ML072060022

Temporary 45-Day and 14-Day Allowed Outage Times to Replace Main Control Room and Emergency Switchgear Room Air Conditioning System Chilled Water Piping, Response to Request for Additional Information

ML072060022
Person / Time
Site:	Surry
Issue date:	07/20/2007
From:	Gerald Bichof Virginia Electric & Power Co (VEPCO)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
07-0443A
Download: ML072060022 (5)

Text

VIRGINIA ELECTRICAND POWER COMPANY RICHMOND,VIRGINIA 23 26 1 July 2 0 , 2007 10 CFR 50.90 U.S. Nuclear Regulatory Commission Serial No. 07-0443A Attention: Document Control Desk SPS-LICICGL RO" Washington, D.C. 20555 Docket Nos. 50-280 50-281 License Nos. DPR-32 DPR-37 VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1 AND 2 PROPOSED TECHNICAL SPECIFICATIONS CHANGE TEMPORARY 45-DAY AND 14-DAY ALLOWED OUTAGE TIMES TO REPLACE MAIN CONTROL ROOM AND EMERGENCY SWITCHGEAR ROOM AIR CONDITIONING SYSTEM CHILLED WATER PIPING RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION By letter dated February 26, 2007 (Serial No. 07-0109), Virginia Electric and Power Company (Dominion) requested amendments to Facility Operating License Numbers DPR-32 and DPR-37 for Surry Power Station Units 1 and 2.

The proposed change will permit the use of temporary 45-day and 14-day allowed outage times (AOTs) to facilitate replacement of Main Control Room (MCR) and Emergency Switchgear Room (ESGR) Air Conditioning System (ACS) chilled water piping.

In a letter dated May 31, 2007, the NRC requested additional information to facilitate their review of the license amendment request, and Dominion responded to the NRC request in a June 28, 2007 letter (Serial No. 07-0443).

On July 3, 2007, the NRC provided questions associated with Dominion's June 28, 2007 response. A conference call with the NRC was held on July 12, 2007, to discuss the NRC's questions, and, as a result of the call, the NRC's questions were combined and reduced to a single question that required a docketed response. The NRC question and Dominion's response is provided in the attachment.

Serial No. 07-0443A Docket Nos. 50-280, 50-281 Page 2 of 3 If you have any questions or require additional information, please contact Mr. Gary D. Miller at (804) 273-2771.

Very truly yours, Gerald T. Bischof Vice President - Nuclear Engineering

Attachment:

Response to July 3, 2007 NRC Request for Additional Information as Modified July 12, 2007 Commitments made in this letter: None.

COMMONWEALTH OF VIRGINIA )

COUNTY OF HENRICO )

The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by Gerald T. Bischof, who is Vice President - Nuclear Engineering, of Virginia Electric and Power Company. He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that Company, and that the statements in the document are true to the best of his knowledge and belief.

Acknowledged before me the ad" day of 9""; ,2007.

My Commission Expires: &u;t 3 / ,h o g h 4 d - h m Notary Public

Serial No. 07-0443A Docket Nos. 50-280, 50-281 Page 3 of 3 cc: U.S. Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth Street, SW Suite 23 T85 Atlanta, Georgia 30303 Mr. E. Riggs NRC Senior Resident Inspector Surry Power Station State Health Commissioner Virginia Department of Health James Madison Building - 7thfloor 109 Governor Street Room 730 Richmond, Virginia 23219 Mr. S. P. Lingam NRC Project Manager - Surry U. S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 8G9A Rockville, Maryland 20852 Mr. R. A. Jervey NRC Project Manager - North Anna U. S. Nuclear Regulatory Commission One White Flint North I1555 Rockville Pike Mail Stop 8G9A Rockville, Maryland 20852

Serial No. 07-0443A Docket Nos. 50-280, 50-281 Attachment Proposed Technical Specifications Change -

Temporary 45-day and 14-day AOTs to Replace MCR and ESGR Air Conditioning System Chilled Water Piping Response to July 3,2007 NRC Request for Additional Information as Modified July 12, 2007 Surry Power Station Units 1 and 2 Virginia Electric and Power Company (Dominion)

Serial No. 07-0443A Docket Nos. 50-280, 50-281 Attachment 1 Page Iof 1 Response to July 3, 2007 NRC Request for Additional Information as Modified July 12,2007 QUESTION: The licensee's PRA model assumes that for a loss of MCR cooling, the MCR would be abandoned and the plant would be shut down from the ASP. The licensee should describe why this PRA assumption is consen/ative, addressing the anticipated temperature transient in the control room, equipment qualification of the MCR components, and the availability and procedural controls for alternate cooling capabilities not assumed to be used in the PRA.

RESPONSE

At the time that the Technical Specifications change request was transmitted

[by our February 26, 2007 letter (Serial No. 07-0109)], the Main Control Room (MCR) GOTHIC analysis referenced in our May 14, 2007 letter (Serial No. 07-0109B) was not available. Therefore, the PRA model conservatively assumed that MCR overheating would require operator relocation to the Auxiliary Shutdown Panel (ASP). The assumed relocation is conservative because the model includes an additional risk of failure to control decay heat removal from the ASP, leading to core damage. The subsequent MCR heatup calculation (i.e., the Gothic analysis) indicates that MCR evacuation would not be necessary in the event of the loss of chilled water. As noted in the Response to Question 8 in Attachment 1 to our June 28, 2007 letter (Serial No. 07-0443), the GOTHIC analysis performed for the loss of chilled water predicts maximum bulk air temperatures in the MCR of 105OF (with no compensatory measures) at 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Additionally, UFSAR Section 7.7.1 addresses MCR instrumentation and indicates that qualification testing has demonstrated that the (safety-related) instrumentation remains operable up to 120°F.

In addition, although not credited in the PRA model, the backup cooling supply provided by the chillers located in the Mechanical Equipment Room No. 1 (MER-1) would be used by the Operations staff to maintain control room cooling in the event of the loss of chilled water and provides additional assurance that control room evacuation would be unnecessary. Use of this backup cooling supply during Phases Ill through VI, if required, was described in Attachment 4 in our February 26, 2007 letter (Serial No. 07-0109). Also as noted in the February 26, 2007 letter, procedural direction regarding the use of the MER-1 chillers will be developed. This procedural direction will be in place prior to the initiation of Phase Ill of the chilled water piping replacement activities.