ML20059E212
| ML20059E212 | |
| Person / Time | |
|---|---|
| Issue date: | 03/04/1992 |
| From: | Zuber N Advisory Committee on Reactor Safeguards |
| To: | Catton I Advisory Committee on Reactor Safeguards |
| References | |
| ACRS-CT-2014, NUDOCS 9311030127 | |
| Download: ML20059E212 (4) | |
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UNITED STATES o,j NUCLEAR REGULATORY COMMISSION m
ADVISORY COMMITTEE ON REACTOR SAFEGUARDS o,
WASHINGTON, D. C. 20555 g*g 2
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March 4, 1992 MEMORANDUM FOR:
I. Catton, Chairman, Themal Hydraulics Subcommittee FROM:
N.
Zuber, ACRS Invited Expert
SUBJECT:
COMMENTS ON PRESENTATIONS - ACRS THERMAL HYDRAULIC PHENOMENA SUBCOMMITI'EE MEETING, MARCH 3, 1992 Presentations by NRR Staff (1)
The staff (Thadani, Jones, and Levin) made a good technical case for the full-pressure, full-length facility.
(2)
NRR's concerns based on the lessons learned over the past 20 years are legitimate, justifiable, and technically sound.
(3)
The presentations, the discussions as well as the questions raised by NRR during the meeting reflect:
a firm grasp of technical problems e
good understanding of potential safety issues e
e good technical judgment, and e
professional integrity bsg p
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Zuber Memorandum 2
March 3, 1992 Therefore, I agree with and support NRR's position.
Presentations by Westinchouse Staff l
(1)
The response of Westinghouse to NRR's concerns was-very weak,.
given the evidence (experimental data
'and/or AP600 calculations) presented to support their arguments 'and maintain their position.
This is not surprising, as.the experiments are still in the planning stage and the AP600 calculations have not been completed.
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(2)
I doubt very much that Westinghouse will be able to produce satisfactory evidence as scheduled, that is, by June 26,1992.
The schedule is too tight and the issues are too complex.
i (3)
Westinghouse intends to perform separate effects tests on a i
full-scale core makeup tank, and to perfom integral tests in the low pressure OSU facility.
I have no doubts that both experiments can and will' yield-valuable results.
However, I am afraid and concerned that this approach will not-provide adequate results to resolve all the issues raised by I
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N. Zuber Memorandum 3
March 3, 1992 NRR.
Consequently, the "what if" questions will be' raisedf at; a.
future date to hunt. this. design.
-It is, therefore, ; most probable that this. approach:will lead'to confrentations.'and-delays. causing great harm to.the nuclear power te'chnology.
I!
Presentations by RES Staff and Contractors =
(1)
RES (Sheron) gave a good summary of available. options..
(2)
RES/INEL presented ~ calculations performed 'with' R. ELAPS 'to compare the effects of a' cold leg-breaks'in-ROSA IV and~in~.
AP600.
The comparison was not..very satisfactory.
l However, I am more concerned with the' approach than with the results.
The approach selected by'RES is, first, to-compare a test facility with AP600, by. using RELAP5; this can be deceptive.
Furthermore, it is of little value because it.is based on a circular argument.
Specifically, if a code has deficiencies'in modeling processes important to the AP600, the same'deficiencyfwill appear in both calculations _ (f acility and plant).
Consequently,. no~
conclusions can. be drawn, concerning the effects of f. test facility geometry and configuration.
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N.
Zuber Memorandum 4
March 3, 1992 It should be noted and stressed here, that RELAPS was developed to address a PWR design with an approach to safety l
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that is quite different from that proposed for the AP600.
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should be noted also, that RELAP5 does a satisfactory job for the mission it was intended 4na 'esigned for.
To apply the cresent version of RELAP5 to the AP600 and to draw from such calculations, conclusions concerning the adequacy of a test facility is ill advised at best.
1 Processes and phenomena that impact safety issues do not have equal importance in two f acilities of dif ferent design and having different safety systems.
Consequently, the set of deficiencies that were acceptable in analyses of operating ("old design") PWRs (because of their small effects), may not be acceptable to AP600 applications because of the (potentially) large effects they may have on the evolution of a postulated accident scenario.
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