ML100491269
| ML100491269 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 04/07/2010 |
| From: | Doug Broaddus Plant Licensing Branch II |
| To: | Annacone M Carolina Power & Light Co |
| Saba F, NRR/DORL/LPL2-2, 301-415-1447 | |
| References | |
| RR-46, TAC ME1249, TAC ME1250 | |
| Download: ML100491269 (9) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 Apr i 1 7, 201 0 Mr. Michael J. Annacone, Vice President Brunswick Steam Electric Plant Carolina Power & Light Company Post Office Box 10429 Southport, North Carolina 28461
SUBJECT:
BRUNSWICK STEAM ELECTRIC PLANT, UNITS 1 AND 2 - RELIEF REQUEST NUMBER RR-46 FOR THE THIRD 1a-YEAR INSERVICE INSPECTION INTERVAL (TAC NOS. ME1249 AND ME1250)
Dear Mr. Annacone:
By letter dated May 8, 2009, as supplemented by letter dated December 2, 2009, Carolina Power & Light Company (the licensee) submitted Relief Request (RR) RR-46 regarding a proposed alternative for examination coverage of certain reactor pressure vessel pressure retaining welds in the peripheral control rod drive (CRD) housings during the third 1a-year inservice inspection (lSI) interval at Brunswick Steam Electric Plant (BSEP) Units 1 and 2, in lieu of the requirements specified in the American Society for Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI. The third 10-year lSI interval began on May 11, 1998, for BSEP Units 1 and 2, and concluded by May 10, 2008, for Unit 1 and by May 10, 2009, for Unit 2, due to a 1-year extension.
The licensee has shown that it is impractical to examine 100 percent of the ASME Code-required surface examinations on 10 percent of peripheral CRD housing welds. Based on the coverage obtained, the licensee's alternative to examine additional CRD housing tube-to-tube welds, and the visual examinations performed on these components during system pressure tests for each refueling outage, the Nuclear Regulatory Commission (NRC) staff has concluded that if significant service-induced degradation occurred, there is reasonable assurance that evidence of it would be detected. The NRC staff has determined that granting relief pursuant to Title 10 of the Code of Federal Regulations (1 OCFR) 50.55a(g)(6)(i) is authorized by law and will not endanger life or property of 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, the NRC grants relief for the subject examinations of the components contained in RR-46 at BSEP, Units 1 and 2 for the third 1a-year lSI interval.
1\\11. Annacone
- 2 The bases for the NRC staff's conclusion are contained in the enclosed safety evaluation. If you have any questions regarding this issue, please contact Farideh Saba at (301) 415-1447 or farideh.saba@nrc.gov.
Sincerely, IRA EBrown forI Douglas A. Broaddus, Acting Chief Plant Licensing Branch 11-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-325 and 50-324
Enclosure:
Safety Evaluation cc w/encl: Distribution via ListServ
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION THIRD 10-YEAR INSERVICE INSPECTION INTERVAL RELIEF REQUEST RR-46 BRUNSWICK STEAM ELECTRIC PLANT, UNITS 1 AND 2 DOCKET NUMBERS 50-325 AND 50-324
1.0 INTRODUCTION
By letter dated May 8, 2009 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML091340100), as supplemented by letter dated December 2,2009 (ADAMS Accession No. ML093440850), Carolina Power & Light Company (the licensee requested Nuclear Regulatory Commission (Commission, NRC) approval of the relief request RR-46 for the third 1O-year interval inservice inspection (lSI) program at the Brunswick Steam Electric Plant (BSEP), Units 1 and 2. The third 10-year lSI interval began on May 11, 1998, for BSEP Units 1 and 2, and concluded by May 10, 2008, for Unit 1 and by May 10, 2009, for Unit 2, due to a 1-year extension.
Relief request RR-46 addresses the examination coverage for certain reactor pressure vessel pressure retaining welds in the peripheral control rod drive (CRD) housings, as required by the American Society of Mechanical Engineers (ASME) Code. In accordance with Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(g)(5)(iii), the licensee proposed to use alternative to the requirements of the ASME Code,Section XI for the BSEP, Units 1 and 2, on the basis that compliance with the ASME Code requirements is impractical due to plant design.
