ML16295A157

Proposed Generic Letter on Individual Plant Examinations and the Proposed Integrated Safety Assessment Program II

ML16295A157
Person / Time
Issue date:	05/10/1988
From:	Banks M Advisory Committee on Reactor Safeguards
To:
References
D880510
Download: ML16295A157 (3)

Text

D880510 The Honorable Lando W. Zech, Jr.

Chairman U.S. Nuclear Regulatory Commission Washington, D.C. 20555

SUBJECT:

PROPOSED GENERIC LETTER ON INDIVIDUAL PLANT EXAMINATIONS AND THE PROPOSED INTEGRATED SAFETY ASSESSMENT PROGRAM II During the 337th meeting of the Advisory Committee on Reactor Safe-guards, May 5-7, 1988, we discussed a draft generic letter prepared by the NRC Staff as guidance for Individual Plant Examinations (IPEs) for severe accident vulnerabilities. We also discussed the proposed Integrated Safety Assessment Program II (ISAP II) and related informa-tion. Both of these topics have been considered during previous meetings of the ACRS, and we reported our preliminary views on the IPE generic letter in our report of June 9, 1987 and on the ISAP process in our report of July 15, 1987. The ACRS Subcommittee on Severe Accidents met on April 26, 1988 to discuss the latest version of the proposed generic letter on IPEs. The ACRS Subcommittee on Generic Items met on April 27, 1988 to discuss ISAP II. We also had the benefit of discussions on both topics with members of the NRC Staff and industry representatives, as appropriate, and the availability of the documents referenced.

These two programs developed by different NRC Staff groups have not been integrated, even though they deal with many of the same issues.

It is for this reason that we are providing our comments on both programs in a single letter. The present Staff positions, as we understand them, are that the IPE generic letter should be issued in its present form and that implementation of the ISAP II should not be pursued at this time. We disagree with both of these positions.

Instead, we believe that the IPE program should be expanded to incor-porate all outstanding safety issues, not just those under the severe accident rubric. The generic letter should be revised accordingly.

The ISAP II approach should then serve as the instrument by which changes in plant equipment or procedures identified by the IPE could be evaluated and assigned priority by the licensees and reviewed by the NRC Staff.

We consider the most recent draft of the IPE generic letter an im-provement over that which we commented on in our report of June 9, 1987. However, in our report of March 15, 1988, we expressed our concern that there was a lack of coherence among the several principal regulatory programs of the Commission. We believe the IPE program offers an opportunity for providing improved coherence. In its present form, the generic letter will, instead, continue the current compartmentalization.

We believe that IPE and ISAP II can be recast in a reasonable time and

with reasonable expenditure of resources. Radical changes are not necessary, but some modifications and improvements in focus are. We propose a program characterized as follows:

~ The purpose of IPEs would be acknowledged as broader than the original intent of "searching for outliers." Instead, it would call for a general risk reassessment of each plant using the body of information available from the TMI-2 accident experience, development of PRA, existing severe accident research, and the general experience of about 1100 reactor-years. All outstanding safety issues, USIs, GIs, etc., would be subsumed by the program.

It would be made clear that the intent of the program would be for this to be the end of new requirements for licensees. This would be changed only by the advent of important new information or experience.

We note that the IPE program proposed by the NRC Staff already has been expanded well beyond the "search for outliers" concept.

In subsuming USI A-45, "Shutdown Decay Heat Removal Require-ments," into the IPE, for example, the Staff has taken a major step in the direction we are suggesting. Our proposal extends this to a more logical conclusion.

~ Each licensee would be required to conduct a substantial and systematic risk analysis for their plant. We recommend that such an analysis would be a full scope PRA (at least Level 2) and include both external and internal initiators. We acknowledge the difficulties inherent in making this an immediate require-ment. However, it should be possible to develop a phased ap-proach with the intent that within several years each plant would have been analyzed by state-of-the-art methods.

~ Conclusions about results of the risk analysis and necessary changes in actual plant systems and procedures would be de-termined by the licensee and reviewed by the NRC Staff through the ISAP process. We believe the risk-based approach embodied in ISAP is the most logical means for resolving most safety issues.

The risk analysis used in the IPE for each plant will be available for use by the licensee and NRC Staff in their ISAP evaluations.

We believe that the approach we have outlined above will provide the opportunity for a more integrated resolution of severe accident issues and other outstanding safety and licensing issues as well. We endorse current efforts on the part of the NRC Staff to formulate an inte-grated program.

Sincerely, W. Kerr Chairman

References:

1. U.S. Nuclear Regulatory Commission, NRR Generic Letter 88-02, dated January 20, 1988, "Integrated Safety Assessment Program II

(ISAP II)."

2. Memorandum dated March 1, 1988, from T. Speis (NRC) to D. Ross (NRC), et. al., "Commission Paper on Integrated Approach to Implementing the Commission's Policy on Severe Accidents" (Draft).

3. Memorandum dated April 1, 1988, from T. Speis (NRC) to W. Kerr (ACRS), "Documentation Necessary for the Initiation of the Severe Accident Policy Implementation" (Draft Predecisional Attach-ments).

4. Draft SECY Paper (undated), Integrated Safety Assessment Program II (Predecisional Document), received April 26, 1988.