ML20202C204
| ML20202C204 | |
| Person / Time | |
|---|---|
| Issue date: | 01/20/1956 |
| From: | Mccullough C Advisory Committee on Reactor Safeguards |
| To: | Fields K US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20202C166 | List: |
| References | |
| FOIA-85-646 ACRS-GENERAL, NUDOCS 8607110145 | |
| Download: ML20202C204 (5) | |
Text
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e APENDII "A" C
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P January 20, 1956 t
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Mr. K. E. Fields General Manager U. S. Atomic Energy Comunission Washington 25, D. C.
NBJECT:
Pressurized Water Reactor
Dear Mr. Fields:
i At its alzteenth Heeting, the Advisory Consnittee on Reactor S f i
reviewed recent studies by Westinghouse Atomic Power Division c a eguards with parety of the Pressurized Water Reactor.
impressed with the progress being made in defining the behavior e
The Comunittee is well system under steady-state and transient conditions.
e would alter its previous recomunendations.The Comunittee eactor which re-emphasized that contairmnent of fission pmducts must be guarant beyond reasonable doubt.
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RECDHMENDATION:
In view of the limitation on pressure testing imposed by the gu lining of the containment shell, it is recomunende nnite I
be capable of containing the nav4=m credible incident Sincerely yours,
/ signed /
C. Rogers McCullough Chairman Advisory Consnittee on Reactor Safeguards 6.
8607110145 860702 PDR FOIA DALOGH85-646 pgg
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Consolidated Edison has applied for a posit for the construction of a i
.500 Mv pressurized-vater thorium converter rea
'New York.
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- developed so far give reasonable confidence that a reactor of this ge I
type can be built and operated at the pmposed site without unduo haz
'to the public.
ard thave been submitted to the Committee during the past f I
ever, a great deal of new work was reported on at this meeting.
e months. Hou-i Mr. G. R. Milne described the site, which appears satisfactory from the standpoint of bearing strength and earthquake hazard.
i sults of comprehensive meteomlogical study now getting underway showP
- a typical valley wind regime, the prevailing daytime vind blowing in the i
general direction of Peekskill (2 miles northeast).
. tion problems are anticipated since its salinity prevents significant use No river contamina-of the river water.
e Mr. W. C.Gumprich discussed the overall plant design.
. core vill be loaded with 275 kg U 35. pressure is 1500 psi and ste Primary coolant 2
rature 500 F.
The 1
2 and 8100 kg Th2
' consist of alternate U 35 and thorium plates, zircalloy clad Fuel elements stresses resulting fmm differe.ntial expansion of the plates are not Themal expected to exceed 1/3 the yield stress but detailed studies are under-
.way on this.
Mr. M. C. Edlund revieve
- 0.6, reactivity due to Ughe core physics.
With product poisoning, so that the reactivity vill drop steadily nversion ratio of
- initial value of 20-25%.
' Thorium cross-section and resonance data are considered 10-20% permitting adequate Doppler calculations.
- mated. coefficients of reactivity were given
The following esti-Fuel plate metal coefficient
/.01to /.02 x 10 8F
' Water coefficient at operation tesaperature 4
-3 to
-5 x 10 8F
_ Water coefficient at mom temperature
-0.7 x 104 8F l Thorium Doppler coefficient
-0.8 x 10-4 /DF
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! Mean void ocefficient
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J ww Pgics experiments planned in a full mockup of the core include 2 different U
concentrations and 3 geometries, detemination of critical mass, contml rod worthg flux and power distribution, ratio of themal to resonance fissions l
in U235 and thorium, not Doppler coefficiet, void coefficient, and detailed resonance properties of both fuels, l
Mr. E. E. Walsh listed themal and mechanical-tests including }G'R loop tests, density and strength tests in-pile and out-of-pile, and heat trans-i fer tests.
l Mr. D. C. Bowersock reviewed the plans for containment and vasta disposal.
Pressurizers, boilers, rotating equipment and container cooling and de-humidifying equipment will be inside the containment vessels, but the high pressure seal pumps will be outside. Two types of accidents have been studied:
(1) a 24" primary coolant pipe failure with failure of boilers, j
pumps and scrams and (2) a piping failure without failure of boilers and j
pumps. Case (1) results in an insnediate rise of containment pressure to t
100 pai followed by a slow dmp to 85 pai. Case (2) gives a gradual rise-l to 85. psi. Final design vill be based on the greatest pressure attained (100 pai). It was stated that any possible chemical reaction was believed to be too slow to affect the pressure rise, 7aste disposal pmvisions include decontamination of routine let-down r
water to AEC drinking water tolerance by means of ion exchange mlumna l
and filters. Plans were described for decontaminating, storing and re-leasing pmducts of an accidental fuel element failure, released into l
the primary coolant water or containment vessel.
