ML051040556

Columbia Generating Station - American Society of Mechanical Engineers Inservice Inspection Program Second 10-Year Interval Request for Relief 2ISI-028

ML051040556
Person / Time
Site:	Columbia
Issue date:	04/14/2005
From:	Gramm R NRC/NRR/DLPM/LPD4
To:	Parrish J Energy Northwest
Fields M B ,NRR/DLPM,415-3062
References
TAC MC2743
Download: ML051040556 (7)

Text

April 14, 2005 Mr. J. V. Parrish Chief Executive Officer Energy Northwest P.O. Box 968 (Mail Drop 1023)

Richland, WA 99352-0968

SUBJECT:

COLUMBIA GENERATING STATION - AMERICAN SOCIETY OF MECHANICAL ENGINEERS INSERVICE INSPECTION PROGRAM SECOND 10-YEAR INTERVAL REQUEST FOR RELIEF 2ISI-028 (TAC NO. MC2743)

Dear Mr. Parrish:

By letter dated April 8, 2004, Energy Northwest, the licensee for the Columbia Generating Station (CGS), submitted relief request number 2ISI-028 to use American Society of Mechanical Engineers (ASME) Code Case N-663, "Alternative Requirements for Class 1 and 2 Surface Examinations," in lieu of the ASME Code Section XI requirements.

The Nuclear Regulatory Commission (NRC) staff has completed its review of relief request 2ISI-028, and our evaluation is contained in the enclosed Safety Evaluation. The NRC staff concludes that the use of ASME Code Case N-663, "Alternative Requirements for Class 1 and 2 Surface Examinations," provides an acceptable level of quality, safety, and may be used in place of the ASME Code Section XI requirements. Therefore, pursuant to 10 CFR 50.55a(a)(3)(i), the NRC staff approves of relief request 2ISI-028 at the CGS.

Sincerely,

/RA by Mel Fields for/

Robert Gramm, Chief, Section 2 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-397

Enclosure:

As stated cc w/encl: See next page

April 14, 2005 Mr. J. V. Parrish Chief Executive Officer Energy Northwest P.O. Box 968 (Mail Drop 1023)

Richland, WA 99352-0968

SUBJECT:

COLUMBIA GENERATING STATION - AMERICAN SOCIETY OF MECHANICAL ENGINEERS INSERVICE INSPECTION PROGRAM SECOND 10-YEAR INTERVAL REQUEST FOR RELIEF 2ISI-028 (TAC NO. MC2743)

Dear Mr. Parrish:

By letter dated April 8, 2004, Energy Northwest, the licensee for the Columbia Generating Station (CGS), submitted relief request number 2ISI-028 to use American Society of Mechanical Engineers (ASME) Code Case N-663, "Alternative Requirements for Class 1 and 2 Surface Examinations," in lieu of the ASME Code Section XI requirements.

The Nuclear Regulatory Commission (NRC) staff has completed its review of relief request 2ISI-028, and our evaluation is contained in the enclosed Safety Evaluation. The NRC staff concludes that the use of ASME Code Case N-663, "Alternative Requirements for Class 1 and 2 Surface Examinations," provides an acceptable level of quality, safety, and may be used in place of the ASME Code Section XI requirements. Therefore, pursuant to 10 CFR 50.55a(a)(3)(i), the NRC staff approves of relief request 2ISI-028 at the CGS.

Sincerely,

/RA by Mel Fields for/

Robert Gramm, Chief, Section 2 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-397

Enclosure:

As stated cc w/encl: See next page DISTRIBUTION:

PUBLIC RidsNrrDlpmiv2(RGramm) RidsAcrsAcnwMailCenter PDIV-2 R/F RidsNrrPMBBenney JDixon-Herrity RidsNrrDlpmiv(HBerkow) RidsNrrLALFeizollahi OgcRp RidsRgn4MailCenter TChan ADAMS ACCESSION NO. ML051040556 NRR-028 E:\Filenet\ML051040556.wpd OFFICE PM/PDIV-2 LA/PDIV-2 SC/EMCB OGC SC/PDIV-2 NAME BBenney LFeizollahi WKoo for TChan SUttal MFields for RGramm DATE 2/15/05 2/15/05 2/22/05 4/5/05 4/14/05 OFFICIAL RECORD COPY

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO RELIEF REQUEST NO. 2ISI-028 ENERGY NORTHWEST COLUMBIA GENERATING STATION DOCKET NO. 50-397

