L-HU-07-003, Inspection and Mitigation of Alloy 600/82/182 Pressurizer Butt Welds

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

ML070310270
Person / Time
Site:	Palisades, Point Beach, Prairie Island
Issue date:	01/30/2007
From:	Cooper D Nuclear Management Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-HU-07-003
Download: ML070310270 (6)

Text

Committed to Nuclear Excellence

/ Nuclear Management Company, LLC January 30,2007 L-HU-07-003 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Prairie Island Nuclear Generating Plant, Palisades Nuclear Plant Units 1 and 2 Docket 50-255 Dockets 50-282 and 50-306 License No. DPR-20 License Nos. DPR-42 and DPR-60 Point Beach Nuclear Plant, Units 1 and 2 Dockets 50-266 and 50-301 License Nos. DPR-24 and DPR-27 Inspection and Mitigation of Allov 600/82/182 Pressurizer Butt Welds

Reference:

NEI letter to NSlAC dated January 19, 2007 In October of 2006, while performing inspections of its pressurizer Alloy 600/82/182 butt welds in accordance with MRP-139, a PWR licensee discovered several circumferential indications in its pressurizer surge, safety, and relief nozzles. Because of the potential importance of this issue, NMC is submitting this letter to commit to fleet actions taken or planned for inspecting or mitigating Alloy 600/82/182 butt welds on pressurizer spray, surge, and relief lines.

Enclosures to this letter, including the information for each of the affected NMC sites, are as follow:

Enclosure I- Palisades Nuclear Plant (PNP) - Point Beach Nuclear Plant (PBNP) - Prairie Island Lluclear Generating Plant (PINGP) 700 First Street Hudson, Wisconsin 54016 Telephone: 715.377.3300 a Fax: 715.386.1013

Document Control Desk Page 2 Summary of Commitments This letter contains two new commitment and no revisions to existing commitments.

Palisades and Prairie Island Unit 2 Only

1. Until all Alloy 600/82/182 Pressurizer butt welds are either mitigated or replaced, all Alloy 600/82/182 Pressurizer butt welds will be examined per the industry guidance on Alloy 600/82/182 butt welds (MRP-139).

2. Until all Alloy 600/82/182 Pressurizer butt welds are either mitigated or replaced, reports of future inspection results will be submitted to the NRC within 60 days of #theend of the station refueling outage during which the inspection was performed.

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DOU~IASE. Cooper Senior vice President and Chief Nuclear Officer Nuclear Management Co., LLC

Enclosures:

(3) cc: Administrator, Region Ill, USNRC Project Manager, Palisades, Point Beach and Prairie Island, USNRC Resident Inspector, Palisades, Point Beach and Prairie Island, USNRC

ENCLOSURE 1 PALISADES NUCLEAR PLANT lnspection of all pressurizer Alloy 600/82/182 butt welds at Palisades has not yet been completed. NMC intends to complete these inspection activities by the refueling outage scheduled for September 2007 (R019). Details concerning the inspection activities at Palisades are provided in the attached table. Results of completed inspections are also summarized in the table. Future inspections of pressurizer butt welds at Palisades will be performed in accordance with the IS1 program, the ASME Code, and industry guidance on Alloy 600/82/182 butt welds (MRP-139). Until all Alloy 600/82/182 Pressurizer butt welds are either mitigated or replaced, reports of future inspection results will be submitted to the NRC within 60 days of the end of the station refueling outage during which the inspection was performed.

In addition to the inspection actions described here, existing procedures for monitoring primary system unidentified leakage will be used until all Alloy 600/82/182 butt weld locations on the pressurizer have been inspected or mitigated. Steady state RCS leakage is measured and compared to Technical Specification limits (1.0 gpm unidentified leakage). The measurement is also compared to a procedural limit of 0.15 gpm total unidentified leakage. By procedure, an investigation is initiated when this 0.15 gpm unidentified leakage limit is exceeded. The intent of this investigation is to locate and assess the source of the unidentified RCS leakage.

lnspection and Mitigation Summary for Alloy 600/82/182 Pressurizer Butt Welds Mitigation MRP-139 Volumetric lnspection Nozzle Completed or to be Requirement Met or t o be Met Completed ResultslComments Function I Susceptible Material Outage Date Designation Description Outage Designation Designation (MMNYW)

Nozzle-to safe end Each of the welds (Nozzle-to safe end weld, A600 weld, A600 safe end, safe end, and safe end-to-elbow weld) have been Spray R017 0912004 NIA and safe end-to-Elbow examined with ultrasonic testing (UT) every other weld outage since 1995.

