ML18153D048
| ML18153D048 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 06/24/1992 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| REF-GTECI-B-56, REF-GTECI-EL, RTR-REGGD-01.155, RTR-REGGD-1.155, TASK-B-56, TASK-OR 92-356, NUDOCS 9207020139 | |
| Download: ML18153D048 (3) | |
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"'.,Y' VIRGINIA ELECTRIC AND PowER COMPANY RICHMOND, VIRGINIA 23261 June 24, 1992 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 Serial No.
NL&P/GDM Docket Nos.
License Nos.92-356 RO 50-280 50-281 DPR-32 DPR-37 STATION BLACKOUT - EMERGENCY DIESEL GENERATOR RELIABILITY Virginia Electric and Power Company has reviewed the NRC staff's supplemental safety evaluation (SSE) provided in your letter dated May 12, 1992.
The SSE approved our February 1 O and March 17, 1992 submittals for compliance with the station blackout rule (1 O CFR 50.63). Since Generic Issue B-56, "Emergency Diesel Generator Reliability", has not been resolved at this time, the SSE (Section 2.7) required that we commit to an emergency diesel generator (EOG) reliability program that contains, as a minimum, the five elements of Section 1.2 of Regulatory Guide 1.155, "Station Blackout". Our current EOG reliability program contains the required five elements. We commit to maintain these elements pending resolution of B-56, and upon resolution of B-56, we will assess our program for continued compliance.
Although we are in agreement with the conclusions of the Staff's evaluation, we would like to clarify our understanding of Section 2.1, Station Blackout Duration, and Section 2.3, Compressed Air. Our clarification is provided in the attachment.
If you have any questions or require additional information, please contact us.
Very truly yours, JL~
W. L. Stewart Senior Vice President - Nuclear Attachment
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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
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ATTACHMENT Section 2.1 - Station Blackout Duration As agreed to by the NRC and NUMARC, compliance with the SBO rule may be met in accordance with Regulatory Guide 1.155 and NUMARC 87-00, which the Reg. Guide endorses.
Determination of the independence of offsite power group per these documents is by Table 5 of the Reg. Guide or Section 3.2.1, Part 1.D, of the NUMARC document. Contrary to the Supplemental Safety Evaluation (SSE), we do not interpret the "or" in Column 1 of Table 5 of Reg. Guide 1.155 as an "and". Pursuant to the direction provided in the Reg. Guide and NUMARC 87-00, if a plant has electrically independent switchyards, as Surry does, it may be considered an "11" plant per the Reg. Guide and an "11/2" plant per NUMARC 87-00. No additional restrictions are imposed for determination of the independence of offsite power group by either document.
The NRC concluded in the SSE that the classification of the independence of offsite power group was "11/2", resulting in an offsite power design characteristic of P2* and a coping duration of four hours. Although we agree with this conclusion, the following clarification is provided:
- 1. The normal AC power supply to the Class1 E (safe shutdown) buses at Surry is through the Reserve Station Service Transformers and not the main unit generator as suggested in the NRC's evaluation.
- 2. The NRC stated that paragraph 8.2.b in Table A.2 of NUREG-1032 is applicable to Surry. This paragraph implies that following a loss of the normal power source there is an automatic transfer of the Class 1 E buses to a preferred or alternate power source.
This is not the case at Surry, as we do not automatically transfer the Class 1 E buses following a loss of the normal offsite power supply. Therefore, paragraph 8.2.b does not accurately describe Surry's Class 1 E bus design.
Section 2.3 - Compressed Air In our February 1 O, 1992 response to the station blackout (SBO) rule, we stated that we were planning to develop station procedures to power a normal 4 KV bus supplying either one of the two station air compressors. While this remains an option, we are also considering a design that would provide an alternate power source directly to the station air compressors from an alternate AC system bus. This design would be functionally the same and would minimize the operator actions required to restore the compressors during a station blackout event.
Regardless of the final design selected, a dependable power source will be made available to a station air compressor in the event of a SBO, and appropriate procedures will be developed and/or revised as necessary. This clarification is provided to verify the intent of the SSE is met by ensuring compressed air will be made available in the event of a SBO by a suitable design.