ML071060002
| ML071060002 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 04/18/2007 |
| From: | Catherine Haney Plant Licensing Branch III-2 |
| To: | Christian D Virginia Electric & Power Co (VEPCO) |
| Lingam, Siva NRR/DORL 415-1564 | |
| References | |
| TAC MD4189, TAC MD4190 | |
| Download: ML071060002 (4) | |
Text
April 18, 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 - PRESSURIZER SURGE, SPRAY, SAFETY, AND RELIEF NOZZLE WELD SUSCEPTIBILITY TO PRIMARY WATER STRESS CORROSION CRACKING (TAC NOS. MD4189 AND MD4190)
Dear Mr. Christian:
This letter acknowledges the receipt of information from Virginia Electric and Power Company (Dominion) pertaining to the pressurizer surge, spray, safety, and relief nozzle and safe end welds at Surry Power Station, Unit Nos. 1 and 2.
The discovery, in October 2006, of five circumferential indications in three Alloy 82/182 dissimilar metal (DM) welds on the pressurizer at the Wolf Creek Generating Station (Wolf Creek) raised safety concerns based on the size and location of the indications. At Wolf Creek, three indications were in the pressurizer surge nozzle-to-safe end weld, and two separate indications were in the safety and relief nozzle-to-safe end welds. These findings also indicated that significant concerns might exist with the inspection schedules for addressing the pressurizer weld concerns issued by the industry-sponsored Materials Reliability Program (MRP), in Primary System Piping Butt Weld Inspection and Evaluation Guideline (MRP-139).
The Nuclear Regulatory Commission (NRC) is concerned about the pressurizer surge nozzle-to-safe end weld indications, as this is the first time that multiple circumferential primary water stress-corrosion cracking (PWSCC) indications have been identified in a weld. This condition calls into question the degree of safety margin present in past structural integrity evaluations for flawed DM welds susceptible to PWSCC, since multiple stress-corrosion cracking flaws may grow independently and ultimately grow together, significantly reducing the time from flaw initiation to leakage or rupture.
Based on discussions with the NRC staff, licensees of plants susceptible to this condition have committed to enhanced inspection frequency and reactor coolant system leakage monitoring until actions to mitigate the potential of PWSCC in the affected welds have been completed.
D. Christian In your letter dated February 12, 2007 (Agencywide Documents Access & Management System (ADAMS) Accession Number ML070440188), you stated that the pressurizer spray, surge, safety and relief nozzles at Surry Power Station, Unit Nos. 1 and 2, do not have Alloy 82/182 butt welds. As a result, your response adequately addresses the concerns that the NRC has at this time regarding PWSCC susceptibility of these welds.
Sincerely,
/RA/
Catherine Haney, Director Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-280 and 50-281 License Nos. DPR-32 and DPR-37 cc: See next page
ML071060002 OFFICE NRR/CPNB NRR/LPL2-1/PM NRR/LPL2-1/LA NAME TLupold SLingam:nc MOBrien DATE 4/17/07 4/12/07 4/12/07 OFFICE NRR/LPL2-1/BC NRR/CPNB/BC NRR/DORL/D NAME EMarinos TChan JLubinski for CHaney DATE 4/16/07 4/17/07 4/18/07
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