1.0 INTRODUCTION

The inservice inspection of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code) Class 1, Class 2, and Class 3 components is to be performed in accordance with Section XI of the ASME Code and applicable edition and addenda as required by 10 CFR 50.55a(g), except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i). Section 50.55a(a)(3) states, in part, that alternatives to the requirements of paragraph (g) may be used, when authorized by the Nuclear Regulatory Commission (NRC), if the licensee demonstrates that: (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 pre-service examination requirements, set forth in the ASME Code,Section XI, "Rules for Inservice Inspection (ISI) of Nuclear Power Plant Components," 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 first 10-year interval and subsequent intervals 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 second 10-year ISI interval for the Columbia Generating Station (CGS), began on February 10, 1995, and ends on December 12, 2005. The ISI Code of record for CGSs second 10-year interval is the 1989 Edition with no Addenda. The components (including supports) may meet the requirements set forth in subsequent editions and addenda of the ASME Code incorporated by reference in 10 CFR 50.55a(b) subject to the limitations and modifications listed therein and subject to Commission approval.

By letter dated April 8, 2004, Energy Northwest, the licensee for the CGS, submitted relief request number 2ISI-028 to use ASME Code Case N-663, "Alternative Requirements for Class 1 and 2 Surface Examinations," in lieu of the ASME Code,Section XI requirements.

2.0 REGULATORY EVALUATION

2.1 Code Requirements IWB-2500 and IWC-2500 of the 1989 Edition of ASME code,Section XI, require components to be examined as specified in Tables IWB-2500-1 and IWC-2500-1, respectively. These tables require inspection of a sampling of piping welds using volumetric, surface, or both examinations and inspections during pressure testing using visual examinations such as VT-2.

2.2 Licensees Code Relief Request and its Proposed Alternative In lieu of the surface examination requirements for piping welds of Class 1 Examination Category B-F Item numbers B5.10 and B5.130 and Class 2 Examination Category C-F-2 Item Numbers C5.50 through C5.82, the licensee proposes to use Code Case N-663, "Alternative Requirements for Class 1 and 2 Surface Examinations,Section XI, Division 1," in its entirety.

2.3 Components for which Relief Is Requested This relief request applies to CGS, ASME Code,Section XI, Class 1 and 2 piping welds of Examination Categories B-F Item numbers B5.10 and B5.130 and C-F-2 Item Numbers C5.50 through C5.82.

2.4 Licensees Basis for Proposed Alternative Two risk-informed methodologies have been developed for the examination of piping welds and approved by the NRC:

• Electric Power Research Institute (EPRI) TR-112657, Revision B-A, "Revised Risk-Informed Inservice Inspection Evaluation Procedure" (NRC safety evaluation (SE), dated 10/28/99).

• WCAP-14572, Revision 1-NP-A, "Westinghouse Owners Group Application of Risk-Informed Methods to Piping Inservice Inspection Topical Report" (NRC SE, dated 12/15/98).

Although the two methodologies use different approaches, they reach a similar conclusion that the only degradation mechanism that requires a surface examination is outside diameter (OD) chloride stress corrosion cracking, and consequently, surface examinations only need to be considered when OD chloride stress corrosion cracking is identified to be the degradation mechanism affecting the structural integrity of applicable welds.

The ASME Code, Section Xl Task Group on ISI Optimization, Report No. 92-01-01, "Evaluation of Inservice Inspection Requirements for Class 1, Category B-J Pressure Retaining Welds in Piping," dated July 1995, concluded, with 50 units responding and a total of 9333 welds inspected, that only two welds (0.02%) were found to have flaws detected by Section Xl surface examinations. These flaws were determined to be fabrication-induced.

Subsequently, Code Case N-663 was developed, which was approved by the ASME Boiler and Pressure Vessel Code Committee on September 17, 2002, but is not yet included in the most

recent listing of NRC approved code cases provided in Revision 13 of Regulatory Guide (RG) 1.147, "Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1."

Code Case N-663 provides that, " . . . in lieu of the surface examination requirements for piping welds of Examination Category B-F (NPS 4 and larger), B-J (NPS 4 and larger), C-F-1 and C-F-2, surface examinations may be limited to areas identified by the Owner as susceptible to outside surface attack." The susceptibility criteria are listed in Table 1 of Code Case N-663 for two types of degradation mechanisms: (1) external (OD) chloride stress corrosion cracking and (2) other outside surface initiated mechanisms. These alternate requirements are acceptable because the inspection requirements defined in the Code Case are equivalent to the corresponding inspection requirements approved by the NRC and adopted by using risk-informed ISI programs. Further, the Code Case requires that licensees conduct a plant-specific service history review to identify other mechanisms susceptible to outside surface attack, and to include plant-specific processes and programs that minimize chlorides and other contaminants. Hence, the alternative provides reasonable assurance that the proposed inspections will not lead to degraded piping performance when compared to the existing performance levels.

