ML12145A048
| ML12145A048 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 06/04/2012 |
| From: | Meena Khanna Plant Licensing Branch 1 |
| To: | Freeman P NextEra Energy Seabrook |
| Lamb J | |
| References | |
| TAC ME6902 | |
| Download: ML12145A048 (10) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 June 4,2012 Mr. Paul Freeman Site Vice President c/o Michael O'Keefe Seabrook Station NextEra Energy Seabrook, LLC P.O. Box 300 Seabrook, NH 03874
SUBJECT:
SEABROOK STATION, UNIT 1 - SECOND 10-YEAR INTERVAL INSERVICE INSPECTION PROGRAM PLAN REQUEST FOR RELIEF NO. 21R-19 (TAC NO.
ME6902)
Dear Mr. Freeman:
By letter dated August 17, 2011, as supplemented March 13, 2012, NextEra Energy Seabrook, LLC (NextEra or licensee) submitted request for relief 21R-19 for the second 10-year inservice inspection (lSI) interval program at the Seabrook Station, Unit 1 (Seabrook) from certain examination requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code). Specifically, the licensee requested relief from the ASME Code,Section XI requirements for examination Category C-F-1, Items C5.11 and C5.21, pressure retaining welds in austenitic stainless steel or high alloy piping. The request is for the risk informed examination for the second 10-year lSI interval, which ended August 18, 2010.
The U.S. Nuclear Regulatory Commission (NRC) staff with technical assistance from its contractor, the Pacific Northwest National Laboratory (PNNL), has reviewed the subject request, and concludes that NexEra has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(g)(6)(i). Therefore, the NRC staff grants relief from the specified ASME Code,Section XI, examination coverage requirements of the subject welds contained in relief request 21R-19 for the Seabrook second 10-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.
P. Freeman -2
. The NRC staffs safety evaluation is enclosed. If you have any questions, please contact John G. Lamb at 301-415-3100 or via e-mail at John.Lamb@nrc.gov.
Sincerely, Meena Khanna, Chief Plant Licensing Branch 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-443
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 SECOND 10-YEAR INTERVAL REQUEST FOR RELIEF NO. 21R-19 NEXTERA ENERGY SEABROOK, LLC.
SEABROOK STATION, UNIT 1 DOCKET NUMBER 50-443
1.0 INTRODUCTION
By letter dated August 17,2011, as supplemented March 13, 2012,1 NextEra Energy Seabrook.
LLC (NextEra or licensee) submitted request for relief 21R-19 for the second 1O-year inservice inspection (lSI) interval program at the Seabrook Station, Unit 1 (Seabrook) from certain examination requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code). Specifically. the licensee requested relief from the ASME Code,Section XI requirements for examination Category C-F-1, items C5.11 and C5.21, pressure retaining welds in austenitic stainless steel or high alloy piping. The request is for the risk informed examination for the second 10-year lSI interval, which ended August 18, 2010.
2.0 REGULATORY EVALUATION
Pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(g)(4), American Society of Mechanical Engineers (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 first 1O-year interval and subsequent intervals comply with the requirements in the latest edition and addenda of Section XI of the ASME Code, which was 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.
10 CFR 50.55a(g)(5)(iii), states, in part, that licensees may determine that conformance with certain code requirements is impractical and that the licensee shall notify the Commission and submit information in support of the determination. Determination of impracticality in accordance with this section must be based on the demonstrated limitations experienced when Agencywide Documents Access and Management System (ADAMS) Accession Numbers ML11234A185 and ML120790313, respectively.
Enclosure
-2 attempting to comply with the code requirements during the inservice inspection interval for which the request is being submitted. Requests for relief made in accordance with this section must be submitted to the NRC no later than 12 months after the expiration of the initial 120-month inspection interval or subsequent 120-month inspection interval for which relief is sought.
10 CFR 50.55a(g)(6)(i), states that 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 licensee has requested relief from ASME Code requirements pursuant to 10 CFR 50.55a(g)(6)(i). The ASME Code of Record for Seabrook second 1O-year interval inservice inspection program, which ended on August 18, 2010, is the 1995 Edition through the 1996 Addenda of Section XI of the ASME Boiler and Pressure Vessel Code.
