ML25167A136
| ML25167A136 | |
| Person / Time | |
|---|---|
| Issue date: | 01/18/1984 |
| From: | Ebersole J Advisory Committee on Reactor Safeguards |
| To: | Palladino N NRC/Chairman |
| References | |
| Download: ML25167A136 (1) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION ADVISORY COMMITTEE ON REACTOR SAFEGUARDS WASHINGTON, D. C. 20555 Honorable Nunzio J. Palladino Chainnan U.S. Nuclear Regulatory Commission Washington, D. C. 20555
Dear Dr. Palladino:
January 18, 1984
SUBJECT:
QUANTIFICATION OF SEISMIC DESIGN MARGINS On January 11, 1983, the ACRS wrote you regarding the quantification of seismic design margins and a possible program to evaluate the contribution to overall LWR risk that arises from earthquakes.
We discussed and elabor-ated on the concerns and recommendations in that letter during our meeting with the Commission on November 17, 1983.
We proposed that a generic solution to our concerns about seismic margins and seismic risk could best be obtained by a four-part program involving both the NRC and the industry.
In a memorandum to Commissioner Ahearne dated April 4, 1983, the EDO concurred that such an effort was timely.
We understand that a task group has been established within the NRC Staff to consider and develop a program, but we have seen no reports of the activities of this group.
The ACRS Subcommittee on Extreme External Phenomena has held several meet-ings with NRR and RES Staff members and their consultants or contractors to discuss our concerns and to learn what was being done to address them.
These meetings have been useful, but it does not appear that muc~ progress has been made toward developing or implementing an integrated program on seismic margins.
Our ongoing review of the research program and budget for FY 1985 revealed a proposed project designated "Seismic Margins."
There are other projects on seismic risk assessment and on seismic resistance (fragility) that would seem to be related to our concerns, but there does not seem to be a focused plan of research to address the problem.
Of equal or greater importance is the fact that we have seen no viable plan for addressing the generic and plant-specific seismic PRAs recommended in our proposed program.
We believe that seismic PRAs, properly done and evaluated, can contribute significantly to the resolution of our concerns.
2178
Honorable Nunzio January 18, 1984 A particular challenge will be how to obtain the cooperation of licensees in connection with the plant-specific seismic PRAs and that part of the program relating to fragilities.
Since the resources required to perfonn a seismic PRA would be substantially reduced if a conventional PRA had already been done, or was being done, the proposed Integrated Safety Assessment Program might be considered as a medium for obtaining the limited number of seismic PRAs required.
The several programs described in our letter and discussed above wil 1 require the i nvo 1 vement of both NRR and RES within the NRC as we 11 as individual utility 1 icensees or an industry group, as appropriate.
For this reason, the program has little chance of being initiated, much less completed, without strong centralized direction, cl early defined objec-tives, adequate funding in both RES and NRR and, above all, support and direction from the Commi.ssion.
The Committee or its appropriate Subcommittee is available to meet with the NRC Staff management to discuss approaches to addressing various as-pec~s of this matter.
¥;c1y~~
Jesse C. Ebersole Chairman 2179