ML20027A728
| ML20027A728 | |
| Person / Time | |
|---|---|
| Issue date: | 01/28/1982 |
| From: | Blond R NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Scoggins R NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| Shared Package | |
| ML20027A699 | List: |
| References | |
| FOIA-82-530 NUDOCS 8202160093 | |
| Download: ML20027A728 (5) | |
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dmTED sT ATEs NUCLEAR REGULATORY COMMISSION y
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January 28, 1982 MEMORANDUM FOR:
Ronald M. Scrogg#ns, Director Administration and Resource Control Staff Office of Nuclear Regulatory Pesearch FROM:
Roger M. Blond i
Reactor Risk Branch Division.of Risk Analysis Office of Nuclear Regulatory Research
SUBJECT:
EMERGENCY PLANNING AND SOURCE TERM DEVELOPMENTS Concerning the C. Starr letter to L. Giuffrida dated December 21, 1981, p.
the following infomation is relevant to the issues raised:
il t 1.
Recent unpublished Geman research results are described as being indicative of the benign impact of all reactor accidents. These research results are preliminary and represent the best estimate of the Geman PWR containment design (for Biblis B Reactor).
The Geman design is roughly equivalent in volume and strength to the best (i.e., largest and strongest) of the U. S. containments and thus could provide a comparable safety margin for retention of radioactive material (i.e., a less severe source tem).
Unfortunately, many of our plants do not share these attributes, and thus cannot be credited with this safety margin.
If all U. S. containments were
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as strong and big as the Geman's Biblis B containment, then this extrapolation would be more reasonable and the source tem could be reduced.
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2.
The significance of the Geman findings were given in the following paragraph:
"The significance of these findings is that the appropriate emergency planning radius around a nuclear plant is very l
much reduced (probably to one-fifth to one-tenth (1/5 - 1/10) i of the presently suggested radius); there would be no early l
health effects from public exposures to radiation; and any latent effects would be so small as not likely to be detectable."
s This paragraph is unsupportable and does not reflect the best judgments regarding the impact of such accidents.
With a source term reduct' ion of a factor of ten,' there would still be the potential for early fatalities and injuries out to about five and twenty five i
miles, respectively.
Even with a source tem reduction of a factor of 100 (EPRI is not yet recommending this large a reduction) there could be early fatalities and injuries out to about one and five
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1 Ronald M. Scroggins,
miles, respectively. With respect to the detectability of latent cancer fatalities, such releases would generate statistically detect-able cancers in the exposed population for many tens of miles.
However latent cancer fatalities played no direct role in developing emergency planning criteria.
Concerning the use of this information as justification for reducing the emergency planning zones EPZ, by one-fifth to one-tenth; carly fatalities and injuriec were only one of the considerations used by the NRC/ EPA Task Force (n.b., NUREG-0396) in selecting the current distances. Of greater concern were the Environmental Protection Agency's Protective Action Guides (PAGs) which designate th6 range of dose at which protective measures are mandated.
The source term issues would not substantively change our perception concerning the distances at which the PAGs would likely be exceeded.
The remainder of the C. Starr letter focuses on the implementation requirements of emergency planning.
Enclosed as attachment 1 is the briefing notes of M. Taylor and I, to V. Stello on January 25, concerning these same questions and our preceptions of the technical relationships between the source term and emergency planning and its implementation (e.g.,sirensystems).
With the current "conserestive" source term, we could not find sufficient justification to demand in early warning system beyond about five miles.
If the source term is reduced by about a factor of ten, two miles would be more than sufficient. However, we still find it necessary to plan to have communications for notifying cognizant cificials within about ten miles of the plant;~and to have considered the ingestion pathways (e.g., milk, water) within about 50 miles.
3.
With respect to the F. Culler letter of January 6, I would generally concur with the research recommendations that are made.
