ol i1 RADINTION - ]
ot b Ini f e BN e [yeven: e | W 1T sk [ o [ faar Tie Ter 1o ao BV 1%4-A2 6L [ MRS [ail e Toy jus [AM- 0T1- & Jawe. Jort AL | F w29 TR
e ioal 2 Tee e Tu |w T R N A aravares | re verpfRun o Ler Tt RM- o121 B leas, [or1 [ AL | ¢ |1y [1%4 Ty Y T B
e Al ST T T e T e B o A | B | | Ay wrvicsipluer fase MM e far B8 R whozh | 3 |ues | avn (e 1 [14s o
TeerwaA L 3 g Jaw | e | [ a1 [Fesvnt 3 W8 o w1 weata-veo (Vi frere a0 [ed |2t R 21n-2h wey [ ek |8 T 145 N .
Teofit | b | T |aiL [ & |ov | o% Crerent- 181 & | 8 [aii | o {13 | s ) i LEve U R wic 1A wey flen. i A | w. zi8 =
Teopred | 1y (AL |« | v | 4% ) 3 fav: © §as | we TeeyTer | M |rerrlied ! Al ey a3z, LM- CP- AL Istan (108 [ Rul | & | 1% |ee M- %00-D ued [ AL [ F [e% |82 m
Te-ttion- 4] -[ 10 fauk f e | v | ae wetor k| (e ST TS s cfwe | eeanuarar | ] ffi.-{‘.‘l--].?".'.‘.,. LM DTV A {at ek | MBIO | ki | v | @1 [2te T uok [ Mk 1k (4 [T )
-pt100" § g |aw e Tu A o th | F L X Few o 77 i Tarane.tre A A |er el LM - OT1-A |ataniwba | A1t | & | % |33 RW- 1B ¢ ned [hun [TV I T
T 11100 &- P A ] e 1| e 100 BA F IR o |a1 SraRe-11LE Jren] A ey | 284 LM S24-CLinet. AL AL | F oy |1712 RM- 581-A | L | upd T |k t7 | 14e
e Vbion 4 Elame | e | |43 waor AL | CETTRCTE AT We” e cTe Lot | & [ea {213 | ITH hre Aliner [Aml Lt | & | ®1 429 R 881 B 1 9 [ned | AT [ [
184101 AV | D ov | 48 e $0Y- 1BA [ ALk | m o1 | TR LTS W b Jhed [ A oy | 277 LW 54%CT k.5 [1H% [hie | @ 148 Ri- so% B r] und | ALl (B 1% 198
e thol- G ’ o [To T Tew Ay 1o | at T e g Ya-cT4- D Ler. | A | et | 28 LM 595611061, 110% | AN, | & | 1% | %6 [RM- ses-c [ g [unk | At | w_ ||
[T Y Ak | e 1% | 1o 18497 LA AL L O 1% | 1ol ra-Nn v |1eee | Lo A o4 265 LM 545020t (188 [ AL | € o1 | 4% RW: 594L-A | of & | asn | ¢ Il 14
e piel- 4 Al 1 < |18 | 1ol e sA || IT TR o e et M- Sitafuct|ten (AL | ¢ [of = T %96 & | F [umd &tk [T Tew 143
e tHor el o [ e et ot k| || [t as [ ® 1w s o A AL Al e | ABE [ adh | & |18 |82 RA: 596 ':. Mo [T [T [tas T
T0-tet00: 4 Ak | O *3 | 109 18401 lu . U1 LM: Goond kcl./ABDB T pll ] ¢ o 153 RM- G15-A| J sl JaLh | ¢ 14 144
witico 4 b | e 1% ek Tt T ™ e o4 SPARTL LY Ve k| W | %G | M- L1686 U Jaga |[htn [F [ 81 [18e L
Th-$4100: & Akt 3 3% |10y 7__33-»1-_:__&_____ A |0 1% Va7 | SPARLINLY Lot | A 13 79 W 6TB'C a1 | M| e 3 L%
Ta-thion 4 amr | | o Thee JCHT 10 T e o | | S FARG -INLE el | A [ v |37 RN w10 p w1 | METF a [1v2
