ML18153C167
| ML18153C167 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 03/30/1990 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 88-414B, NUDOCS 9004090317 | |
| Download: ML18153C167 (3) | |
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VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 March 30, 1990_
United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C.
20555 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1 AND 2 NORTH ANNA POWER STATION UNITS 1 AND 2 SUPPLEMENTAL RESPONSE TO 10 CFR 50.63:
LOSS OF ALL ALTERNATING CURRENT POWER Serial No.
NO/JZL:
Docket Nos.
License Nos.
88-414B 50-280 50-281 50-338 50-339 DPR-32 DPR-37 NPF-4 NPF-7 On April 17, 1989, we submitted our response to 10 CFR 50.63, "Loss of All Alternating Current Power." Our response was formatted using the "Generic Response to Station Blackout Rule for Plants Using Alternate AC Power" provided by the Nuclear Management and Resources Council (NUMARC) and was based upon the guidance contained in NUMARC 87-00, "Guidelines and Technical Bases for NUMARC Initiatives Addressing Station Blackout at Light Water Reactors." In January of 1990, we received additional guidance from NUMARC concerning interpretation of NUMARC 87-00 and have been requested to supplement our previous station blackout (SBO) submittal to the NRC with a letter indicating that (1) our previous submittal was based on use of the NUMARC 87-00 guidance including the clarifications in the attachments, and/or (2) any deviations from the accepted NUMARC 87-00 guidance have been or will be clearly indicated. NUMARC has also requested that we affirm our understanding that diesel generator target reliability chosen for each of our plants is to be maintained.
As stated in our April 17, 1989 response to the SBO rule, our submittal was intended to comply with NUMARC 87-00, except where Regulatory Guide (RG) 1.155, "Station Blackout," takes precedence. It has come to our attention, however,-that the NRC staff may be interpreting NUMARC 87-00 differently than we have. For example, the NUMARC 87-00 Supplemental Questions/Answers, dated December 27, 1989, show three configurations for alternate AC (AAC) cross-ties between units of a two unit site.
Figures A and B are acceptable. Figure C is stated as being unacceptable. Our current response to the SBO rule provided a figure showing our proposed AAC cross-tie, which was similar to the NUMARC Figure C cross-tie. Our interpretation of the SBO rule and NUMARC 87-00 led us to the conclusion that a Figure C type cross-tie would
be acceptable. It is our understanding that the NRC provided NUMARC with the guidance that the Figure C cross-tie was unacceptable.
Another example involves the use of load management schemes (load shedding) in the non-black-out unit. It is our interpretation that load management schemes for both the black-out and non-black-out units are allowed by the SBO rule. This includes shedding AC loads which might normally be available during a loss of off site AC power, but are not necessary to maintain the plant in a safe shutdown condition. We also consider it appropriate to shed electrical loads for which there are redundant non-electrical equipment. For example, we assume that the turbine-driven auxiliary feedwater pump is available and that electric-driven auxiliary feedwater pumps are not necessary to place the non-black-out unit in a safe shutdown condition.
With regard to diesel generator target reliability, we understand that the target reliabilities chosen for each of our plants is to be maintained.
As previously stated, our April 17, 1989 response to the SBO rule was in compliance with NUMARC 87-00, as we interpret that document. There may, however, be significant variance between NRC's interpretation and ours. It is our desire to fully comply with 1 O CFR 50.63, RG 1.155, and NU MARC 87-00. As such, we request a meeting to clarify NRC interpretation of NUMARC 87-00 requirements. Following this meeting, we will revise our SBO submittal, as applicable, to comply with NRC acceptance criteria.
Our previous submittal committed to various modifications to our Surry and North Anna Stations and stated that the modifications, as well as appropriate procedure changes, would be completed within two years after the notification provided for in 1 O CFR 50.63(C)(3). Implicit in this commitment was the assumption that our basic approach was in compliance with the SBO rule. Changes to our current SBO submittal are likely to impact our proposed schedule.
Should you have any questions concerning this response, please contact us.
W. L. Ste art Senior Vice President - Nuclear
,J,.
cc:
U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, N. W.
Suite 2900 Atlanta, Georgia 30323 Mr. W. E. Holland NRC Senior Resident Inspector Surry Power Station Mr. J. L. Caldwell NRC Senior Resident Inspector North Anna Power Station Mr. Byron Lee, Jr.
President and Chief Executive Officer Nuclear Management and Resources Council 1776 Eye Street, N.W., Suite 300 Washington, D.C. 20006-2496