Enclosed as attachment 2, is our program brief for the March-2 computer code development. We held the first meeting of the MARCH - developers group on January 15. Battelle Columbus, Sandia, Brookhaven, Oak Ridge, TVA,:
and EPRI agreed to participate and coordinate their effects under Sandia/BCL responsibility. We are trying to have a new March-2 code available by the end of the summer, In addition to the above comments, I would like to comment on a portion of i
attachment 3 to the F. Culler letter.
The comment is made concerning the Review of Effectiveness of Engineered Safety Features that NUREG-0771 only recommended additonal requirements without relaxing old ones. 'This is We stated that the changes required by altering the des.ign basis wrong.
accident were so pervasive that the only way to address the problem was l
through formal rulemaking and not by patching up the'old structure with l
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i Ronald M. Scroggins.
" quick" fixes.
In addition, we are now in tha procass of reviewing NUREG-0771 and will revise it as necessary within tha next few months.
If I can be of additional help please contact me.
Mb Roger M. Blond Reacter Risk Branch Division of Risk Analysis Office of Nuclear Regulatory Research Attachments:
As stated N
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SUBJECT:
EMERGENCY PLANNING FOR NUCLEAR POWER PLANTS CoIIsr LA Slair -
- -: a r M r. Giuffrida:
Recent experimental and theoretical,research in' Germany has indicated that in the event of a major nuclear power plant failure resulting-in a core meltdown, the amount of radi,nuclides o
release.d into the atmosphere would be drastically reduced from Nuclear
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the conventional es't'imates 'that have been used by the
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to'edaluatepublic risk.
Regula, tory Commission and others The significance of these findings is that'the appropria~te is very much emergency planning radius _around a nuclear plant one-tenth [1/5 - 1/10].of L
reduced (prisbably to one-fif th to there would be no-carly the presently suggested radius);
health effects from public exp'osures to radiation; and any latent effects vould be so-small hs not likely to b,e detectab1'e.
,Further, there are likely,to be several days available after I
the accident before the containment building leaks significantly.
(4.5 days in the German study), and very little' iodine release.
So the present early warning criterion serves no useful iodine absorption prevention is. '.
function,,and prepa'ratory unnecessary.
l Under these circumstances, the emergency plans being implemented l
by FEMA in accord with the~old criteria wou'Id be grossly of an unwarranted exce'ssive, and mi'ght indeed be the source civilian evacuation exercises, public risk.
Such activities as distribution of potassium iodide tablets, and the routine -
testing of 15-minute warning sirens and alarm systems, may not only be unnecessary, but may,also result in physical injury from continued public anxiety and stress.
and psychological harm possibility of a major reduction in the estimates of the i
The (the " source of radioa'etivity from such. accidents to the attent' ion of release in nuclear parlance) was brought the NRC in September 1980 by our staff, and resulted in NRC term,"
November 18, 1980.
The accumulated hearings on this subject on 12/28...To EDO for Appropriate Act. ion..Cpys to: RF. 81-2543 v20 94
~v~wmauan; arrvow Avence.. Pest 0:!;ce Box 10412. Palo A'lo.CA 94303 (415) 855;2000
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Page 2 Mr. Louis O.
Giuffrida Director, FIMA December 21, 1981 accident information'during th,e past several decades provided as well as the specialized the basis for these p r e s e nt a t.'.on s,
testimony of experts from our national laboratories and overseas.
The subject was again reviewed with the NRC on October 26, 1981.
Because o'f the importance of this topic.
professional attention has been' focused to public safety, n this topic internationally.
The German studies are part-
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of this effort.
As the professional studies and research continue, the mounting eyidence appears to support the estimates of a reduced source -
term.
The NRC staff is being kept ' abreast of this work, and its significance was recognized by.its Executive Director for E-Operations, William J. Dircks, in his memo to the NRC of-June 19, 1981.
While it may take several years'to experimentally verify all the analytical details of the source term, it is cl'a,rly evident that it should be reduced.
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becoming In view of,the importance of d$is: matter to establishing public-confidence in governdeht regulf(ory agencies and in our many.-
that FEMA work closely with the NRC in assessing the developing source term situation.
