ML13255A507
| ML13255A507 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 03/12/2014 |
| From: | Meena Khanna Plant Licensing Branch 1 |
| To: | Emily Larson FirstEnergy Nuclear Operating Co |
| Whited J | |
| References | |
| TAC MF1006 | |
| Download: ML13255A507 (9) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 March 12, 2014 Mr. Eric A. Larson, Site Vice President FirstEnergy Nuclear Operating Company Beaver Valley Power Station Mail Stop A-BV-SEB1 P.O. Box 4, Route 168 Shippingport, PA 15077
SUBJECT:
BEAVER VALLEY POWER STATION, UNIT NO.2- REQUEST FOR RELIEF 2-TYP-3-RVSE-2 FOR ALTERNATIVE EXAMINATION FOR REACTOR VESSEL SAFE-END WELDS (TAC NO. MF1 006)
Dear Mr. Larson:
By letter dated March 11, 2013, FirstEnergy Nuclear Operating Company (the licensee) requested relief from the depth sizing requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI, Code Cases N-695, "Qualification Requirements for Dissimilar Metal Piping Welds," and N-696, "Qualification Requirements for Appendix VIII Piping Examinations Conducted from the Inside Surface."
Relief Request (RR) 2-TYP-3-RVSE-2 proposed an alternative to the 0.125 inch root mean square error criteria of ASME Code Cases N-695 and N-696 qualification for the dissimilar metal butt weld and the austenitic piping butt weld examinations performed from the inner diameter surface. RR 2-TYP-3-RVSE-2 is applicable to the remainder of the third 10-year inservice inspection (lSI) interval of the Beaver Valley Power Station (Beaver Valley), Unit 2, which began on August 29, 2008, and will end on August 28, 2018.
Specifically, pursuant to section 50.55a of Title 10 of the Code of Federal Regulations (10 CFR),
the licensee requested relief and to use alternative requirements (if necessary), for lSI items identified in RR 2-TYP-3-RVSE-2 on the basis that the ASME Code Cases N-695 and N-696 requirements are impractical.
The Nuclear Regulatory Commission (NRC) staff has reviewed the subject request and concludes, as set forth in the enclosed safety evaluation, that it is impractical for the licensee to comply with the ASME Code Cases N-695 and N-696 requirements. The NRC staff also determines that the proposed alternative provides reasonable assurance of structural integrity and leak tightness of the subject welds.
The NRC staff grants the use of the alternate depth-sizing qualification subject to the licensee providing, for NRC staff review and approval prior to the expiration of the relief, the information identified in the SE, should a crack requiring depth-sizing be identified. 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.
E. Larson 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) and is in compliance with the requirements of the ASME Code for which relief was not requested. Therefore, the NRC staff grants RR 2-TYP-3-RVSE-2 to Beaver Valley, Unit 2, for the remainder of the third 10-year lSI interval, which commenced on August 29, 2008, and will end on August 28, 2018.
All other ASME Code,Section XI, requirements for which relief was not specifically requested and authorized herein by the NRC staff remain applicable, including the third party review by the Authorized Nuclear In service Inspector.
If you have any questions, please contact the Beaver Valley Project Manager, Mr. Jeffrey A.
Whited at 301-415-4090 or via e-mail at Jeffrey.Whited@nrc.gov.
Sincerely, P ant Licensing Branch 1-2 ivision of Operating Reactor Licensing ffice of Nuclear Reactor Regulation Docket No. 50-412
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 RELIEF REQUEST NO. 2-TYP-3-RVSE-2 FOR THE REMAINDER OF THE THIRD 10-YEAR INSERVICE INSPECTION INTERVAL FIRSTENERGY NUCLEAR OPERATING COMPANY BEAVER VALLEY POWER STATION, UNIT 2 DOCKET NUMBER 50-412
1.0 INTRODUCTION
By letter dated March 11, 2013, 1 FirstEnergy Nuclear Operating Company (the licensee) requested relief from the depth sizing requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI, Code Cases N-695, "Qualification Requirements for Dissimilar Metal Piping Welds," and N-696, "Qualification Requirements for Appendix VIII Piping Examinations Conducted from the Inside Surface."
Relief Request (RR) 2-TYP-3-RVSE-2 proposed an alternative to the 0.125 inch root mean square error (RMSE) criteria of ASME Code Cases N-695 and N-696 qualification for the dissimilar metal (OM) butt weld and the austenitic piping butt weld examinations performed from the inner diameter (I D) surface. The licensee's request is applicable to the third 10-year inservice inspection (lSI) interval, which began on August 29, 2008, and will end on August 28, 2018, at the Beaver Valley Power Station (Beaver Valley), Unit 2.