W. F. Osborne of Consolidated Edison described the instmmentation and contml plans based on the principles of duality and auctioneering. The power level scram is to be set at 600 Hw and the period scram at 10 sec.
K. R. Osborn, Chairman of the ACRS Subcommittee on Consolidated Edison, called attention to the following pmblems:
(1) The importance of containment in view of the nearness of Peekskill and the undesirable meteorological characteristics of the site; (2) The possibility of violent chemical reactions, which had not yet been fully considered; i
(3) The question whether the proposed water sprinklers would actnally j
hold the pressure within design limits; (4) The possibility of containment penetration by missiles.
He also pointed out that it would be necessary to depart fmm the pres-
- sure vessel code by eliminating safety valves and by not stress-relieving the containment vessels.
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! The Chairman suggested that Consolida,ted Edison explore with the Reactor Hazards Evaluation Staff the possibility of obtaining the existing clas-l sified information on zirconium-water reactions.
Dr. H. Wexler commended Consolidated Edison on their meteomlogical i
'i program and stressed its importance, particularly in view of the likeli-hood that stable nighttime vinds would carry contaminants down the Hudson Valley to New York City with little dilution.
Dr. R. L. Doan cautioned against over-optimism regarding the ease of de-contaminating primary coolant water. He mentioned the HIR experience of U escaping fmm amall fuel element defects, plating on the reactor sup-porting structure and acting as a source of fission products henceforth regardless of water changes.
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Regarding the control rods, it was stated that all are black, that they
. are worth 40% reactivity, and that they will require replacement in 5
- to 10 years.
' The Chairman noted that an ambitious experimental program is planned and l vill indeed be necessary to verify the theoretical calculations, which
. look unexpectedly favorable. He pointed out the need for a careful l analysis of possible sequences of events including the possibility of t meltdown, metal-ger reactions and a secondary critical mass resulting l from selective U meltdown.
Later, in executive session it was agreed that Consolidated Edison has j made excellent pmgress, and appears to be taking a sound approach and to have assembled a competent staff. The hazards problem generally I
I appear to be such as can probably be solved by further analysis, experi-ment and design. The letter attached as Appendix "G" was sent to the r
General Manager.
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I Bazards Evaluation Branch - Infonnation Dr. C.'E. Beck Chief f
actions and pen, ding pr,ojects of the staff, as list d iHazards Eva In addition to these items it was mentioned th t th e
University of Michigan reactor are expected to b n Appendix 8A8 a
e ETR, NR and staff short3y for final review before operation e sulmaitted to the s
Assistant General Manager for Research and Indu t i lMr. A. Tasmaro, stated that the ETR, OHRE and PWR will not be operat dDevelopmen sra have been evaluated by the Hazards Evaluation B until they e
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work load taken over by the staff.Dr. Milla expressed the gratitu d
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Jb e 6, 1956 1
Mr. K. E. Fields General Manager Washington 25, D. C.U. S. Atomic Energy Connaission l
RTBJECT:
Power Reactor Development Co Zast Power Raaetor Ij_
Dear Mr. Fields:
(Reports APDA 100 and 114)*
Development CompanyThe present status of the reactor bein associated with Atomic Power Devthpmentg proposed b was reviewed by the, Advisory Committee on Re Eighteenth Meeting on June 3,1056 actor Safaguards at itsAssociates, i
the reactor, the state of infomation o This review incluaca the design of relation of the reactor to its contaiment n the nuclear properties and the
'PRDC reactor represents a greater step beyond th and its site. The proposed art than any other reacter of posed by an industrial group. comparable power level which has beee exist Faca this review the following conclusi n pro-ons were derived:
1.
Cosmittee that clearly indicate that thEven though there u a ions available to the.
for this site, the Committee believes th e proposed reactor is.not safe operated at this site without public bazavailable at this tim ere is insufficient information i
a ard.
e PRDC reactor can be j
2 It appears doubtful that sufficient available in time to give assurance of safarperimental information w l
- rated as detailsd below.less the present fast reactor program of th e operation of this reactor un-
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give sufficient information to pemit safIt is impossible to s j
the Lagoona Beach ' site on the time sch d
, an accelerathd program would.
e ule pre % tion of this reactor at -
e ope 1 information to judge the safetThe following program of investiga sently pacposed.
