ML16246A219
| ML16246A219 | |
| Person / Time | |
|---|---|
| Issue date: | 12/18/1992 |
| From: | Shewmon P Advisory Committee on Reactor Safeguards |
| To: | Selin I NRC/Chairman |
| References | |
| D921218 | |
| Download: ML16246A219 (2) | |
Text
D921218 The Honorable Ivan Selin Chairman U.S. Nuclear Regulatory Commission Washington, D.C. 20555
Dear Chairman Selin:
SUBJECT:
RESOLUTION OF GENERIC SAFETY ISSUE B-56, "DIESEL GENERATOR RELIABILITY" During the 392nd meeting of the Advisory Committee on Reactor Safeguards, December 9-11, 1992, we reviewed the NRC staff's latest proposals for amendment of the Station Blackout (SBO) Rule, 10 CFR 50.63, and the corresponding revision of Regulatory Guide 1.9, which address resolution of Generic Safety Issue (GSI) B-56, "Diesel Generator Reliability." During this review, we had the benefit of discussions with representatives of the NRC staff and NUMARC. We also had the benefit of the documents referenced. On several occasions in recent years we have reviewed the staff's proposals for resolution of GSI B-56, and have offered our advice.
As stated in our previous reports, we continue to believe that additional regulations and guidance are not warranted to ensure adequate diesel generator reliability. The recent industry-wide diesel generator reliability is better than 98 percent, as measured by failure history over the past few years. This is well above the reliability suggested by the relevant regulatory guide as adequate to meet the requirements of the SBO Rule. It is an improvement over what was being observed five years ago, and the improvement has been achieved through industry and staff initiatives without the proposed amendment.
A principal argument of the staff for a rule amendment is that a future relaxation in licensee attention to the diesel generators may occur, and that if it does, the monitoring requirements of the amendment will reveal it. We believe the current NUMARC Initiative 5A and implementation of the Maintenance Rule should ensure adequate attention to diesel generators.
In addition, current regulations require that every diesel generator failure receive a detailed analysis and if a cause of the failure is identified, it must be remedied. This requirement alone makes it likely that the current high level of reliability will be maintained.
It is not necessary for us to repeat our position on the statistical questions that have plagued the diesel generator reliability assurance issue. In addition, the deterministic reliability standards of 0.95 and 0.975, which led to the diesel generator dilemma, are still in place.
In summary, we believe that existing regulations and industry
initiatives will ensure adequate diesel generator reliability, and recommend that the Generic Safety Issue B-56 be resolved without further regulatory action.
Sincerely, Paul Shewmon Chairman
References:
- 1. Memorandum dated November 6, 1992, from W. Minners, Office of Nuclear Regulatory Research, NRC, to R. Fraley, ACRS,
Subject:
Resolution of GSI B-56, "Emergency Diesel Generator Reliability"
- 2. NUMARC Initiative 5A of NUMARC 8700, "Guidelines and Technical Bases for NUMARC Initiatives Addressing Station Blackout at Light Water Reactors," Revision 1, August 1991
- 3. Letter dated March 5, 1992, from A. Marion, NUMARC, to H.
Lewis, ACRS, regarding industry-wide data on emergency diesel generator performance
Subject:
Reliability of Emergency AC Power at Nuclear Power Plants
Subject:
Resolution of Generic Safety Issue B-56, "Diesel Generator Reliability"
Subject:
Proposed Resolution of Generic Safety Issue B-56, "Diesel Generator Reliability"