ML13179A110

Request for Relief No. ANO1-ISI-021, from ASME Volumetric Requirements for Full Penetration Welded Nozzles in Vessels - Inspection Program B; Fourth 10-Year ISI Interval

ML13179A110
Person / Time
Site:	Arkansas Nuclear
Issue date:	07/16/2013
From:	Markley M Plant Licensing Branch IV
To:	Entergy Operations
Kalyanam N
References
TAC ME9147
Download: ML13179A110 (9)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 July 16, 2013 Vice President, Operations Arkansas Nuclear One Entergy Operations, Inc.

1448 S.R. 333 Russellville, AR 72802

SUBJECT:

ARKANSAS NUCLEAR ONE, UNIT 1 - REQUEST FOR RELIEF AN01-ISI-021 FROM ASME CODE, SECTION XI, VOLUMETRIC EXAMINATION REQUIREMENTS FOR THE FOURTH 10-YEAR INSERVICE INSPECTION INTERVAL, FIRST PERIOD (TAC NO. ME9147)

Dear Sir or Madam:

By letter dated July 25, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12207A594), as supplemented by letter dated February 26, 2013 (ADAMS Accession No. ML13058A097), Entergy Operations, Inc. (Entergy, the licensee),

submitted Request for Relief AN01-ISI-021 from certain requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code),Section XI, at Arkansas Nuclear One (ANO), Unit 1. The licensee's request is applicable to the fourth 10-year inservice inspection (lSI) interval, first period, which began on May 31,2008, and ended on May 30,2011.

Entergy requested relief from compliance with Code-required coverage when performing volumetric examinations of non-Appendix VIII pressurizer nozzle-to-vessel welds05-012 and 05-013, since during ultrasonic examination of the welds, Entergy could not obtain greater than 90 percent coverage of the required examination volume.

The U.S. Nuclear Regulatory Commission (NRC) staff reviewed the subject request and concludes, as set forth in the enclosed safety evaluation, that the ASME Code requirements are impractical for the two pressurizer spray nozzle-to-vessel welds identified above. Based on the volumetric coverage obtained for the nozzle-to-vessel weld, the NRC staff determined that it is reasonable to conclude that if significant service-induced degradation had occurred in the nozzle-to-vessel weld, evidence of degradation would have been detected in the portion that was examined. Therefore, the staff concludes that the examinations performed provide reasonable assurance of structural integrity of the nozzle-to-vessel weld of the pressurizer spray nozzle for ANO, Unit 1.

As set forth above, the NRC staff has determined that granting relief pursuant to paragraph 50.55a(g)(6)(i) of Title 10 of the Code of Federal Regulations (10 CFR) 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. Furthermore, the staff concludes that the examinations performed to the extent practical provide reasonable assurance of structural integrity of the pressurizer spray and pressurizer safety valve nozzles. Accordingly,

-2 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 for the subject examinations of the pressurizer spray and pressurizer safety valve nozzles contained in Request for Relief AN01-1 SI-021 for the ANO, Unit 1, fourth 10-year lSI interval, first period.

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 Inservice Inspector.

If you have any questions, please contact the Project Manager, Kaly Kalyanam at 301-415-1480 or via e-mail at Kaly.Kalyanam@nrc.gov.

Sincerely, Michael T. Markley, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-313

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 REQUEST FOR RELIEF AN01-ISI-021 FOR THE FIRST PERIOD OF THE FOURTH 10-YEAR INSERVICE INSPECTION INTERVAL ENTERGY OPERATIONS, INC.

ARKANSAS NUCLEAR ONE. UNIT 1 DOCKET NO. 50-313

1.0 INTRODUCTION

By letter dated July 25, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12207A594), as supplemented by letter dated February 26,2013 (ADAMS Accession No. ML13058A097), Entergy Operations, Inc. (Entergy, the licensee),

requesting that the U.S. Nuclear Regulatory Commission (NRC) grant Request for Relief AN01-ISI-021 from certain requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code),Section XI, at Arkansas Nuclear One (ANO),

Unit 1. The licensee's request is applicable to the fourth 10-year inservice inspection (lSI) interval, first period, which began on May 31, 2008, and ended on May 30,2011.

