HNP-07-026, Inspection and Mitigation of Alloy 82/182 Pressurizer Butt Welds

Inspection and Mitigation of Alloy 82/182 Pressurizer Butt Welds

ML070650468
Person / Time
Site:	Harris
Issue date:	02/27/2007
From:	Duncan R Progress Energy Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
HNP-07-026
Download: ML070650468 (8)

Text

C WW-AJRobert J. Duncan, 11 Progress Energy ViceRbr Nuclear Harris JPresidentDna,l Plant Progress Energy Carolinas, Inc.

FEB 2 7 2007 Serial: HNP-07-026 U.S. Nuclear Regulatory Commission ATTENTION: Document Control Desk Washington, DC 20555 SHEARON HARRIS NUCLEAR POWER PLANT, UNIT NO. 1 DOCKET NO. 50-400/LICENSE NO. NPF-63 INSPECTION AND MITIGATION OF ALLOY 82/182 PRESSURIZER BUTT WELDS Ladies and Gentlemen:

By letter dated January 31, 2007, Carolina Power and Light Company (CP&L) doing business as Progress Energy Carolinas, Inc., notified the NRC of actions taken or planned at the Harris Nuclear Plant (HNP) for inspecting or mitigating Alloy 82/182 butt welds on the pressurizer spray, surge and relief lines. By a phone call with the NRC on February 20, 2007, HNP discussed the previous letter and the NRC's expectations for mitigation of the pressurizer Alloy 82/182 butt welds and enhanced unidentified RCS leakage monitoring.

During this phone call, HNP confirmed its previous commitment to mitigate the subject welds by installing full structural weld overlays by the end of refueling outage 14 (RFO-14) scheduled in the fall 2007, and to continue performing daily unidentified RCS leakage monitoring. By a follow-up phone call with the NRC on February 22, 2007, HNP committed to implement enhanced unidentified RCS leakage monitoring in Modes 1-3 until the subject welds are mitigated in the fall 2007. The enhanced unidentified RCS leakage monitoring will be in effect by March 6, 2007.

Attachment 1 provides HNP's response to the NRC's expectations for mitigation of the pressurizer Alloy 82/182 butt welds and enhanced unidentified RCS leakage monitoring, which supersedes the HNP response contained in the letter dated January 31, 2007.

Attachment 2 provides the commitments to this letter, which includes the original commitment as documented in the letter dated January 31, 2007, as well as new or revised regulatory commitments.

HNP will notify the NRC prior to any revisions to the commitments contained in this letter.

P.O.Box 165 New Hill, NC 27562 T> 919.362.2502 F> 919.362.2095

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HNP-07-026 Page 2 Our staff is available to meet with the NRC to discuss any of the information in this letter. Please refer any questions regarding this submittal to Dave Corlett at (919) 362-3137.

J. Duncan, II Vice President Harris Nuclear Plant RJD/jpy Attachments:

1. HNP's Response to the NRC's Expectations for Mitigation of Pressurizer Alloy 82/182 Butt Welds and Enhanced RCS Leakage Monitoring

2. Commitments c:

Mr. P. B. O'Bryan, NRC Senior Resident Inspector Mr. C. P. Patel, NRC Project Manager Dr. W. D. Travers, NRC Regional Administrator

Attachment 1 to SERIAL: HNP-07-026 SHEARON HARRIS NUCLEAR POWER PLANT, UNIT NO. 1 DOCKET NO. 50-400/LICENSE NO. NPF-63 HNP'S RESPONSE TO THE NRC EXPECTATIONS FOR MITIGATION OF PRESSURIZER ALLOY 82/182 BUTT WELDS AND ENHANCED REACTOR COOLANT SYSTEM LEAKAGE MONITORING Expectation 1: Mitigation Date The licensee should confirm its commitment to mitigate the pressurizerAlloy 82/182 butt welds in 2007.

Response 1:

HNP will comply with Expectation 1.

The Harris Nuclear Plant (HNP) confirms its commitment, as discussed in the letter dated January 31, 2007, to mitigate the pressurizer Alloy 82/182 butt welds by installing full structural weld overlays on these welds and to inspect post-overlay during refueling outage 14 (RFO-14) in the fall 2007.