2.0 REGULATORY EVALUATION
The inservice inspection of ASME Code Class 1, Class 2, and Class 3 components is to be performed in accordance with the applicable edition and addenda of ASME Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components," as required by Title 10 of the Code of Federal Regulations (10 CFR), Part 50 (specifically, paragraph (g) of Section 50.55a), except where specific relief has been granted by the NRC pursuant to 10 CFR 50.55a(g)(6)(i). Paragraph (a)(3) of 10 CFR 50.55a states in part that alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if the applicant demonstrates that: (i) the proposed alternatives would provipe 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.
In accordance with 10 CFR 50.55a(g)(4), ASME Code Class 1,2, and 3 components (including supports) will meet the reqUirements set forth in the ASME Code,Section XI to the extent Enclosure
- 2 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 1O-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.
Furthermore, 10 CFR 50.55a(g)(5)(iii) states that If the licensee has determined that conformance with certain code requirements is impractical for its facility, the licensee shall notify the Commission and submit, as specified in 10 CFR 50.4, information to support the determinations.
Paragraph (g)(5)(iv) of 10 CFR 10 CFR 50.55a states that where an examination requirement by the code or addenda is determined to be impractical by the licensee and is not included in the revised inservice inspection program as permitted by paragraph (g)(4) of this section, the basis for this determination must be demonstrated to the satisfaction of the Commission not later than 12 months after the expiration of the initial 120-month period of operation from start of facility commercial operation and each subsequent 120-month period of operation during which the examination is determined to be impractical.
Pursuant to 10 CFR 50.55a(g)(6)(i), the Commission will evaluate determinations under paragraph (g)(5) of this section that code requirements are impractical. The Commission may grant such relief and may impose such alternative requirements as it determines 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.
The code of record for the third 10-year lSI interval at BSEP, Units 1 and 2 is the ASME Code,Section XI, 1989 Edition with no Addenda.
3.0 TECHNICAL EVALUATION
OF RELIEF REQUEST RR-46 3.1 Components for Which Relief is Requested ASME Code, Class 1, Pressure Retaining Welds in Control Rod Housings Examination Category B-O, Welds in CRD Housing, Item Number B14.10, in Table IWB-2500-1 of Section XI of the ASME Code requires essentially 100 percent volumetric or surface examination of 10 percent of the peripheral CRD housing welds. The licensee elected to perform surface examinations on the selected CRD housing welds.
- 3 BSEP, Unit 1 Component No. and Description 1C11-CRD06-11-SW1, CRD Housing Weld 1C11-CRD06-15-SWl, CRD Housing Weld 1C11-CRD10-07-SW1, CRD Housing Weld 1C11-CRD14-07-SW1, CRD Housing Weld BSEP, Unit 2 Component No. and Description 2C11-CRD38-47-SW1, CRD Housing Weld 2C11-CRD42-47-SW1, CRD Housing Weld 2C11-CRD46-39-SW1, CRD Housing Weld 2C11-CRD46-43-SW 1, CRD Housing Weld 3.2 Applicable ASME Code Edition and Addenda The code of record for the third 10-year lSI interval is the 1989 edition of ASME Code,Section XI. Relief request RR-46 supports the third 10-year lSI interval for BSEP, Units 1 and 2.
The third 10-year lSI interval for both units began on May 11, 1998. As allowed by ASME Code,Section XI, IWA-2430(d), the third 10-year inspection interval for BSEP, Unit 2 was extended for one year. This extension enabled the examination of BSEP, Unit 2 components to coincide with the B219R 1 refueling outage, which began February 28, 2009. As such, the third 10-year inspection interval for BSEP, Unit 2 concluded on May 10, 2009, and the third 1O-year inspection interval for BSEP, Unit 1 concluded on May 10, 2008.
3.3 Licensee's Proposed Alternative Examination In accordance with 10 CFR 50.55a(g)(5)(iii), the licensee requested relief for the components listed above on the basis that the required examination coverage of "essentially 100 percent" is impractical due to physical obstructions and severely limited access in the work area. As an alternative, the licensee proposed selecting the four additional upper CRD housing tube-to-tube welds, listed in Section 3.6 of this safety evaluation, in lieu of the four lower housing-to-flange welds. This would provide the same total number of CRD housing welds for examination (i.e.,
eight welds) and will be an equivalent 100 percent inspection of 10 percent of the peripheral housings.
