ML13141A256

Relief Request Serial # 12-MN-004, Response to Request for Additional Information

ML13141A256
Person / Time
Site:	McGuire
Issue date:	05/07/2013
From:	Capps S Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TAC MF0515
Download: ML13141A256 (6)

Text

Steven D. Capps

@DUKE ENERGY. Vice President McGuire Nuclear Station Duke Energy MG01VP I 12700 Hagers Ferry Road Huntersville, NC 28078 o: 980.875.4805 f: 980.875.4809 Steven.Capps@du ke-energy.com May 7, 2013 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 1 Docket No. 50-369 Relief Request Serial # 12-MN-004, Response to Request for Additional Information (TAC No. MF0515)

By letter dated November 29, 2012 (ADAMS Accession No. ML12355A149), Duke Energy submitted the subject relief request (RR) seeking relief for the welds listed in Table 1 of the RR.

On April 8, 2013, the Nuclear Regulatory Commission staff electronically requested additional information regarding this RR. Please find enclosed Duke Energy's response to your request for additional information.

If you have any questions, please contact P. T. Vu of Regulatory Affairs at (980) 875-4302.

Sincerely, Steven D. Capps Enclosure www.duke-energy.com

U. S. Nuclear Regulatory commission May 7, 2013 Page 2 xc:

Victor McCree, Region II Administrator U. S. Nuclear Regulatory Commission Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, GA 30303-1257 James Kim, Project Manager U. S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop 0-8 C2 Rockville, MD 20852-2738 John Zeiler NRC Senior Resident Inspector McGuire Nuclear Station

Enclosure Duke Energy Corporation McGuire Nuclear Station, Unit 1 Relief Request #12-MN-004 Response to Request for Additional Information Duke Energy Corporation McGuire Nuclear Station, Unit 1 Relief Request No.12-MN-004, Response to Request for Additional Information Enclosure - Page 1 of 3 ll.m-. =.-M ...

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NRC Reauest for Additional Information:

For Request for Relief No. 12-MN-004, Section 10, the licensee requested relief from the ASME Code-required volumetric examination MNS, Unit 1 Head Ring-to-Head Cap, Weld # 1RPV-446B, Summary Number M1 .B1.21.0001 of the Reactor Coolant System.

The US Nuclear Regulatory Commission (NRC) staff recognizes that licensees use their own various nomenclatures in naming the components of their particular plant. Based on the licensee's provided drawings in "Attachment B" of the relief request, the NRC staff interprets that for the Reactor Pressure Vessel (RPV) Head Ring-to-Head Cap Weld the licensee means it's seeking relief for the examination of the weld commonly known in the industry as the "RPV Head-to-Flange Weld." The licensee listed its RPV Head Ring-to-Head Cap component under ASME Code, Category B-A, Item B1.21 which is described under the ASME Code, Table IWB-2500-1 as Head Welds Circumferential and Meridional. Industry generally recognizes these welds as bottom Reactor Pressure Vessel Dollar Plate Circumferential Welds and the ASME Code requirements are different.

The RPV Head-to-Flange comes under ASME Code Category B-A, Item B1.40 which requires Figure IWB-2500-5, Examination Volume A-B-C-D Essentially 100% volumetric and surface examination coverage of the weld length. "Essentially 100 percent", as clarified by ASME Code Case N-460 "Alternative Examination Coverage for Class I and Class 2 Welds,Section XI, Division 1", is greater than 90 percent coverage of the examination volume, or surface area, as applicable. ASME Code Case N-460 has been approved for use by the NRC in Regulatory Guide G 1.147, Revision 16 "Inservice Inspection Code Case Acceptability."

For the Bottom Reactor Pressure Vessel Dollar Plate Circumferential and Meridional Welds the ASME Code,Section XI, Table IWB-2500-1, Examination Category B-A, Item Number B1.21, Figure IWB-2500-3, Examination Volume A-B-C-D requires essentially 100% volume coverage of the accessible weld length and no surface examination. For the Bottom Reactor Pressure Vessel Dollar Plate Circumferential and Meridional Welds, the ASME Code Committees recognize the limitations of examining these welds and specifically stated in this particular ASME Code requirement to examine the "accessible length" of the welds. If a licensee stated that it did examine the "accessible length" of the subject welds they met the ASME Code requirements and do not require relief from the ASME Code requirements.

Provide a clarification of the component in which the licensee is seeking relief and state ifthe licensee met the ASME Code examination requirements including the surface examination, if required.

Duke Energy Corporation McGuire Nuclear Station, Unit 1 Relief Request No. 12-MN-004, Response to Request for Additional Information Enclosure - Page 2 of 3

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A. ý Duke Energy Response:

See attached Figure No. 1. Duke is not seeking relief for the weld commonly known as the "RPV Head-to-Flange Weld." The Reactor Pressure Vessel Closure Head Ring to Head Cap Weld is identified correctly as shown in Relief Request Serial No.12-MN-004. This weld is correctly categorized as part of Examination Category B-A, Pressure Retaining Welds in Reactor Vessel, Item No. B1.21, Head Circumferential Welds, Figure No. IWB-2500-3. This category requires a volumetric examination only. Therefore, the examination method requirement for Examination Category B-A / Item No. B13.21 has been met for Summary Number M1 .B1.21.0001 / Weld ID 1 RPV-446B. Relief is requested because greater than 90 percent coverage was not obtained as described below.

Table IWB-2500, Item B13.21 requires "Accessible Length of all welds (Note 2)", which includes essentially 100% of the weld length. The entire length of the weld was scanned, with the exception of inaccessible length being covered by the three permanent lifting lugs. The three lugs cover a total of 24 inches of the weld. The total length of the weld is 456 inches. The actual length of the weld scanned was 432/456(100) = 94.7% of the total length of the weld. If the lugs were removed, the coverage obtained would be at 73.8%, as the true limiting factor for this weld is the taper configuration. Therefore, the weld was scanned to the extent possible, and the requirements of Note 2 have been met.

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