Teasren we My ] o [eb | w7 etk | T vt e oY (et TraRE-INCE Aok [ h [T 1A%y PUMPR 4 PetD M 8127 A “Tues | MUTE w18 - .
Ta-etoN & Al ] e T4y [ 1en 1ot 2h ML e [ o8 [1ee APARA-THLA Lol A | i |38 St BP B JRLEC (TR (M3 | & [o6 | e g 83 o | tues AW+ ot |2%% ]
N 100 A6 | Yo JerPlhil | € | o% | &3 Te-¢ol- & ‘ e | w o [ov | tet rmetEM-t | 7 (TCPey Lod| A | 1% | 108 1T +P 41 (L. [18% | ath | ¢ | o4 (114 R 821-€ | U wed | ol |y w17
TH-100: ALY | KL, (ans JALE | B ) [ A FW-10 [ Ve Jieor |Aih | & 1 1 e san) __}N o] A W {34t ST cral Bt | TRG [ AL | B iy |47 AV G010 ke [HBD Tl ¢ " 53 @ ~
10 ALY 6.cl jAvs fMIL. | B o1 1o T horihd Lol jwedk [ ALLE 3 11 Te.ynt ver | B | 216 Vel @) lute: (106 | AV ] ¥ " L) Vet ;an WG, M, ITAR, WG  ALL CAMMET WMOD. B4 £°  [Owuh- Y7458
TN 100 AYS 6.1, ' Abe (AN | © " 4\ o A0S 4 [t Terr L ALL | & ey ) ied TR-OHY vic [tevr { vol | M 9 | 00 1 — - _ AL el e o T foae e sTen
oo S | Ve jtert JAUL | € | o1 | od W AOR YA Yo lTeep [ALEL [ & oy |iea . { - =
ez A At |« |8 oy WAV e |ye fYereiaii [® 1 ov lies | A RADIATOR |PoweR - S = el W T A ittt
1a:1e3- 50 : ALL | B |o% | o} Y ADS-TA | Tfe 1 T6PP{ AL | & Y Vb WENG W T Ypd-201-A2 |B.c.L[ADZ JTOL | A W et e * 10N, CABINEY Mew. 'A o-wn- - ¥4 6L
18-101: AdM ! A | & W Gl IU-ADY-8AT [8cl. med AL | & 13, vy ' WW-IDI €4 [Vieh. (1B T AL | # 1 {15 _ REFERENCE DRAWINGS NO.
B ML | & 1 | ol Th-Re- | Ye Jveee [ Aot | ¢ 18| the WM DT ¢4 [aran | tew [asi | 0 (e — OAK RIDGE NATIONAL LABORATORY
Ta-201A10 At s | w0 Tee-1 et | A Jet | ey WWEH-c4 [man]1ey [pr T v o3 [307 (_._ OPERATED BY
Te- e A 16 Tailt | » .y 9 T™-nc- 1.04.] A ey | 138 WM=CDl ¢4 [aran | 1oy [ALL | & [y [11) MASCELL ANEOUS UNION CMIDE Nucm COMPW
e -281 Ve  [reeeintl | & o3 'S Tas Ré- 4 el | A oy | 184 WE 21 €4 | vaa] 14 LAt |+ 1 |l Erh- IVA_ lwired e Lt DIVISION OF UNION CARBIDE CORPORATION .?"-
‘ TR At | B 1% | teo . - EeM- DL luewe. [ Shan f 2 a T n_[1a2 OAX RIDGE, TENNESSEE ¢
ek G | et | b | et |26l e S T "oo
. Tewc-T (3o werecoc] a [os |1ret LR On, DiMENSIONS UMLESS JMOLTEN HALT BEACTOR SXPERIMENT %" 7503
DEN™ 519 ?
Y REVISIONS \ FRAGTIONS & RAIA LOGGED SioHAL INTERcouutelion Wikl .
e . DECWALS & e ] _GAL ASSIGHMENT JABULATION
Qe 14 Gb
mass & - APROVED |
g M, HIRGER LN -
REw o _ oy D- B [57457| 0[]
1 120{94RH 628D 1
s -
Fig. 2.12.6. Data Logger Signal Interconnection Wiring Signal Assignment Tabulation.
|

