ML072420116

Evaluation of Finite Element Analysis in Support of Alloy 82/182 Pressurizer Butt Weld Inspections in 2008 as Provided by CAL NRR-07-007 (Tac MD4150)

ML072420116
Person / Time
Site:	Diablo Canyon
Issue date:	09/07/2007
From:	Catherine Haney NRC/NRR/ADRO/DORL/LPLIV
To:	Keenan J Pacific Gas & Electric Co
Wang, A B, NRR/DORL/LPLIV, 415-1445
References
TAC MD4150, NRR-07-007
Download: ML072420116 (4)

Text

September 7, 2007 Mr. John S. Keenan Senior Vice President and Chief Nuclear Officer Pacific Gas and Electric Company Diablo Canyon Power Plant P.O. Box 770000, Mail Code B32 San Francisco, CA 94177-0001

SUBJECT:

DIABLO CANYON POWER PLANT, UNIT NO. 2 - EVALUATION OF FINITE ELEMENT ANALYSIS IN SUPPORT OF ALLOY 82/182 PRESSURIZER BUTT WELD INSPECTIONS IN 2008 AS PROVIDED BY CONFIRMATORY ACTION LETTER NRR-07-003 (TAC NO. MD4150)

Dear Mr. Keenan:

On March 15, 2007, the U.S. Nuclear Regulatory Commission (NRC) issued Confirmatory Action Letter (CAL) No. NRR-07-003 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML070670425) regarding dissimilar metal welds in the pressurizer surge, spray, and safety/relief nozzle-to-safe end welds at Diablo Canyon Power Plant (DCPP), Unit No. 2. The CAL and the supporting commitment letter (ADAMS Accession No. ML070580128) indicate that inspection and mitigation actions may be conducted during your spring 2008 refueling outage, contingent on the industry providing an analysis that demonstrates an acceptable level of safety to the NRC for the operation of these welds until spring 2008. This letter acknowledges receipt of your letter dated August 7, 2007 (ADAMS Accession No. ML072410199), informing the NRC that the analysis referred to by this CAL and the supporting commitment letter has been completed, and that the analysis is applicable to your plant.

The NRC received MRP-216, Rev. 1, Materials Reliability Program: Advanced FEA [Finite Element Analysis] Evaluation of Growth of Postulated Circumferential PWSCC [Primary Water Stress-Corrosion Cracking] Flaws in Pressurizer Nozzle Dissimilar Metal Welds, on August 13, 2007 (ADAMS Accession No. ML072410235). Based on our review of this report, the NRC concludes that the analysis provides adequate justification to permit inspections during your spring 2008 refueling outage, and that the analysis is applicable to DCPP, Unit No. 2. The results of the staffs review are contained in a safety assessment dated August 31, 2007 (ADAMS Accession No. ML072400199), and the associated contractor report (ADAMS Accession No. ML072470394).

Based on the above, the NRC concludes that a plant shutdown by December 31, 2007, is no longer required. Therefore, the pressurizer surge, spray, and safety/relief nozzle-to-safe end Alloy 82/182 butt weld inspections for DCPP, Unit No. 2 must be performed prior to exiting your scheduled spring 2008 refueling outage. All other requirements of the CAL and the supporting commitment letter regarding enhanced inspection and leakage monitoring requirements for the reactor coolant system and associated reports remain valid.

J. S. Keenan The CAL will remain open until all CAL commitments pertaining to DCPP, Unit No. 2 are complete.

Current NRC guidance regarding CALs is contained in the NRC Enforcement Policy and the NRC Enforcement Manual, which are available at the NRC web site at http://www.nrc.gov/about-nrc/regulatory/enforcement.html (click on Enforcement Policy or Enforcement Guidance) or by contacting the Government Printing Office (GPO) toll-free at 1-888-293-6498. The GPO is open from 7:00 a.m. to 9:00 p.m. EST, Monday through Friday (except Federal holidays).

In accordance with Section 2.390 of Title 10 of the Code of Federal Regulations, of the NRC's "Rules of Practice," a copy of this letter will be made available electronically for public inspection in the NRC Public Document Room or from the NRCs document system (ADAMS),

accessible from the NRC Web site at http://www.nrc.gov/reading-rm.html.

Sincerely,

/RA/

Catherine Haney, Director Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-323 cc: See next page

ML072420116 OFFICE DCI/CPNB DCI/CPNB LPL4/PM LPL4/LA LPL4/BC NAME TLupold TChan Awang, JND for JBurkhardt Thiltz, BKS for DATE 9/6/07 9/6/07 9/6/07 9/5/07 9/6/07 OFFICE DCI/D DRP/D, RGN4 DORL/D NAME MEvans DChamberlain CHaney DATE 9/7/07 9/7/07 WJones for 9/7/07 Diablo Canyon Power Plant, Units 1 and 2 cc:

NRC Resident Inspector Jennifer Post, Esq.

Diablo Canyon Power Plant Pacific Gas & Electric Company c/o U.S. Nuclear Regulatory Commission P.O. Box 7442 P.O. Box 369 San Francisco, CA 94120 Avila Beach, CA 93424 City Editor Sierra Club San Lucia Chapter The Tribune ATTN: Andrew Christie 3825 South Higuera Street P.O. Box 15755 P.O. Box 112 San Luis Obispo, CA 93406 San Luis, Obispo, CA 94306-0112 Ms. Nancy Culver Director, Radiologic Health Branch San Luis Obispo State Department of Health Services Mothers for Peace P.O. Box 997414, MS 7610 P.O. Box 164 Sacramento, CA 95899-7414 Pismo Beach, CA 93448 Mr. James Boyd, Commissioner Chairman California Energy Commission San Luis Obispo County 1516 Ninth Street MS (31)

Board of Supervisors Sacramento, CA 95831 1055 Monterey Street, Suite D430 San Luis Obispo, CA 93408 Mr. James R. Becker, Vice President Diablo Canyon Operations and Mr. Truman Burns Station Director Mr. Robert Kinosian Diablo Canyon Power Plant California Public Utilities Commission P.O. Box 56 505 Van Ness, Room 4102 Avila Beach, CA 93424 San Francisco, CA 94102 Jennifer Tang Diablo Canyon Independent Safety Field Representative Committee United States Senator Barbara Boxer Attn: Robert R. Wellington, Esq. 1700 Montgomery Street, Suite 240 Legal Counsel San Francisco, CA 94111 857 Cass Street, Suite D Monterey, CA 93940 Mr. John T. Conway Site Vice President Regional Adminstrator, Region IV Diablo Canyon Power Plant U.S. Nuclear Regulatory Commission P. O. Box 56 Harris Tower & Pavillion Avila Beach, California 93424 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-8064 August 2007