ML063540620

Browns Ferry, Unit 1, Relief Request, from ASME ISI Requirements RPV Welds - 1-ISI-21 (TAC No. MD2681)

ML063540620
Person / Time
Site:	Browns Ferry
Issue date:	02/07/2007
From:	Raghavan L NRC/NRR/ADRO/DORL/LPLII-2
To:	Singer K W Tennessee Valley Authority
REGNER, Lisa, DORL/LPL2-2, 415-1906
References
TAC MD2681
Download: ML063540620 (7)

Text

February 7, 2007Mr. Karl W. SingerChief Nuclear Officer and Executive Vice President Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801

SUBJECT:

BROWNS FERRY NUCLEAR PLANT, UNIT 1 - RE: REQUEST FOR RELIEFFROM THE REQUIREMENTS OF THE ASME CODE (TAC NO. MD2681)

Dear Mr. Singer:

By letter dated July 12, 2006, the Tennessee Valley Authority (TVA) submitted a request forrelief from the requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI at Browns Ferry Nuclear Plant, Unit 1.

Specifically, TVA requested relief from ASME Code inservice inspections (ISI) requirements forthree reactor pressure vessel longitudinal shell welds as the examination requirement of essentially 100 percent coverage is impractical due to permanently installed piping that restricts access to the examination areas.The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed and evaluated theinformation provided in support of TVA's Relief Request 1-ISI-21, related to the first 10-year interval ISI requirements. Based on the conclusions contained in the enclosed safety evaluation, the NRC staff agrees that the ASME Code requirements are impractical and grants relief pursuant to Title 10, Code of Federal Regulations (10 CFR), Section 50.55a(g)(6)(i) on thebasis that the inservice examination of the reactor pressure vessel welds to the maximum extent possible provides a reasonable assurance of structural integrity.The NRC staff has determined that granting relief pursuant to 10 CFR 50.55a(g)(6)(i) isauthorized 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. Therefore, relief is granted for the above requested first 10-year interval inspection pursuant to 10 CFR 50.55a(g)(6)(i).Sincerely,/RA Patrick D. Milano for/L. Raghavan, ChiefPlant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor RegulationDocket No. 50-259

Enclosure:

Safety Evaluation cc w/encl: See next page

ML063540620 NRR-028OFFICELPL2-2/PMLPL2-2/PMLPL2-2/LAOGCCVIB/BCLPL2-2/BCNAMELRegnerMChernoffBClaytonMBarkman NLOMMitchell by Memo datedPMilano forLRaghavanDATE02/07/07 02/07/07 02/07/06 02/05/0709/26/0602/07/07 EnclosureSAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATIONAMERICAN SOCIETY OF MECHANICAL ENGINEERS SECTION XIFIRST 10-YEAR INSERVICE INSPECTION OF REACTOR VESSEL WELDSREQUEST FOR RELIEF 1-ISI-21TENNESSEE VALLEY AUTHORITYBROWNS FERRY NUCLEAR PLANT UNIT 1DOCKET NO. 50-25

91.0INTRODUCTION

In accordance with Section 50.55a(g)(6)(ii)(A)(2) of Part 50 to Title 10 of the Code of FederalRegulations (CFR), the Tennessee Valley Authority (TVA, the licensee) has requested to satisfythe American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (ASME Code) inservice inspection (ISI) requirements with the examinations performed during the augmented reactor pressure vessel (RPV) circumferential and longitudinal shell weld examinations. Therefore, by letter dated July 12, 2006, the licensee submitted relief request (RR) 1-ISI-21 from certain ISI requirements in the ASME Code,Section XI, Rules forInservice Inspection of Nuclear Power Plant Components, for RPV longitudinal shell weldsV-3-A, V-3-B, and V-3-C for Unit 1. 2.0REGULATORY REQUIREMENTSThe ISI requirements of ASME Code Class 1, 2, and 3 components are performed inaccordance with Section XI of the ASME Code and applicable addenda as required by 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). In accordance with 10 CFR 50.55a(g)(4), ASME Code Class 1, 2, and 3 components shall meetthe requirements, except the design and access provisions and the pre-service examination requirements, set forth in the ASME Code to the extent practical within the limitations of design, geometry, and materials of construction of the components. The regulations require that the ISI of components and system pressure tests conducted duringthe 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 ASME Code of record for the Unit 1 first interval 10-year ISI program is the 1995 Edition through the 1996 Addenda of Section XI of theASME Code.

