ML070590205

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

ML070590205
Person / Time
Site:	Waterford  (NPF-038)
Issue date:	02/21/2007
From:	Burford F Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
CNRO-2007-00005
Download: ML070590205 (10)

Text

1M34011 Echlomno, Inct.

1340 Echelon Parkwiay E tergy Jackson, Mississippi 39213-8298 Acting Director Nuclear Safety & Licensing CNRO-2007-00005 February 21, 2007 U. S. Nuclear Regulatory Commission Attn.: Document Control Desk Washington, DC 20555-0001

SUBJECT:

Inspection and Mitigation of Alloy 600/82/182 Pressurizer Butt Welds Waterford Steam Electric Station, Unit 3 Docket. No. 50-382 License No. NPF-38

REFERENCES:

1.

NEI letter to the NRC, industry Actions Associated with Potential generic Implications of Wolf Creek Inspection Findings, dated January.26, 2007

2.

Entergy Operations, Inc. letter CNRO-2007-00002 to the NRC, Inspection and Mitigation of Alloy 600/82/182 Pressurizer Butt Welds, dated January 3,1, 2007

Dear Sir or Madam:

In October 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 importance of this issue, Entergy Operations, Inc. (Entergy) notified the NRC staff of actions planned for Waterford Steam Electric Station, Unit 3 (Waterford 3) to mitigate Alloy 600/82/182 butt welds on pressurizer spray, surge, and relief lines via Reference #2.

On February 13, 2007, representatives from Entergy and the NRC staff discussed the Waterford 3 action plan. As a result of that call, Entergy has revised its action plan and commitments. This letter supersedes Reference #2. Entergy will inform the NRC prior to revising any of the committed actions identified in Enclosure 1.

Entergy is aligned with positions pertaining to this issue as discussed in Reference #1 from NEI to the NRC and is actively participating with the industry to address them.

Our staff is available to meet with the NRC to discuss any of the information in this letter.

Should you have any questions pertaining to this letter, please contact Guy Davant at (601) 368-5756.

• CNRO-2007-00005 Page 2 of 2 This letter contains commitments identified in Enclosure 2. These commitments supersede those provided in Reference #2.

Sincerely, FGB/GHD/ghd

Enclosures:

1.

Mitigating Actions and Associated Schedule for Alloy 600/82/182 Pressurizer Butt Welds at Waterford 3

2.

Licensee-Identified Commitments cc:

Mr. W. A. Eaton (ECH)

Mr. K. T. Walsh (W3)

Dr. Bruce S. Mallet Regional Administrator, Region IV.,

U. S. Nuclear Regulatory Commission 611 Ryan Plaza. Drive, Suite 400 Arlington,.TX 76011-;8064 NRC Senior Resident Inspector Waterford Steam Electric Station, Unit 3 P.O. Box 822 Killona, LA 70066 U.S. Nuclear Regulatory Commission Attn: Mr. M. B. Fields MS 0-7 D1 Washington, DC 20555-0001

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ENCLOSURE 1 CNRO-2007-00005 MITIGATING ACTIONS AND ASSOCIATED SCHEDULE' FOR ALLOY 600/82/182 PRESSURIZER BUTT WELDS AT WATERFORD 3

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• Enclosure 1 to CNRO-2007-00005 Page 1 of 3 MITIGATING ACTIONS AND ASSOCIATED SCHEDULE, FOR ALLOY 600182J182 PRESSURIZER. BUTT WELDS AT-WATERFORD 3 Mitigation activities of the pressurizer Alloy 600/82/182 dissimilar metal (DM) butt welds at Waterford Steam Electric Station, Unit 3 (Waterford 3) have'not yet been completed, but are scheduled to be completed during the upcoming spring 2008 refueling outage (RF-15).

Entergy Operations, Inc. (Entergy) will perform and complete the following mitigative activities at Waterford 3 pertaining to these welds on the pressurizer:

1.

If Waterford 3 enters an outage of sufficient duration prior to RF-1 5, Entergy will visually inspect pressurizer DM butt welds for signs of leakage. Entergy will also re-baseline the unidentified leakage rate following any such outage and incorporate the new information into the Waterford 3 primary system leakage monitoring program.

2.

During RF-15:

a.

Entergy will visually inspect pressurizer DM butt welds for signs of leakage; and

b.

To permanently mitigate potential degradation of these welds, Entergy will install full structural weld overlays on these welds.

3.

Entergy will report the results of the mitigation actions performed to the NRC within 60 days following startup from the associated outage.

4.

If Waterford 3 should shut down due to primary system unidentified leakage prior to RF-15, Entergy shall either confirm that the leak does not originate from the pressurizer DM butt welds (including quantifying the leak from the suspected location) or will perform, prior to restart, a bare metal visual examination of the pressurizer DM butt weld locations to determine whether the leakage originated at these locations.

5.

Entergy will report the results of any bare metal visual inspections of the pressurizer DM butt welds to the NRC within 60 days following startup from the associated outage.

6. Entergy will develop plans and strategies to shutdown before December 31, 2007 and perform mitigation actions on the pressurizer DM butt welds if either:

a. The results of on-going analytical work [Materials Reliability Project (MRP) advanced finite element analysis (FEA)] do not provide reasonable assurance to the NRC that primary water stress corrosion cracking (PWSCC) conditions will remain stable and not lead to rupture without significant time from the onset of detectable leakage; or

b. New findings from inspections performed by industry during 2007 outages that challenge current analytical assumptions.

to CNRO-2007-00007 Page 2 of 3 These actions will be incorporated into the ANO-1 primary system leakage monitoring program by March 1, 2007 and remain in place until the mitigation actions-fJr the pressurizer DM butt welds are completed.