Specifically, pursuant to section 50.55a of Title 10 of the Code of Federal Regulations (1 0 CFR),
the licensee requested relief and to use alternative requirements (if necessary), for lSI items identified in RR 2-TYP-3-RVSE-2 on the basis that the ASME Code Cases N-695 and N-696 requirements are impractical.
2.0 REGULATORY EVALUATION
The regulations in 10 CFR 50.55a(g)(4) specifiy that ASME Code Class 1, 2 and 3 components (including supports) must meet the requirements, except the design and access provisions and the preservice examination requirements, set forth in the ASME Code,Section XI, "Rules for lnservice Inspection 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 1
Agencywide Documents Access and Management System (ADAMS) Accession No. ML13071A097.
Enclosure
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 conditions listed therein.
The regulations in 10 CFR 50.55a(g)(6)(ii)(F), "Examination requirements for Class 1 piping and nozzle dissimilar-metal butt welds," require licensees of existing operating pressurized-water reactors (PWR) to implement the requirements of ASME Code Case N-770-1, "Alternative Examination Requirements and Acceptance Standards for Class 1 PWR Piping and Vessel Nozzle Butt Welds Fabricated With UNS N06082 or UNS W86182 Weld Filler Material With or Without Application of Listed Mitigation ActivitiesSection XI, Division 1," subject to the conditions specified in paragraphs (g)(6)(ii)(F)(2) through (g)(6)(ii)(F)(1 0) of Section 50.55a.
Pursuant to 10 CFR 50.55a(b)(2)(xv), licensees using Appendix VIII in the 1995 Edition through the 2001 Edition of the ASME Code may elect to comply with all of the provisions in paragraphs (b)(2)(xv)(A) through (b)(2)(xv)(M) of this section, except for paragraph (b)(2)(xv)(F) of this section, which may be used at the licensee's option. Licensees using editions and addenda after 2001 Edition through the 2006 Addenda shall use the 2001 Edition of Appendix VIII, and may elect to comply with all of the provisions in paragraphs (b)(2)(xv)(A) through (b)(2)(xv)(M) of this section, except for paragraph (b)(2)(xv)(F), which may be used at the licensee's option.
The regulations in 10 CFR 50.55a(g)(5)(iii) state, 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.
The regulations in 10 CFR 50.55a(g)(6)(i), state, in part, 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.
Based on the above, and subject to the following technical evaluation, the NRC staff concludes that regulatory authority exists for the licensee to request and the NRC to grant the relief requested by the licensee.
3.0 TECHNICAL EVALUATION
3.1 The Licensee's Relief Request The ASME Code components affected by this request include:
- Six Class 1 reactor pressure vessel (RPV) hot and cold leg nozzle-to-safe end DM butt welds of the reactor coolant system (RCS)
- Six Class 1 RPV hot and cold leg safe end-to-pipe butt austenitic welds of the RCS The components for which a relief is requested are identified in Section 1.0 of RR 2-TYP RVSE-2.
3.2 ASME Code Requirements ASME Code Case N-770-1, which is mandated by 10 CFR 50.55a{g)(6)(ii)(F), requires the RPV hot and cold leg nozzle-to-safe end OM butt welds to be inspected by ultrasonic testing {UT).
The Beaver Valley risk informed {RI)-ISI program (approved by the NRC in letter dated March 23, 2011 2) requires the RPV hot and cold leg safe end-to-pipe austenitic butt welds to be inspected by UT. The Beaver Valley RI-ISI program is based on WCAP-14572, Rev. 1-NP-A,
'Westinghouse Owners Group Application of Risk-Informed Methods to Piping lnservice Inspection Topical Report." 3 In this RI-ISI program, the RPV hot and cold leg safe end-to-pipe austenitic butt welds have been categorized as R1.11 that is susceptible to thermal fatigue.
Paragraph IWA-2232 of the ASME Code requires the UT to be conducted in accordance with 1-2220 of Appendix I. 1-2220 requires the UT procedures, equipment, and personnel to be qualified by the performance demonstration in accordance with Appendix VIII.
For examination of the subject welds, the UT qualifications requirements of Supplements 2 and 10 of Appendix VIII of the ASME Code apply. The licensee has adapted ASME Code Case N-695 as an alternative to Supplement 10 when examining only the RPV nozzle-to-safe end OM welds. In addition, the licensee has adapted ASME Code Case N-696 as an alternative to combined Supplements 2 and 10 when examining both the RPV nozzle-to-safe end OM welds and safe end-to-pipe austenitic welds. The NRC has accepted ASME Code Cases N-695 and N-696 in Regulatory Guide (RG) 1.147, "lnservice Inspection Code Case Acceptability, AMSE Section XI, Division 1," Rev. 16. 4 According to ASME Code Cases N-695 and N-696, the UT procedures, equipment, and personnel are qualified for depth sizing when the flaw depths estimated by the UT, as compared with the true depths, do not exceed 0.125 inch RMSE.
