ML12020A248

Relief Request 12-MN-001

ML12020A248
Person / Time
Site:	Mcguire
Issue date:	01/03/2012
From:	Repko R Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML12020A248 (7)

Text

REGIS T. REPKO Duke Vice President Eanergy McGuire Nuclear Station Duke Energy MG01 VP / 12700 Hagers Ferry Rd.

Huntersville, NC 28078 980-875-4111 980-875-4809 fax regis.repko@duke-energy.com January 3, 2012 10 CFR 50.55a U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

SUBJECT:

Duke Energy Carolinas, LLC (Duke Energy)

McGuire Nuclear Station Unit 2 Docket Number 50-370 Relief Request 12-MN-001 Pursuant to 10 CFR 50.55a(a)(3)(i), Duke Energy hereby submits Relief Request 12-MN-001 for the use of an alternative to the examination requirements of ASME Code, Section Xl. This request supports the examination of reactor vessel hot leg and cold leg nozzle-to-pipe welds performed from the inside surface during the McGuire Unit 2 fall 2012 refueling outage. The proposed alternative provides for an acceptable level of quality and safety, consistent with 10 CFR 50.55a(a)(3)(i).

Attachment 1 contains this relief request. Duke Energy requests approval of this relief request by August 15, 2012 to support the inspection of these welds.

If you have any questions or require additional information, please contact P. T. Vu at (980) 875-4302.

Sincerely, Regis T. Repko Attachment 1 www. duke-energy.corn

. 1 U. S. Nuclear Regulatory Commission January 3, 2012 Page 2 xc:

V. M. McCree, Region II Administrator U.S. Nuclear Regulatory Commission Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, GA 30303-1257 J. H. Thompson, Project Manager U. S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop 0-8 G9A Rockville, MD 20852-2738 J. Zeiler NRC Senior Resident Inspector McGuire Nuclear Station

Attachment 1 McGuire Unit 2 Relief Request for Alternate Depth Sizing Criteria Duke Energy McGuire Unit 2 12-MN-O01 Page I of 5

ALTERNATIVE DEPTH SIZING CRITERIA Proposed Alternative In Accordance with 10 CFR 50.55a(a)(3)(i)

-Alternative Provides Acceptable Level of Quality and Safety -

Background

Duke Energy Carolinas, LLC (Duke Energy) is submitting a request for the use of an alternative to the examination requirements of ASME Code,Section XI, at McGuire Nuclear Station Unit 2 (MNS 2). This request supports the examination of Reactor Vessel (RV) hot leg Nozzle-to-Pipe and cold leg Nozzle-to-Pipe dissimilar metal welds performed from the inside surface during the next scheduled outage. Duke Energy has determined the proposed alternative provides for an acceptable level of quality and safety, consistent with 10 CFR 50.55a(a)(3)(i).

1.0 Applicable Code Edition and Addenda MNS 2 is currently in the third 10-year Inservice Inspection (ISI) interval that began on 03/01/2004 and is scheduled to end on 07/15/2014. The ASME Boiler and Pressure Vessel Code (ASME Code) of record is the 1998 Edition of Section XI through the 2000 addenda. Section Xl Code Case N-695 (Qualification Requirements for Dissimilar Metal Piping Welds) is referenced in the ISI program. This Code Case is listed in Regulatory Guide 1.147, Rev. 16, Table 1- "Acceptable Section XI Code Cases".

2.0 Applicable Code Requirement The RV Nozzle butt welds are part of the MNS 2, Risk-Informed ISI program. The RV Nozzle butt welds on the hot and cold legs are dissimilar metal welds and are required to be volumetrically examined.

The volumetric examinations are to be conducted in accordance with ASME Section XI, Appendix VIII, Supplement 10, 1998 Edition through 2000 Addenda. Code Case N-695 is an acceptable alternative to Appendix VIII, Supplement 10.

The specific Code Case N-695 requirement for which relief is requested pertains to the depth sizing qualification requirements for performance demonstration of ultrasonic examination systems for dissimilar metal piping welds.

Code Case N-695 3.3 Depth-Sizing test:

"(c) Examination procedures, equipment, and personnel are qualified for depth-sizing when the RMS error of the flaw depth measurements, as compared to the true flaw depths, do not exceed 0.125 in. (3 mm)."

12-MN-001 Page 2 of 5

3.0 Alternative Duke Energy proposes to use a contracted examination vendor that has demonstrated ability to meet a depth sizing qualification requirement with a root mean square error (RMSE) of 0.189 inch instead of the 0.125 inch required for Code Case N-695. In the event an indication is detected that requires depth sizing, the difference between the required RMSE and the proposed demonstrated RMSE, as applicable, will be added to the measured through-wall extent for comparison with applicable acceptance criteria. If the examination vendor demonstrates an improved depth sizing RMSE prior to the examination, the excess of that improved RMSE over the 0.125 inch RMSE requirement, if any, will be added to the measured value for comparison with applicable acceptance criteria.

