ML061140372

Third 10-Year Interval Inservice Inspection Program Relief Request I3R-02

ML061140372
Person / Time
Site:	Wolf Creek
Issue date:	05/10/2006
From:	Terao D Plant Licensing Branch III-2
To:	Muench R Wolf Creek
Donohew J N, NRR/DLPM,415-1307
References
TAC MD0298
Download: ML061140372 (8)

Text

May 10, 2006 Mr. Rick A. Muench President and Chief Executive Officer Wolf Creek Nuclear Operating Corporation Post Office Box 411 Burlington, KS 66839

SUBJECT:

WOLF CREEK GENERATING STATION - THIRD 10-YEAR INTERVAL INSERVICE INSPECTION PROGRAM RELIEF REQUEST I3R-02 (TAC NO. MD0298)

Dear Mr. Muench:

By letter dated March 2, 2006 (ET 06-0010), the Wolf Creek Nuclear Operating Corporation (the licensee) submitted its inservice inspection (ISI) program for the third 10-year interval at Wolf Creek Generating Station (WCGS). Included in the submittal were the following three relief requests (RRs): I3R-01, I3R-02, and I3R-04. This letter only addresses RR I3R-02.

In the enclosed safety evaluation (SE), the Nuclear Regulatory Commission (NRC) staff has evaluated the information provided by the licensee in its letter dated March 2, 2006, for the proposed third 10-Year ISI interval RR I3R-02 for WCGS. Based on the SE, the NRC staff concludes that the licensees proposed alternative in RR I3R-02 for Class 1, 2, and 3 vessel welded attachments provides an acceptable level of quality and safety. Therefore, the licensees alterative in RR I3R-02 is authorized pursuant to 10 CFR 50.55a(a)(3)(i) for the WCGS third 10-year ISI interval or until Code Case N-700 is approved for general use by reference in Regulatory Guide 1.147, "Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1," and incorporated by reference in 10 CFR 50.55a(b). At that time, if the licensee intends to continue implementing the code case, it must follow all provisions of Code Case N-700 with conditions as specified in Regulatory Guide 1.147 and limitations as specified in 50.55a(b)(4), (b)(5), and (b)(6), if any.

Sincerely,

/RA/

David Terao, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-482

Enclosure:

Safety Evaluation cc w/encl: See next page

May 10, 2006 Mr. Rick A. Muench President and Chief Executive Officer Wolf Creek Nuclear Operating Corporation Post Office Box 411 Burlington, KS 66839

SUBJECT:

WOLF CREEK GENERATING STATION - THIRD 10-YEAR INTERVAL INSERVICE INSPECTION PROGRAM RELIEF REQUEST I3R-02 (TAC NO. MD0298)

Dear Mr. Muench:

By letter dated March 2, 2006 (ET 06-0010), the Wolf Creek Nuclear Operating Corporation (the licensee) submitted its inservice inspection (ISI) program for the third 10-year interval at Wolf Creek Generating Station (WCGS). Included in the submittal were the following three relief requests (RRs): I3R-01, I3R-02, and I3R-04. This letter only addresses RR I3R-02.

In the enclosed safety evaluation (SE), the Nuclear Regulatory Commission (NRC) staff has evaluated the information provided by the licensee in its letter dated March 2, 2006, for the proposed third 10-Year ISI interval RR I3R-02 for WCGS. Based on the SE, the NRC staff concludes that the licensees proposed alternative in RR I3R-02 for Class 1, 2, and 3 vessel welded attachments provides an acceptable level of quality and safety. Therefore, the licensees alterative in RR I3R-02 is authorized pursuant to 10 CFR 50.55a(a)(3)(i) for the WCGS third 10-year ISI interval or until Code Case N-700 is approved for general use by reference in Regulatory Guide 1.147, "Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1," and incorporated by reference in 10 CFR 50.55a(b). At that time, if the licensee intends to continue implementing the code case, it must follow all provisions of Code Case N-700 with conditions as specified in Regulatory Guide 1.147 and limitations as specified in 50.55a(b)(4), (b)(5), and (b)(6), if any.