3.0TECHNICAL EVALUATION

3.1BackgroundBy letter dated March 15, 2006, TVA submitted RR 1-ISI-20 in accordance with 10 CFR50.55a(g)(6)(ii)(A) for augmented volumetric examinations of the Unit 1 RPV shell welds when essentially 100 percent of the weld examinations was not obtained. This RR contained an alternative to the examinations for welds V-3-A, V-3-B, and V-3-C. The licensee's alternative was authorized pursuant to 10 CFR 50.55a(a)(3)(i) and 10 CFR 50.55a(g)(6)(ii)(A)(5) by the NRC staff in a safety evaluation dated August 23, 2006 (Agencywide Documents Access and Management System Accession No. ML060960040) as it provided an acceptable level of quality and safety.3.2Components for Which Relief is RequestedThe affected component is the Unit 1 RPV; specifically, the welds identified in the table below. The examination category and item number are from the ASME Code,Section XI, Table IWB-500-1.Examination CategoryItem NumberDescriptionWeld Nos.B-AB1.12RPV Longitudinal ShellWeldsV-3-A, V-3-B, V-3-C3.3ASME Code RequirementsASME Code,Section XI, Table IWB-2500-1, Examination Category B-A, Item Number B1.12,requires volumetric examination of essentially 100 percent of the weld length of all longitudinal shell welds in accordance with the examination requirements illustrated in Figure IWB-2500-2. ASME Code Case N-460, Alternative Examination Coverage for Class 1 and Class 2 Welds

,approved for use by the NRC staff in Regulatory Guide (RG) 1.147, Revision 14, InserviceInspection Code Case Acceptability (RG 1.147), states that a reduction in examinationcoverage due to part geometry or interference for any Class 1 and 2 weld is acceptable provided that the reduction is less than 10 percent (i.e., greater than 90-percent examination coverage is obtained).3.4Basis for ReliefIn accordance with 10 CFR 50.55a(g)(5)(iii), the licensee has requested relief from certain ISIweld examination requirements specified in Section XI of the ASME Code for the Unit 1 RPV under RR 1-ISI-21.TVA has determined that 3 of the 15 longitudinal shell welds in the RPV have nondestructiveexamination coverage limitations (less than 90 percent coverage completed), which exceeds that specified in Table IWB-2500-1 of Section XI of the ASME Code. The licensee states thatcompliance with the extent of the examination which requires "essentially 100 percent" of the weld length is impractical and will result in unusual difficulty and unnecessary radiation exposure to various plant personnel without any compensating increase in the level of quality or safety. TVA states that areas of the V-3-A, V-3-B, and V-3-C welds were inaccessible for ultrasonicexamination due to the design configuration of the RPV and vessel internals. The examinations were performed with automated ultrasonic equipment from the vessel inside surface; however, portions of the shell weld scans were obstructed by core spray piping and feedwater spargers.

TVA also stated that conducting ultrasonic examination of these subject welds from the outside surfaces is not practical because of inaccessibility due to RPV outside insulation design and the proximity to the biological shield wall. In lieu of the ASME Code-required essentially 100-percent volume coverage using ultrasonicexamination, TVA performed an ultrasonic examination of accessible areas to the maximumextent practical given the component design and configuration of the subject RPV welds for Unit 1.Volumetric Coverage ObtainedWeld No.Percent CoverageExaminationLimitationV-3-A77.7Core Spray Piping andFeedwater SpargersV-3-B77.4Core Spray Piping andFeedwater SpargersV-3-C77.6Core Spray Piping andFeedwater Spargers4.0STAFF EVALUATIONThe ASME Code requires volumetric examination of essentially 100 percent of the weld lengthof all RPV longitudinal shell welds in accordance with the examination requirements illustrated in Figure IWB-2500-2. The licensee proposed that the ultrasonic examinations performed during the augmented RPV shell weld examination of accessible areas to the maximum extent practical be accepted in lieu of the ASME Code requirements for RPV longitudinal shell welds V-3-A, V-3-B, and V-3-C. For RPV longitudinal shell welds V-3-A, V-3-B, and V-3-C, the staff determined that, based ondrawings provided and the licensee's basis for relief, complete ASME Code examination is impractical due to core spray piping and the feedwater spargers that restrict access to the examination areas. To perform the required ASME Code examination, the RPV and associated components would require design modifications. The licensee considered examining the subject welds from the outside of the RPV; however, it was not possible due to the insulation design and biological shield wall. Therefore, the staff determined that the ASME Code-requiredinspections are impractical and imposition of this requirement would cause a burden on the licensee without a compensating increase in the level of quality and safety.For welds V-3-A, V-3-B, and V-3-C the licensee obtained 77.7 percent, 77.4 percent, and77.6 percent volumetric coverage, respectively. The licensee obtained essentially 100 percent volumetric coverage on the twelve other RPV longitudinal shell welds. The coverage obtained for welds V-3-A, V-3-B, and V-3-C by the licensee represents a significant portion of the ASME Code-required weld length. The staff determined that these examinations and the examinations on the other 12 RPV longitudinal shell welds would have detected significant patterns of degradation, if any had occurred. The staff also determined that the examinations performed on welds V-3-A, V-3-B, and V-3-C and the 12 other RPV longitudinal shell welds provide a reasonable assurance of the structural integrity of the subject welds.

