ML020110120

STP 1 & 2, Approval of Request for Relief from ASME Boiler & Pressure Vessel Code Section XI Requirements for Weld Examinations, Relief Request RR-ENG-38

ML020110120
Person / Time
Site:	South Texas
Issue date:	01/24/2002
From:	Gramm R NRC/NRR/DLPM/LPD4
To:	Cottle W South Texas
References
RR-ENG-38, TAC MB3115, TAC MB3116
Download: ML020110120 (9)

Text

January 24, 2002 Mr. William T. Cottle President and Chief Executive Officer STP Nuclear Operating Company South Texas Project Electric Generating Station P. O. Box 289 Wadsworth, TX 77483

SUBJECT:

SOUTH TEXAS PROJECT, UNITS 1 AND 2 - APPROVAL OF REQUEST FOR RELIEF FROM ASME BOILER AND PRESSURE VESSEL CODE SECTION XI REQUIREMENTS FOR WELD EXAMINATIONS, RELIEF REQUEST RR-ENG-38 (TAC NOS. MB3115 AND MB3116)

Dear Mr. Cottle:

By letter dated September 18, 2001, pursuant to Title 10 of the Code of Federal Regulations (10 CFR), Section 50.55a(g)(5)(iv), STP Nuclear Operating Company (STPNOC) requested relief from achieving complete coverage of examinations required by the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI in the inservice inspection (ISI) program for Class 1 and Class 2 components. The request was for the first 10-year ISI interval at South Texas Project, Units 1 and 2.

Specifically, STPNOC requested relief from obtaining results from 100 percent of the examination volume or area of the Class 1 and 2 component welds, excluding reactor pressure vessel welds inspected by automated examination, as provided in ASME Section XI, Tables IWB-2500-1 and IWC-2500-1, for ISI by nondestructive examination of component welds during the first inspection interval.

The U. S. Nuclear Regulatory Commission staff has reviewed the STPNOC relief request for not complying with the Code requirements to perform a 100 percent volumetric and/or surface examination on the subject components and finds that the examinations performed by STPNOC provide reasonable assurance of structural integrity of the subject components, as discussed in the enclosed Safety Evaluation.

W. Cottle Therefore, STPNOC is granted relief from obtaining results from 100 percent of the examination volume or area of the Class 1 and 2 component welds pursuant to 10 CFR 50.55a(g)(6)(i), for the first 10-year ISI interval at South Texas Project, Units 1 and 2.

Sincerely,

/RA/

Robert A. Gramm, Chief, Section 1 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos.: 50-498 and 50-499

Enclosure:

Safety Evaluation cc w/encl: See next page

W. Cottle Therefore, STPNOC is granted relief from obtaining results from 100 percent of the examination volume or area of the Class 1 and 2 component welds pursuant to 10 CFR 50.55a(g)(6)(i), for the first 10-year ISI interval at South Texas Project, Units 1 and 2.

Sincerely,

/RA/

Robert A. Gramm, Chief, Section 1 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos.: 50-498 and 50-499

Enclosure:

Safety Evaluation cc w/encl: See next page DISTRIBUTION:

PUBLIC RidsNrrLAMMcAllister RidsNrrPMTAlexion PDIV-1 r/f RidsNrrDlpmLpdiv-1 (R. Gramm) SMorris, EDO G. Hill (4) RidsAcrsAcnwMailCenter TMcLellan RidsNrrDlpmLpdiv (S.Richards) RidsOgcRp RidsNrrPMMThadani RidsRgn4MailCenter (DGraves, LHurley, DBujol)

RidsNrrPMGShukla ACCESSION NO: ML020110120 *See previous concurrence OFFICE PDIV-2/PM PDIV-1/PM PDIV-1/LA EMCB* OGC PDIV-1/SC NAME GShukla MThadani MMcAllister TChan RHoefling RGramm DATE 01/11/02 01/22/02 01/11/02 12/20/01 01/17/02 01/23/02 OFFICIAL RECORD COPY

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REQUESTS FOR RELIEF FROM ASME SECTION XI REQUIREMENTS RELIEF REQUEST RR-ENG-38 STP NUCLEAR OPERATING COMPANY SOUTH TEXAS PROJECT, UNITS 1 AND 2 DOCKET NOs. 50-498 AND 50-499

1.0 INTRODUCTION

By letter dated September 18, 2001, and pursuant to Title 10 of the Code of Federal Regulations (10 CFR), Section 50.55a(g)(5)(iv), STP Nuclear Operating Company (STPNOC or the licensee) submitted the bases for not achieving complete coverage of examinations required by the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI Code in the inservice inspection (ISI) program for Class 1 and Class 2 components. These examination requirements are provided in ASME Section XI, Tables IWB-2500-1 and IWC-2500-1, for ISI by nondestructive examination of component welds during the first inspection interval. The request was for the first 10-year ISI interval at South Texas Project, Units 1 and 2.