Sincerely,

/RA/

David Terao, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-482 DISTRIBUTION PUBLIC LPLIV r/f

Enclosure:

Safety Evaluation RidsNrrDorl RidsNrrDorlDpr RidsNrrDorlLpl4 GOttenberg, RI cc w/encl: See next page RidsNrrPMJDonohew MMitchell, NRR/ADES RidsNrrLALFeizollahi RidsOgcRp RidsAcrsAcnwMailCenter TBloomer, RIV EDO RidsRegion4MailCenter (BJones)

ACCESSION NO.: ML061140372 OFFICE NRR/LPL4/PM NRR/LPL4/LA CVIB/BC OGC NLO NRR/LPL4/BC NAME JDonohew LFeizollahi MMitchell MLemoncelli DTerao DATE 5/3/06 5/10/06 04/20/06 5/3/06 5/10/06 OFFICIAL RECORD COPY

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO INSERVICE INSPECTION PROGRAM RELIEF REQUEST NO. I3R-02 WOLF CREEK NUCLEAR OPERATING CORPORATION WOLF CREEK GENERATING STATION DOCKET NO. 50-482

1.0 INTRODUCTION

By letter dated March 2, 2006, the Wolf Creek Nuclear Operating Corporation (the licensee) submitted its inservice inspection (ISI) program for the third 10-year interval at Wolf Creek Generating Station (WCGS). Included in the licensee's submittal were the following three relief requests (RRs): I3R-01, I3R-02, and I3R-04. This safety evaluation (SE) addresses only RR I3R-02.

2.0 REGULATORY REQUIREMENTS The ISI of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) Class 1, 2, and 3 components is performed in accordance with Section XI of the ASME Code, Rules for Inservice Inspection of Nuclear Power Plant Components, and applicable addenda as required by Title 10 of the Code of Federal Regulation (10 CFR) 50.55a(g), except where specific relief has been granted by the Nuclear Regulatory Commission (NRC) pursuant to 10 CFR 50.55a(g)(6)(i). Paragraph 50.55a(a)(3) of 10 CFR states that alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if: (i) the proposed alternatives would provide an acceptable level of quality and safety or (ii) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.

Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1, 2 and 3 components (including supports) shall meet the requirements, except the design and access provisions and the preservice examination requirements, set forth in the ASME Code,Section XI, to the extent practical within the limitations of design, geometry, and materials of construction of the components. The regulations require that inservice examination of components and system pressure tests conducted during the initial 120-month inspection interval and subsequent intervals must comply with the requirements in the latest edition and addenda of Section XI of the ASME Code incorporated by reference in 10 CFR 50.55a(b) twelve months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein.

The ASME Code of record for the third 10-year ISI interval at WCGS, is the 1998 Edition through the 2000 Addenda of the ASME Code,Section XI. The third 10-year ISI interval at WCGS is scheduled to end on September 2, 2015.

3.0 TECHNICAL EVALUATION

FOR RR I3R-02 3.1 ASME Code Requirement The applicable ASME Code requirements are the 1998 Edition through the 2000 Addenda of ASME Code,Section XI, Table IWB-2500-1, Examination Category B-K, Footnote 4; Table IWC-2500-1, Examination Category C-C, Footnote 4; and Table IWD-2500-1, Examination Category D-A, Footnote 3 requirements as follows:

• ASME Code,Section XI, Examination Category B-K, Footnote 4 and Examination Category C-C, Footnote 4 state that for multiple vessels of similar design, function, and service, only one of the multiple vessels shall be selected for a surface examination.

• ASME Code,Section XI, Examination Category D-A, Footnote 3 states that selected samples of welded attachments shall be examined each inspection interval. All welded attachments selected for examination shall be those most subject to corrosion, as determined by the Owner, such as the welded attachments of the Service Water or Emergency Service Water systems. For multiple vessels of similar design, function, and service, the welded attachments of only one of the multiple vessels shall be selected for examination. For welded attachments of piping, pumps, and valves, a 10%

sample shall be selected for examination. This percentage sample shall be proportional to the total number of nonexempt welded attachments connected to the piping, pumps, and valves in each system subject to these examinations.

Therefore, relief is being requested from the following requirements of ASME Code, Section XI:

• Table IWB-2500-1, Examination Category B-K, Footnote 4;

• Table IWC-2500-1, Examination Category C-C, Footnote 4; and

• Table IWD-2500-1, Examination Category D-A, Footnote 3.

