LIC-07-0006, Inspection and Mitigation of Alloy 600/82/182 Pressurizer Dissimilar Metal Butt Welds

Inspection and Mitigation of Alloy 600/82/182 Pressurizer Dissimilar Metal Butt Welds

ML070320251
Person / Time
Site:	Fort Calhoun
Issue date:	01/31/2007
From:	Faulhaber H Omaha Public Power District
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LIC-07-0006, MRP-139
Download: ML070320251 (3)

Text

Fort Calhoun Station PO.Box 550 Fort Calhoun, NE 68023 January 3 1,2007 LIC-07-0006 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001

References:

1. Docket No. 50-285

2. Material Reliability Program: Primary System Piping Butt Weld Inspection and Evaluation Guideline (MRP-139), EPRI, Palo Alto, CA: 2005, 1010087

SUBJECT:

Inspection and Mitigation of Alloy 6001821182 Pressurizer Dissimilar Metal Butt Welds In October of 2006, while performing inspections of its pressurizer Alloy 821182 butt welds in accordance with MRP-139 (Reference 2), a PWR licensee discovered several circumferential indications in its pressurizer surge, safety and relief nozzles. Because of the potential importance of this issue, the Omaha Public Power District (OPPD) is providing the following summary of actions taken for inspecting or mitigating Alloy 600/82/182 dissimilar metal butt welds on pressurizer spray, surge and relief lines.

In the fall of 2006, during Refueling Outage No. 23, the pressurizer at Fort Calhoun Station (FCS) was replaced with a component that uses resistant materials and contains no Alloy 6001821182 dissimilar metal butt welds. Further inspections to address Alloy 6001821182 dissimilar metal butt weld concerns in the pressurizer are not necessary.

Future inspections of pressurizer dissimilar metal butt welds at FCS will be performed in accordance with industry guidance (MRP- 139). MRP- 139 classifies the FCS pressurizer as Category A, which allows these inspections to be performed in accordance with our existing ASME Code inservice inspection (ISI) program.

Attached is a table listing the regulatory commitment and its tracking number. OPPD will inform the NRC prior to revising this commitment.

U.S. Nuclear Regulatory Commission LIC-07-0006 Page 2 If you have additional questions, or require further information, please contact Mr. Thomas C.

Matthews at (402) 533-6938.

Sincerely, H. J. Faul aber Division Manager Nuclear Engineering

Attachment:

Regulatory Commitment

LIC-07-0006 Attachment Page I Regulatory Commitment Commitment AR Number Future inspections of pressurizer dissimilar metal butt welds at FCS will be performed in accordance with industry guidance (MRP- 139). OPPD ,

will inform the NRC prior to revising this commitment.