MUC-LAO-41.txt

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1944 CEx ..ok RESEARCH Liphalx
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Those: 'pres'ent:t Allison, Szilard, Wigner, Mo;'rism_x,‘ Fz;an_ck,
- Creutz Vernon, Young, Ohlinger

Besides the use of the chain reaction for the production of
he production of isotopes, a ‘third very important use mentioned
ther outline presented at one of the early discussions was a ‘small:’
ar-the production. of radiation with =& very high level of intensit

the speaker at this meeting, explained a pile of Y
type,. t , & radiation source for experimental purposes in ' &
% military use of the product. There is no plle now: operat—
ux as high as Hanford which can-be used for experimental
purposess. - While' such-a unit might seem expensive at first (the cost
would be: about $150,000- to. $200,000); itiwould give an important too: 5
or study: at- & cost not too much more: than & cyclotron-and with & much
~ better source. The flux in the pile proposed by ¥re Morrison would be:
“ about ‘five times tha ; the W pile. . 5.0 & e R

e principle of the pile proposed by Mra Morrison is
_reaction in U9, using a homogeneous mixture of L9 and a. moderator with
. “cemtral core,. Water as & mgderator would not be: very useful because:of
* fts rapid decomposition under the intense radiation to be obtained.
‘Therefore, it ‘igsuggested ‘that beryllium or beryllium oxide: or some
- gimilar material be used as- a-moderator—with-the L9 probably in the:

of “the: oxide, - Cooling would be.obtained by radiation from the surface

of the pile proper with the heat. removed by cooling coils in the: reflee

. -around the pile. With beryllium oxide as the moderator and 2 ~ 3 kg of
“}9 in the form of the oxide as- the active metal, the temperature drop

i : le: would.be about 1000% C. . Pt

‘Thegeneral ‘arrangement of such a pilé would be as indicated
tically in'the sketch ’a‘bfaéqhfifir. ; AR

.- ' The-core of the pile:would be'a beryllium metal (or perhaps BeO
"or graphite) bottle into which could be poured pellets of beryllium-and
plutonium oxide as needed.: Surrounding this to form the pile proper
. would be a cube 80'cm on a sidé composed of closely fitted beryllium
oxide blocksiwith small depressions af regular intervals into which = .
- would be placed: small.compressed bricks of the plutonium oxide. (pure-
' beryllium blocks, and-pure L9 could be.used in place of the oxide),
" ‘Surrounding the. cubical pile would be a 2" thick graphite crucible -
“ contained within a shell of bismuth-lead eutectic covering all sides
of the pile’dnd crucible exoept the top. Embedded in this bismuth-lead.

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; reproduction factor would be around 5 times that of
s machine.. The total leakage flux would be around 1012 or-1013
measured: as surface flux at the face of the thermal column, At the
-thimble, the flux would be about five times this-value. - Mr. Morrisom
.felt that the- d:asign-wae eminently stable and that no nnclear catastrophe

; mmring parts.

: M. w:\.gnervfear:sd‘[that the beryll;i.um might reduce 4he oxide’ leav-

‘ing pure L9 which melts at 625% and therefore it would be preferable to

either use oxides for both the moderator and the active metal or else .

the. pure metals‘ The latter gives:<a smaller unit but does not:give off

any-gassaus: fission products for othert uses: in the Isborat.ary whereas:
vid th.ese products. L :

. Hogness”™ suggested the use of thsmium as the allaying element
/ at, the center. " This has a high melting point and produces some faat

Er gner‘ compared Mr. Morr:.son's h:.gh tamperature operabing pil
with one using water-ab high' pressure and felt that one could realize a:.
factor of only say 2 or:3 in: favor of the former..  However, Mr. ‘Morrison-
explained that he was suggesting this type-of pile only for its advantage
. of having high fiemperature operation and that other types were probably
“as, good or better, Mr. \fl.gngr: still felt somewhat: disturbed by the cam—
bination qf high tempera’cure wit.h high flu.x.

In answer to the quest:.on,wlr. Morrison expla::.ned that the ‘
-'specifie act‘lvity‘ in the P~9' pile at.-Argonne was rather low-and. that !
the pile he had designed:-had the advantage of not depending upon neutfon’
~‘capture to- ob‘tain ‘high specific activity.. ‘He felt it was better to get
~out the gaseous fission products carrier free as occurs in this type .

ppile. Likewise with the use of high temperature metal, it is probable

. that many corrosion problems will be avoided. Mr. Allison reiterated
his favorable:reaction to high. temperature operation and reported that
- he had approved-a program for studying the bismuth-lead alloys for this -
purpose. This included the solubility of iron in these alloys, wetting
-of. ferrous metals, etc. -Since there are only four main materiaIs suit~-
able for pile tubes—-iren, beryllium, aluminum, and sta.inlesa steg

. action of bismuth—lead and. pure hismuth on these materjal®
: :[nvestigatod. 2 - 2

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