ML16004A181

Oconee Nuclear Station, Units 1, 2, and 3 - Relief Request 14-ON-003 Alternative Requirements for Class 1 Category B-J Piping Welds (CAC Nos. MF6299, MF6300, and MF6301)

ML16004A181
Person / Time
Site:	Oconee
Issue date:	01/07/2016
From:	Markley M T Plant Licensing Branch II
To:	Batson S Duke Energy Carolinas
Whited J A
References
CAC MF6299, CAC MF6300, CAC MF6301
Download: ML16004A181 (8)

Text

Mr. Scott Batson Site Vice President Oconee Nuclear Station Duke Energy Carolinas, LLC 7800 Rochester Highway Seneca, SC 29672-0752 January 7, 2016 \

SUBJECT: OCONEE NUCLEAR STATION, UNITS 1, 2, AND 3 -RELIEF REQUEST 14-0N-003 ALTERNATIVE REQUIREMENTS FOR CLASS 1 CATEGORY B-J PIPING WELDS (CAC NOS. MF6299, MF6300, AND MF6301)

Dear Mr. Batson:

By letter dated May 4, 2015, Duke Energy Carolinas, LLC (the licensee) requested U.S. Nuclear Regulatory Commission (NRC) authorization to use an alternative to the requirements of Section XI of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) for the Oconee Nuclear Station, Units 1, 2, and 3 (ONS) as identified in relief request no. 14-0N-003. Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(1 ), the licensee requested to use the applicable Code Case N-609-1, as a proposed alternative to the method of selection of Class 1 Category B-J Piping welds for examination, on the basis that the alternative provides an acceptable level of quality and safety. The NRC staff has concluded, that the use of the proposed alternative described in relief request 14-0N-003, provides an acceptable level of quality and safety. Accordingly, the NRC staff concludes, as stated in the enclosed Safety Evaluation, that the licensee has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(z)(1 ). Therefore, the NRC staff authorizes the use of the proposed alternative described in relief request 14-0N-003 at ONS, for the remainder of the fifth 10-year ISi interval, which commenced on July 15, 2014, and will end on July 15, 2024. All other ASME Code requirements for which relief was not specifically requested and approved in this relief request remain applicable, including third-party review by the Authorized Nuclear lnservice Inspector. If you have any questions, please contact the ONS Senior Project Manager, Mr. James R Hall, at randy.hall@nrc.gov or 301-415-4032. Docket Nos. 50-269, 50-270, and 50-287

Enclosure:

Safety Evaluation cc w/encl: Distribution via ListServ

Sincerely,Michael T. Markley, Chief Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REGARDING RELIEF REQUEST 14-0N-003 REGARDING CLASS 1 CATEGORY B-J PIPING WELDS DUKE ENERGY CAROLINAS, LLC OCONEE NUCLEAR STATION, UNITS 1, 2, AND 3 DOCKET NOS. 50-269, 50-270 AND 50-287 1.0 INTRODUCTION By letter dated May 4, 2015,1 Duke Energy Carolinas, LLC (Duke, the licensee) requested U.S. Nuclear Regulatory Commission (NRG) authorization to use an alternative to the requirements of Section XI of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) for the Oconee Nuclear Station, Units 1, 2, and 3 (ONS) as identified in relief request no. 14-0N-003. Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(1 ), the licensee requested to use the applicable Code Case N-609-1, as a proposed alternative to the method of selection of Class 1 Category B-J Piping welds for examination, on the basis that the alternative provides an acceptable level of quality and safety. 2.0 REGULATORY EVALUATION The licensee requested authorization of an alternative to the lnservice Inspection (ISi) requirements of article IWB-2500, Table IWB-2500-1 of the ASME Code,Section XI, pursuant to 10 CFR 50.55a(z)(1 ). Pursuant to 1 O CFR 50.55a(g)(4), the ASME Code Class 1, 2, and 3 components (including supports) must meet the requirements, except the design and access provisions and the pre-service examination requirements, set forth in the ASME Code,Section XI, "Rules for lnservice Inspection of Nuclear Power Plant Components," to extent practical within the limitations of design, geometry, and materials of construction of the components. Pursuant to 10 CFR 50.55a(z) alternatives to the requirements of paragraph 10 CFR 50.55a(g) may be used, when authorized by the NRG, if the licensee demonstrates that: (1) the proposed

