ML092720862
| ML092720862 | |
| Person / Time | |
|---|---|
| Site: | McGuire  |
| Issue date: | 09/15/2009 |
| From: | Brandi Hamilton Duke Energy Carolinas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 09-MN-007 | |
| Download: ML092720862 (7) | |
Text
Duke BRUCE H. HAMILTON Vice President
- SEnergy, McGuire Nuclear Station Duke Energy MG01 VP / 12700 Hagers Ferry Road Huntersville, NC 28078 980-875-5333 980-875-4809 fax bruce.hamilton@duke-energy. corn September 15, 2009 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
SUBJECT:
Duke Energy Carolinas, LLC (Duke)
McGuire Nuclear Station Unit 1 Docket Number 50-369 Relief Request 09-MN-007 Pursuant to 10 CFR 50.55a(a)(3)(i), Duke hereby submits Relief Request 09-MN-007 for the use of an alternative to the examination requirements of ASME Code,Section XI. This request supports the examination of reactor vessel cold leg nozzle-to-safe end and safe end-to-pipe welds performed from the inside surface during the upcoming McGuire Unit 1 spring 2010 refueling outage. The proposed alternative provides for an acceptable level of quality and safety, consistent with 10 CFR 50.55a(a)(3)(i). contains this relief request. Duke requests approval of this relief request by February 12, 2010 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, Bruce H. Hamilton www, duke-energy. corn
ill
.1l U. S. Nuclear regulatory Commission September 15, 2009 Page 2 xc:
L. A. Reyes, Region II Administrator U.S. Nuclear Regulatory Commission Sam Nunn Atlanta Federal Center, 23 T85 61 Forsyth St., SW Atlanta, GA 30303-8931 J. H. Thompson, Project Manager U. S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop 0-8 H 4A Rockville, MD 20852-2738 J. B. Brady.
NRC Senior Resident Inspector McGuire Nuclear Station
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McGuire Unit 1 Relief Request for Alternate Depth Sizing Criteria Duke Energy McGuire Unit 1 09-MN-007 Page 1 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) is submitting a request for the use of an alternative to the examination requirements of ASME Code, Section Xl, at McGuire Nuclear Station Unit 1 (MNS 1). This request supports the examination of Reactor Vessel (RV) cold leg Nozzle-to-Safe end
-(dissimilar metal) and Safe end-to-pipe (similar metal) welds performed from the inside surface during the next scheduled outage. Duke 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 1 is currently in the third 10-year ISI interval that began on 12/01/2001 and is scheduled to end on 12/01/2011. The ASME Boiler and Pressure Vessel Code (ASME Code) of record for the current period of the third 10-year ISI interval is the 1998 Edition of Section Xl of the ASME Code, 2000 addendum.Section XI Code Case N-695 (Qualification Requirements for Dissimilar Metal Piping Welds) and Code Case N-696 (Qualification Requirements for Appendix VIII Piping Examinations Conducted from the Inside Surface) are referenced in the ISI program. These Code Cases are listed in Regulatory Guide 1.147, Rev. 15, Table 1- "Acceptable Section XI Code Cases".
2.0
Applicable Code Requirement
The RV Nozzle-to-Safe end Butt Welds and the Safe end-to-pipe welds are part of the MNS 1, Risk-Informed Inservice Inspection program. The RV Nozzle-to-Safe end Butt Welds are dissimilar metal welds and the Safe end-to-pipe welds are similar metal welds. Both the RV Nozzle-to-Safe end Butt Welds and the Safe end-to-pipe welds will be volumetrically examined.
The volumetric examinations are to be conducted in accordance with ASME Section Xl, Appendix VIII, Supplements 2 and 10, 1998 Edition with 2000 Addenda. Code Cases N-695 and N-696 are acceptable alternatives to Appendix VIII, Supplements 2 and 10.
The specific Supplements 2 and 10 requirements for which relief is requested pertains to the depth sizing qualification requirements for performance demonstration of ultrasonic examination systems for dissimilar and similar metal piping welds as listed below.
09-M N-007 Page 2 of 5
Supplement 2 (Similar Metal Welds) 3.2 Sizing Acceptance Criteria:
"(b) The RMS [root mean square] error of the flaw depths estimated by ultrasonics, as compared with the true depths, shall not exceed 0.125 in.