3.3 Applicable Code Edition The Code of record for the third 10-year lSI interval at Beaver Valley, Unit 2, is the 2001 Edition through 2003 Addenda of the ASME Code. The third 10-year lSI interval began on August 29, 2008, and will end on August 28, 2018.
3.4 Basis for Relief The licensee's basis for impracticality and burden caused by compliance to the ASME Code Cases N-695 and N-696 requirements is as follows.
An Electric Power Research Institute (EPRI) letter dated March 8, 2012 states,
"[t]o date, no domestic or international vendor has met the applicable [RMSE]
requirement specified in the ASME Code."
The vendors' attempts to meet the Supplement 10 {ASME Code Case N-695) and combined Supplement 2 and 10 (ASME Code Case N-696) required RMSE values {0.125 inch) for flaw depth sizing for the examination from the 10 have been unsuccessful. Process enhancements 2
ADAMS Accession No. ML110630403.
3 ADAMS Accession No. ML042610469.
4 ADAMS Accession No. ML101800536.
including new delivery systems, new transducers, and software modifications have been implemented, but have not achieved the desired improvements in performance.
Compliance with the Performance Demonstration Initiative (POl) qualification program without an alternative qualification requirement would necessitate significant modifications to the RCS welds. Modifications and alterations of these welds to meet the requirements may result in reduced structural integrity of the reactor coolant pressure boundary. Even with modifications, the vendor depth sizing accuracy issue would not likely be fully addressed.
In a supplemental letter dated June 1, 2012, 5 (a supplement to RR 2-TYP-3-RVSE-1 dated December 27, 2011 6 ) the licensee stated that use of an alternate approach, such as performance of the examinations from the outside diameter (00) surface, would represent a burden, as access to the welds is restricted and inspectors would be subject to significant radiation dose while performing the inspections.
The inspection vendor has achieved an RMSE of 0.189 inches for the examination of OM welds and an RMSE of 0.245 for the combined examination of OM welds and austenitic welds. The licensee proposed that if both the RPV nozzle-to-safe end OM welds and the safe end-to-pipe austenitic welds are examined, the difference between the vendor demonstrated 0.245 inch RMSE and the ASME Code Case N-696 required 0.125 inch RMSE would be added to the flaw depths determined during actual sizing of flaws. If the examination will only cover the OM welds, the licensee proposed that the difference between the vendor demonstrated 0.189 inch RMSE and the ASME Code Case N-695 required 0.125 inch RMSE would be added to the flaw depths determined during actual sizing of flaws.
Furthermore, the licensee proposed that if a flaw or flaws are detected and measured as less than 50 percent through-wall in depth, adding the above proposed correction factor (vendor demonstrated RMSE minus the ASME Code required 0.125 inch RMSE) to the depths of any flaws is an acceptable alternative. However, if a flaw or flaws are detected and measured as greater than 50 percent through-wall depth and will be left in service without mitigation or repair, flaw evaluations will be submitted to the NRC for review and approval prior to reactor startup.
With its flaw evaluation, the licensee proposed to provide the information concerning the mechanism that caused the crack, the surface roughness and profile in the area of the pipe and weld required to perform the inspection, and areas in which the UT probe may lift off from the surface of the pipe and weld.
3.5 NRC Staff Evaluation The NRC staff has evaluated RR 2-TYP-3-RVSE-2 pursuant to 10 CFR 50.55a(g)(6)(i). The NRC staff focused on whether a technical justification exists to support the determination that the ASME Code requirement is impractical, imposing the requirements could result a burden upon the facility, and the structural integrity and leak tightness of the affected component is reasonably assured.
5 ADAMS Accession No. ML12156A227.
6 ADAMS Accession No. ML120230441 .
The NRC staff notes that the current request (RR 2-TYP-3-RVSE-2) is a continuance of the request 2-TYP-3-RVSE-1 that was authorized by the NRC in letter dated July 18, 2012/ for the third 10-year lSI interval prior to the end of the fall 2012 refueling outage for Beaver Valley, Unit
- 2. Within context of RR 2-TYP-3-RVSE-2, the NRC staff determined that the licensee provided an adequate description and technical information to support the basis for impracticality. The NRC staff confirmed that attempts have been made by the industry to qualify the 10 ultrasonic inspection procedures since 2002. Enhancements in examination such as use of commercially available advanced UT systems, transducers, and software have not resulted in the desired improvements in performance to meet the ASME Code-acceptable RMSE criteria for the 10 ultrasonic inspection. To date, there has not been any inspection vendor capable of meeting the qualification requirement of the RMSE of not greater than 0.125 inch established by the ASME Code for the UT inspection procedure from the 10 surface.