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Attachment 1 to SERIAL: HNP-07-026 SHEARON HARRIS NUCLEAR POWER PLANT, UNIT NO. 1 DOCKET NO. 50-400/LICENSE NO. NPF-63 HNP'S RESPONSE TO THE NRC EXPECTATIONS FOR MITIGATION OF PRESSURIZER ALLOY 82/182 BUTT WELDS AND ENHANCED REACTOR COOLANT SYSTEM LEAKAGE MONITORING Expectation 2: RCS Leakage Monitoring Frequency The licensee should confirm its commitment to monitor RCS leakage daily while the plant is in Modes 1-3.

Response 2:

HNP will comply with Expectation 2.

HNP confirms its commitment, as discussed in the letter dated January 31, 2007, to continue monitoring unidentified RCS leakage daily while the plant is in Modes 1-3 during stable plant conditions until mitigation of the pressurizer Alloy 82/182 butt welds scheduled in RFO-14 (fall 2007).

As discussed during the phone call on February 20, 2007, HNP may extend the monitoring frequency within the 25% allowance for daily surveillance intervals provided by the Technical Specifications (TS) at HNP. In addition, HNP may extend the monitoring frequency during transient plant conditions such as power ascension.

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Attachment 1 to SERIAL: HNP-07-026 SHEARON HARRIS NUCLEAR POWER PLANT, UNIT NO. 1 DOCKET NO. 50-400/LICENSE NO. NPF-63 HNP'S RESPONSE TO THE NRC EXPECTATIONS FOR MITIGATION OF PRESSURIZER ALLOY 82/182 BUTT WELDS AND ENHANCED REACTOR COOLANT SYSTEM LEAKAGE MONITORING Expectation 3: RCS Leakage Monitoring Action Levels The action levels for RCS leakage monitoring should include the following two parts:

1. A 0. 1 gpm change from one day to the next sustainedfor 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> with at least 0. 1 gpm not confirmed from sources other than the pressurizernozzle welds.

2. A 0. 25 gpm above the baseline sustained for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> with at least 0. 25 gpm not confirmed from sources other than the pressurizernozzle welds.

For Part 2, the baseline is established using unidentified RCS leakrate information collected during the first seven (7) days of Mode I full power operationsafter the most recent bare metal visual inspection of the pressurizernozzle welds.

Response 3:

HNP will comply with Expectation 3.

As discussed during the phone call on February 20, 2007, HNP will implement the two unidentified RCS leakage monitoring actions levels as follows:

1. A 0.1 gpm increase in the daily measurement to the mean, sustained for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> with at least 0.1 gpm not confirmed from sources other than the pressurizer nozzle welds.

2. A 0.25 gpm above the baseline, sustained for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> with at least 0.25 gpm not confirmed from sources other than the pressurizer nozzle welds.

For Part 1, the mean has been established in accordance with standard statistical analysis methodologies and is updated periodically.

For Part 2, the baseline was established using unidentified RCS leakrate information collected during the first seven (7) days of Mode 1 full power operations after the most recent bare metal visual inspection of the pressurizer nozzle welds.

For both Parts 1 and 2, any leakage that is confirmed to be from sources other than the pressurizer nozzle welds is not required to meet the Technical Specifications' definition of identified leakage.

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a Attachment 1 to SERIAL: HNP-07-026 SHEARON HARRIS NUCLEAR POWER PLANT, UNIT NO. 1 DOCKET NO. 50-400/LICENSE NO. NPF-63 HNP'S RESPONSE TO THE NRC EXPECTATIONS FOR MITIGATION OF PRESSURIZER ALLOY 82/182 BUTT WELDS AND ENHANCED REACTOR COOLANT SYSTEM LEAKAGE MONITORING Expectation 4: RCS Leakage Monitoring Actions Once the 72-hour sustainedperiod is complete and the leak rate is still elevated, place the unit in Mode 3 within six (6) hours and Mode 5 within the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> and perform bare metal visual inspection of the unmitigatedpressurizersurge, spray, safety, and relief nozzle butt welds and safe end butt welds containingAlloy 82/182 material.

Response 4:

HNP will comply with Expectation 4.

