ML18153C941
| ML18153C941 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 03/17/1992 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 91-738B, NUDOCS 9203300001 | |
| Download: ML18153C941 (3) | |
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e VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, V1ROIN1A 23261 March l7, 1992 U.S. 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 Serial No.
NL&P/GDM Docket Nos.
91-7388 R4 50-280 50-281 50-338 50-339 License Nos. DPR-32 DPR-37 NPF-4 NPF-7 STATION BLACKOUT SAFETY EVALUATION REPORTS RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION In our letter dated February 10, 1992 (Serial No. 91-738A), we provided our response to the open items detailed in your December 6, 1991 letter and the attached supplemental safety evaluation report (SER). We also noted that an in-depth review of the project activities entailed to implement the station blackout (SBO) modifications at both Surry and North Anna Power Stations was underway to determine whether our previously proposed five year schedule could be realistically improved.
This evaluation has now been completed.
We have determined the five year SBO implementation schedule for North Anna can potentially be reduced to four years. The
. Surry schedule, however, must remain at four and one half years as previously proposed.
Based on our understanding of your December 6, 1991 letter, a schedule completing the Surry SBO modifications by the end of the presently scheduled September 1995 Unit 1 refueling outage and the North Anna modifications by the end of the April 1995 Unit 2 refueling outage would be acceptable without further justification. With the improved schedule, the North Anna SBO modification schedule is consistent with these dates. Furthermore, earlier partial compliance at North Anna will be achieved at the completion of the October 1994 Unit 1 refueling outage. By the completion of this outage, the alternate AC (AAC) diesel will have been installed and the 'D' transfer bus tie-in completed. This will enable the AAC diesel to energize the 1 J emergency bus and mitigate an SBO event on Unit 1.
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As.,rfoted in our letter referenced above, partial compliance with the SBO rule for Surry will be achieved by the completion date identified as acceptable in the NRC SER.
Both alternate AC (AAC) diesels will have been installed and will be able to power either the 1J or 2H emergency bus. This assures that an SBO on either unit at Surry could be mitigated by the SBO modifications which will be implemented at that time.
Our proposed schedule for full compliance with the SBO rule at Surry is the end of the Unit 2 refueling outage which is presently scheduled to begin in February 1996. It should be noted that as the SBO design modifications are implemented at Surry, temporary relief from certain Technical Specification requirements may be necessary to permit the final 'F' transfer bus tie-in. Contingency actions will be evaluated to minimize risk during this period as well as any installation period which relies on entry into a TS action statement.
The difference between your identified and our proposed completion date for Surry is approximately five months. We have reviewed the significance of the delay beyond the NRC staff's desired schedule and believe it to be of minimal risk to safety based on our earlier partial compliance as discussed above. Furthermore, to fully complete the Surry SBO modifications within the NRC's schedule would require either a two-unit outage or an extended one-unit outage concurrent with Technical Specification relief similar to that noted above. The adverse economic impact of dual or extended one-unit outage costs associated with either approach to accommodate an accelerated schedule would greatly exceed the cost projected in the generic backfit analysis performed for the rule. Therefore, we conclude that the minimal increase in safety associated with accelerating the proposed project schedule for Surry is not commensurate with the significant operational impacts. We are currently proceeding with the engineering and procurement for the SBO modifications for both stations. We will also continue our efforts to assess ways to improve these schedules and advise the NRC of any significant changes.
If you have any questions or require additional information, please contact us.
Very truly yours, J Lt~({~~={}..,
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/ Q,vJ' W. L. Stewart Senior Vice President - Nuclear Attachments
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cc:
U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, N.W.
Suite 2900 Atlanta, Georgia 30323 Mr. M. W. Branch NRC Senior Resident Inspector Surry Power Station Mr. M. S. Lesser NRC Senior Resident Inspector North Anna Power Station