3.2 ASME System/Component(s) Affected The licensee stated that the systems and components for which relief was requested from the applicable ASME Code requirements are the following vessel welded attachments: the ASME Code,Section XI, Class 1, 2, and 3 vessel welded attachments.

3.3 Licensees Proposed Alternative Examination In lieu of implementing the requirements listed in Section 3.1 of this SE, the licensee has proposed that the alternative requirements of ASME Code Case N-700 be implemented at WCGS.

3.4 Licensees Basis for Requesting Relief In Attachment 2 to its application, the licensee provided the following justification for the relief it requested in RR I3R-02:

This 10 CFR 50.55a Request addresses two issues. First, ASME Section XI,

1998 Edition through 2000 Addenda, Table IWB-2500-1, Examination Category B-K, Footnote 4; Table IWC-2500-1, Examination Category C-C, Footnote 4; and Table IWD-2500-1, Examination Category D-A, Footnote 3; do not include specific criteria for the selection of welded attachments in situations where a plant has multiple vessels of similar design, function and service. The requirements in these Footnotes do specify that only one welded attachment of only one of the multiple vessels shall be selected for examination, but no additional criteria are provided for the selection of the appropriate welded attachment.

Second, these Footnotes do not provide any specific criteria for the selection of welded attachments on single vessels. The current wording under the Extent of Examination in [ASME Code,Section XI,] Tables IWX-2500-1, Categories B-K, C-C, and D-A can be interpreted to require that all welded attachments on a single vessel be examined. This wording has since been reconsidered by ASME [Code,] Section XI and Code Case N-700 has been published to clarify the requirements for examining welded attachments on both multiple and single vessels.

One of the bases for Code Case N-700 was previously published Code Case N-509, Alternative Rules for the Selection and Examination of Class 1, 2, and 3 Integrally Welded Attachments, which was incorporated into ASME

[Code,] Section XI in the 1995 Addenda. The technical basis of Code Case N-509 concluded that there have been very few welded attachment failures identified during normal Section XI examinations. Instead, failures have been identified when the connected support member has been found to be deformed due to operational transients or water hammer events. For this reason, Code Case N-509 and Section XI versions that include the 1995 and later Addenda require welded attachments to be examined whenever component support deformation is identified. In addition, a sampling plan for welded attachments was maintained.

Although Code Case N-509 and ASME [Code,] Section XI, beginning with the 1995 Addenda, represent an improvement to previously stated Code criteria for the examination of welded attachments, neither address the examination of welded attachments on a single vessel nor which welded attachment should be selected for examination. Code Case N-700 provides clarification for the selection of Class 1, 2, and 3 vessel welded attachments for examination, and was developed to address the selection criteria currently not included in Code Case N-509 and ASME [Code,] Section XI, 1998 Edition through 2000 Addenda.

Code Case N-700 clarifies the requirements for the examination of welded attachments on vessels by stating the following criteria:

1) For multiple vessels of similar design, function and service, only one welded attachment of only one of the multiple vessels shall be selected for examination.

2) For single vessels, only one welded attachment shall be selected for examination.

3) The attachment selected for examination on one of the multiple vessels or the single vessel, as applicable, shall be an attachment under continuous load during normal system operation, or an attachment subject to a potential intermittent load (seismic, water hammer, etc.) during normal system operation if an attachment under continuous load does not exist.

Because the selection criteria provided by Code Case N-700 is supported by the same failure data that forms the basis for Code Case N-509 and also addresses scenarios in which Section XI is silent, the alternative requirements of [Code Case] N-700 are deemed to be a more complete and detailed set of rules for the selection of welded attachments on vessels. Accordingly, pursuant to 10CFR50.55a(a)(3)(i), relief is requested on the basis that the proposed alternative provides an acceptable level of quality and safety.

3.5 NRC Staff Evaluation For ASME Code Class 1 and 2 welded attachments, the 1998 Edition through the 2000 Addenda of ASME Code,Section XI, Table IWB-2500-1, Examination Category B-K, Footnote 4, and Table IWC-2500-1, Examination Category C-C, Footnote 4, require that for multiple vessels of similar design, function, and service, only one welded attachment of only one of the multiple vessels shall be selected for examination. For ASME Code Class 3 welded attachments, Table IWD-2500-1 requires selected samples of welded attachments to be examined each inspection interval and requires that those selected for examination be those most subject to corrosion. For multiple vessels of similar design, function, and service, the welded attachments of only one of the multiple vessels shall be selected for examination.