Based on the above, and subject to the following technical evaluation, the NRC staff finds that regulatory authority exists for the licensee to request and the Commission to grant the relief requested by the licensee.
3.0 TECHNICAL EVALUATION
The information provided by the licensee in support of the request for relief to ASME Code requirements has been evaluated and the bases for disposition are documented below.
3.1 Request for Relief 2IR-19, ASME Code,Section XI. Examination CategorY C-F-1, Items C5.11 and C5.21, Pressure Retaining Welds in Austenitic Stainless Steel or High Alloy Piping ASME Code Requirement ASME Code,Section XI, Examination Category C-F-1, Items C5.11 and C5.21, require 100 percent surface and volumetric examination, as defined by Figure IWC-2500-7, of selected Class 2 austenitic stainless steel or high alloy circumferential piping welds. ASME Code Case N-460, as an alternative approved for use by the NRC in Regulatory Guide 1.147, Revision 16, InseIVice Inspection Code Case Acceptability, states that a reduction in examination coverage due to part geometry or interference for any Class 1 and 2 weld is acceptable provided that the reduction is less than 10 percent, Le., greater than 90 percent examination coverage is obtained.
Licensee's ASME Code Relief Request In accordance with 10 CFR 50.55a(g)(5)(iii), the licensee requested relieffrom the ASME Code required 100 percent volumetric examination for the ASME Code, Class 2 austenitic stainless steel or high alloy piping welds shown in Table 3.3.1 below.
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C5.11 CBS 1207-0202 12" Pipe-ta-Valve 50.0 C5.11 CBS 1208-0301 10" Reducer-ta-Tee 50.0 C5.11 CBS 1209-01 02 12" Pipe-ta-Valve 50.0 C5.11 CBS 1212-16 10 16" Pipe-ta-Valve 49.0 C5.11 CBS 1214-0221 8" Valve-ta-Penetratian 50.0 C5.11 CBS 1215-01 01 6" Flange-ta-Pipe 50.0 C5.11 CBS 1216-0220 8" Pipe-ta-Valve 50.0 C5.11 RC 0013-0410 14" Pipe-ta-Safe end 50.0 C5.11 RH 0152-01 03 8" Valve-ta-Pipe 50.0 C5.11 RH 0155-02 32 8" Pipe-ta-Valve 50.0 C5.11 RH 0159-01 14 8" Pipe-ta-Valve 50.0 C5.11 RH 0162-0402 6" Pipe-ta-Flange 50.0 C5.11 RH 0163-05 04 6" Flange-ta-Pipe 50.0 C5.11 RH 0180-01 01 8" Tee-ta-Pipe 50.0 C5.21 CS 0324-01 01 3" Pipe-ta-Valve 50.0 C5.21 CS 0324-01 02 3" Valve-ta-Pipe 50.0 C5.21 CS 0355-01 01 3" Valve-ta-Pipe 50.0 C5.21 CS 0355-01 04 3" Pipe-ta-Valve 50.0 C5.21 CS 0355-06 01 3" Pipe-ta-Valve 50.0 C5.21 CS 0362-01 02 4" Valve-ta-Pipe 50.0 C5.21 CS 0364-01 01 4" Flange-ta-Pipe 50.0 C5.21 CS 0364-02 01 3" Pipe-ta-Valve 50.0 C5.21 CS 0369-03 08 8" Pipe-ta-Valve 50.0 CS.21 CS 0371-03 08 6" Elbow-ta-Pipe 65.0 C5.21 CS 0374-01 02 4" Flange-to-Pipe 50.0 C5.21 CS 0375-01 04 3" Valve-ta-Pipe 50.0 CS.21 SI 02S0-02 07 4" Valve-ta-Pipe 50.0 C5.21 SI 02S0-03 01 4" Valve-ta-Pipe SO.O CS.21 SI 0250-03 04 4" Pipe-ta-Tee 50.0 CS.21 SI 0251-0208 4" Pipe-ta-Flange SO.O CS.21 SI 0251-0301 4" Pipe-ta-Valve SO.O C5.21 SI 0256-01 02 4" Valve-ta-Pipe 50.0 CS.21 SI 0257-01 02 4" Valve-ta-Pipe SO.O C5.21 SI 0272-02 10 4" Valve-ta-Pipe SO.O
-4 Note: In the licensee's response to the NRC Request for Additional Information (RAI),
Seabrook withdrew Pipe-to-Valve Weld CS 0364-02 01 and Elbow-to-Pipe Weld CS 0371-03 08 from Request for Relief 21R-19, Examination Category C-F-1, Item C5.21. The licensee stated that these welds were removed from the relief request and lSI program selection, as these welds were not needed to meet ASME Code minimum inspection requirements.
