ULNRC-05360, Inspection/Mitigation Plans for Alloy 82/182 Pressurizer Butt Welds

Inspection/Mitigation Plans for Alloy 82/182 Pressurizer Butt Welds

ML070380277
Person / Time
Site:	Callaway
Issue date:	01/31/2007
From:	Fitzgerald D AmerenUE
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
ULNRC-05360
Download: ML070380277 (6)

Text

AmerenUE P0 Box 620 Ca//away Plant Fulton, MO 65251 January 31, 2007 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop P1-137 Washington, DC 20555-0001 Ladies and Gentlemen: ULNRC-05360 DOCKET NUMBER 50-483 CALLAWAY PLANT UNIT 1 UNION ELECTRIC CO.

UF INSPECTION/MITIGATION PLANS FOR 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, a PWR licensee discovered several circumferential indications in its pressurizer surge, safety and relief nozzles. Because of the potential importance of this issue, AmerenUE (Union Electric) is submitting this letter to notify the NRC of actions being taken or planned with regard to Alloy 82/182 butt welds on the pressurizer spray, surge, safety, and relief lines at Callaway Plant.

The action being taken at Callaway Plant is a mitigation activity to be implemented during the forthcoming refueling outage (RF- 15) which is scheduled to commence on April 2, 2007. Specifically, the activity planned is the application of pre-emptive full structural weld overlays for the nozzle-to-safe end dissimilar metal and safe-end-to piping stainless steel butt welds associated with the pressurizer and connected piping. Because pre-emptive full structural weld overlays are to be applied to the noted nozzle welds, no pre-mitigation inspections are planned.

A 10 CFR 50.55a request to support the planned installation and examination of overlays was submitted by AmerenUE via letter ULNRC-05292, "10 CFR 50.55a Request for Relief from ASME Section XI Repair and Replacement Requirements: Proposed Alternatives for Application of Structural Weld Overlays to Pressurizer Nozzle Welds," dated August 14, 2006. The 10 CFR 50.55a request is currently under review by the NRC staff. Details regarding the pre-emptive full structural weld overlays were provided in the 10 CFR 50.55a request. However, mitigation summary information is provided in Attachment 1 to this letter.

a subsidiaryof Ameren Corporation

ULNRC-05360 January 31, 2007 Page 2 It should be noted that bare metal visual (BMV) inspections of the Alloy 82/182 butt welds on the pressurizer spray, surge, safety, and relief lines at Callaway Plant were completed in the Spring of 2004 (during Refuel 13) and Fall of 2005 (during Refuel 14). Those inspections revealed no cracking or leakage.

Nevertheless, with Callaway Plant currently at power, and until commencement of the refuel outage on April 2, reactor coolant system (RCS) leakage will continue to be monitored in accordance with current requirements and procedures. Highlights of the RCS leakage monitoring program at Callaway Plant are as follows:

" RCS monitoring method employed: RCS inventory balancing every 3 days.

• Overall sensitivity to RCS leakage: An increase of 0.03 gpm since previous balancing.

• Action levels: An absolute unidentified leakage > 0.2 gpm, or an increase of 0.03 gpm since previous balancing.

" Responses to exceeding action levels: Initiation of actions to review indication of RCS leakage and determine cause, which may include review of containment humidity, radiation, and sump level indication.

For any questions regarding the mitigation plans or any of the information provided in this letter or its attachments, please contact me at 573-676-8763 or David E. Shafer at either 314-554-3104 or 573-676-4722. The NRC will be informed if AmerenUE revises any of the information contained in this letter.

