NRC Generic Letter 87-02, Verification of Seismic Adequacy of Mechanical and Electrical Equipment in Operating Reactors (USI A-46)
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WASHINGTON, D. C. 20555
February 19,1987
TO: All Holders of Operating Licenses Not Reviewed to Current Licensing Criteria on Seismic Qualification of Equipment
GENTLEMEN:
SUBJECT: VERIFICATION OF SEISMIC ADEQUACY OF MECHANICAL AND ELECTRICAL EQUIPMENT IN OPERATING REACTORS, UNRESOLVED SAFETY ISSUE (USI) A-46 (Generic Letter 87-02)
As a result of the technical resolution of USI A-46, "Seismic Qualification of Equipment in Operating Plants," the NRC has concluded that the seismic adequacy of certain equipment in operating nuclear power plants must be reviewed against seismic criteria not in use when these plants were licensed. The technical basis for this conclusion is set forth in References 1 and 2.
Direct application of current seismic criteria to older plants could require extensive, and probably impracticable, modification of these facilities. An alternative resolution of this problem is set out in the enclosure to this letter. This approach makes use of earthquake experience data supplemented by test results to verify the seismic capability of equipment below specified earthquake motion bounds. In the staff's judgment, this approach is the most reasonable and cost-effective means of ensuring that the purpose of General Design Criterion 2 (10 CFR Part 50 Appendix A) is met for these plants.
Because affected plants are being asked to carry out this evaluation against criteria not used to establish the design basis of the facility, this resolution is a backfit under 10 CFR 50.109. The backfit analysis and findings may be found in the Regulatory Analysis (Reference 2) at pp. 31.
Seismic verification may be accomplished generically, as described in the enclosure. Utilities participating in a generic program should so state in their reply to this letter, identifying the utility group and the schedule established for completion of the effort. The implementation schedule will be negotiated with utility groups or individual utilities in accordance with the NRC policy on integrated schedules for plant modifications. See Generic Letter 83-20, May 9, 1983. Utilities not participating in a generic review may be allowed some additional time to complete the review.
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We therefore request* that you provide within 60 days of receipt of this letter a schedule for implementation of the seismic verification program at your facility.
Sincerely,
Harold R. Denton, Director Office of Nuclear Reactor Regulation
Enclosure:
Seismic Adequacy Verification Procedure
References:
- (1) NUREG-1030, "Seismic Qualification of Equipment in Operating Nuclear Power Plants (USI A-46)," February 1987
- (2) NUREG-1211, "Regulatory Analysis for Resolution of Unresolved Safety Issue A-46, Seismic Qualification of Equipment in Operating Plants," February 1987
- This request is covered by Office of Management and Budget Clearance Number 3150-0011 which expires September 30, 1989. Comments on burden and duplication may be directed to the Office of Management and Budget, Room 3208, New Executive Office Building, Washington, DC 20503.
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