Licensee's Basis for Relief Request (as stated)
There are currently no Performance Demonstration Initiative (POI) qualified single side examination procedures that demonstrate equivalency to two-sided examination procedures on austenitic piping welds. Current technology is not capable of reliably detecting or sizing flaws on the far side of an austenitic weld.
POI Performance Demonstration Qualification Summary (PDQS) certificates for austenitic piping list the limitation that single side examination is performed on a best effort basis. The best effort qualification is provided in place of a complete single side qualification to demonstrate that the examiners qualification and the subsequent weld examination is based on application of the best available technology.
Relief is requested from compliance with the 100 percent required examination coverage for piping welds listed in Table [3.3.1 above] based on configurations limited to single side access. Examination coverage listed was obtained during examination with no credit taken for the far side of each weld.
Compliance would require extensive modification or replacement of components with a design that allows examination from both sides of the weld. This option to meet the 100 percent examination coverage requirement is considered impractical.
Licensee's Proposed Alternative Examination:
The licensee did not propose any alternative examinations for the subject welds. However, the licensee's examinations were performed to the maximum extent practical.
NRC Staff Evaluation
The ASME Code requires 100 percent volumetric and surface examination for selected ASME Code, Class 2 pressure retaining in austenitic stainless steel welds or high alloy circumferential piping welds. However, volumetric examinations of the subject welds are limited by the materials of construction and geometry of the welds, and the associated piping configurations, which restrict scanning to one side only. To gain access for examination, the welds and piping would require design modifications. Imposition of this requirement would create a burden on the licensee, therefore, the ASME Code-required 100 percent volumetric examinations from both sides of the welds are considered impractical.
As shown in the sketches and technical descriptions included in the licensee's submittals, access for examination of the subject welds is limited primarily to the pipe, or penetration, side of the welds due to the stainless steel materials involved and the weld deSign geometries, such
- 5 as proximity to flanges, tapers from the valve-to-pipe, pipe-to-tee, pipe-to-flange, pipe-to-safe end, reducer-to-pipe, and valve-to-penetration weld configurations (see Table 3.3.1 above for specific weld configurations). The ultrasonic thickness (UT) techniques employed for these welds have been qualified through the industry's POI, which meets ASME Code,Section XI, Appendix VIII requirements. These techniques have been qualified for flaws located on the near-side of the welds; far-side detection of flaws is considered to be a "best effort. n For this reason, the licensee has taken credit for completing only 50 percent of the ASME Code-required inspection volume on many of the subject piping welds. The licensee completed the ASME Code surface examinations (liquid penetrant (PT)) to their full extent as required by the ASME Code. No unacceptable indications were noted during the performance of the volumetric or surface examinations.
The licensee's UT techniques included 45-, 60- and 70-degree shear waves and 60- and 70 degree refracted longitudinal waves (L-waves), as applicable. For piping equal to or less than 0.50-inches thick, procedures that include a 70-degree shear wave are the POI approved techniques for flaw detection in piping welds. For piping greater than 0.50-inches thick, longitudinal wave search units that provide supplemental coverage of the far-side of the weld are included in POI approved techniques for detection in austenitic stainless steel welds. L waves have been shown to provide enhanced detection on the far-side of austenitic stainless steel welds. 2 3 4 While the licensee has only taken credit for obtaining 50 percent volumetric coverage, it is expected that the techniques employed would have provided coverage beyond the near-side of the welds. This is confirmed from a review of the welds' cross-sectional information, which indicates that limited volumetric coverage on the far-side of the welds has been obtained.
