ML18153C682
| ML18153C682 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 07/31/1991 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 91-402, NUDOCS 9108060005 | |
| Download: ML18153C682 (7) | |
Text
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ee ee VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 July 31, 1991 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 Serial No.91-402 NL&P/RMN:R4 Docket Nos. 50-280 50-281 50-338 50-339 License Nos. DPR-32 DPR-37 NPF-4 NPF-7 NORTH ANNA POWER STATION UNITS 1 AND 2 SUPPLEMENTAL RESPONSE TO STATION BLACKOUT SAFETY EVALUATION REPORTS Virginia Electric and Power Company has reviewed the Safety Evaluation Reports (SERs) dated October 15, 1990 and October 18, 1990, respectively, for the Surry and North Anna Station Blackout submittal. Based upon the SERs, we submitted revised plans for complying with 1 O CFR 50.63 on April 30, 1 ~-~1.
This letter provides additional information to the April 30, 1991 letter.
The.-additional information is enclosed as Attachment 1 for Surry Power Station and Attachment 2 for North Anna Power Station and completes our revised submittal on the Station Blackout issue. We anticipate that a favorable SER will be issued by the end of 1991.
Upon the issuance of the SER and the resolution of any related issues, the detailed design change process will be initiated.
The design and implementation of the modifications will require approximately five years.
The first two and one-half years of the project will consist of developing the design change packages, developing the purchase and construction specifications, and constructing the buildings for housing the new non-safety related diesel generators.
Upon completion of this work, final installation and functional testing for each unit will be scheduled to take place during the next two individual unit outages of sufficient duration (i.e. refueling outages). Until the construction phase begins, we cannot firmly 9108060005 PDF<:
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50-280&281 50-338&339 Serial No.91-402 establish a schedule for the completion of construction. Therefore, we anticipate that the final installation and functional testing might add as much as two and one-half years to the project.
If you have any questions or require additional information, please contact us.
Very truly yours, tJl)~
W. L. Stewart Senior Vice President - Nuclear Attachments
- 1.
Supplemental Response to Station Blackout Rule for Surry Power Station
- 2.
Supplemental Response to Station Blackout Rule for North Anna Power Station pc: U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, N.W.
Suite 2900 Atlanta, Georgia 30323 Mr. M. S. Lesser NRC Senior Resident Inspector North Anna Power Station Mr. M. W. Branch NRC Senior Resident Inspector Surry Power Station Page 2 of 2
ee ee Response to Station Blackout Rule Surry Power Station Virginia Electric and Power Company
ee e &ocket Nos.
50-280&281 50-338&339 Serial No.91-402 SUPPLEMENTAL RESPONSE TO STATION BLACKOUT RULE SURRY POWER STATION This response addresses Section D, REVIEW OF SYSTEM ADEQUACIES, Items 3 and 4d, which were not addressed in our April 30, 1991 submittal.
D. Review of System Adeguacies
- 3.
Compressed Air Air-operated valves relied upon to cope with a station blackout for four hours can either be operated manually or have sufficient back-up sources independent of the preferred and blacked-out unit's Class 1 E power supplies.
Valves requiring manual operation or that need back-up sources for operation are or will be identified in plant procedures.
Evaluations are continuing and compressed air may be made available.
However, this is not required for compliance with station blackout. Should instrument air not be restored, then containment cooling discussed in Section D, REVIEW OF SYSTEM ADEQUACIES item 4f, would not be restored. However, as discussed in that section, temperatures are projected to be acceptable without cooling.
- 4.
Effects of Loss of Ventilation
- d.
Auxiliary Feedwater Pump House The temperature profile analysis for the auxiliary feedwater pump area* of the combination main steam valve - auxiliary feedwater pump house has been completed. For the worst case condition, with the turbine driven and one motor driven auxiliary feedwater (AFW) pump running and without forced ventilation, the temperature at the AFW pump elevation is projected to be 114 degrees. This is due to a stack effect which is produced in the area by the buoyancy of hot air, the outlet of hot air through the open roof vents, and the intake of fresh air through the open wall dampers at the auxiliary feedwater pump elevation. Based on the NUMARC equipment operability data base, this temperature is acceptable for all AFW pumps.
ee Response to Station Blackout Rule North Anna Power Station Virginia Electric and Power Company
e e Docket Nos. 50-280&281 50-338&339 Serial No.91-402 SUPPLEMENTAL RESPONSE TO STATION BLACKOUT RULE NORTH ANNA POWER STATION This response supplies additional information to our April 30, 1991 submittal, by (1) clarifying our position on Section D, REVIEW OF SYSTEM ADEQUACIES item 3, and (2) providing a corrected electrical one line diagram of the North Anna Station Blackout AAC system.
D. Review of System Adeguacies
- 3.
Compressed Air The following information supercedes the similar section of Attachment 2 to our April 30, 1991 letter.
Air-operated valves relied upon to cope with a station blackout for four hours can either be operated manually or have sufficient back-up sources independent of the preferred and blacked-out unit's Class 1 E power supplies.
Valves requiring manual operation or that need back-up sources for operation are or will be identified in plant procedures.
Based on our planned primary paths for response to an SBO, compressed air will normally be restored by powering an instrument air compressor immediately on the NBO unit or within one hour on the SBO unit. However this is not required for our compliance with SBO. Should instrument air not be restored, then containment cooling discussed in Section D, REVIEW OF SYSTEM ADEQUACIES item 4g, would not be restored.
However, as discussed in that section, temperatures are projected to be acceptable without cooling.
ELECTRICAL ONE LINE DIAGRAM The one line diagram included in the April 30, 1991 submittal indicated that the existing tie from Unit 2 station service buss B was connected to Unit 2 emergency buss H which is incorrect. The tie is actually from Unit 2 station service buss B to Unit 1 emergency buss J. This is reflected in the one line diagram included herewith.
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EXIST. t NEW TO SW ITCH YARD 34.5 KV. t BUS 4 RSST"A" N.C.
D SS2A lJ NORMAL SWITCHGEAR
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LOADS AAC BUS
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NOTES:
2G SSlC SS2C
- 1. STATION SERVICE CSSJ BUSES ARE NORMALLY FED FROM THE STATION SERVICE TRANSFORMERS CSSTsl-WHICH ARE NOT SHOWN. DRAWING REF. 11715-FE - 188.
e e
e NEW AAC EQUIPMENT WILL BE NON-SAFETY RELATED VIRGINIA POWER tlJCLEM ENGU£ERING SERVICES NORTH CAROLI._ POWER RICIMN),YIRGINIA ONE LINE DIAGRAM STATION BLACKOUT AAC NORTH ANNA POWER STATION DR WI ND. N-5783B-3-E-0301 SH 1 OF 1 y
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