As an alternative to the ASME Code requirements, the licensee proposed to invoke ASME Code Case N-700 for the selection of Class 1, 2, and 3 vessel welded attachments for examination. Code Case N-700 requires that for multiple vessels of similar design, function, and service, only one welded attachment of only one of the multiple vessels shall be selected for examination. In addition, Code Case N-700 requires that only one welded attachment on a single vessel is to be examined. The attachment selected for examination on one of the multiple vessels or the single vessel, as applicable, is to be an attachment under continuous load during operation if such an attachment exists.

Code Case N-700 utilizes the basis for development of Code Case N-509. ASME Code Case N-509 was incorporated in the ASME Code,Section XI, 1995 Edition, 1995 Addenda. The technical basis for development of Code Case N-509 was that operational transients and water hammer events were the main contributors to the potential for welded attachment failure and that the possibility for corrosion-related failure also existed. Industry experience found that welded attachment failures have been identified as a result of connected support member deformation and have not been identified by the present ASME Code examinations. ASME Code,Section XI, 1995 Edition, and later addenda, requires welded attachments to be examined whenever component support deformation is identified.

Code Case N-700 maintains the same sampling philosophy for welded attachments on vessels as does ASME Code Case N-509 and most of the ASME Code examination requirements. The sampling philosophy ensures the detection of service-induced degradation. For multiple

vessels the Code Case N-700 sampling plan requires only one welded attachment of only one of the multiple vessels to be selected for examination and for a single vessel only one welded attachment is to be examined. Code Case N-700 also requires that the attachment selected for examination is to be an attachment under continuous load during operation if such an attachment exists. Therefore, the NRC staff determined that Code Case N-700 provides an acceptable level of quality and safety for ASME Code,Section XI Code Class 1, 2, and 3 vessel welded attachments.

3.6 Conclusion The NRC staff concludes that the licensees proposed alternative to use Code Case N-700 for Class 1, 2, and 3 vessel welded attachments provides an acceptable level of quality and safety.

Therefore, the licensees alterative is authorized pursuant to 10 CFR 50.55a(a)(3)(i) for the WCGS third 10-year ISI interval or until ASME Code Case N-700 is approved for general use by reference in Regulatory Guide 1.147, "Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1," and incorporated by reference in 10 CFR 50.55a(b). At that time, if the licensee intends to continue implementing the code case, it must follow all provisions of Code Case N-700 with conditions as specified in Regulatory Guide 1.147 and limitations as specified in 50.55a(b)(4), (b)(5), and (b)(6), if any.

All other requirements of the ASME Code, Sections III and XI for which relief has not been specifically requested remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.

Principal Contributor: Geoffrey K. Ottenberg Date: May 10, 2006

Wolf Creek Generating Station cc:

Jay Silberg, Esq. Vice President Operations/Plant Manager Pillsbury Winthrop Shaw Pittman LLP Wolf Creek Nuclear Operating Corporation 2300 N Street, NW P.O. Box 411 Washington, D.C. 20037 Burlington, KS 66839 Regional Administrator, Region IV Supervisor Licensing U.S. Nuclear Regulatory Commission Wolf Creek Nuclear Operating Corporation 611 Ryan Plaza Drive, Suite 400 P.O. Box 411 Arlington, TX 76011 Burlington, KS 66839 Senior Resident Inspector U.S. Nuclear Regulatory Commission U.S. Nuclear Regulatory Commission Resident Inspectors Office/Callaway Plant P.O. Box 311 8201 NRC Road Burlington, KS 66839 Steedman, MO 65077-1032 Chief Engineer, Utilities Division Kansas Corporation Commission 1500 SW Arrowhead Road Topeka, KS 66604-4027 Office of the Governor State of Kansas Topeka, KS 66612 Attorney General 120 S.W. 10th Avenue, 2nd Floor Topeka, KS 66612-1597 County Clerk Coffey County Courthouse 110 South 6th Street Burlington, KS 66839 Chief, Radiation and Asbestos Control Section Kansas Department of Health and Environment Bureau of Air and Radiation 1000 SW Jackson, Suite 310 Topeka, KS 66612-1366 February 2006