The methods of leak detection described above are sufficient to ensure RCS leakage is readily detected and corrective actions initiated prior to conditions degrading to a level resulting in a failure of the RCS pressure boundary.

to CNRO-2007-00005 Page 3 of 3 TABLE 1 Mitigation Summary for Waterford 3 Alloy 600/82/182 Pressurizer Butt Welds MRP-139 Volumetric Nozzle Inspection Requirement to Mitigation to be be Met Completed Comments Function I Susceptible Outage t

Outage Material SatDt Designation Descriaion Designation StDDesignation a -SA-508 carbon steel nozzle with 182 Sra-Nozwle RF-15 Spring 2008 RF-i5 butter to stainless steel safe end with 182

1. RC-301 A/B weld utwl butt weld SA-508 carbon steel nozzle with 182 Surge Nozzle-to-safe end RF-15 Spring 2008 RF-15, butter to stainless steel safe end with 182 weld weldbutt weld SA-508 carbon steel nozzle with 182 Relief Valve -

Nozzle-to-safe end RF-15 Spring 2008 RF-15 butter to cast stainless steel safe end with

1. RC-317A weld 182 butt weld R-we182 butt weld e VSA-508 carbon steel nozzle with 182 Rapele Valve ole a

e RF-1i5 Spring 2008 RF-15 butter to cast stainless steel safe end with cape nz w182 butt weld

ENCLOSURE 2 CNRO-2007-00005 LICENSEE-IDENTIFIED COMMITMENTS

- Enclosure 2 to CNRO-2007-00005 Page 1 of 3 LICENSEE-IDENTIFIED COMMITMENTS

".(Checkvone, SCHEDULED ONE-TIME CONTINUING COMPLETION'DATE COMMITMENT ACTION COMPLIANCE

1. Entergy will inform the NRC prior to revising V

any of the committed actions identified in Until the end of.

RF-1 5

2.

If Waterford 3 enters an outage of sufficient.

duration prior to RF-15, Entergy will visually Until the end of inspect pressurizer DM butt welds for..signs of RF-15 leakage. Entergywill also re-baseline the unidentified leakage rate following plant startup and incorporate the new information into the Waterford 3 primary system leakage monitoring program.

3.

During RF-15:.

End of RF-15

a.

Entergy will visually inspect pressurizer DM butt welds for signs of leakage; and

b. To permanently mitigate potential degradation of these welds, Entergy will install full structural weld overlays on these welds.

4.

Entergy will report the results of the mitigation 60 days following actions (structural weld overlays) performed to startup from the the NRC within 60 days following startup from associated outage the associated outage.

5.

If Waterford 3 should shut down due to' primary system unidentified leakage prior to Until the end of RF-15, Entergy shall confirm that the leak RF-15 does not originate from the pressurizer DM butt welds (including quantifying the leak from the suspected location) or will perform, prior to restart, a bare metal visual examination of these weld locations to determine whether the leakage originated at these, locations.

6.

Entergy will report the results of any bare V

metal visual inspections of the pressurizer DM Until the end of butt welds to the NRC within 60 days following RF-15 startup from the associated outage.

to CNRO-2007-00005 Page 2 of 3 TYPE.

(Check one),

SCHEDULED ONE-TIME CONTINUING COMPLETION'DATE COMMITMENT ACTION COMPLIANCE

7. Entergy will develop plans and strategies to December 31, 2007 shutdown before December 31, 2007 and perform mitigation actions on the pressurizer DM butt welds if either:

a. The results of on-going analytical work

[Materials Reliability Project (MRP) advanced finite element analysis (FEA)]

do not provide reasonable assurance to the NRC.that primary water stress, corrosion cracking (PWSCC) conditions will remain stable and not lead to rupture without significant time from the onset of detectable leakage; or

b. New findings from inspections performed by industry during 2007 outages that challenge current analytical assumptions.

8. Until the pressurizer DM butt welds are mitigated, Entergy will revise the Waterford 3 Until the end of primary system leakage monitoring program RF-15 to include the following actions:

Daily measurement and recording of unidentified leakage while in Modes 1, 2, and 3.

If unidentified leakage exceeds either of the two limits below and is sustained for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, and if the source of the leakage cannot be verified to be from a location other than the pressurizer DM butt welds, then Waterford 3 will shutdown and perform a bare metal visual examination of all such weld locations.

> 0.25 gpm greater than a baseline value.

The baseline value should be established using leakage rates measured within 7 days after achieving 100% reactor power following the most recent bare metal visual examination of the pressurizer Alloy 600/82/182 butt weld locations.

to CNRO-2007-00005 Page 3 of 3 TYPE (Check one)

SCHEDULED ONE-TIME CONTINUING COMPLETION DATE COMMITMENT ACTION COMPLIANCE

> 0.1 gpm increase over the preceding day's 7-day average unidentified leakage.

Following initiation of a shutdown, the plant shall be in HOT STANDBY in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN in the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

Should the leakage return to within limits or be confirmed to be from a source other than the pressurizer DM butt welds, then the shutdown actions may be halted and a return to normal operating conditions may commence.

9. The new primary system unidentified leakage March 1, 2007 criteria will be incorporated into the Waterford 3 primary system leakage monitoring program by March 1, 2007 and remain in place until the mitigation actions for the pressurizer DM butt welds are completed.