Duke Energy proposes to use an alternative through-wall depth sizing criteria for dissimilar metal welds that are examined from the inside surface. Examinations of these components will be performed during the next scheduled refueling outage at MNS 2 scheduled for September, 2012.

4.0 Basis for Relief To date, although qualified for detection and length sizing on these welds, the examination vendors have not met the established RMSE requirement for depth sizing (0.125 inch) when examining from the inside surface. Duke Energy's examination vendor has demonstrated the ability to meet the depth sizing qualification requirement with an RMSE of 0.189 inch instead of the required 0.125 inch. EPRI Policy/Procedure 03-01 describes the criteria for issuing documentation of depth sizing errors that exceed the 0.125 inch RMS Appendix VIII requirement.

Duke Energy has determined the alternative in this request will result in an acceptable level of quality and safety, pursuant to the provisions of 10 CFR 50.55a(a)(3)(i). The subject welds will be examined by procedures, personnel and equipment qualified by demonstration in all aspects except depth sizing. For depth sizing, the proposed addition of the difference between the qualified and demonstrated sizing tolerance to any flaw that is required to be sized provides an acceptable level of quality and safety.

12-MN-001 Page 3 of 5

A, -.

5.0 ASMECode Components Affected Category and System Details:

Code Class: Class 1 System Welds: Reactor Coolant System Examination Category: Category R-A for the dissimilar metal welds Code Item Number: RI. 11 for RV dissimilar metal nozzle-to-pipe welds MNS 2 Debscription Size Nozzle to Pipe SS-CS DM

_Weld No.

NC Hot Leg RV Nominal 29.0" 2RPV-W15-SE / 2NC2F1-1 Pipe Nozzle ID with 2.33"

-A Loop min wall NC Hot Leg RV Nominal 29.0" Pipe Nozzle ID with 2.33" 2RPV-W16-SE / 2NC2F2-1

- B Loop min wall NC Hot Leg RV Nominal 29.0" Pipe Nozzle ID with 2.33" 2RPV-W17-SE / 2NC2F3-1

- C Loop min wall NC Hot Leg RV Nominal 29.0" Pipe Nozzle ID with 2.33" 2RPV-W18-SE / 2NC2F4-1

- D Loop min wall NC Cold Leg RV Nominal 27.5" Pipe Nozzle - A Loop ID with 2.21" 2RPV-Wl 1-SE / 2NC2F1-8 min wall NC Cold Leg RV Nominal 27.5" Pipe Nozzle - B Loop ID with 2.21" 2RPV-W12-SE / 2NC2F2-8 min wall NC Cold Leg RV Nominal 27.5" Pipe Nozzle - C Loop ID with 2.21" 2RPV-W13-SE / 2NC2F3-8 min wall NC Cold Leg RV Nominal 27.5" Pipe Nozzle - D Loop ID with 2.21" 2RPV-W14-SE / 2NC2F4-8 min wall Component Materials:

1. Nozzles: ASME SA-508 Class 2

2. First Butter Layer: Filler Material Type 309S

3. Remaining Butter Layers: Filler Material Type 308L

4. Inside Diameter & Outside Diameter Nozzle Buttering Weld Inlays: Alloy 82/182

5. Buttering-to-Pipe Weld: Filler Material Type 308

6. Pipe: Type ASME SA-351 Grade CF8A 12-MN-001 Page 4 of 5

6.0 Duration of Proposed Alternative The proposed alternative to the ASME Code is applicable for the remainder of the third 10-year ISI interval at MNS 2.

7.0 Precedents A similar alternative request has been approved for use at MNS 1 in NRC letters dated May 13, 2009 (ADAMS Accession No. ML091140066) and June 7, 2010 (ADAMS Accession No. ML101480011), at V.C. Summer Station in an NRC letter dated February 3, 2004 (ADAMS Accession No. ML040340450), and at Diablo Canyon, Units 1 and 2 in an NRC letter dated October 26, 2005 (ADAMS Accession No. ML052660331).

8.0 References (1) 1998 Edition through 2000 Addenda, ASME Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components."

(2) 1998 Edition through 2000 Addenda, ASME Code, Section Xl, Appendix VIII, Supplement 10.

(3) Code Case N-695, Qualification Requirements for Dissimilar Metal Piping Welds,Section XI, Division 1.

(4) EPRI Policy/Procedure Directive 03-01: Criteria for Issuing Documentation of Depth Sizing Errors That Exceed the 0.125-inch RMS Appendix VIII Criteria.

(5) EPRI Letter addressed to Mr. Dave Zimmerman. "Summary of WESDYNE International, LLC Supplements 2 & 10 Depth Sizing Results Obtained from the Inside Surface." August 28, 2009.

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