The licensee has shown that it is impractical to meet the ASME Code-required 100 percent volumetric examination coverage for the subject piping welds due to their configurations and materials. Although the ASME Code-required coverage could not be obtained, the UT techniques employed would have provided full volumetric coverage for the near-side of the welds and limited volumetric coverage for the weld fusion zone and base materials on the opposite side of the welds. Based on the volumetric and full surface coverage obtained for the subject welds, and considering the licensee's performance of ultrasonic techniques used to maximize this coverage, it is reasonable to conclude that if significant service-induced degradation had occurred, evidence of it would have been detected. Furthermore, the NRC staff determined that the examinations performed to the extent practical on the subject welds provide reasonable assurance of structural integrity of the subject welds.
2 F.V. Ammirato, X. Edelmann, and S.M. Walker, Examination of Dissimilar Metal Welds in BWR Nozzle-to th Safe End JOints, 8 International Conference on NDE in the Nuclear Industry, ASM International, 1987.
3 P. Lemaitre, TD. Koble, and S.R. Doctor, PISC III Capability Study on Wrought-to-Wrought Austenitic Steel Welds: Evaluation at the Level of Procedures and Techniques, Effectiveness of Nondestructive Examination Systems and Performance Demonstration, PVP-Volume 317, NDE-Volume 14, ASME, 1995.
4 M. T. Anderson, AA Diaz, A.D. Cinson, S.L. Crawford, S.E. Cumblidge, S.R Doctor, K.M. Denslow, and S.
Ahmed, 2011. An Assessment of Ultrasonic Techniques for Far-Side Examinations of Austenitic Stainless Steel Piping Welds, NUREG/CR-7113, PNNL-19353, U. S. Nuclear Regulatory Commission, Washington, DC.
- 6
4.0 CONCLUSION
S As set forth above, 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 given due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility.
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). Therefore, the NRC staff grants relief from the specified ASME Code,Section XI, examination coverage requirements of the subject welds contained in relief request 21R-19 for the Seabrook second 10-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 Contributors: Tom McLellan and Steve Cumblidge Date: June 4, 2012
SEABROOK STATION, UNIT 1 Second 10-Year lSI Interval TABLE 1
SUMMARY
OF RELIEF REQUEST ASME ASME Relief TLR Code Code, Request RR Exam. Item Required Licensee Proposed Relief Request Number Sec. System or Component Category No. Volume or Area to be Examined Method Alternative Disposition 21R-19 3.1 Pressure Retaining C-F-1 CS.11 100% of ASME Code, Class 2 Volumetric Use volumetric and Granted Welds in Austenitic CS.21 austenitic stainless steel or high and Surface surface coverage 10 CFR SO.SSa(g)(6)(i)
Stainless Steel or High alloy circumferential piping achieved Alloy Piping welds ATTACHMENT 1
P. Freeman -2 The NRC staff's safety evaluation is enclosed. If you have any questions, please contact John G. Lamb at 301-415-3100 or via e-mail at John.Lamb@nrc.gov.
Sincerely, Ira!
Meena Khanna, Chief Plant Licensing Branch 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-443
Enclosure:
Safety Evaluation cc w/encl: Distribution via Listserv DISTRIBUTION:
PUBLIC LPLI-2 r/f RidsAcrsAcnw_MailCTR Resource RidsNrrDeEvib Resource RidsNrrDorlDpr Resource RidsNrrDorlLpll-2 Resource RidsNrrLAABaxter Resource RidsNrrPMSeabrook Resource RidsOgcRp Resource RidsRgn1 MailCenter Resource MMcCoppin, EDO RI CSyndor, NRR/DE/EVIB ADAMS Accession No. ML12145A048 'via memorandum **via email NRR/LPLI-2/PM NRR/LPLI-2/LA NRR/DE/EPNB/BC N RRILPLI-2/BC JLamb ABaxter ** JTsao' for TLupold hanna 06/01/12 06/01/12 05/18/12 04/2012 OFFICIAL AGENCY RECORD