ML071300650

Pressurize Surge, Spray, Safety, and Relief Nozzle Weld Susceptibility to Primary Water Stress Corrosion Cracking

ML071300650
Person / Time
Site:	Point Beach
Issue date:	05/16/2007
From:	Catherine Haney Plant Licensing Branch III-2
To:	Koehl D Nuclear Management Co
Milano P, NRR/DLPM , 415-1457
References
TAC MD4172, TAC MD4173
Download: ML071300650 (5)

Text

May 16, 2007 Mr. Dennis L. Koehl Site Vice President Point Beach Nuclear Plant Nuclear Management Company, LLC 6610 Nuclear Road Two Rivers, WI 54241-9516

SUBJECT:

POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 - PRESSURIZER SURGE, SPRAY, SAFETY, AND RELIEF NOZZLE WELD SUSCEPTIBILITY TO PRIMARY WATER STRESS CORROSION CRACKING (TAC NOS. MD4172 AND MD4173)

Dear Mr. Koehl:

This letter acknowledges the receipt of information from Nuclear Management Company, LLC pertaining to the pressurizer surge, spray, safety, and relief nozzle and safe end welds at Point Beach Nuclear Plant, Units 1 and 2 (Point Beach).

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.

In your letter dated January 30, 2007 (Agencywide Documents Access & Management System (ADAMS) Accession No. ML070310270), you stated that the pressurizers at Point Beach 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.

D. Koehl May 16, 2007 This completes the NRC staff efforts on TAC Nos. MD4172 and MD4173 for the review associated with this issue. If you have any questions regarding this matter, please contact Patrick Milano, Sr. Project Manager, at 301-415-1457.

Sincerely,

/RA/

Catherine Haney, Director Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-266 and 50-301 cc: See next page

D. Koehl May 16, 2007 This completes the NRC staff efforts on TAC Nos. MD4172 and MD4173 for the review associated with this issue. If you have any questions regarding this matter, please contact Patrick Milano, Sr. Project Manager, at 301-415-1457.

Sincerely,

/RA/

Catherine Haney, Director Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-266 and 50-301 cc: See next page Distribution:

PUBLIC RidsNrrPMPMilano RidsEdoMailCenter LPL3-1 R/F RidsNrrLATHarris RidsOgcRp RidsNrrDorlLpl3-1 RidsNrrDciCpnb RidsRgn3MailCenter RidsNrrDorl ESullivan, NRR RidsOEMailCenter RidsNrrDci TLupold, NRR RidsAcrsAcnwMailCenter ADAMS Accession No. ML071300650 OFFICE CPNB LPL3-1/GE LPL3-1/PM LPL3-1/LA CPNB/BC NAME TLupold GTaylor PMilano THarris TChan DATE 05/ /07 05/ /07 05/ /07 05/ /07 05/ /07 OFFICE LPL3-1/BC DORL/D NAME LRaghavan CHaney DATE 05/ /07 05/ /07

D. Koehl OFFICIAL RECORD COPY

Point Beach Nuclear Plant, Units 1 and 2 cc:

Jonathan Rogoff, Esquire Mr. Jeffery Kitsembel Vice President, Counsel & Secretary Electric Division Nuclear Management Company, LLC Public Service Commission of Wisconsin 700 First Street P.O. Box 7854 Hudson, WI 54016 Madison, WI 53707-7854 Mr. F. D. Kuester Nuclear Asset Manager President & Chief Executive Officer Wisconsin Electric Power Company WE Generation 231 West Michigan Street 231 West Michigan Street Milwaukee, WI 53201 Milwaukee, WI 53201 Michael B. Sellman Regulatory Affairs Manager President and Chief Executive Officer Point Beach Nuclear Plant Nuclear Management Company, LLC Nuclear Management Company, LLC 700 First Street 6610 Nuclear Road Hudson, MI 54016 Two Rivers, WI 54241 Douglas E. Cooper Mr. Ken Duveneck Senior Vice President & Chief Nuclear Town Chairman Officer Town of Two Creeks Nuclear Management Company, LLC 13017 State Highway 42 700 First Street Mishicot, WI 54228 Hudson, WI 54016 Chairman Site Director of Operations Public Service Commission Nuclear Management Company, LLC of Wisconsin 6610 Nuclear Road P.O. Box 7854 Two Rivers, WI 54241 Madison, WI 53707-7854 Regional Administrator, Region III U.S. Nuclear Regulatory Commission Suite 210 2443 Warrenville Road Lisle, IL 60532-4351 Resident Inspector's Office U.S. Nuclear Regulatory Commission 6612 Nuclear Road Two Rivers, WI 54241