Specifically, STPNOC requested relief from obtaining results from 100 percent of the examination volume or area of the Class 1 and 2 component welds, excluding reactor pressure vessel welds inspected by automated examination. STPNOC stated that 100 percent examination coverage of these welds is impractical because of component configuration and geometry, and because of the limitations of the examination equipment and techniques used to perform these examinations.

2.0 BACKGROUND

ISI of the ASME Code Class 1, 2, and 3 components is to be performed in accordance with Section XI of the ASME Boiler and Pressure Vessel (B&PV) Code and applicable addenda as required by 10 CFR 50.55a(g), except where specific relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i). The requirement at 10 CFR 50.55a(a)(3) states that alternatives to the requirements of paragraph (g) may be used, when authorized by the 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 preservice 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) 12 months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein. The Code of record for the South Texas Project Electric Generating Station, Units 1 and 2 first 10-year ISI interval is the 1983 Edition through the Summer 1983 Addenda of the ASME B&PV Code.

3.0 EVALUATION The NRC staff has reviewed the information concerning South Texas Project Electric Generating Station, Units 1 and 2 first 10-year ISI program Request for Relief No. RR-ENG-38, as provided by the licensee in a letter dated September 18, 2001, and the clarifying information in its e-mail dated November 8, 2001, regarding Break Exclusion Zone (BEZ) Welds. The information provided by the licensee in support of the request for relief from Code requirements has been evaluated by the NRC staff as discussed below.

3.1 Licensee Request for Relief RR-ENG-38

• Code Requirements: (As stated)

ASME Section XI Code Table IWB-2500-1 and Table IWC-2500-1 specifies the examination method and extent of coverage for nondestructive examination of welds. Relief is requested from the full volumetric or surface examination coverage requirements of the Section XI Code when the obtained coverage is 90% or less. The welds for which relief is requested are listed in the attached tables1.

Welds having a reduction in volumetric or surface examination coverage of less than 10% are considered to have essentially 100% coverage in accordance with Section XI Code Case N-460.

• System/Components(s) for Which Relief is Requested:

Class 1 and 2 Piping Welds, Components, Valves, Pumps, and Integral Attachments.

The licensee listed the subject components in Weld Examination Tables for Units 1 and 2 as part of its submittal dated September 18, 2001. The subject tables are not included in this safety evaluation.

The licensee also included 22 welds on which they performed augmented examinations and classified as BEZ welds.

1 The Weld Examination Tables are part of the licensees submittal dated September 18, 2001, and are not included in this safety evaluation.

• Licensees Code Relief Request (as stated):

The South Texas Project requests relief from full examination coverage requirements for the welds listed in the attached tables based on the impracticality of achieving required coverage.

Obtaining required examination coverage of welds may not be practical due to various factors, including:

• component configuration,

• geometry, and

• examination equipment and techniques utilized for the examinations.

• Licensees Basis for Requesting Relief (as stated):

100% examination coverage of these welds is impractical because of component configuration and geometry, and because of the limitations of the examination equipment and techniques used to perform these examinations. However, volumetric and surface examinations of accessible locations will continue as required.

Pursuant to 10 CFR 50.55a(g)(5)(iv), the South Texas Project submitted the bases for not achieving complete coverage of examinations required by the ASME Section XI Code in the inservice inspection program. Examination requirements for Class 1 and Class 2 components are provided in ASME Section XI, Tables IWB-2500-1 and IWC-2500-1, for inservice inspection by nondestructive examination of component welds during the first inspection interval. The South Texas Project requests relief from obtaining results from essentially 100% of the examination volume or area of component welds during the first inspection interval, excluding reactor pressure vessel welds inspected by automated examination. 100% examination coverage of these welds is impractical because of component configuration and geometry, and because of the limitations of the examination equipment and techniques used to perform these examinations.

Limitations on examination coverage by automated examination of reactor pressure vessel welds were approved by the NRC in the referenced letter2.

• Licensees Proposed Alternative Examination (as stated):

No alternate examinations are proposed for the welds for which relief is requested.

3.2 Staff Evaluation:

ASME Code,Section XI, Table IWB-2500-1 and Table IWC-2500-1 specifies the examination method and extent of coverage for nondestructive examination of welds. The licensee requested relief from 100 percent volumetric and/or surface examination coverage requirements of the Code.