The NRC staff determined that the licensee has considered an alternative approach such as examining the subject welds from the 00 surface (per the licensee's letter dated June 1, 2012).
The NRC staff notes that the qualification requirement of the RMSE of not greater than 0.125 inch established by the ASME Code for the 00 ultrasonic inspection procedures have been successful. However, the licensee determined that access to the subject welds from the 00 was restricted and the examination from the 00 would subject personnel conducting inspection to significant radiation dose. Therefore, the NRC staff concludes that a technical justification exists to support the determination that the ASME Code required RMSE of 0.125 inch for the 10 ultrasonic inspection qualification is impractical and if the ASME Code requirement was imposed on the facility, these welds would require major design modifications and replacement, which would be a burden upon the licensee.
In July 2012, the NRC staff reviewed the proprietary POl program (administered by the EPRI) data used in blind tests. This review was conducted to verify the information and analysis presented by industry in the public meeting held between the NRC, POl, EPRI, and industry on March 16, 2012, 8 and June 19, 2012. 9 Based on this review, the NRC staff determined that adding the industry proposed correction factor (procedure RMSE - 0.125 inch) to the depths of any flaw found by the UT prior to flaw evaluation for flaws less than 50 percent through-wall satisfactorily reduces the effect of the increased sizing error associated with not meeting the ASME Code-required 0.125 inch RMSE. If any cracks are detected and measured by the UT as 50 percent through-wall depth or greater and remain in service without mitigation or repair, a flaw evaluation shall be performed and submitted for the NRC review and approval prior to reactor startup. The flaw evaluations shall include: (1) the inner profile of the weld, pipe, and nozzle in the region at and surrounding the flaw; (2) an estimate of the percentage of potential surface areas with UT probe lift-off; and (3) information on mechanism which caused the crack.
Requiring the NRC approval for restart when a flaw greater than 50 percent through-wall is discovered and is to be left in service without mitigation or repair, addresses the NRC staff concerns with the possibilities of large undersizing errors in deep flaws.
Therefore, the NRC staff finds that for flaws measured at 50 percent or less through-wall depth, adding the licensee's proposed correction factor (procedure RMSE - 0.125 inch) to the depths of 7
ADAMS Accession No. ML12188A110.
8 ADAMS Accession No. ML12097A071 .
9 ADAMS Accession Nos. ML12173A517 and ML12173A522.
any flaw found by the inspections, and obtaining the NRC review and approval prior to startup for any flaws measured as greater than 50 percent through-wall depth, provides reasonable assurance of structural integrity and leak tightness of the subject welds.
4.0 CONCLUSION
As discussed above, the NRC staff finds that it is impractical for the licensee to comply with the ASME Code Cases N-695 and N-696 requirements. The NRC staff also finds that the proposed alternative provides reasonable assurance of structural integrity and leak tightness of the subject welds. 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. 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) and is in compliance with the requirements of the ASME Code for which relief was not requested. Therefore, the NRC staff grants RR 2-TYP-3-RVSE-2 to Beaver Valley, Unit 2, for the remainder of the third 10-year lSI interval which commenced on August 29, 2008, and will end on August 28, 2018.
All other ASME Code,Section XI, requirements for which relief was not specifically requested and authorized herein by the NRC staff remain applicable, including the third party review by the Authorized Nuclear In service Inspector.
Principal Contributor: A. Rezai Date: March 12, 2014
E. Larson 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) and is in compliance with the requirements of the ASME Code for which relief was not requested. Therefore, the NRC staff grants RR 2-TYP-3-RVSE-2 to Beaver Valley, Unit 2, for the remainder of the third 10-year lSI interval, which commenced on August 29, 2008, and will end on August 28, 2018.
All other ASME Code,Section XI, requirements for which relief was not specifically requested and authorized herein by the NRC staff remain applicable, including the third party review by the Authorized Nuclear In service Inspector.
If you have any questions, please contact the Beaver Valley Project Manager, Mr. Jeffrey A.
Whited at 301-415-4090 or via e-mail at Jeffrey.Whited@nrc.gov.
Sincerely, John G. Lamb for Meena K. Khanna, Chief Plant Licensing Branch 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-412
Enclosure:
Safety Evaluation cc w/encl: Distribution via ListServ DISTRIBUTION:
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DATE 03/12/2014 03/06/2014 10/24/2013 03/12/2014 OFFICIAL RECORD COPY