Nozzle-to safe end Mechanical Stress Improvement Process (MSIP) weld, A600 safe end, was applied to the safe end-to-pipe weld in 1995.

Surge and safe end-to-Elbow R018 0412006 Roll Each of the welds (nozzle-to safe end weld, A600 weld safe end, and safe end-to-elbow weld) have been examined with UT every other outage since 1995.

Alloy 821182 weld and Radiography Testing (RT) & Dye-Penetrant (PT) of Safety A600 Flange R019 0912007 NIA the ID & OD surfaces was performed in 1993. PT RV-1039 and UT examinations were also performed in 1995.

Safety Alloy 821182 weld and Radiography Testing (RT) & Dye-Penetrant (PT) of A600 Flange R019 0912007 NIA the ID & OD surfaces was performed in 1993.

RV-1040 Alloy 821182 weld and Radiography Testing (RT) & Dye-Penetrant (PT) of Safety A600 Flange R019 0912007 NIA the ID & OD surfaces was performed in 1993. PT RV-1041 and UT examinations were also performed in 1995.

No A6001821182 Safe end welds replaced with Alloy 690 material in PORV NIA NIA Roll 1995.

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ENCLOSURE 2 POINT BEACH NUCLEAR PLANT UNITS 1 AND 2 The pressurizers at Point Beach Units 1 & 2 do not have Alloy 600/82/182 butt welds.

Future inspections of pressurizer butt welds at Point Beach Units 1 & 2 will be performed in accordance with the IS1 Program, the ASME Code, and industry guidance (MRP-139).

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ENCLOSURE 3 PRAIRIE ISLAND NUCLEAR GENERATING PLANT (UNIT I ONLY)

The pressurizer at Prairie Island Unit 1 does not have Alloy 600/82/182 butt welds.

Future inspections of pressurizer butt welds at Prairie Island Unit 1 will be performed in accordance with the IS1 Program, the ASME Code, and industry guidance (MRP-139).

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ENCLOSURE 3 PRAIRIE ISLAND NUCLEAR GENERATING PLANT (UNIT 2 ONLY)

The pressurizer Alloy 600/82/182 butt weld at Prairie Island Unit 2 has been inspected. Details concerning the location inspected are provided below. Results of completed inspections are also included below. Future inspections of the pressurizer butt welds at Prairie Island Unit 2 will be performed in accordance with the IS1 Program, the ASME Code and industry guidance (MRP-139). Until the Alloy 600/82/182 Pressurizer butt weld is either mitigated or replaced, reports of future inspection results will be submitted to the NRC within 60 days of the end of the station refueling outage during which the inspection was performed.

lnspection and Mitigation Summary for Alloy 600/82/182 Pressurizer Butt Welds Nozzle I MRP-139 Volumetric lnspection Requirement Met or t o be Met I Mitigation Completed or t o be completed I

ResultslComments Susceptible Function I Outage Start Date Outage Material Designation Designation (MMNYYY) Designation Descri~tion Spray No A6001821182 NIA NIA NIA NIA Surge Alloy 82 The surge line W-17 weld was examined using ultrasonic testing (UT) during the November 2006 RFO (2R24). The examination was PDI qualified and achieved

>95% coverage.

Current plans are to mitigate this location via weld overlay during the (2R25) 2008 refueling outage or continue with inspections based on guidance provided in MRP-139.

Safety X No A600/82/182 NIA NIA NIA NIA Safety Y No A6001821182 NIA NIA NIA NIA Relief - Z No A6001821182 NIA NIA NIA NIA Relief - T No A6001821182 NIA NIA NIA NIA Page 2 of 2