2.0 REGULATORY EVALUATION

Inservice inspection of ASME Code Class 1, 2, and 3 components is performed in accordance with Section XI of the ASME Code and applicable addenda, as required by paragraph 50.55a(g) of Title 10 of the Code of Federal Regulations (10 CFR), except where specific relief has been granted by the Commission in accordance with 10 CFR 50.55a(g)(6)(i). The regulation at 10 CFR 50.55a(a)(3) 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 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 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 lSI interval and subsequent lSI intervals comply with the Enclosure

- 2 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 ANO, Unit 1, fourth 10-year lSI interval, first, period, is the 2001 Edition through the 2003 Addenda of the ASME Code. The fourth 10-year lSI interval, first period, for ANO, Unit 1, began on May 31, 2008, and ended on May 30, 2011.

With respect to examination coverage, "essentially 100 percent" is clarified by ASME Code Case N-460, "Alternative Examination Coverage for Class 1 and Class 2 Welds,Section XI, Division 1," to be greater than 90 percent coverage of the examination volume, or surface area, as applicable. ASME Code Case N-460 has been approved for use by the NRC in Regulatory Guide 1.147, Revision 16, "Inservice Inspection Code Case Acceptability," October 2010 (ADAMS Accession No. ML101800536).

3.0 TECHNICAL EVALUATION

3.1 Code Requirement ASME Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components,"

2001 Edition through the 2003 Addenda, Table IWB-2500-1, Category B-D, "Full Penetration Welded Nozzles in Vessels -Inspection Program B," Item No. B3.110, "Nozzle-to-Vessel Welds" (Pressurizer) requires volumetric examination of 100 percent of the weld and adjacent base material as depicted in Figure IWB-2500-7(a).

Subsubarticle IWA-2230, "Volumetric Examination," of Section XI of the ASME Code identifies volumetric examination techniques that may be employed for the examinations specified in Table IWB-2500-1. The licensee elected to use ultrasonic examination techniques for examination of the subject nozzle weld. For ultrasonic examination techniques, Paragraph IWA-2232, "Ultrasonic Examination," of Section XI of the ASME Code specifies that ultrasonic examination shall be conducted in accordance with Appendix I, "Ultrasonic Examinations," to Section XI of the ASME Code. Finally, Subsubarticle 1-2120, "Other Vessels,"

of Appendix I to Section XI of the ASME Code specifies that ultrasonic examination of all other vessels greater than 2 inches in thickness shall be conducted in accordance with Article 4 of Section V of the ASME Code, as supplemented by Table 1-2000-1. Therefore, the licensee's examination was classified as "non-Appendix VIII" in RR AN01-ISI-021 indicating that the requirements of Appendix VIII, "Performance Demonstration for Ultrasonic Examination Systems," to Section XI of the ASME Code were not utilized.

3.2 Component Identification ASME Code,Section XI, Table IWB-2500-1, Examination Category B-D, "Full Penetration Welded Nozzles in Vessels - Inspection Program B," Item No. B3.11 0, "Nozzle-to-Vessel Welds."

Components: Pressurizer Spray Nozzle and Pressurizer Safety Valve Nozzle.

Welds: Pressurizer Spray Nozzle-to-Head Circumferential Weld 05-012 and Pressurizer Safety Valve Nozzle-to-Head Circumferential Weld 05-013.

-3 3.3 Licensee's Code Relief Request (as stated by the licensee)

Pursuant to 10 CFR 50.55a(g)(6)(i), Entergy Operations, Inc. (Entergy) requests relief from achieving the Code-required coverage when performing volumetric examinations of the components identified in Table 1 [of the licensee's July 25, 2012, submittal].

3.4 Licensee's Basis for Requesting Relief (as stated by the licensee)

During ultrasonic examination of the non-Appendix VIII Pressurizer Nozzle-to Vessel welds listed in Table 1 [of the licensee's July 25, 2012, submittal], greater than 90% coverage of the required examination volume could not be obtained.

Examinations were performed utilizing Entergy approved procedures specific to ferritic vessels greater than 2 inches in thickness.

Due to the geometric configuration of the components, effective volumetric examination could only be performed from the shell side of the welds. The use of 0°, 45° and 60° beam angles in the axial and circumferential direction were not able to achieve greater than 90 percent code required volume as required by Code Case N-460. See Table 1 [of the licensee's July 25, 2012, submittal] for additional information.

Radiography is not practical on these types of nozzle-to-vessel weld configurations, which prevent placement of the film and exposure source. To effectively perform any significant additional Code allowable ultrasonic examinations, modification and/or replacement of the component would be required. The examinations performed on the subject items in addition to the examination of other vessel welds contained in the Inservice Inspection program would detect generic degradation, if it existed, therefore demonstrating an acceptable level of integrity.