.f nuclear generating stations, Igu,rge It is very important that FEMA avoid premature and Excessively
- undone severe'public programs which will probably have.to be almost as soon as they are f ully -implemented.
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detailed technical review If you,or the FEMA
- staff would like a
of,the source term developments and their implications, we I'.
would undertake to arrange it.
Sincerely, s
.1 Chauncey Starr Vice Chairman
.CS:ebn cc J.
N.
Palladino
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Chairman, NRC l
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ELECTRIC POWER RESEARCH INSTITUTE 7"M r l
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January 6, 1982 Hon. Nunzio J. Palladino, Chairman ll. S. Nuclear Regulatory Corrnission Washington, D. C. 20555
Dear Chairman Palladino:
At the October 26 briefing by the EPRI staff on the source term issue, we agreed to make specific suggestions on which research is could most advantageously be expedited.
During the past.
. our staff has talked to members of your research staff and
- e v.3ited NRC-supported laboratories in order to gain the most up-to-date picture.
We recommend that acceleration of thelollowfnq Od projects be considtred:
improved thermal-hydraulic modeling, primary j
.~ source characterization, aerosol transport in the primary and secondary systems, and containment failure mode.' These suggestions are amplified in Attachment 1. presents the tentative
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schedule for EPRI's related work.
During the briefing, you also asked me what specific actions the Conmission could take today in response to the growing technical concensus that a smaller source term is reasonable.
In Attachment 3, we have amplified our oral statement with some suggestions for your consideration.
You will recall that the original motivation for our briefing was our concern about the requirements for emergency response planning; for example,10- and 50-mile Emergency Planning Zones, routine testing of 15-minute warning sirens, distribution of potassium iodide tablets. We therefore recommend that the NRC/ EPA Task Force on Emergency __Rasponse Planninole recnny.ened to reconsider g
iTe current planning basis and associated implementing requirements.,
We also recommend that the focus and scope of the Severe Accident We believe that a large reduction in tAe I
[fd WASH-14.00 source term is sufficiently likely that NRC should base its rulemakina bemidered.
g planning on an approximately order-of-magnitude reduction with due consideration of current uncertainties.
Concurrently, research would be proceeding such that technical support for a final position would be available when a draft rule is issued.
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s\\h o o mwes 3m muco Avenue. Post /ce so,10 i2. eato Ano. cA 943a3 (415) ess 2000
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January 6, 1982 Letter to Palladino PAGE TWO
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The Electric Power Research Institute is pleased to contribute If I or my staff can provide any further to your deliberations.
assistance, please do not hesitate to call me or John Taylor, Director of Nuclear Power Division:
1 Yours very truly, l[
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Floyd LT Culler, Jr.
Prpp{ dent
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FLC:JT:ck cc: C. Starr J. Taylor W. Loewenstein 1
EPRI Thoughts on NRC Research Programs EPRI welcomes the opportunity to work with NRC in the definition of.
For orientation purposes the the source term research programs.
tentative schedule and funds for related CPRI programs are presented
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We wish to comment only on what seems to us to be in Attachment 2.
the very significant points regarding the NRC program.
Thermal Hydraulic Madelin$g. The prediction of the time-temperature Fe~havior of a reactor core during the various stages of a degraded core accident is basic to the ability to predict other important phenomena such as the releases of the various gaseous fission products The and the releases of aerosols at successive stages of an accident.
reactor safety technical community, in general, lacks confide
' p.
We urge that this ii the current PARCH code.
industry effort is being made to improve tnis code.
work be accelerated, since it is the " starting point" for mucn other Additionally, we urge that the improved PARCH code (or its fl ect
. replacement) be "modularized" so that the code can be changed to re work.
the improved understanding of the physical pro. cesses which the current We understand"that your Division of research programs will develop. Risk Analysis plans such work at S We would be pleased to coordinate our PARCH upgrade efforts with NRC Significant -
and encourage activation of the proposed PARCH users group.
improvements by the end of 1982 would be a great help with continui improvements in 1983.