J y of the proposed operationss suggested in order to provi
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The origin of the positive component of the temperature coefficient in EBR-I must be established. A clear demonstration must be given that a coefficient of this magnitude cannot azist in the PRDC design. The l
experimental program required would involve three phases l
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Study of the spontaneous behavior of a new EBR-I core de-signed with rigid fuel elements to insure against the possibility I
of bowing, aich a study might have to include experiments with both series and parallel flow thmugh core and blanket, Extensive studies of oscillator autperiments on the PRDC de-b.
sign with a. sianlator, using a vide variety of component temper-I
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ature coefficients and associated time constants. These studies should be designed to demonstrate that oscillator tests in the i~
i startup of the PRDC reactor can produce all tle temperature co-efficient information required to assure safe transient proper-ties of the reactor, i.
e., a negative prompt temperature co-efficient of sufficient magnitude to prevent a fuel meltdown.
c.
Further experimental work on ZPR-III to show the magnitude f!
and size of the Doppler effect in order to verify the theory.
2 The magnitude, time constant, and sign of the various components of the temperature coefficients in the PRDC design must be evaluated together with a reasonably complete theoretical understanding of their origin in terms of the mechanical design. This program has three aspects:
A demonstration by the siam 11ator studies under lb. - that a.
the proposed startup program on PRDC can'give the Information required over a vide range of possible coefficients and time constants.
b.
Conduct of oscillator studies on the EBR-II reactor to show that they are feasible and capable of being interpreted to give the necessary infozzation.
c.
Startup program on the PRDC reactor itself to obtain the final information needed before the reactor can be safely operated at full power without meteorological restrictions.
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- The objoo'tive of this program sust be to asoortain whether the various L
.L negative coefficients are sufficient to. prevent meltdown under any com-esivable aircumstances'of control ma.lgperayone..'" ~- - > ~ W
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3.
The Cossaittee as a whole was not satisfied with the evidence pre-sented that no credible supercriticality accident resulting from molt-down could breach the container.
It is felt that m'more extensive theoreticel and experimental program to eramine all the po'saibilities needs to be established and pursued vigorously.
The following are ex-amples:
f mechanical mock-up studies designed to study distortion of core on sudden melting criticality studies in ZPR-III design to in-vestigate==*= super, critical arrangements,' detailed design studies of the reactor structure, with supporting mock-up experiments, to in-sure suberitical distribution of melted fuel and to assure that free
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fall of core parts cannot re-assemble a critical nass suddenly.
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It is considered critically important that the EBR-II program be
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pursued more aggressively and coordinated more closely with the PRDC design than is presently the case.
The EBR-II program is the only pm-gram now constituted which could pavide engineering information and operating experience on a high-power-density fast reactor in advance l
of the' scheduled date for operation of the PRDC reactor.
The nature and content of the EBR-II program which the Cosmittee con-siders essential depends on the outcome of investigation 3 above.
1 it can be shown that a supercritical accident with' sufficient energy l
If release to breach the building cannot take place, then the EBR-II pm-f gram should be aimed at providing general engineering information rel-evant to the economical design and safe operation of the.PRDC reactor.
On the other hand, if it canmt be shown that breaching of the building during a meltdown is impossible, then a much more extensive EBR-II pro-gram is* required.
be a genuine prototype of the PRDC reactor.The test reactor to be operated as E l
The fuel elements of the test reactor should be identical in all essentials to those proposed '
for the PRDC reactor, and operated at power densities at least as high j
as those to be used in the PRDC reactor.
ties of the test reactor should be fully investigated, completely under-The stati stood theorotically and proved incapable of causing meltdown.
These properties should be investigated both for the reactor with its initial charge of U-235 and U-238 and for the reactor with the steady-state non-centration of plutonium in the core.
The Cosmittee vishes to note that th'e experience that, now exists on fast power reactors of high power density is not wholly reassuring.
EBRmI incident is n6t directly relevant in this connection because the p
While the
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i June 6,1956 the conditions of the teminal experireactor was know apt power coefficient under lishediand.therefore its possible occurrethat the ment, nevertheless the fact remains j
c ent has not been cleab37-estab-be definitely excluded on the basis of p t
nce in the PRDC design cannot Opinions differ as to whether its abs ence can be completely assured i the PRDC racetor in 5112. safe way ty the oscillator tests in e-startup pmgram proposed for a
The Committee considers it important th t b I
the. development of the fast breeder re old steps be taken to advance
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a ingness of the Power Reactor Develo Committee does not feel that the steps tprest i
t of this reactor concept.