3.4 Impracticality of Compliance In accordance with 10 CFR 50.55a(g)(5)(iii), relief is requested from the requirement of the ASME Code,Section XI, Sub-article IWB-2500, Table IWB-2500-1 (Volumetric or Surface Examination Category B-O, "Pressure Retaining Welds in Control Rod Drive Housings"),
Examination Item Number B14.10, "Welds in CRD Housing." Limited accessibility for the 36 peripheral CRD housing-to-flange welds is due to the close proximity of adjacent CRD housing
- 4 flanges, neutron monitoring instrumentation and associated cabling, and horizontal beams, support bars and grids.
Piping systems and associated components for BSEP, Units 1 and 2 were designed and fabricated before the examination requirements of ASME Code,Section XI were formalized and published. Since the plant was not specifically designed to meet the requirements of the ASME Code,Section XI, literal compliance is not feasible or practical within the limits of the current plant design.
3.5 Burden Caused by Compliance Compliance with the examination coverage requirements of the ASME Code,Section XI would require modification, redesign, or replacement of components where geometry is inherent to the component design.
3.6 Licensee's Basis for Requesting Relief ASME Code,Section XI, Sub-article IWB-2500, Table IWB-2500-1 requires essentially 100 percent volumetric or surface examination of 10 percent of the peripheral CRD housing welds (Examination Category B-O, Item No. B14.10, as defined by Figure IWB-2500-18). Each CRD housing contains two pressure retaining welds. Table IWB-2500-1 requires both the upper and lower welds of each of the selected CRD housings to be examined. BSEP has 36 peripheral CRD housings; therefore, this requires four CRD housings (i.e., a total of eight CRD housing welds) to be examined. As previously stated, each CRD housing contains two pressure retaining welds: the housing-to-flange weld and the housing tube-to-tube weld. The housing-to-flange weld is located in the inaccessible lower section of the CRD housing, whereas the housing tube to-tube weld is located in the accessible upper section of the CRD housing.
Limited access to the 36 peripheral CRD housing-to-flange welds is due to the work area under the reactor vessel being highly congested. Physical obstructions imposed by design, geometry, and materials of construction include vessel appurtenances, insulation support rings, structural and component supports, adjacent CRD housing flanges, and neutron monitoring instrumentation and associated cabling. These obstructions are not practical to remove or replace to achieve 100 percent vOlumetric or surface coverage of the welds in the CRD housings. The upper housing tube-to-tube welds are without obstruction and can be completely examined.
Therefore, as an alternative, the licensee proposes selecting four additional upper CRD housing tube-to-tube welds in lieu of the four lower CRD housing-to-flange welds. This would provide the same total number of CRD housing welds for examination (i.e., eight welds). The licensee performed qualified surface examinations that achieved the maximum, practical amount of coverage obtainable within the limitations imposed by the design of the components, (i.e., 100 percent coverage was achieved). The examinations conducted confirmed satisfactory results, with no unacceptable flaws being identified and no evidence of degradation mechanisms.
Original Sample Additional Sample 1C11-CRD06-11-SW2 1C11-CRD38-47-SW2 1C11-CRD06-15-SW2 1C11-CRD42-47-SW2
- 5 Original Sample Additional Sample 1C11-CRD1 0-07-SW2 1C11-CRD46-39-SW2 1C11-CRD14-07-SW2 1C11-CRD46-43-SW2 2C11-CRD38-47-SW2 2C11-CRD06-11-SW2 2C11-CRD42-47-SW2 2C11-CRD06-15-SW2 2C11-CRD46-39-SW2 2C11-CRD10-07-SW2 2C11-CRD46-43-SW2 2C11-CRD14-07-SW2 As Class 1 Examination Category B-O components, a visual (VT-2) examination is also performed on these components during system pressure tests each refueling outage. This was completed during the BSEP, Unit 1, 2008 refueling outage (Le., the B117R1 outage) and BSEP, Unit 2,2009 refueling outage (Le., the B219R1 outage), and no evidence of leakage was identified for these components. Reactor coolant system leak rate limitations and atmospheric particulate radioactivity monitoring also ensure that any leakage would be detected prior to gross failure.
