ML071170090
| ML071170090 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 05/03/2007 |
| From: | Siva Lingam NRC/NRR/ADRO/DORL/LPLII-1 |
| To: | Christian D Virginia Electric & Power Co (VEPCO) |
| Lingam, Siva NRR/DORL 415-1564 | |
| References | |
| TAC MD4622, TAC MD4623 | |
| Download: ML071170090 (6) | |
Text
May 3, 2007 Mr. David A. Christian Senior Vice President and Chief Nuclear Officer Virginia Electric and Power Company Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711
SUBJECT:
SURRY POWER STATION, UNIT NOS. 1 AND 2, REQUEST FOR ADDITIONAL INFORMATION (RAI) REGARDING THE PROPOSAL TO REVISE TECHNICAL SPECIFICATION FOR TEMPORARY 45-DAY AND 14-DAY ALLOWED OUTAGE TIMES TO REPLACE CHILLED WATER PIPING IN MAIN CONTROL ROOM AND EMERGENCY SWITCHGEAR ROOM AIR-CONDITIONING SYSTEM (TAC NOS. MD4622 AND MD4623)
Dear Mr. Christian:
By letter dated February 26, 2007, Virginia Electric and Power Company (the licensee) proposed technical specification (TS) changes for Surry Power Station, Unit Nos. 1 and 2, related to main control room and emergency switchgear room air-conditioning system.
The proposed changes would revise TS 3.23 to temporarily extend the allowable outage time associated with an inoperable chilled water loop from 7 days up to 45 days. The temporary change has been proposed in order to permit repairs, replacement, and modifications to the chilled water piping. The NRC staff is reviewing the submittal and has determined that additional information is required to complete its evaluation.
The NRC staffs RAI is enclosed. The licensee is requested to provide a response to the RAI within 30 days.
Sincerely,
/RA/
Siva P. Lingam, Project Manager Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-280 and 50-281
Enclosure:
RAI cc: See next page
ML071170090 NRR-088 OFFICE NRR/LPL2-1/PM NRR/LPD2-1/LA NRR/DRA/APLA/BC NRR/LPL2-1/BC NAME SLingam:nc MOBrien MRubin LOlshan forEMarinos DATE 4/26/07 5 /3/07 4/19/07 5/3/07
Enclosure REQUEST FOR ADDITIONAL INFORMATION REGARDING REVISION OF TECHNICAL SPECIFICATION FOR 45-DAY AND 14-DAY ALLOWED OUTAGE TIMES TO REPLACE MAIN CONTROL ROOM AND EMERGENCY SWITCHGEAR ROOM AIR-CONDITIONING SYSTEM CHILLED WATER PIPING SURRY POWER STATION, UNIT NOS. 1 AND 2 DOCKET NOS. 50-280 AND 50-281 1.
Virginia Electric and Power Company (the licensee) identified that the probabilistic risk assessment (PRA) internal events model includes the main control room (MCR) and emergency switchgear room (ESGR) air-conditioning (AC) system as a mitigating system, and loss of the function of ESGR cooling as an initiating event. The submittal states that a manual reactor trip is required prior to reaching 120°F in the ESGR.
However, the submittal does not provide any further details as to the failure effects of the unavailability of this system, the success criteria used for the system compared to the design bases, or any other assumptions regarding system operation and impacts in the PRA relevant to this amendment request. The licensee is requested to describe the plant impact assumed in the PRA model upon loss of the MCR/ESGR AC system, including any related assumptions, system success criteria, and any modeled alternate cooling capabilities. This should also include discussion regarding how the initiating event frequency for loss of control room AC was adjusted to account for the unavailability of a chilled water loop. If appropriate to assess any non-conservative assumptions applied, the licensee should also discuss the sensitivity of their results to this assumed plant response, including any sensitivity studies conducted using different assumed responses to a loss of the system.
2.
The licensees submittal did not identify if the risk analyses provided point estimates of the mean or actual means, nor was there any discussion of uncertainty analyses to support the calculations. The licensee is requested to address PRA model and parametric uncertainty consistent with the guidance of Regulatory Guide 1.174, Section 2.2.5.
Surry Power Station, Units 1 & 2 cc:
Mr. David A. Christian Senior Vice President and Chief Nuclear Officer Virginia Electrical and Power Company Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711 Ms. Lillian M. Cuoco, Esq.
Senior Counsel Dominion Resources Services, Inc.
Building 475, 5th Floor Rope Ferry Road Waterford, Connecticut 06385 Mr. Donald E. Jernigan Site Vice President Surry Power Station Virginia Electric and Power Company 5570 Hog Island Road Surry, Virginia 23883-0315 Senior Resident Inspector Surry Power Station U. S. Nuclear Regulatory Commission 5850 Hog Island Road Surry, Virginia 23883 Chairman Board of Supervisors of Surry County Surry County Courthouse Surry, Virginia 23683 Dr. W. T. Lough Virginia State Corporation Commission Division of Energy Regulation Post Office Box 1197 Richmond, Virginia 23218 Dr. Robert B. Stroube, MD, MPH State Health Commissioner Office of the Commissioner Virginia Department of Health Post Office Box 2448 Richmond, Virginia 23218 Office of the Attorney General Commonwealth of Virginia 900 East Main Street Richmond, Virginia 23219 Mr. Chris L. Funderburk, Director Nuclear Licensing & Operations Support Dominion Resources Services, Inc.
Innsbrook Technical Center 5000 Dominion Blvd.
Glen Allen, Virginia 23060-6711