ML18153C567
| ML18153C567 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 03/12/1991 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 91-134, GL-88-20, NUDOCS 9103180133 | |
| Download: ML18153C567 (2) | |
Text
VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 March 12, l99l 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 INDIVIDUAL PLANT EXAMINATION (IPE}
SCHEDULE REVISION Serial No.
NO/CGL Docket Nos.
License Nos.91-134 RS 50-280 50-281 50-338 50-339 DPR-32 DPR-37 NPF-4 NPF-7 In an October 22, 1990 letter (Serial No.90-613), the submittal date for the Individual Plant Examination (IPE) for Surry Power Station was extended from November 1990 to March 1991. This date remained consistent with the Generic Letter 88-20 request for IPE submittals.
The Surry IPE has now been completed in draft form, consistent with a March 1991 submittal date. The draft report identifies that the internal events core damage model (excluding internal flooding) results in a point estimate frequency of 6.8E-5 per year.
This value may change as review comments are resolved.
However, based upon preliminary results, the contribution to core damage frequency (CDF) from the internal flooding analysis may be higher than expected. As a result, we require additional time to perform a further review of the flooding analysis, including generation of a detailed component failure analysis, with the. assistance of an independent consultant. The results of the component failure analysis will supplement the present data base, which used data consistent with the IDCOR flooding methodology to predict the flood frequency associated with the critical Surry components. The present data base was initially used in the flooding analysis since internal flooding has not been considered significant in previous Surry evaluations (i.e., NUREG-1150/NUREG-4550, Volume 3, Part 3).
However, based upon preliminary results, it has been recognized that the data associated with the IDCOR 1
flooding methodology may not be representative for the critical flood sources identified at Surry. Therefore, a detailed component failure analysis is being performed.
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Should the final results indicate that an internal flooding vulnerability exists, an evaluation of potential modifications will also be necessary.
It is our desire to complete these activities prior to issuing and submitting the final Surry IPE. Therefore, we plan to submit the Surry IPE by the end of August 1991.
The June 1992 submittal date for the North Anna IPE, identified in our October 22, 1990 letter, remains unchanged. Although we have changed the Surry schedule, submittal of both the Surry and North Anna IPEs will continue to be within the three year time frame specified in Generic Letter 88-20.
If you have any questions regarding this submittal, please contact us.
Very truly yours, uL')~
W. L. Stewart Senior Vice President - Nuclear 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. M. S. Lesser NRC Senior Resident Inspector North Anna Power Station