Sincerely, David T. 1tzgerald Manager - Regulatory Affairs TBE/jdg Attachments: 1. Mitigation Information Table

2. List of Commitments

ULNRC-05360 January 31, 2007 Page 3 cc: Mr. Bruce S. Mallett Regional Administrator U.S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-4005 Senior Resident Inspector Callaway Resident Office U.S. Nuclear Regulatory Commission 8201 NRC Road Steedman, MO 65077 Mr. Jack N. Donohew (2 copies)

Licensing Project Manager, Callaway Plant Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop O-7D1 Washington, DC 20555-2738 Missouri Public Service Commission Governor Office Building 200 Madison Street PO Box 360 Jefferson City, MO 65102-0360

ULNRC-05360 January 31, 2007 Page 4 bcc: C. D. Naslund (w/a) D. J. Maxwell (w/a)

A. C. Heflin (w/a) M. G. Hoehn II (w/a)

D. T. Fitzgerald (w/a) K. A. Mills (w/a)

T. E. Herrmann (w/a) T. B. Elwood (w/a)

L. E. Thibault (w/a) G. A. Forster (w/a)

G. A. Hughes (w/a) A160.0761 D. E. Shafer (w/a)

S. L. Gallagher (100)

L. M. Belsky (NSRB)

S. L. Klang (w/a)

D. M. Stepanovic (w/a)

Certrec Corporation 4200 South Hulen, Suite 630 Fort Worth, TX 76109 (Certrecreceives ALL attachments as long as they are non-safeguards and public disclosed).

Send the following without attachments:

Ms. Diane M. Hooper Mr. Dennis Buschbaum Supervisor, Licensing TXU Power WCNOC Comanche Peak SES P.O. Box 411 P.O. Box 1002 Burlington, KS 66839 Glen Rose, TX 76043 Mr. Scott Bauer Mr. Stan Ketelsen Regulatory Affairs Manager, Regulatory Services Palo Verde NGS Pacific Gas & Electric P.O. Box 52034, Mail Stop 104/5/536 Mail Station 7636 P.O. Box 56 Phoenix, AZ 85072-2034 Avila Beach, CA 93424 Mr. Scott Head Mr. John O'Neill Supervisor, Licensing Pillsbury Winthrop Shaw Pittman LLP South Texas Project NOC 2300 N. Street N.W.

Mail Code N5014 Washington, DC 20037 P.O. Box 289 Wadsworth, TX 77483

Attachment 1 to ULNRC-05360 MITIGATION INFORMATION TABLE Mitigation Summary for Alloy 82/182 Pressurizer Butt Welds MRP-139 Volumetric Mitigation to Nozzle Inspection Requirement Be Completed to Be Met Comments Susceptible Function/ Material Outage Start Date Outage Designation Description Designation (MMI/YYYY) Designation Spray 82/182 Refuel 15 04/2007 Refuel 15 See Note 1 (below).

Surge 82/182 Refuel 15 04/2007 Refuel 15 See Note 1 (below).

Safety X 82/182 Refuel 15 04/2007 Refuel 15 See Note 1 (below).

Safety Y 82/182 Refuel 15 04/2007 Refuel 15 See Note 1 (below).

Relief - Z 82/182 Refuel 15 04/2007 Refuel 15 See Note 1 (below).

Relief - T 82/182 Refuel 15 04/2007 Refuel 15 See Note 1 (below).

Note 1: The existing weld contours limit the capability to perform volumetric inspections of the existing welds. Therefore, inspections of the weld overlays are to be performed after overlay installation.

-Attachment 2 to ULNRC-05360 LIST OF COMMITMENTS The following table identifies an action committed to by AmerenUE in this document (letter).

Any other statements in this document (letter) are provided for information purposes and are not considered commitments. Please direct questions regarding this commitment to David E. Shafer, Superintendent, Licensing at either 314-554-3104 or 573-676-4722.

COMMITMENT Due Date/Event Pre-emptive full structural weld overlays for the nozzle-to-safe Prior to end dissimilar metal and safe end-to-piping stainless steel butt completion of welds associated with the pressurizer and connected piping at Refuel 15 outage.

Callaway will be installed and examined during Refuel 15.

The NRC will be informed if AmerenUE revises any of the Upon revision of information contained in this letter (ULNRC-05360). any of the information contained in this letter.