This monitoring action applies to both Parts 1 and 2 of the RCS Leakage Monitoring Action Levels discussed in Response 3 above, and these actions will be implemented by HNP procedure, OPT-9002T, Temporary Test for Pressurizer Dissimilar Weld Enhanced Leakage Monitoring, Daily Interval, Modes 1,2, 3, Expires 10/30/07, which will be in effect by March 6, 2007.

As discussed during the phone call on February 20, 2007, a positive determination that the unidentified RCS leakage came from a source other than the pressurizer Alloy 82/182 butt welds will terminate the required actions, conditioned upon finding the source and quantifying the leak. In addition, whenever unidentified RCS leakage is reduced to less than the action levels in Response 3 above, then the actions may be terminated.

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Attachment 1 to SERIAL: HNP-07-026 SHEARON HARRIS NUCLEAR POWER PLANT, UNIT NO. 1 DOCKET NO. 50-400/LICENSE NO. NPF-63 HNP'S RESPONSE TO THE NRC EXPECTATIONS FOR MITIGATION OF PRESSURIZER ALLOY 82/182 BUTT WELDS AND ENHANCED REACTOR COOLANT SYSTEM LEAKAGE MONITORING Expectation 5: Reporting

1. Report details of any corrective or mitigative actions taken within 60 days of unit restart.

2. Report bare metal visual inspection results within 60 days of unit restart.

Response 5:

HNP will comply with Expectation 5.

As discussed during the phone call on February 20, 2007, HNP will implement the reporting as follows:

1. HNP will report information of any corrective or mitigative actions taken within 60 days of unit restart.

2. If HNP shuts down due to unidentified RCS leakage (i.e., the action of Response 4 above), then HNP will report bare metal visual inspection results within 60 days of unit restart.

For Report 1, the details of the mitigation actions will be contained in the associated relief request, so this report will provide information confirming completion of the mitigation actions and post-mitigation inspection results.

For Report 2, this reporting is conditioned upon a shutdown due to the action of Response 4 above for unidentified RCS leakage, and it does not add a requirement to perform a pre-mitigation inspection.

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Attachment 2 to SERIAL: HNP-07-026 SHEARON HARRIS NUCLEAR POWER PLANT, UNIT NO. 1 DOCKET NO. 50-400/LICENSE NO. NPF-63 INSPECTION AND MITIGATION OF ALLOY 82/182 PRESSURIZER BUTT WELDS COMMITMENTS Scheduled.

SCorrCmmitment(s) Completion, Date

1. HNP will mitigate the pressurizer Alloy 82/182 butt welds by installing full structural weld overlays on these welds and will End of RFO-14 inspect post-overlay during refueling outage 14 (RFO-14) in (fall 2007) the fall 2007.

2. HNP will monitor unidentified RCS leakage daily while the Beginning on plant is in Modes 1-3 during stable plant conditions until March 6, 2007 until mitigation of the pressurizer Alloy 82/182 butt welds mitigation of the scheduled in RFO-14 (fall 2007). pressurizer Alloy 82/182 butt welds

3. If unidentified RCS leakage should increase by 0.1 gpm in the daily measurement to the mean, sustained for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> with at least 0.1 gpm not confirmed from sources other than Beginning on the pressurizer nozzle welds, then the unit will be placed in March 6, 2007 until Mode 3 within six (6) hours and Mode 5 within the next 36 mitigation of the hours, and a bare metal visual inspection of the unmitigated pressurizer Alloy pressurizer surge, spray, safety, and relief nozzle butt welds 82/182 butt welds and safe end butt welds containing Alloy 82/182 material will be performed.

4. If unidentified RCS leakage should increase by 0.25 gpm above the baseline, sustained for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> with at least 0.25 gpm not confirmed from sources other than the pressurizer Beginning on nozzle welds, then the unit will be placed in Mode 3 within March 6, 2007 until six (6) hours and Mode 5 within the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />, and a mitigation of the bare metal visual inspection of the unmitigated pressurizer pressurizer Alloy surge, spray, safety, and relief nozzle butt welds and safe 82/182 butt welds end butt welds containing Alloy 82/182 material will be performed.

5. HNP will report information of any corrective or mitigative actions taken, and if HNP shuts down due to unidentified Within 60 days of RCS leakage (i.e., the action of Response 4 of this letter), unit restart then HNP will report bare metal visual inspection results.

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