3.0 TECHNICAL EVALUATION

The proposed use of Code Case N-663 by the licensee to replace the ASME Code,Section XI required surface examinations for Class 1 and 2 piping welds of Examination Categories B-F Item Numbers B5.10 and B5.130 and C-F-2 Item Numbers C5.50 through C5.82 is consistent with the NRC-approved underlying EPRI and Westinghouse methodologies on risk-informed ISI contained in TR-112657, Revision B-A, and WCAP-14572, Revision 1-NP-A. Although the two topical reports use different approaches, both have reached their objectives of identifying the risk-important areas of the piping systems and defining the appropriate examination methods, examination volumes, procedures, and evaluation standards necessary to address the degradation mechanisms of concern and the ones most likely to occur at each location to be inspected. Risk-informed ISI analyzes specific pipe segments for probability of failure and operational safety significance.

In regard to the current issue of surface examinations for Class 1 and 2 piping welds of Examination Categories B-F Item Numbers B5.10 and B5.130 and C-F-2 Item Numbers C5.50 through C5.82, all plants that performed risk-informed ISI of their Class 1 and 2 piping systems in accordance with the topical reports referenced above arrived at the conclusion that the only degradation mechanism that requires surface examination is OD chloride stress corrosion cracking. Consequently, within these plants, surface examination should be considered when OD chloride stress corrosion cracking is identified as the degradation mechanism affecting the structural integrity of the subject piping welds.

The staff determined that the surface inspection requirements of Code Case N-663 are acceptable because the inspection requirements defined in the Code Case are comparable to the corresponding inspection requirements approved by the NRC and adopted by using risk-informed ISI programs. Further, the Code Case requires that licensees conduct a plant-specific service history review to identify other mechanisms which can result in outside surface attack, and to implement plant-specific processes and programs that minimize chlorides and

other contaminants. Hence, the alternative provides reasonable assurance that the proposed inspections will not lead to degraded piping performance when compared to the existing performance levels.

4.0 CONCLUSION

The staff has reviewed the licensees proposal, relief request 2ISI-028, to use of Code Case N-663 for Class 1 and 2 surface examinations, in lieu of the Table IWB-2500-1, examination requirements for the components listed above. Based on the NRC staff's review of the licensees proposed justification, the NRC staff finds relief request 2ISI-028 will provide an acceptable level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(a)(3)(i), the licensees proposed use of Code Case N-663 as stated in relief request 2ISI-028 is authorized for the CGS, for the second 10-year ISI interval, or until Code Case N-663 is published in a future version of RG 1.147. At that time, if the licensee intends to continue implementing this Code Case, the licensee must follow all provisions of Code Case N-663 with limitations or conditions specified in RG 1.147, if any.

All other ASME Code,Section XI requirements for which relief was not specifically requested and approved in this relief request remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.

Principal Contributor: J. Collins Date: April 14, 2005

Columbia Generating Station cc:

Mr. W. Scott Oxenford (Mail Drop PE04) Mr. Dale K. Atkinson (Mail Drop PE08)

Vice President, Technical Services Vice President, Nuclear Generation Energy Northwest Energy Northwest P. O. Box 968 P.O. Box 968 Richland, WA 99352-0968 Richland, WA 99352-0968 Mr. Albert E. Mouncer (Mail Drop PE01) Mr. William A. Horin, Esq.

Vice President, Corporate Services/ Winston & Strawn General Counsel/CFO 1400 L Street, N.W.

Energy Northwest Washington, DC 20005-3502 P.O. Box 968 Richland, WA 99352-0968 Mr. Matt Steuerwalt Executive Policy Division Chairman Office of the Governor Energy Facility Site Evaluation Council P.O. Box 43113 P.O. Box 43172 Olympia, WA 98504-3113 Olympia, WA 98504-3172 Ms. Lynn Albin Mr. Douglas W. Coleman (Mail Drop PE20) Washington State Department of Health Manager, Regulatory Programs P.O. Box 7827 Energy Northwest Olympia, WA 98504-7827 P.O. Box 968 Richland, WA 99352-0968 Technical Services Branch Chief FEMA Region X Mr. Gregory V. Cullen (Mail Drop PE20) 130 228th Street S.W.

Supervisor, Licensing Bothell, WA 98201-9796 Energy Northwest P.O. Box 968 Richland, WA 99352-0968 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-4005 Chairman Benton County Board of Commissioners P.O. Box 190 Prosser, WA 99350-0190 Senior Resident Inspector U.S. Nuclear Regulatory Commission P.O. Box 69 Richland, WA 99352-0069 March 2005