ML070580244

Inspection and Mitigation of Alloy 82/182 Pressurizer Butt Welds

ML070580244
Person / Time
Site:	Mcguire, McGuire
Issue date:	02/09/2007
From:	Gordon Peterson Duke Energy Carolinas, Duke Power Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
MRP-139
Download: ML070580244 (6)

Text

Duke GARY R. PETERSON

rPower, A Duke Energy Company Vice President McGuire Nuclear Station Duke Power MG01VP / 12700 Hagers Ferry Rd.

Huntersville, NC 28078-9340 704 875 5333 704 875 4809 fax grpeters@duke-energy. corn February 9, 2007 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001

Subject:

Duke Power Company LLC d/b/a Duke Energy Carolinas, LLC (Duke)

McGuire Nuclear Station, Units 1 and 2 Docket Numbers 50-369 and 50-370 Inspection and Mitigation of Alloy 82/182 Pressurizer Butt Welds In October of 2006, while performing inspections of its pressurizer Alloy 82/182 butt welds in accordance with MRP-139, "Primary System Piping Butt Weld Inspection and Evaluation Guideline," a pressurized water reactor licensee discovered several circumferential indications in its pressurizer surge, safety, and relief nozzles. Because of the potential importance of this issue, Duke is submitting this letter to notify the NRC regarding McGuire's actions taken or planned for inspecting or mitigating Alloy 600/82/182 butt welds on pressurizer spray, surge, and relief lines.

This letter contains two attachments. Attachment 1 is a description of the current Reactor Coolant System (RCS) leakage monitoring program for McGuire Units 1 and 2. Attachment 2 is a compilation of the inspection and mitigation effort for pressurizer Alloy 600/82/182 butt welds for McGuire Units 1 and

2. Details concerning the locations inspected and mitigated are provided in Attachment 2. Future inspections of pressurizer butt welds at McGuire Units 1 and 2 will be performed in accordance with the ASME Code and MRP-139.

The NRCwill be informed if McGuire revises any of the information contained in this letter.

www.dukepower.com f//o

1.

U.S. Nuclear Regulatory Commission February 9, 2007 Page 2 Our staff is available to meet with the NRC to discuss any of the information contained in this letter. If there are any questions, please contact P.T. Vu at (704) 875-4302.

Very truly yours, Gary R. Peterson Attachments

U.S. Nuclear Regulatory Commission February 9, 2007 Page 3 xc (with attachments):

W.D. Travers, Regional Administrator U.S. Nuclear Regulatory Commission, Region II Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, GA 30303 J.B. Brady, Senior Resident Inspector U.S. Nuclear Regulatory Commission McGuire Nuclear Station J.F. Stang, Jr., Senior Project Manager U.S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop 0-8 H4A Rockville, MD 20852-2738

U.S. Nuclear Regulatory Commission Attachment 1 February 9, 2007 Page 1 and 1 Attachment 1 RCS Leakage Monitoring Information for McGuire Units 1 and 2 A water inventory balance program monitors reactor coolant leakage with established limits for continued operation specified in the technical specifications. This program will measure any leakage from components and small diameter nozzles as unidentified system leakage, which has an established operational limit of less than 1.0 gallon per minute. More restrictive plant procedures require an assessment of potential leak sources whenever unidentified leakage exceeds 0.15 gallon per minute (unidentified leakage calculations are typically performed every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />). If leakage exceeds the more restrictive limit and the leak source remains unidentified, plant management would assess what additional leak investigation activities are required, or if plant shutdown is necessary.

If leakage increases based on the mass balance, limited walk downs at power would be performed to identify the source of the leakage. Evidence of leakage is evaluated and resolved through the corrective action program and Fluid Leak Management Program.

U.S. Nuclear Regulatory Commission Attachment 2 February 9, 2007 Page 1 of 2 Attachment 2 McGuire Unit 1 Inspection and Mitigation Summary for Alloy 600/82/182 Pressurizer Butt Welds MRP-139 Volumetric Mitigation to be Nozzle Inspection Requirement Met Completed or to be Met Comments Function / Susceptible Outage Outage Dination Material Start Date D e Designation Description Designation Designation Spray Nozzle to safe-end NA' NA' 1EOC18 Bare Metal Visual 2 per NRC Bulletin 1PZR-W2SE weld 3/2007 2004-01: 1EOC17, 9/2005.

Surge Nozzle to safe-end NA' NA' 1EOC18 Bare Metal Visual2 per NRC Bulletin 1PZR-W1SE weld 3/2007 2004-01: 1EOC 17, 9/2005.

Safety Nozzle to safe-end NA' NA' 1EOC18 Bare Metal Visual 2 per NRC Bulletin 1PZR-W4CSE weld 3/2007 2004-01: 1EOC17, 9/2005.

Safety Nozzle to safe-end NA' NA' 1EOC18 Bare Metal Visual 2 per NRC Bulletin 1PZR-W4BSE weld 3/2007 2004-01: 1EOC17, 9/2005.

Safety Nozzle to safe-end NA' NA' 1EOC18 Bare Metal Visual 2 per NRC Bulletin 1PZR-W4ASE weld 3/2007 2004-01: 1EOCI7, 9/2005.

Relief Nozzle to safe-end NA' NA' 1EOC18 Bare Metal Visual 2 per NRC Bulletin 1PZR-W3SE weld 3/2007 2004-01: 1EOC17, 9/2005.

Note 1: Welds are not inspectable using PDI qualified methods.

Note 2: Bare Metal Visual inspections detected no evidence of cracking or leakage.

U.S. Nuclear Regulatory Commission Attachment 2 February 9, 2007 Page 2 of 2 McGuire Unit 2 Inspection and Mitigation Summary for Alloy 600/82/182 Pressurizer Butt Welds MRP-139 Volumetric Mitigation Nozzle Inspection Requirement Met Completed or to be Met Comments Function / Susceptible Outage Otg Material Start Date Outage Designation Description Designation Designation Spray Nozzle to safe-end NA' NA' 2EOC 17' Bare Metal Visual 2 per NRC Bulletin 2PZR-W2SE weld 9/2006 2004-01: 2EOC 16, 3/2005.

Surge Nozzle to safe-end NA' NA' 2EOC17 3 Bare Metal Visual 2 per NRC Bulletin 2PZR-W1SE weld 9/2006 2004-01: 2EOC 16, 3/2005.

Safety Nozzle to safe-end NA' NA' 2EOC17 3 Bare Metal Visual 2 per NRC Bulletin 2PZR-W4ASE weld 9/2006 2004-01: 2EOC16, 3/2005.

Safety Nozzle to safe-end NAT NA' 2EOC17 3 Bare Metal Visual2 per NRC Bulletin 2PZR-W4BSE weld 9/2006 2004-01: 2EOC16, 3/2005.

Safety Nozzle to safe-end NA' NA' 2EOC17 3 Bare Metal Visual2 per NRC Bulletin 2PZR-W4CSE weld 9/2006 2004-01: 2EOC16, 3/2005.

Relief Nozzle to safe-end NA' NA' 2EOC173 Bare Metal Visual 2 per NRC Bulletin 2PZR-W3SE weld 9/2006 2004-01: 2EOC16, 3/2005.

Note 1: Prior to 2EOC17, welds were not inspectable using PDI qualified methods.

Note 2: Bare Metal Visual inspections detected no evidence of cracking or leakage.

Note 3: A full structural weld overlay was applied during 2EOC17 to mitigate the effects of PWSCC. (Reference Relief Request 06-GO-001, Revision 1, dated September 27, 2006).