5 Coupled with an improved predictive Primary Source Characterization.
ability of the time-temperature behavior of a reactor core during a,
degraded core accident is the need for an enhanced ability to use the i
By this, we mea'n data to predict the primary source characteristics.
the methods of predicting the amounts of safety-significant fission products released from a degraded core as a function of time and This includes an identification as a degraded core accident proceeds.
of the. chemical compounds and the physical forms (gas, aerosol with concentration and particle size specified) of the released fission produ Although we feel that it is appropriate to start aerosol work with tne information now available, new information is needed as quickly as L
to better characterize the starting material to be used in studies in th aerosol work and in the water scrubbing of fission product work soon t for acceler-The specific programs we have in mindThe particular be initiated by EPRI.
ation are those described as " accident source term" work.
subtasks include a) fission produce release from LWR fuel-high tests (ORNL), b) high temperature fission pro PRNL), and e) post accident fission product chemistry (ORNL).
Significant characterization of the aerosol primary source term b Of course a continuing flow of supporting of 1982 would be constructive.
data during 1983 will be useful.
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'n PAGE TWO EPRI is about to place a significant Water Scrubbing of Fission Products.
contract to obtain a data base on the water scrubbing of fission products.
An area which EPRI does not address is the behavior of fission products in an ice condensor. Such an effort by NRC would be, in EPRI's opinion, quite useful.
It is beyond EPRI's resources to undertake in the near term.
Aerosol Transport in Frimary Containment System. The Marviken program is being defined to study the behavior of aerosols in the primary coolant This large scale series of experiments system of the Marviken reactor.
is designed to enhance our predictive ability on the attenuation of It is understood that NRC has not aerosol within the primary system.
definitely committed to participation in the Marviken program but NRC participation in planning these experiments along with increased emphasis on reaching a decision by spring of 1982 concerning its direct involvement
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would be very constructive.
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Corium/ Concrete Interaction. Sandia National Laboratories has performed melt / concrete interaction experiments in which corium was melted by a i
Aerosol concentrations in thermite reaction and poured on concrete.
were observed by optical scattering techniques early 3
excess of 100 g/m Even after about 40 seconds, when the. elt had nearly m
in the test.
3~ During large-scale' solidified, aerosol concentrations were about 20 g/m.
i steel melt / concrete interaction tests, average concentrations were about However, during recent German (KfK) corium melt / concrete tests, 3
10 g/m.
It is important to clarify the reasons for little aerosol was observed.
these differences since, in both WASH-1400 and the German Risk Study, the vaporization release during the interaction between the melt and the concrete foundation is assumed to produce s300 kg of aerosols in the We, therefore, recommeno that in future corium/
containment atmoshpere.
concrete tests, there be greater emphasis on the measurement of aerosol concentrations and of the fission product concentrations in the aerosols.
Results by the end of 1982 would be useful The current scope of the Marviken Aerosol Transport in the Containment _.
experiment does not include a study of aerosl behavior after the aerosol EPRI feels that this area of work being carried leaves the primary system.
out at ORNL on aerosol behavior in condensing steam atmospheres (NSPP) is EPRI at the present time.has very important and should be accelerated.
The development only modest plans in this area because of limited funds.
of experimentally validated codes should, of course, also be accelerated.
The mode of containment failure is a key question in predicting Containment.
the magnitude and timing of the atmospheric release of aerosol bearing A cracking failure mode would not only permit gressure fission products.
relief and hence delay in more catastrophic failure but would result in The Office of Research substantial plateout of aerosol within the crack.
4 W ee
PAGE THREE has initiated an experimental program at Sandia National Laboratory In our opinion, using scaled models of steel and concrete containments.
this program is underfunded and therefore data will be limited and If Recent budget cuts have eliminated many tests.
slow in coming.
we could demonstrate that the several possible containment. types leaked before breaking, this aspect of the reactor safety question would be greatly minimized.