mea e

 

 
 

393

2.13 MSRE Beryllium Monitoring System1

Atmospheric beryllium concentration is monitored by 15 air sampling
stations located at strategic places throughout the reactor building. The
beryllium content of the air is monitored by drawing air through filter
papers which are then collected and analyzed for beryllium content.

The radiator air stack air is monitored by an arc spectrograph. Air
is drawn through the spectrograph for a set period and then analyzed by
the light spectrographic method. The result of the analysis is printed
on a recorder located in the spectrograph cabinet.

The spectrograph is equipped with a manual switch so that the coolant
cell can be monitored during reactor maintenance operations.

 

iN. E. Bolton and T. C. Whitson, Revised Beryllium Control Program
for MSRE, ORNL~CF-63-11-44. (Supersedes ORNL CF-~63-7~63.)

 
 

1. R. K. Abele

2. R. K. Adams

3. G. M. Adamson

L. R. G. Affel

5. L. G. Alexander

6. G. W. Allin

T. A. H. Anderson

8. J. L. Anderson

9. R. F. Apple
10. C. F. Baes
11. J. M. Baker
12. S. J. Ball
13. C. J. Barton
14, A. E. G. Bates
15. H. F. Bauman
16. S. E. Beall
17. R. L. Beatty
18. M. Bender
19. C. E. Bettis
20. E. S. Bettis
2l1. R. E. Blanco
22. F. F. Blankenship
23. J. 0. Blomeke
24, R. Blumberg
25. E. G. Bohlmann
26. C. J. Borkowski
2T7. G. E. Boyd
28. H. R. Brashear
29. J. Braunstein
30. M. A. Bredig
31. R. B. Briggs
32. H. R. Bronstein
33. F. R. Bruce
34. G. D. Brunton
35. J. B. Bullock
36. 0. W. Burke
37. D. A. Canonico
38. S. Cantor
39. W. L. Carter
4Lo. T. M. Cate
41. G. I. Cathers
L2, 0. B. Cavin
43. A. Cepolino
LYy, J. M. Chandler
45, C. W. Collins
46. E. L. Compere
4LT. K. V. Cook

395

INTERNAL DISTRIBUTION

RROOYESEHHIOERAYE QIO I W LN SN QUORHP ORGSO 000 GG o

ORNL-TM-T29

Cook
Corbin
Crowley
Culler
Dale
Davis
DeBakker
Ditto

. Dworkin

. Dyslin

. Eatherly
. Engel

. Epler
Ferguson
. Ferris
Fraas
Friedman
Fry

Frye, Jr.
Gabbard
Gallaher
Goeller
Grimes

. Grindell
. Guymon

. Hammond

. Hannaford
Harley
Harman
Harms
Harrill

. Haubenreich
Heddleson
Herndon
Hightower
Hill
Hoffman
Holmes
Horton
Hudson
Hungerford
nouye

. Jordan
Kasten

. Kedl
Kelley
Kelly

Egt;*?:?flffl?d?dg}?@zglp.flfflb*dmmwmwmm-?bhdlgbjhdw*meMQQE{t‘bl—]’:I!

Y9 EH

 
 

95.
96-97.
98.
99.
100.
101.
102.
103.
10L.
105.
106.
107.
108.
109.
110.
111.
112.
113.
11k,
115.
116.
117.
118.
119.
120.
121.
122.
123.
12k,
125.
126.
127.
128,
129-132.
133.
134,
135.
136.
137.
138.
139.
1ko0.
1h1.
142,
143.
1k,
145,
146.
147.
148-1L49.
150.