• alternative provides an acceptable level of quality and safety, or (2) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. 1 Agencywide Documents Access and Management System (ADAMS) Accession No. ML 15132A280. Enclosure

-2 -Based on the above, and subject to the following technical evaluation, the NRC staff finds that regulatory authority exists for the licensee to request and the NRC to authorize the proposed alternative. 3.0 TECHNICAL EVALUATION 3.1 Component Affected The components affected are ASME Code Class 1 Piping Welds. In accordance with the ASME Code,Section XI, IWB-2500, Table IWB-2500-1, they are classified as Examination Category B-J Piping Welds. -3.2 Applicable Code Edition and Addenda The code of record for the fifth 10-year ISi interval at ONS is the 2007 Edition through 2008 Addenda of the ASME Code. 3.3 Duration of Relief Request The licensee requested the proposed alternative in 14-0N-003 for use during the fifth 10-year ISi interval which started on July 15, 2014, and is scheduled to end on July 15, 2024. 3.4 ASME Code Requirement The ASME Code,Section XI, IWB-2500-1 Examination Category B-J, requires Class 1 piping welds to be selected for examination in accordance with Note (2) (b), which states, in part; All terminal ends and joints in each pipe or branch run connected to other components where the stress levels exceed either of the following limits under loads associated with specific events and operational conditions: 1. Primary plus secondary stress intensity range of 2.4Sm for ferritic steel and austenitic steel. 2. Cumulative usage factor U of 0.4. 3.5 Background In its letter dated May 4, 2015, the licensee states that the Class 1 piping at ONS was originally designed in accordance with ANSI B31.7 requirements. This design code did not require an analysis to determine the primary plus secondary stress intensity range or cumulative usage factors, which are usually included in pipe designed in accordance with Section Ill of the ASME Code. During the previous 10-year ISi interval at ONS, Duke implemented the requirements in ASME Code Case N-609, "Alternative Requirements to Stress-Based Selection Criteria for Category B-J Welds." This code case allows the licensee to implement an alternative examination approach which does not include stress and usage factor parameters. Code Case N-609 is included in Regulatory Guide (RG) 1.147, Revision 17, "lnservice Inspection Code Case

-3 -Acceptability, ASME Section XI, Division 1".2 According to the Applicability Index for Section XI Cases, the use of N-609 is limited to the 2004 Edition up to and including the 2005 Addenda of the ASME Code. For the fifth 10-year ISi interval at ONS, the Section XI Code of Record is ASME Section XI, 2007 Edition with the 2008 Addenda. In this edition of the code, the footnotes for Table IWB-2500-1, Category B-J have been edited (the stress and cumulative usage factors that were addressed in Footnote 1 are now addressed in Footnote 2). This change in the footnotes has been addressed by ASME by revising Code Case N-609. The new Code Case, N-609-1 was published in September 2010 and has not, as yet, been included in RG 1.147. Code Case N-609-1 is specifically applicable to the ONS fifth 10-year ISi interval Section XI Code of Record. Code Case N-609 is no longer valid for the fifth 10-year.ISI interval at ONS because it would conflict with which'states, "Code.Cases shall be applicable to the Edition and Addenda specified in the Inspection Plan." Consequently, Duke has chosen to pursue the use of Code Case N-609-1, since the technical requirements of Code Case N-609 and Code Case N-609-1 are identical. 3.6 Proposed Alternative Pursuant to 10 CFR 50.55a(z)(1 ), the licensee proposes to use Code Case N-609-1 as an alternative to the IWB-2500, Table IWB-2500-1, Examination Category B-J, Note (2) weld examination selection requirements. Code Case N-609-1 states that Category B-J welds shall be selected for examination such that 25 percent of the total non-exempt welds are examined during the interval. The welds selected shall include the following: (a) All terminal ends in each pipe or branch run connected to vessels. (b) All terminal ends in each pipe or branch run connected to other components. (c) All dissimilar metal welds not covered under Category B-F, between one of the following combinations: (1) carbon or low alloy steels and high alloy steels; (2) carbon or low alloy steels and high nickel alloys; (3) high-alloy steels and high nickel alloys. (d) Additional piping welds, such that the total number of circumferential butt welds (or branch connection or socket welds) selected for examination equals 25% of the total number of nonexempt circumferential butt welds (or branch connection or socket welds) in the reactor coolant piping system. These additional piping welds shall be distributed as follows: (1) The examinations shall be distributed among the Class 1 systems prorated, to the degree practicable, on the number of nonexempt welds in each system (e.g., if a system 2 ADAMS Accession No. ML 13339A689.

