L-HU-07-003, 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: 71 5.377.3300 a Fax: 71 5.386.1013
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 #the end of the station refueling outage during which the inspection was performed.
_-.- -.-l.
I
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_s DOU~IAS E. 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 Page 1 of 1 Nozzle Function I Designation Spray Surge Safety RV-1039 Safety RV-1040 Safety RV-104 1 PORV Susceptible Material Description Nozzle-to safe end weld, A600 safe end, and safe end-to-Elbow weld Nozzle-to safe end weld, A600 safe end, and safe end-to-Elbow weld Alloy 8211 82 weld and A600 Flange Alloy 8211 82 weld and A600 Flange Alloy 8211 82 weld and A600 Flange No A6001821182 MRP-139 Volumetric lnspection Requirement Met or to be Met Mitigation Completed or to be Completed Outage Designation NIA R o l l NIA NIA NIA R o l l Outage Designation R017 R018 R019 R019 R019 NIA ResultslComments Each of the welds (Nozzle-to safe end weld, A600 safe end, and safe end-to-elbow weld) have been examined with ultrasonic testing (UT) every other outage since 1995.
Mechanical Stress Improvement Process (MSIP) was applied to the safe end-to-pipe weld in 1995.
Each of the welds (nozzle-to safe end weld, A600 safe end, and safe end-to-elbow weld) have been examined with UT every other outage since 1995.
Radiography Testing (RT) & Dye-Penetrant (PT) of the ID & OD surfaces was performed in 1993. PT and UT examinations were also performed in 1995.
Radiography Testing (RT) & Dye-Penetrant (PT) of the ID & OD surfaces was performed in 1993.
Radiography Testing (RT) & Dye-Penetrant (PT) of the ID & OD surfaces was performed in 1993. PT and UT examinations were also performed in 1995.
Safe end welds replaced with Alloy 690 material in 1995.
Date (MMNYW) 0912004 0412006 0912007 0912007 0912007 NIA
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).
Page 1 of 1
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).
Page 1 of 2
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 MRP-139 Volumetric Mitigation I lnspection Requirement Met I Completed or to be I Surge Function I Designation Spray Alloy 82 Susceptible Material Descri~tion 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.
or to be Met No A6001821182 completed Outage Designation Outage Designation Page 2 of 2 ResultslComments Start Date (MMNYYY)
NIA Safety X Safety Y Relief - Z Relief - T NIA No A600/82/182 No A6001821182 No A6001821182 No A6001821182 NIA NIA NIA NIA NIA NIA NIA NIA NIA NIA NIA NIA NIA NIA 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.