3.5 Licensee's Proposed Alternative Examination (as stated by the licensee)

No alternative testing is proposed at this time. Entergy has examined these welds to the extent practical and will continue to perform pressure testing on the subject components as required by the Code.

3.6 NRC Staff Evaluation 3.6.1 Pressurizer Spray Nozzle-to-Head Circumferential Weld ASME Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components,"

2001 Edition through the 2003 Addenda, Table IWB-2500-1, Category B-D, "Full Penetration Welds of Nozzles in Vessels," Item No. B3.110, "Nozzle-to-Vessel Welds," requires volumetric examination of 100 percent of the weld and adjacent base material.

-4 The design configuration of pressurizer spray nozzle-to-vessel weld precludes an ultrasonic examination of essentially 100 percent of the required volume. The component design configuration limits ultrasonic test (UT) examination coverage of the weld to 36.6 percent coverage (Table 1 of licensee's July 25, 2012, submittal). In order to examine the weld in accordance with ASME Code requirements, the pressurizer would require extensive design modifications. The physical arrangement of the pressurizer spray nozzle-to-vessel weld precludes UT examination from the nozzle side. The licensee noted in Table 1 of its submittal dated July 25, 2012, that the examination was essentially a single-sided exam from the vessel surface due to the component configuration limiting access to a single side of the weld. In response to the NRC staff's request for additional information (RAI) Questions 2 and 6 dated January 3,2013 (ADAMS Accession No. ML13003A104), the licensee specifically indicated in its letter dated February 26, 2013, that the cumulative scan coverage was reduced considerably because the scan from the nozzle side could not be performed, and the circumferential scans could not be performed completely across the Code-required surface area. In order to meet the ASME Code requirements, the nozzle and/or pressurizer would have to be modified to facilitate access for UT search units. In addition, the pressurizer spray nozzle design prevents placement of the film and exposure source for radiographic examination.

Previous examinations of the pressurizer spray nozzle were completed during the ANO, Unit 1 third 10-year lSI interval, which ended on May 30, 2008. The percentage of examination coverage obtained in the fourth 10-year lSI interval (36.6 percent coverage) was similar to the coverage (45 percent) previously reported by the licensee for the third 10-year lSI interval in AN01-ISI-001 dated December 2,2003 (ADAMS Accession No. ML033430465). Intermittent geometriC indications were identified and recorded during the fourth 10-year lSI interval inspection of Weld 05-012. As noted in the licensee's response to RAI Question 3, these indications were evaluated as non-relevant and were found to be acceptable. No other relevant indications were noted or recorded.

Based on the above, the NRC staff determined that the ASME Code requirements are impractical for the pressurizer spray nozzle-to-vessel weld and, based on the volumetric coverage obtained for the nozzle-to-vessel weld, it is reasonable to conclude that if significant service-induced degradation had occurred in the nozzle-to-vessel weld, evidence of degradation would have been detected in the portion that was examined. Therefore, the NRC staff concludes that the examinations performed provide reasonable assurance of structural integrity of the nozzle-to-vessel weld of the pressurizer spray nozzle for ANO, Unit 1.

In addition, as indicated in the licensee's February 26,2013, to the NRC staff's RAI Question 4, the pressurizer spray nozzle receives a visual (VT-2) examination in conjunction with the Class 1 System Leakage Test conducted during each refueling outage in accordance with ASME Code,Section XI. Consequently, the pressurizer spray nozzle has undergone several VT -2 examinations during past refueling outages. The VT-2 visual examinations of the nozzle area, which will continue to be performed during each refueling outage in conjunction with the ASME Code, Class 1 System Leakage Test, will provide reasonable assurance of the leak tightness of the nozzle-to-vessel weld because the system leakage test will provide for detection of flaws when they are small and can be repaired prior to the pressurizer spray nozzle losing its ability to perform its intended function.

- 5 3.6.2 Pressurizer Safety Valve Nozzle-to-Head Circumferential Weld The same requirements specified for the pressurizer spray nozzle-to-head circumferential also weld apply to the pressurizer safety valve nozzle-to-head circumferential weld. Therefore, ASME Code,Section XI, Table IWB-2500-1, Category B-D, "Full Penetration Welds of Nozzles in Vessels," Item No. B3.11 0, "Nozzle-to-Vessel Welds" requires volumetric examination of 100 percent of the weld and adjacent base material for this nozzle.