In capsule form, EPRI views a) thermal hydraulic Concluding Comments.
code development and experimental validation, b) fission product release (gaseous and aerosol) attenuation characterization, c) fission product in the primary system and containment, and d) containment failure mode during a degraded core accident as being high priority areas _andI candidates for acceleration.
has accelerated its TMI-2 programs involving 17.2M over a five year These programs will be yielding information germane to the
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subject of this letter.
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i Potential Commission Actions Related to a Smaller Source Term Reconsider the Focus and Scope of Severe Accident Rulemaking.
1.
With respect to severe accidents, a major thrust of the Advanced Notice of Rulemaking (Federal Register, pp. 65474-65477, October 2,1980) was on additional hardware to mitigate potential core melting accidents.
Existing probabilistic risk assessments which incorporate a more realistic source term strongly suggest that reactor accident risks to the public are very small and data from the TMI accident do not change that conclusion. By comparison to the proposed safety goals (e.g., HUREG-0739), most existing designs appear to be acceptable such that further mitigative systems would have ;
k By c.onsidering the new perspective upon thet limited value.
t source term, the recent PRAs and the ' safety goal, we recommend that the Commission issue a revised Advanced Notice of Rulemaking for severe accidents.
Although we recognize that existing data may be insufficient to support a change in, regulatory requirements +
today, we believe a large reduction in the WASH-1400 source term is so probable on a generic basis, that tee NRC should expressi its proposals in such a context rather than in the tone of Specifically, we recommend that the NRC base previous notices.
its planning upon an approximately order-of-magnitude generic The NRC should also examine the reduction in the source term.
sensitivity of their proposals to values three-fold higher and Concurrently, research would lower than the reduced source term.
be proceeding.such that technical support for a final position j
would be available when a draft rule is issued.
Review Requirements for Emergency Response Planning.
Many of a
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the current requirements for emergency response planning are based upon the NRC/ EPA Task Force Report (NUREG-0396). The 10-and 50-mile Emergency Planning Zones were established in large part by considering the atmospheric re' lease magnitudes predicted Other implementing requirements (e.g.,15-minute in WASH-1400.
warning within 10-mile radius) are weakly founded upon NUREG-0396 and WASH-1400.
It is recommended that the Commission reconvene the NRC/ EPA Task Force with a mandate to reconsider this planning basis and the implementing requirements (e.g.15 minute warnings, testing of the plans) in the light of the new technical insights.
NUREG-0771 Review Effectiveness of Engineered Safety Features.
EPRI's iEluded an overview of ESF effectiveness (Table 4.2).
3.
coments on NUREG-0771 (John J. Taylor letter to Commission,
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PAGE TWO 1 October,1981) pointed up the importance of this table a recommended continued effort.
is discouraging to the industry, was the implication that a
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revised source term warranted new regulatory requirementsA re without deleting any existing ones.
term and a fresh perspective on ESF effectiveness seems to us to warrant the deletion of all weakly-founded requirements We and replacinn them with new and more realistic ones.
d their recommend t!.at the Commission ask the NRR staff to expan f the review of ESF effgetiveness to determine whether some o existing requirements can be deleted.
There is general concensusl deficiencies. ~
Issue an Updated NUREG-0771.
within NRC and industry that NUREG-0771 has severa 4.
However, at the October 26 briefing, Mr. Pasadag stated In view
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- NRR did not intend to publish an updated NUREG-0771.
8 RC either of the importance of this document, we re h
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comments as an appendix.
ify NRC's existing report with the public the report is updated, it jiogld be very helpful to clar For intentions with respect to-the~ spectrum of release groups.
l d or example, is NRC proposing th8t such a spec t
?
In view of its importance, ScheduieanUpdateforNUREG-0772.we believe that lly as new 5.
data and analyses are acquired.for research, we reco We suggest Research schedule such updates in its research plan.
that the first update be about March 1983.
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