3.7
NRC Staff Evaluation
The ASME Code requires 100 percent volumetric or surface examination of 10 percent of the peripheral CRD housing welds. The licensee elected to perform surface examinations on the selected CRD housing welds. However, for the CRD housing-to-flange welds located in the inaccessible lower section of the CRD housing, the required inspection surface could not be obtained due to physical obstructions imposed by design, geometry, and materials of construction including vessel appurtenances, insulation support rings, structural and component supports, adjacent CRD housing flanges, and neutron monitoring instrumentation and associated cabling. Therefore, obtaining 100 percent of the ASME Code-required surface examinations is not practical for the lower CRD housing-to-flange welds. The NRC staff further determined that in order for the licensee to perform the ASME Code-required examinations, the subject components would have to be modified, redesigned, or replaced placing a burden on the licensee. The drawings and descriptions provided by the licensee support the fact that the area under the reactor pressure vessel is highly congested and show that examinations of the subject welds have been performed to the extent practical. No unacceptable indications, or evidence of degradation mechanisms were found during these examinations.
The licensee has added four additional housing tube-to-tube welds located in the accessible upper section of the CRD housing in each unit to the inspection population to account for the limited examinations and ensure that an equivalent 100 percent inspection of 10 percent of the peripheral housings will be obtained. A visual (VT-2) examination is also performed on these components during system pressure tests for each refueling outage. This was completed during the BSEP, Unit 1, 2008 refueling outage and BSEP, Unit 2, 2009 refueling outage and no evidence of leakage was identified for these components. Reactor coolant system leak rate limitations and atmospheric particulate radioactivity monitoring also ensure that any leakage would be detected prior to gross failure.
The licensee has shown that it is impractical to examine 100 percent of the ASME Code-required surface examinations on 10 percent of peripheral CRD housing-to-flange welds.
Based on the coverage obtained, the licensee's alternative to examine additional CRD housing tube-to-tube welds, and the VT-2 examinations performed on these components during system
- 6 pressure tests for each refueling outage, the NRC staff has concluded that if significant service induced degradation occurs, there is reasonable assurance that evidence of it will be detected.
Therefore, the NRC staff has determined that granting relief pursuant to 10 CFR 50.55a(g)(6)(i) 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.
4.0 CONCLUSION
The NRC staff has reviewed the licensee's submittal and concludes that ASME Code examination coverage requirements are impractical for the lower CRD housing-to-flange welds listed in relief request RR-46. Furthermore, imposition of these ASME Code requirements would create a burden on the licensee. The NRC staff also determined that based on the visual examination obtained of the CRD housing welds, it is reasonable to conclude that if significant service-induced degradation had occurred, evidence of it would have been detected by the examinations that were performed. Furthermore, the NRC staff concludes that examinations performed to the extent practical on the upper CRD housing tube-to-tube welds provide reasonable assurance of structural integrity of the sUbject welds since we conclude that both the upper and lower CRD housing welds are subject to similar degradation mechanisms.
Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(g)(6)(i). The NRC staff has further determined that granting relief request RR-46 pursuant to 10 CFR 50.55a(g)(6)(i) is authorized by law and will not endanger life or property, or the common defense and security, and is otherwise in the public interest given due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility. Therefore, the NRC grants relief for the subject examinations of the components contained in relief request RR-46 at BSEP, Units 1 and 2 for the Third 1O-year lSI interval.
All other ASME Code,Section XI requirements for which relief was not specifically requested and approved in the subject requests for relief remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.
Principal Contributor: Edward V. Andruszkiewicz Date: April 7, 2010
M. Annacone
-2 The bases for the NRC staff's conclusion are contained in the enclosed Safety Evaluation. If you have any questions regarding this issue, please contact Farideh Saba at (301) 415-1447 or farideh.saba@nrc.gov.
Sincerely, IRA EBrown forI Douglas A. Broaddus, Acting Chief Plant Licensing Branch 11-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-325 and 50-324
Enclosure:
Safety Evaluation cc w/encl: Distribution via ListServ Distribution:
PUBLIC RidsNrrPMBrunswick RidsAcrsAcnw MailCTR RidsNrrDciCvib LPL2-2 R/F RidsOgcRp RidsRgn2MailCenter SLingam, NRR RidsNrrDorlLpl2-2 RidsNrrLACSola RidsNrrDorlDpr EAndruszkiewicz, t\\lRR ADAMS ACCESSION NO' ML100491269 NRR-106 OFFICE LPL2-2/PM LPL2-2/PM LPL2-2/LA CVIB/BC LPL2-2/BC (A)
NAME SLingam FSaba CSoia MMitchell*
EBrown for DBroaddus DATE 3/17/10 3/30/10 3/17/10 02/12/10 4/7/10
- By memorandum OFFICIAL RECORD COpy