-4-contains 30% of the nonexempt welds, 30% of the nondestructive examinations required by Category 8-J should be performed on that system). ' (2) Within each system, examinations shall be distributed between line sizes prorated, to the degree practicable, on the number of nonexempt welds in each line size. 3. 7 NRC' Staff Evaluation The NRC staff has evaluated relief request 14-0N-003 pursuant to 10 CFR 50.55a(z)(1). The NRC staff's evaluation focused on whether the proposed alternative provides an acceptable . level of quality and safety. Review of the two code cases, Code Case N-609 and Code Case N-609-1, reveals that their technical aspects are identical. The only difference between the two code cases is that Code Case N-609-1 was altered to take into account changes in the ASME Code 2004 Edition with the 2005/2006 Addenda,Section XI, IW8-2500, Table IW8-2500-1, Footnotes (1) and (2). In the 2004 Edition with the 2005 Addenda and earlier, the pertinent information was contained in Footnote (1 ), and was referenced in Code Case N-609. In the 2004 Edition with the 2005/2006 Addenda and beyond, the information previously contained in Footnote (1) was moved, word for word, to Footnote (2). Therefore, Code Case N-609-1 addresses this by specifying which footnote to reference depending on which edition of the code is the Code of Record. All other technical aspects of N-609 and N-609-1 are identical. As stated in 10 CFR 50.55a(g)(4)(ii), the licensee must comply with the requirements of the latest edition and addenda of the Code incorporated by reference in paragraph 1 O CFR 50.55a(a) 12 months before the start of the 120-month inspection interval (or the optional ASME Code Case listed in NRC RG 1.147, Revision 17, when using Section XI, that are incorporated by reference in paragraphs 10 CFR 50.55a(a)(3)(ii)). As stated in 10 CFR 50.55a(z), the licensee is permitted to use alternatives to the requirements of paragraphs 10 CFR 50.55a(b) through (g), when authorized by the Director, Office of Nuclear Reactor Regulation. The NRC staff also notes that Code Case N-609-1 has already been reviewed. This Code Case has been proposed to be accepted in the next revision of RG 1.147. The NRC staff notes that in relief request 14-0N-003, the licensee stated that the ASME Code,Section XI, IW8-2500-1 Examination Category 8-J, requires Class 1 piping welds to be selected for examination in accordance with Note (2)(b), which states, in part; All terminal ends and joints in each pipe or branch run connected to other components where the stress levels exceed either of the following limits under loads associated with specific events and operational conditions: 1. Primary plus secondary stress intensity range of 2.4Sm for ferritic steel and austenitic steel. 2. Cumulative usage factor U of 0.4 examination of the nozzle-to-shell welds when the inside of the vessel is accessible ....

-5 -The licensee clarified their original request by noting that Note (2)(b)(2) should only read, "Cumulative usage factor U of 0.4." The rest of the sentence (in italics above) was a typographical error in relief request 14-0N-003. 4.0 CONCLUSION As set forth above, the NRC staff concludes that the use of the proposed alternative described in request 14-0N-003, provides an acceptable level of quality and safety. Accordingly, the NRC staff concludes that the licensee has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(z)(1 ). Therefore, the NRC staff authorizes the use of relief request 14-0N-003 at ONS for the remainder of the fifth 10-year ISi interval, which commenced on July 15, 2014, and will end on July 15, 2024. All other ASM E Code, requirements for which relief was not 'specifically requested and approved in this relief request remain applicable, including third-party review by the Authorized Nuclear lnservice Inspector. Principal Contributor: Donald Becker Date: January 7, 2016