?.fi??fl??fl!fl?*dp?fl?‘?flf#i‘d?flp?fl?flb?flI:—'C—cfls‘)’;flmwCEHQGEUEWZHQPSUZQOWQPCAUU)EO

at

ic

396

Kennedy
Kerr
Kirslis
Knowles
Koger
Krakiovak
Krewson
Kryter
Lamb
Lane
Lin

. Lindauer

. Litman

. Llewellyn
. Long

. Lundin

. Lyon

. MacPherson
. MacPherson
. Manning

Martin
Mauney

cClain

McClung
McCoy
McDuffie
McGlothlan
McHargue
McWherter
McNeese
Metz

. Meyer
. Minue
. Moore
. Mossman
. Nelms
. Neumann
. Nichols

Nicholson

. Osakes
. Parker

Partain
riarca
Perry
Pickel
Piper
Potts
Prince
Ragan
Redford
hardson

151.
152.
153.
15k,
155.
156.
157.
158.
159.
160.
161.
162.
163.
16k,
165.
166.
167.
168.
169.
170.
171.
172.
173.
17k,
175.
176.
177.
178.
179.
180.
181.
182.
183.
18L.
185.
186-191.
192.
193.
194,
195.
196.
197.
198.
199.
200.
201.
202.
203.
20k .
205.
206.

0. Robbins
C. Robertson
C. Robinson
C. Roller

W. Rosenthal
P

. C. Bavage

. F. Schaffer
E. Schilling
Dunlap Scott
Scott
Seagren
Sessions
Shaffer
Simpson
Skinner
Slaughter
Sliski
Smith
Smith
Smith
Smith
Smith

. Spencer
Spiewak
Squires
Steffy
Stoddart
Stone
Stone
Strehlow
. Stripling
. Sweet

. Tallackson
. Taylor
erry

. Thoma
Toth

. Trauger
Tucker

. Ulrich

. Walker

. Watson.
Watts

. Weaver

. Webster
Weinberg
Weir
Werner -

QXD YuoO=RREHE 9@
HoapyhyuyEY"qEnEES

.Z:ffl?s‘.flf):':flf—if')_flbdUL—";USH"—I';U.'I%W'JUCHE!';UU’JHfl"UOCD":IP'-fl(DZUMO';E{C-c

GCIo=EHmH"HprnnaxnuwEHdgamdE g ErnHdOO
207T.
208.
209.
210.
211.
212.
213.

232-233.
234,
235,

236-237,
238,
239,
240.
241,

242,
243,
2kl ,
oks5,
246,

247,
248,

249263,
264 .

397

K. W. West 21k, J. P. Young

M. E. Whatley - 215. E. L. Youngblood

J. C. White 216. F. C. Zapp

H. D. Wills 217-218. Central Research Library

L. V. Wilson : 219-220. Document Reference Section

G. Young 221~-230. Laboratory Records Department
H. C. Young 231. Laboratory Records, ORNL R.C.

EXTERNAL DISTRIBUTION

D. F. Cope, RDT Site Office, ORNL

A. Giambusso, Atomic Energy Commission, Washington

W. J. Larkin, Atomic Energy Commission, Oak Ridge

T. W. McIntosh, Atomic Energy Commission, Washington

H. M. Roth, Atomic Energy Commission, Oak Ridge

M. Shaw, Atomic Energy Commission, Washington

W. L. Smalley, Atomic Energy Commission, Oak Ridge

G. H. Burger, Mining and Metals Division, Union Carbide
Corporation, Niagara Falls, N.Y.

E. N. Fray, General Electric Company, San Jose, California
S. H. Hanauer, University of Tennessee, Knoxville, Tenn.

T. W. Kerlin, University of Tennessee, Knoxville, Tenn.

C. L. Matthews, Atomic Energy Commission, Oak Ridge

J. A. H. Kersten, P/A Kema, Utrechtsweg 310, Arnhem,

The Netherlands

K. A. Warschauer, Jacob Marislaan 48, Arnhem, The Netherlands
William Kerr, Director, Michigan Memorial, Phoenix Project,
Ann Arbor, Michigan

Division of Technical Information Extension

Laboratory and University Division, AEC, ORO