ML13045A485
| ML13045A485 | |
| Person / Time | |
|---|---|
| Site: | McGuire  |
| Issue date: | 01/31/2013 |
| From: | Capps S Duke Energy Carolinas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML13045A485 (7) | |
Text
Duke Duke STEVEN D.CAPPS Vice President
-En*ergy McGuire Nuclear Station Duke Energy MG01 VP / 12700 Hagers Ferry Rd.
Huntersviyle, NC 28078 980-875-4805 980-875-4809 fax Steven. Capps@duke-energy.corn January 31, 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 Number 50-369 Updated Relief Request 13-MN-001 By letter dated January 9, 2013, Duke Energy submitted Relief Request 13-MN-001 requesting approval for use of an alternative depth-sizing qualification for volumetric examinations of the reactor vessel hot leg and cold leg nozzle-to-safe end dissimilar metal welds performed from the inside surface.
In a telephone conference call on January 28, 2013, Duke Energy provided clarification to the Nuclear Regulatory Commission staff regarding Duke Energy's proposed alternative for flaw depth sizing as described in Section 5 of the relief request. As a result of the conference call, Duke Energy is re-submitting the relief request with revised Sections 4 and 5 to include the clarification. Duke Energy requests approval of this relief request by March 20, 2013 to support inspections scheduled during the McGuire Unit 1, 2013 spring refueling outage.
If you have any questions or require additional information, please contact P. T. Vu at (980) 875-4302.
Sincerely, Steven D. Capps Enclosure LJ www. duke-energy.com
U. S. Nuclear Regulatory Commission January 31, 2013 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
Enclosure Duke Energy Carolinas, LLC McGuire Nuclear Station, Unit 1 Relief Request Serial No. 13-MN-001 Relief Request for Alternative Depth Sizing Criteria, Submitted Pursuant to 10 CFR 50.55a(g)(5)(iii)
Relief Request 13-MN-001 Page 2 of 5
1.0 ASME Code Components Affected
Class 1 Reactor Coolant System Reactor Pressure Vessel (RPV) Nozzle-to-Safe End Dissimilar Metal Welds Listed in Table 1 Below.
Table I Description Size Nozzle-to-Safe Inspection Code Case End Weld No. Plan Summary N-770-1 Number Inspection Item Cold Leg Nozzle 1A 27.5" ID (Nom.) 1RPV3-445A-SE M1.G5.3.0005 B to Safe End Weld Cold Leg Nozzle 1B 27.5" ID (Nom.) 1RPV3-445B-SE M1.G5.3.0006 B to Safe End Weld Cold Leg Nozzle 1C 27.5" ID (Nom.) 1RPV3-445C-SE M1.G5.3.0007 B to Safe End Weld Cold Leg Nozzle 1D 27.5" ID (Nom.) 1RPV3-445D-SE M1.G5.3.0008 B to Safe End Weld Hot Leg Nozzle 1A 29.0" ID (Nom.) 1RPV3-445E-SE M1.G5.3.0001 A-2 to Safe End Weld Hot Leg Nozzle 1B 29.0" ID (Nom.) 1RPV3-445F-SE Ml.G5.3.0002 A-2 to Safe End Weld Hot Leg Nozzle 1C 29.0" ID (Nom.) 1RPV3-445G-SE M1.G5.3,0003 A-2 to Safe End Weld Hot Leg Nozzle 1D 29.0" ID (Nom.) 1RPV3-445H-SE M1.G5.3.0004 A-2 to Safe End Weld Component materials and nozzle weld configurations are shown in Figure 1.
Relief Request 13-MN-001 Page 3 of 5 Safe End to Nozzle Weld O.D. Cladding (Alloy 82)
Nozzle-to-Safe End Weld Safe End O.D. Cladding (312 SS)
(Full Penetration Alloy 182) 3 Type End (SA-182, Safe Saf Safe End I.D. Cladding (312 SS)
S Safe EL to Nozzle Weld End Nozzle I.D. Cladding I.D. Cladding (Alloy(SS) 82)
Figure 1 Inlet/Outlet - to - Safe End Welds (Not to Scale) 2.0 ADplicable Code Edition and Addenda 2.1 ASME Boiler and Pressure Vessel Code,Section XI, 1998 Edition through the 2000 Addenda.
Note: Use of this Code Edition and Addenda during Period 1 of the 4th Inservice Inspection Interval was authorized via Relief Request Serial #10-MN-001 (U. S. Nuclear Regulatory Commission (NRC) Safety Evaluation dated March 3, 2011, ADAMS Accession No. ML110550770). During Periods 2 and 3 of the 4th Inservice Inspection Interval, the applicable Section XI Code of Record shall be determined as specified in this Relief Request.
2.2 ASME Code Case N-770-1, Alternative Examination Requirements and Acceptance Standards for Class 1 Pressurized Water Reactor (PWR) Piping and Vessel Nozzle Butt Welds Fabricated With UNS N06082 or UNS W86182 Weld Filler Material With or Without Application of Listed Mitigation Activities, Section Xl, Division 1. Use of this Case is required by 10 CFR 50.55a(g)(6)(ii)(F).
2.3 The 4th Inservice Inspection Interval Program for Unit 1 includes ASME Code Case N-695, Qualification Requirements for Dissimilar Metal Piping Welds,Section XI, Division 1, which has been approved for use in Regulatory Guide 1.147, Rev. 16, Table 1- "Acceptable Section XI Code Cases".