(3.2 mm)."
Supplement 10 (Dissimilar Metal Welds) 3.2 Sizing Acceptance Criteria:
(b) 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, is less than or equal to 0.125 in. (3.2 mm)."
These same requirements are stated within Code Cases N-695 and N-696.
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)."
Code Case N-696 3.3 Depth-Sizing test:
"(d) Supplement 2 or Supplement 3 examination procedures, equipment, and personnel are qualified for depth-sizing when the flaw depths estimated by ultrasonics, as compared to the true depths, do not exceed 0.125 in. (3 mm) RMS when they are combined with a successful Supplement 10 qualification."
3.0 Alternative Duke 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 Supplement 10 and a RMSE of 0.245 inch instead of the 0.125 inch for Supplements 10 and 2 combined, as per approved Code Case N-696. Duke proposes to use approved Code Case N-695 with an RSME of 0.189 inch and approved Code Case N-696 with a combined RMSE of 0.245 inch instead of the 0.125 inch specified for depth sizing in the Code Cases. 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.
09-MN-007 Page 3 of 5
J 1 Duke proposes to use an alternative through-wall depth sizing criteria for similar and 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 1 scheduled for March, 2010.
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 ID. Duke's examination vendor has demonstrated ability to meet the depth sizing qualification requirement with an RMSE of 0.189 inch (Supplement 10) and 0.245 inch (Supplement 2 andO1 combined) instead of the required 0.125 inch. EPRI has published under their Policy/Procedure Directives the criteria of error in the RMS which has utility approval.
Duke has determined that 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 proposed alternative assures that the subject welds will be fully 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 compensates for the potential variation and likewise assures an acceptable level of quality and safety.
5.0 ASME Code Components Affected
Category and System Details:
Code Class:
System Welds:
Examination Categories:
Code Item Numbers:
Class 1 Reactor Coolant System Category R-A for the dissimilar metal welds Category R-A for the stainless steel welds R1.11, R1.15 for RV dissimilar metal nozzle-to-safe end welds R1.11 for RV stainless steel safe end-to-pipe welds MNS 1 Description Size DM Weld No.
Equipment NC Pipe Cold Leg RV Nozzle -
Nominal 27.5" ID 1RPV3-445A-SE 1NClFl-8 LAS nozzle/Alloy 82-182 A Loop with 2.281" wall weld/SS safe end/SS weld NC Pipe Cold Leg RV Nozzle -
Nominal 27.5" ID 1RPV3-445B-SE 1NC1F2-8 LAS nozzle/Alloy 82-182 B Loop with 2.281" wall weld/SS safe end/SS weld NC Pipe Cold Leg RV Nozzle -
Nominal 27.5" ID 1RPV3-445C-SE 1NC1F3-8 LAS nozzle/Alloy 82-182 C Loop with 2.281" wall weld/SS safe end/SS weld NC Pipe Cold Leg RV Nozzle -
Nominal 27.5" ID 1RPV3-445D-SE 1NCIF4-8 LAS nozzle/Alloy 82-182 D Loop with 2.281" wall weld/SS safe end/SS weld 09-MN-007 Page 4 of 5 1ý
6.0 Duration of Proposed Alternative The proposed alternative to the ASME Code is applicable for the remainder of the third 10-year Inservice inspection (ISI) interval at MNS 1.
7.0 Precedents A similar alternative request has been approved for use at MNS 1 in an NRC letter dated May 13, 2009 (ADAMS Accession No. ML091140066), 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, ASME Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components," 2000 Addenda.
(2) 1998 Edition, ASME Code,Section XI, with the 2000 Addenda, Appendix VIII, Supplements 2 and 10.
(3) Code Case N-695, Qualification Requirements for Dissimilar Metal Piping Welds, Section Xl, Division 1.
(4) Code Case N-696, Qualification Requirements for Appendix VIII Piping Examinations Conducted From the Inside Surface,Section XI, Division 1.
(5) EPRI Policy/Procedure Directive 03-01: Criteria for Issuing Documentation of Depth Sizing Errors That Exceed the 0.125-inch RMS Appendix VIII Criteria (6) 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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