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to pmvide sufficient develoyaient facilitito risk the a and But the o be taken should be so bold as
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that the safety aspects of the PRDC r l
eactor can be reliably appraised in advance of operation of the r'eactor itself li
, Sincerely yours, i
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/s/ C. Rogers McCullo$gb/i C. Rogers McCullough eAPDA-108 Description of Developmental l
I Fast Neutmn Breeder Power:
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Reactor Plant, Sept.1 APDA-114 Location and Envimrsnen,tal 1955.
+.l Safety of Developmental Fast
- Some SupplementaiBreeder Power Reactor Plant.
7 Safeguard Topics Relevant to the Power Reactor Develop i
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Power Reactor Development Corcoration's Fast Breeder Reactor (APDA-108,114 "Some Supplementary Safeguard Topics...." and abstract by B. J. Garrick)
The Committee considered the question, sutsnitted by the Division of Civilian Applicat' ion, "whether or not there is sufficient information available to allow them to state with reasonable assurance that a reactor of the general type under consideration can be constructed and operated at the site so-lected without undue risk to the health and ' safety of the public."
l i - The discussion centered around the following more specific questionst 1
Is it feasible on the basis of presently available theoretical and l
experimental data to design a full-scale fast neutmn power reactor having such stable transient response that there is no significant risk of melt down?
r 2
If not, can it be assured that, in the event of melt down, a disastmus nuclear'
' rangement of the fuel? energy release cannot be brought about by resulting changes in ar-t 3.
If this cannot be assured beyond reasonable' doubt is it feasible to design an enclosure such that, in the event of any cre,dible supercriticality-accident, the resulting radioactive debris will be safely contained?
4.
Can an experimental program be designed, to be carried out in the PRDC
' all the necessary data can be obtained to assure satisfactory trans about by the experimental pmgram itself? behavior under operating conditions 5.
If the answer to question (4) is not clearly affirmative, can the AEC's
. program of theoretical and experimental investigations scheduled to be
- carried out in other facilities prior to startu Ia reasonably amplified and accelerated pmgram,p of the PRDC reactor, or provide sufficient infor-mation to give assurance that the operation of the PRDC reactor, including the necessary startup tests, can be conducted safely?
6 What additional infonnation and experiments will be required to assure continued safo operation after substantial amounts of plutonium have been built up in the core blanket?
Dr. Edward Teller participated as a consultant to the Comunittee.
1
. Dr. Walter H, Zinn of ANL presented an account of the EBR-I experiment of
' November 29, 1955, which led to fuel melting,'and he showed pictures of the core during removal and initial disassembly. Because of extensive alloying of uranium with the stainless steel cladding, and coalesconoe of fuel elements, the core is being brought to ANL for further study,
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e.~.-~.m ee-y I ne remrds of power versus time and temperature, as well as the results
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ibtained earlier fmm oscillator experiments, establish quantitatively a
the magnitude and time constant of the positive temperature coefficient
' in this reactor, but its origin has not yet been definitely detemined, j
Dr. Glen W. Wensch of the AEC, Division of Reactor Development, outlined l
the major fast reactor experiments contemplated. These ares l
l ' 1.
EBR-II, an intemediate power-breeder reactor similar in concept to
.f the PRDC reactor, to go critical in 1959 or possibly late 1958, at a site I
i l not yet finally selected. Comments by Drs. Zinn and Barnes of ANL, and l l Dr. A. Amomsi of APDA indicated that this pmgram as presently conceived vin not serve as a pilot plant for the PRDC reactor. Since the PRDC
' [ schedule calls for startup in late 1959, EBR-II operation vin be too
, late to influence the PRDC, design. Furthemore the amallar size and di-i g lution of the EBR-II core make it doubtful thht its nuclear characteristics gcan be extrapolated to PRDC design conditions, although there seems to be i some possibility that the EBR-II design can still be modified to be more suitable for such extrapolation.
h; 2
LAMPRE-I, an experimental reactor, not to generate electricity, but to explore the concept of a molten plutonium eutectic with oobalt, nickel, inn or magnesium as fuel, contained in a tantalum t'alaMeia tank, and cooled by sodium flowing through the calaMria tubes. This reactor was described briefly by Dr. David Hall of Los Alamos. Although it is hoped to start up in 1958, it was agreed that this program has no bearing on the PRDC problem because of the great difference in concept.
l 3.