Relief Request 13-MN-001 Page 4 of 5 3.0 Applicable Code Requirements 3.1 Code Case N-770-1, Table 1, Footnote (4) applies to volumetric examination of Inspection Items A-2 and B, and requires that "Ultrasonic volumetric examination shall be used and shall meet the applicable requirements of Appendix VIII."
Appendix VIII, Supplement 10, Paragraph 3.2(b) requires that examination procedures, equipment, and personnel are qualified for depth sizing when the Root Mean Square Error (RMSE) of the flaw depth measurements, as compared to the true flaw depths, is less than or equal to 0.125 in. (3.2 mm).
Note that volumetric examinations of the RPV nozzle-to-safe end dissimilar metal welds are also required to be performed in accordance with Section XI, Appendix VIII, as required by 10 CFR 50.55a(b)(2)(xv) and 10 CFR 50.55a(b)(2)(xvi).
3.2 Code Case N-695 provides alternatives to the requirements of Appendix VIII, Supplement 10, but paragraph 3.3(c) of this case requires that examination procedures, equipment, and personnel are qualified for depth-sizing when the RMSE of the flaw depth measurements, as compared to the true flaw depths, do not exceed 0.125 in. (3 mm). Code Case N-695 has been accepted by the NRC without condition and is listed in Table 1 of Regulatory Guide 1.147, Rev. 16.
4.0 Impracticality of Compliance Since 2002, the nuclear power industry has attempted to qualify personnel and procedures for depth-sizing examinations performed from the inside surface of dissimilar metal and austenitic stainless steel butt welds in PWR piping. As of November 26, 2012, no domestic or international vendor has met the applicable RMSE requirement of ASME Section X1 Appendix VIII, Supplement 10, or the alternative qualification requirements of ASME Code Case N-695, as applicable.
The examination vendor that Duke Energy intends to use for performing these examinations has an RMSE of 0.189 inch.
5.0 Proposed Alternative and Basis for Use Duke Energy proposes to use the following alternative for flaw depth sizing when dissimilar metal welds are examined from the inside surface:
- 1. Examinations shall be performed using ultrasonic testing (UT) techniques that are qualified for flaw detection and length sizing using procedures, personnel and equipment qualified by demonstration in all aspects except depth sizing.
- 2. A correction factor of the RMSE - 0.125 inches shall be added to the depths of any measured flaws. The correction factor shall be applied to the most critical location on the flaw in relation to surface proximity.
- 3. Eddy Current examinations shall be used to confirm whether any detected flaws are surface-breaking.
- 4. If any inner diameter (ID) surface-breaking flaws are detected, or if any flaw is detected and measured as 50% through-wall depth or greater, Duke Energy shall repair the indications or shall perform flaw evaluations and shall submit the evaluations to the NRC for review and approval prior to reactor startup.
These flaw evaluations shall include the following:
- a. Information concerning the mechanism which caused the flaw.
Relief Request 13-MN-001 Page 5 of 5
- b. Information concerning the surface roughness/profile in the area of the pipe/weld required to perform the examination, and an estimate of the percentage of potential surface areas with UT probe "lift-off'.
All other ASME Code,Section XI, requirements for which relief was not specifically requested apply, including the third party review by the Authorized Nuclear Inservice Inspector.
Because compliance with the applicable requirements is impractical, this request is submitted pursuant to 10 CFR 50.55a(g)(5)(iii). Duke Energy believes that the proposed alternative provides reasonable assurance that flaws detected during examination will be sufficiently sized to disposition in accordance with acceptance standards of ASME Code Case N-770-1.
6.0 Duration of Proposed Alternative The proposed alternative to the ASME Code is applicable for the remainder of the fourth 10-year Inservice Inspection Interval at McGuire Nuclear Station, Unit 1, which began on December 1, 2011 and is currently scheduled to end on November 30, 2021.
7.0 Related Industry Relief Requests A similar request was approved for use at McGuire Nuclear Station, Unit 2 in NRC letter dated September 24, 2012 (ADAMS Accession No. ML12258A363).
8.0 References 8.1 1998 Edition through 2000 Addenda, ASME Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components."
8.2 1998 Edition through 2000 Addenda, ASME Code,Section XI, Appendix VIII, Supplement 10.
8.3 ASME Code Case N-695, Qualification Requirements for Dissimilar Metal Piping Welds,Section XI, Division 1.
8.4 ASME Code Case N-770-1, Alternative Examination Requirements and Acceptance Standards for Class 1 PWR Piping and Vessel Nozzle Butt Welds Fabricated With UNS N06082 or UNS W86182 Weld Filler Material With or Without Application of Listed Mitigation Activities, Section Xl, Division 1.
8.5 EPRI Policy/Procedure Directive 03-01: Criteria for Issuing Documentation of Depth Sizing Errors That Exceed the 0.125-inch RMS Appendix VIII Criteria.
8.6 EPRI Materials Reliability Program Letter MRP 2012-046, dated November 26, 2012,
Subject:
Assessment of Effect of the Depth-Sizing Uncertainty for Ultrasonic Examinations from ID Surface of Large-Bore Alloy 82/182 and Austenitic Stainless Steel Butt Welds in PWR Primary System Piping, Revision 1.