5.0CONCLUSION

For RR 1-ISI-21, the NRC staff concludes that the ASME Code-required examinations of RPVlongitudinal shell welds V-3-A, V-3-B, and V-3-C are impractical to perform due to physical obstructions and that imposition of this requirement would cause a burden on the licensee. The volumetric examinations performed to the extent practical on welds V-3-A, V-3-B, and V-3-C and the twelve other RPV longitudinal shell welds provide a reasonable assurance of the structural integrity of the subject RPV welds. Therefore, pursuant to 10 CFR 50.55a(g)(6)(i),

relief is granted from the ASME Code ISI requirements of essentially 100 percent coverage for RPV longitudinal shell welds V-3-A, V-3-B, and V-3-C, for the first 10-year ISI program at Unit 1.The staff has determined that granting relief pursuant to 10 CFR 50.55a(g)(6)(i) is authorizedby 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. All other requirements of the ASME Code,Section XI for which relief has not been specifically requested remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.Principal contributors: Atif A. Shaikh Mr. Karl W. SingerBROWNS FERRY NUCLEAR PLANTTennessee Valley Authority cc:

Mr. Ashok S. Bhatnagar, Senior Vice President Nuclear Operations Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Mr. Larry S. Bryant, Vice PresidentNuclear Engineering & Technical Services Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801Brian O'Grady, Site Vice PresidentBrowns Ferry Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Decatur, AL 35609Mr. Preston D. Swafford, Senior Vice PresidentNuclear Support Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 General CounselTennessee Valley Authority ET 11A 400 West Summit Hill Drive Knoxville, TN 37902Mr. John C. Fornicola, General ManagerNuclear Assurance Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801Mr. Bruce Aukland, Plant ManagerBrowns Ferry Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Decatur, AL 35609Mr. Masoud Bajestani, Vice PresidentBrowns Ferry Unit 1 Restart Browns Ferry Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Decatur, AL 35609Mr. Robert G. Jones, General ManagerBrowns Ferry Site Operations Browns Ferry Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Decatur, AL 35609Mr. Larry S. MellenBrowns Ferry Unit 1 Project Engineer Division of Reactor Projects, Branch 6 U.S. Nuclear Regulatory Commission 61 Forsyth Street, SW.

Suite 23T85 Atlanta, GA 30303-8931 Ms. Beth A. Wetzel, ManagerCorporate Nuclear Licensing and Industry Affairs Tennessee Valley Authority 4X Blue Ridge 1101 Market Street Chattanooga, TN 37402-2801Mr. William D. Crouch, ManagerLicensing and Industry Affairs Browns Ferry Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Decatur, AL 35609Senior Resident InspectorU.S. Nuclear Regulatory Commission Browns Ferry Nuclear Plant 10833 Shaw Road Athens, AL 35611-6970State Health OfficerAlabama Dept. of Public Health RSA Tower - Administration Suite 1552 P.O. Box 303017 Montgomery, AL 36130-3017ChairmanLimestone County Commission 310 West Washington Street Athens, AL 35611Mr. Robert H. Bryan, Jr., General ManagerLicensing and Industry Affairs Tennessee Valley Authority 4X Blue Ridge 1101 Market Street Chattanooga, TN 37402-2801