EBR-I. Dr. Zinn suggested that further experiments on a core identichl to the old one would not be likely to be more fruitful than those already carried out. It was agreed, bovever, that experiments on a rigidly anchored, bonded and welded core, in ubich fuel-element bowing is prevented, might
' throw considerable light on the origin of the positive temperature coef-ficient. It might be possible to obtain such data in a year or so.
4.
British Dounreay reactor, a 60 Hv contained reactor at an isolated t site, to go critical in early 1958 Close liaison is. planned with the U.K.
I on this program.
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[ as possible in the ZPR-III fast critical facility at ARCO, and that a nov som power reactor (ZPR-VI) for fundamental research on fast Te&ctbr' physics is plahnod at ANL. The latter may be too far in the future to help with the
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Mr. Richard H. Graham of the AEC, Division of Reactor Develspoent, dis-cussed the possibility of conducti'ng kinetics experiments at the Nevada test site on simple fast reactor systems.
j It was estimated that an as-sembly of rods of enriched uranium with a U-238 blanket 'in a pot of sodissa or NaK' oculd possibly be put in operation by the summer of 1958 A heat removal system would have to be added later in order to obtain transient data under realistic temperature conditions.
Experiments in molt-down would be undertaken only after sufficient non-damaging arperiments had been conducted.
Considerable doubt was expressed in the discussion as to whether such transient arperiments would be applicable without closely mocking up the reactor in question, and also whether meltdown experiments could be designed so that the subsequent events had any general applica-l tion.
Representatives of PRDC and Atomic Power Development Corporation, Mr. W.
Cisler lI consu1I,a.Dr. A. Anomsi,Bethe Mr. R. Nicbolson and Mr. W. McCarthyband their
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, and Dr. H. Gomberg, discussed 8
l aspects of the PRDC reactor and containment building.
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Naval Ordnance Laboratory has estimated that'a building of this, design could withstand g
a 500 lb TFr arplosion inside the concrete reactor shield.
[ unde'r gravity of a melting fast reactor core (the $50/sec acc This exceeds s
' ;k viewed.Available evidence on the magnitude of the Doppler coefficient was re-It was generally, agreed that, while fundamental data are F it is highly unlikely that it contributed significantly to the EBR y instability, and'even more unlikely that it would affect adversely the o safety of the PRDC reactor, with its greater dilution.
b planned on a critical mockup of the PRDC core in ZPR-III to measurExperiments are
, the Doppler coefficient, to test the iffects of changes in. composition e
(and'to measure thermal expansion effe' cts by differential heating, f
' Irradiation tests of PRDC fuel elements are underway at Hanford and in the MTR, Mechanics 1 atsdies'of diashsiorial to16rihees ahd force 4 be-t lInstituteundercontract. tween adjacent fuel elements are being conducted by the Fr General Motors is also doing tests for PRDC
( on bowing and cooling.
bowing coefficient or to make it negative will be tested. Fuel element designs i
,j The start-g up test program is being relied on to provide information on the tran-J sient characteristics of the reactor under test conditions which will
, be safer than nomal operating conditions in the following ways:
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Iower power levels, and hence lower heat dissipation, less chance of meltdown, less fission product hazard.
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A (2) Feasibility of running critical tests only when the vind direction is favorable for minienn population exposure.
(3) Ilse of the non-hazardous oscillator technique to piedict response of tho' reactor to load transients.
(4) Use of slower mari== rod withdrawal rates than those planned for i.
operation.
Al=21stor studies will be conducted in advance of the startup tests to make certain that the experiments are designed adequately to detect all relevant coefficients and time constants.
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The need for redetermining the coeffici, ants after plutonium has bbt up and after irradiation has changed the themal and mechanical pmporties
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of the fuel elements was recognized but no firm plan has yet been developed.
I Yarious possibilities of maintaining suberitic.ality after the begimming
. of melting are under consideration, including directing the flow of molten fuel, and flooding with poison.
Dr. Gomberg presented new results as to the numbers of people who would be exposed to various radiation dose levels as a function of metoonlogical conditions in the event of a complete release of fission paducts. The fraction of the fission paducts which,/m{ inhalation exposurerelease', would i
d ternal gamma radiation, or 10 curie sec
, at 1 mile dcwnwind was also given. The pomissible release ' traction ranges from
.006% for inhlation under inversion conditions to 40% for external samma radiation, under lapse conditions;,
Later, in exe.cutive session, the Constittee was unable to agree on a yes-or-no answer to the precise question put to it by the Commission staff.
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. The deliberations extended into the second and third days of the meeting, ending with unonimous agreenent on the wording of a letter to the General Manager,'which is attached a's Appendiz "A".
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