ML20036A751
| ML20036A751 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 05/05/1993 |
| From: | Perkins K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Townsend J PACIFIC GAS & ELECTRIC CO. |
| References | |
| NOED-93-5-001, NOED-93-5-1, NUDOCS 9305140124 | |
| Download: ML20036A751 (3) | |
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UNITED STATES f
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NUCLEAR REGULATORY COMMISSION m
E REGION V e
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14so MARIA LNJE WALNUT CREEK, CAUFORNIA 94sE5368 4
May 5, 1993 Docket No. 50-275 N0ED No. 93-5-001 John D. Townsend Vice President-Diablo Canyon Operations and Plant Manager Diablo Canyon Power Plant P. O. Box 56 Avila Beach, California 93424 Gentlemen:
SUBJECT:
NOTICE OF ENFORCEMENT DISCRETION FOR PACIFIC GAS AND ELECTRIC REGARDING DIABLO CANYON UNIT 1 On May 3, 1993, at approximately 6:30 p.m., you requested by telephone that the U. S. Nuclear Regulatory Commission (NRC) exercise its discretion not to enforce compliance with the required actions of Technical Specification (TS) 3.8.2.1, "Onsite Power Distribution." You informed the NRC that Diablo Canyon Unit I would not be in compliance with the requirements of TS 3.8.2.1, Action Statement e, after 6:57 p.m. on May 3, in that one of the supplemental vital instrument A.C. buses would not be reenergized from its associated inverter and connected to its associated D.C. bus within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of a failure of supplemental inverter IY-13A, which was experienced on May 2.
You requested that verbal enforcement discretion be granted for a period of four hours to prevent a required plant shutdown.
Your letter dated May 4,1993, documented your verbal request.
As justification for continued operation, you stated that maintenance activities were nearing completion, that testing of the inverter was being initiated, and that the additional four-hour period would avoid plant transients and reduce both operational and shutdown risk. Furthermore, your letter stated that your probabilistic risk assessment (PRA) of the safety significance of the requested extension resul.ted in an increase of 0.2% in the total annual core damage frequency (8.8 X 10') due to internal events.
Although the Plant Safety Review Committee (PSRC) had not reviewed and approved your request when you initially contacted the NRC for enforcement discretion, you subsequently confirmed during our telephone discussion on May 3 that PSRC approval of your request had been obtained.
In addition, you stated that, as a compensatory measure, you would provide an uninterruptible source of power to Bus G (the alternate source of power to the associated vital instrument bus) by starting and running emergency diesel generator 1-2 for the duration of the enforcement discretion.
Based on our review of your justification, including the compensatory measures discussed in our telephone conversation on May 3, and as confirmed in your May 4 leMer, we concluded that this course of action involved minimum safety impact, and that we were clearly satisfied that this exercise of enforcement
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discretion was warranted from a public health and safety perspective.
There-fore, as previously communicated during our May 3 telephone conversation, we verbally approved the exercise of discretion not to enforce compliance with TS 3.8.2.1, Action Statement e, for the period from 6:57 to 10:57 p.m. on May 3, 1993. However, we noted at that time that we will consider enforcement action, as appropriate, for the conditions that led to the need for this exercise of enforcement discretion.
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t= ott K. E. Perkins, Jr., Director Division of Reactor Safety and Projects cc:
Dr. Richard Ferguson, Energy Chair, Sierra Club California Ms. Nancy Culver, San Luis Obispo Mothers for Peace Ms. Jacquelyn C. Wheeler Managing Editor, The County Telegram Tribune Chairman, San Luis Obispo County Board of Supervisors Mr. Truman Burns, California Public Utilities Commission Mr. Robert Kinosian, California Public Utilities Commission Robert R. Wellington, Esq., Diablo Canyon Independent Safety Committee Mr. Steve Shu, Radiologic Health Branch, State Department of Health Services Mr. Peter H. Kaufman, Deputy Attorney General, State of California Michael M. Strumwasser, Esq., Special Assistant Attorney General, State of California Christopher J. Warner, Esq., PG&E Mr. G. M. Rueger, Senior Vice President and General Manager, Nuclear Power Generation Business Unit, PG&E i
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