The design configuration of pressurizer safety valve nozzle-to-vessel weld precludes a UT examination of essentially 100 percent of the required volume. The component design configuration limits UT examination coverage of the weld to 42 percent coverage (Table 1 of the licensee's July 25, 2012, submittal). In order to examine the weld in accordance with ASME Code requirements, the pressurizer would require extensive design modifications. The physical arrangement of the pressurizer safety valve nozzle-to-vessel weld precludes UT examination from the nozzle side. The licensee noted in Table 1 of its submittal dated July 25,2012, that the examination was essentially a single-sided exam from the vessel surface due to the component configuration limiting access to a single side of the weld. In response to the NRC RAI Questions 2 and 6, the licensee specifically indicated in its letter dated February 26, 2013, that the cumulative scan coverage was reduced considerably because the scan from the nozzle side could not be performed, and the circumferential scans could not be performed completely across the Code-required surface area. In order to meet the ASME Code requirements, the nozzle and/or pressurizer would have to be modified to facilitate access for UT search units. In addition, the pressurizer safety valve nozzle design prevents placement of the film and exposure source for radiographic examination.

Previous examinations of the pressurizer safety valve nozzle were completed during the AND, Unit 1 third 10-year lSI interval, which ended on May 30,2008. The percentage of examination coverage obtained in the fourth 10-year lSI interval (40 percent coverage) was similar to the coverage (38 percent) previously reported by the licensee for the third 10-year lSI interval in AND1-ISI-001 dated December 2,2003. Intermittent geometric indications were identified and recorded during the fourth 10-year lSI interval inspection of Weld 05-013. As noted in the licensee's response to NRC RAI Question 3, these indications were evaluated as non-relevant and were found to be acceptable. No other relevant indications were noted or recorded.

Based on the above, the NRC staff determined that the ASME Code requirements are impractical for the pressurizer spray nozzle-to-vessel weld and, based on the volumetric coverage obtained for the nozzle-to-vessel weld, it is reasonable to conclude that if significant service-induced degradation had occurred in the nozzle-to-vessel weld, evidence of degradation would have been detected in the portion that was examined. Therefore, the staff concludes that the examinations performed provide reasonable assurance of structural integrity of the nozzle to-vessel weld of the pressurizer safety valve nozzle for AND, Unit 1.

In addition, as indicated in the licensee's letter dated February 26,2013, in response to the staff's RAI Question 4, the pressurizer safety valve nozzle receives a visual (VT-2) examination in conjunction with the Class 1 System Leakage Test conducted during each refueling outage in accordance with ASME Code,Section XI, requirements to complement the limited examination coverage. Consequently, the pressurizer safety valve nozzle has undergone several VT-2 examinations during past refueling outages. The VT -2 visual examinations of the nozzle area,

- 6 which will continue to be performed during each refueling outage in conjunction with the ASME Code, Class 1 System Leakage Test, will provide reasonable assurance of the leak tightness of the nozzle-to-vessel weld because the system leakage test will provide for detection of flaws when they are sma" and can be repaired prior to the pressurizer safety valve nozzle losing its ability to perform its intended function.

4.0 CONCLUSION

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.

Furthermore, the staff concludes that the examinations performed to the extent practical provide reasonable assurance of structural integrity of the pressurizer spray and pressurizer safety valve nozzles. 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 for the subject examinations of the pressurizer spray and pressurizer safety valve nozzles contained in Request for Relief AN01-ISI-021 for the ANO, Unit 1, fourth 10-year lSI interval, first period.

All other ASME Code,Section XI requirements for which relief was not specifically requested and approved in the subject request for relief remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.

Principal Contributors: G. Stevens J. Poehler Date: July 16. 2013

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 for the subject examinations of the pressurizer spray and pressurizer safety valve nozzles contained in RequestforReliefAN01-ISI-021 for theANO, Unit 1, fourth 10-year lSI interval, first period.

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 Inservice Inspector.

If you have any questions, please contact the Project Manager, Kaly Kalyanam at 301-415-1480 or via e-mail at Kaly.Kalyanam@nrc.gov.

Sincerely, Ira!

Michael T. Markley, Chief Plant licensing Branch IV Division of Operating Reactor licenSing Office of Nuclear Reactor Regulation Docket No. 50-313

Enclosure:

Safety Evaluation cc w/encl: Distribution via ListServ DISTRIBUTION:

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