ML20035H633
| ML20035H633 | |
| Person / Time | |
|---|---|
| Issue date: | 04/22/1993 |
| From: | Shewmon P Advisory Committee on Reactor Safeguards |
| To: | Selin I, The Chairman NRC COMMISSION (OCM) |
| References | |
| ACRS-R-1514, NUDOCS 9305060129 | |
| Download: ML20035H633 (2) | |
Text
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NUCLEAR REGULATORY COMMISSION ACRSR-1514 j'
E ADVISORY COMMITTEE ON REACTOR SAFEGUARDS c
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WASHINGTON, D. C. 20555
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April 22, 1993 The Honorable Ivan Selin Chairman U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Chairman Selin:
SUBJECT:
DEFINITION OF A LARGE RELEASE FOR USE WITH SAFETY GOAL POLICY l
During the 396th meeting of the Advisory Committee on Reactor l
Safeguards, April 15-17,
- 1993, we discussed the staff's i
recommendations in regard to the definition of a large release related to the implementation of the Commission's Safety Goal Policy.
During this meeting, we had the benefit of discussions with members of the NRC staff and of the document referenced.
i l
l In the draft Commission paper and in the presentation to the Committee, the staff expressed its belief that the development of the definition of a large release is no longer practical or useful and, therefore,'it is requesting Commission approval to terminate efforts in this area.
We believe the staff has made a
conscientious effort with this activity and we agree with its basic l
conclusions.
Our views are as follows:
1.
A large release definition would either represent a
j replacement for the existing safety goals or, if made consistent with the quantitative health objectives (QHOs),
would be redundant and unnecessary.
2.
New guidelines being developed for implementing the Safety l
Goal Policy within regulatory analysis and issue prioritization processes adequately meet the originally perceived need for a large release component of the safety goals.
These utilize a core damage frequency (CDF) and a conditional containment failure probability (CCFP).
3.
Plant performance objectives, viz CDF S10 and CCFP $0.1, provide an easily understandable and adequate surrogate for the QHos and provide quantitative prioritization for two basic aspects of defense in depth (prevention and mitigation).
These could help ensure that a plant does not end up with great core protection but marginal containment performance.
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9305060129 930422 0
P The Fonorable Ivan Selin 2
April 22, 1993 We support the recommendation that the Commission approve the staff's proposal to terminate its effort to develop a definition of a large release.
Sincerely, Paul Shewmon Chairman
Reference:
Memorandum dated March 11, 1993, from Warren Minners, Director, RES/DSIR, for John T.
Larkins, Acting Executive Director, ACRS,
Subject:
ACRS Review of Draft Commission Paper on Large Release Determination, w/ Enclosure i
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l P
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