2 The licensees submittal dated September 18, 2001, references NRC letter dated June 20, 2001 to William T. Cottle. This letter is not included in this safety evaluation.

As a part of the Code relief, the licensee included 22 BEZ welds, as defined by NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants (SRP) Section 3.6.2, Determination of Rupture Locations and Dynamic Effects Associated with the Postulated Rupture of Piping, which are subjected to augmented examination requirements. The licensee noted that these are circumferential and longitudinal pipe welds within the BEZ of high energy fluid system piping at containment penetrations. These welds will either be 100 percent volumetrically examined during each inspection interval of the ISI program in accordance with ASME Code,Section XI and SRP Section 6.6, Inservice Inspection of Class 2 and 3 Piping, or exceptions due to access limitations will be documented in the ISI program.

The NRC staff determined that, because of the physical limitations due to geometric configuration of the subject welded areas, the Code requirements are impractical. In order for the licensee to perform 100 percent volumetric examination and/or 100 percent surface examination, the subject welds would have to be redesigned. The resulting increase in plant safety would not be commensurate with the burden that would result from imposition of the Code requirements.

The licensee has obtained 28 percent to 89 percent volumetric coverage, and 28 percent to 100 percent surface examination coverage. The volumetric and surface examinations obtained should detect any significant patterns of degradation. Therefore, the licensees proposed volumetric and/or surface examination coverages of the subject components provides reasonable assurance of structural integrity of the subject components.

4.0 CONCLUSION

The NRC staff concludes that compliance with the Code requirements to perform a 100 percent volumetric and/or surface examination on the subject components is impractical and that the examinations performed by the licensee provide reasonable assurance of structural integrity of the subject components. The NRC staff further concludes that in order for the licensee to perform 100 percent volumetric examination and/or 100 percent surface examination, the subject welds would have to be redesigned. The resulting increase in plant safety would not be commensurate with the burden that would result from imposition of the Code requirements.

Therefore, the licensees relief is granted pursuant to 10 CFR 50.55a(g)(6)(i) for the Class 1 and 2, and BEZ welds for the 10-year ISI interval at South Texas Project, Units 1 and 2.

The NRC staff has determined that this grant of relief is authorized by law and will not endanger life or property, or the common defense and security and is otherwise in the public interest giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility.

Principal Contributor: T. K. McLellan Date: January 24, 2002

South Texas, Units 1 & 2 cc:

Mr. Cornelius F. OKeefe A. H. Gutterman, Esq.

Senior Resident Inspector Morgan, Lewis & Bockius U.S. Nuclear Regulatory Commission 1800 M Street, N.W.

P. O. Box 910 Washington, DC 20036-5869 Bay City, TX 77414 Mr. J. J. Sheppard, Vice President A. Ramirez/C. M. Canady Engineering & Technical Services City of Austin STP Nuclear Operating Company Electric Utility Department P. O. Box 289 721 Barton Springs Road Wadsworth, TX 77483 Austin, TX 78704 S. M. Head, Manager, Licensing Mr. M. T. Hardt Nuclear Quality & Licensing Department Mr. W. C. Gunst STP Nuclear Operating Company City Public Service Board P. O. Box 289, Mail Code: N5014 P. O. Box 1771 Wadsworth, TX 77483 San Antonio, TX 78296 Office of the Governor Mr. C. A. Johnson/R. P. Powers ATTN: John Howard, Director AEP - Central Power and Light Company Environmental and Natural P. O. Box 289 Resources Policy Mail Code: N5022 P. O. Box 12428 Wadsworth, TX 77483 Austin, TX 78711 INPO Jon C. Wood Records Center Matthews & Branscomb 700 Galleria Parkway 112 East Pecan, Suite 1100 Atlanta, GA 30339-3064 San Antonio, TX 78205 Regional Administrator, Region IV Arthur C. Tate, Director U.S. Nuclear Regulatory Commission Division of Compliance & Inspection 611 Ryan Plaza Drive, Suite 400 Bureau of Radiation Control Arlington, TX 76011 Texas Department of Health 1100 West 49th Street D. G. Tees/R. L. Balcom Austin, TX 78756 Houston Lighting & Power Co.

P. O. Box 1700 Jim Calloway Houston, TX 77251 Public Utility Commission of Texas Electric Industry Analysis Judge, Matagorda County P. O. Box 13326 Matagorda County Courthouse Austin, TX 78711-3326 1700 Seventh Street Bay City, TX 77414 June 2001