ML14251A468

Relief Request NDE-SFW-13, ASME Code Section XI, Request for Alternative to Allow Use of Alternate Examination Requirements, Third 10-Year Inservice Inspection Interval

ML14251A468
Person / Time
Site:	Diablo Canyon
Issue date:	09/16/2014
From:	Eric Oesterle, Balwant Singal Plant Licensing Branch IV
To:	Halpin E Pacific Gas & Electric Co
Watford M
References
TAC MF3284, TAC MF3285
Download: ML14251A468 (7)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 September 16, 2014 Mr. Edward D. Halpin Senior Vice President and Chief Nuclear Officer Pacific Gas and Electric Company Diablo Canyon Power Plant P.O. Box 56, Mail Code 104/6 Avila Beach, CA 93424

SUBJECT:

DIABLO CANYON POWER PLANT, UNIT NOS. 1 AND 2- REQUEST FOR ALTERNATIVE NDE-SFW-13, ASSOCIATED WITH THE THIRD 10-YEAR INSERVICE INSPECTION INTERVAL, REGARDING REACTOR VESSEL SHELL-TO-FLANGE WELD EXAMINATIONS (TAC NOS. MF3284 AND MF3285)

Dear Mr. Halpin:

By letter dated December 18, 2013, as supplemented by letter dated August 12, 2014, Pacific Gas and Electric Company (the licensee) submitted a request to the U.S. Nuclear Regulatory Commission (NRC) for the use of alternatives to certain American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI requirements at Diablo Canyon Power Plant (DCPP), Unit 1 and 2, for the third 10-year in service inspection (lSI) program interval.

Specifically, pursuant to Title 10 of the Code of Federal Regulations (1 0 CFR) paragraph 50.55a(a)(3)(i), the licensee requested to use the proposed alternative on the basis that the alternative provides an acceptable level of quality and safety. ASME Code,Section XI, IWA-2232 requires that ultrasonic examinations be conducted in accordance with the ASME Code,Section XI, Appendix I. Appendix I, 1-2110 requires that ultrasonic examinations of the reactor pressure vessel (RPV) shell-to-flange weld be conducted in accordance with the ASME Code,Section V, Article 4. The licensee proposed alternative NDE-SFW-13 to use an examination that will be performed using examination procedures, personnel, and equipment qualified in accordance with ASME Code,Section XI, Appendix VIII, Supplements 4 and 6, as modified by 10 CFR 50.55a.

The NRC staff has completed its review of the relief request as discussed in the enclosed safety evaluation. The NRC staff concludes that in lieu of the ASME Code,Section V, Article 4, the procedures, equipment, and personnel qualified to the ASME Code Section XI, Appendix VIII requirements have proven to be at least as effective as the prescriptive requirements of ASME Code,Section XI, Appendix Ill. The NRC staff has determined that the alternative examinations described in request for alternative NDE-SFW-13 provides an acceptable level of quality and safety. Therefore, the NRC staff authorizes the use of alternative NDE-SFW-13 pursuant to 10 CFR 50.55a(a)(3)(i) for the DCPP, Unit 1 and 2 for the duration of the third 10-year lSI interval, nominally scheduled to end on May 6, 2015, and March 12, 2016, respectively.

E. Halpin All other ASME Code,Section XI requirements for which relief was not specifically requested and authorized in the subject proposed alternative remain applicable, including third-party review by the Authorized Nuclear In-service Inspector.

If you have any questions, please contact the Diablo Canyon Project Manager, Balwant Singal, at 301-415-3016 or via e-mail at Balwant.Singal@nrc.gov.

Sincerely, Eric R. Oesterle, Acting Chief Plant Licensing Branch IV-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-275 and 50-323

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 ALTERNATIVE NDE-SFW-13 FOR THE THIRD 10-YEAR INSERVICE INSPECTION INTERVAL PACIFIC GAS AND ELECTRIC COMPANY DIABLO CANYON POWER PLANT, UNITS 1 AND 2 DOCKET NOS. 50-275 AND 50-323

1.0 INTRODUCTION

By letter dated December 18, 2013, as supplemented by letter dated August 12, 2014 (Agencywide Documents Access and Management System (ADAMS) Accession Nos. ML13353A475 and ML14224A658, respectively), Pacific Gas and Electric Company (the licensee), submitted a request to the U.S. Nuclear Regulatory Commission (NRC) for relief from the requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI to use an inspection procedure qualified to ASME Code,Section V, Article 4 inspections of the reactor pressure vessel (RPV) shell-to-flange weld for the third 10-year inservice inspection (lSI) program interval for Diablo Canyon Power Plant (DCPP),

Unit 1 and 2.

Specifically, pursuant to Title 10 of the Code of Federal Regulations (1 0 CFR) paragraph 50.55a(a)(3)(i), the licensee proposed to use alternative NDE-SFW-13 in lieu of ASME Code,Section XI, IWA-2232, which requires that ultrasonic examinations be conducted in accordance with the ASME Code,Section XI, Appendix I. Appendix I, 1-2110 requires that ultrasonic examinations of the RPV shell-to-flange weld be conducted in accordance with the ASME Code,Section V, Article 4. The proposed alternative uses an examination that will be performed using examination procedures, personnel, and equipment qualified in accordance with ASME Code,Section XI, Appendix VIII, Supplements 4 and 6, as modified by 10 CFR 50.55a.

2.0 REGULATORY EVALUATION

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 pre-service examination requirements, set forth in the ASME Code,Section XI, "Rules for lSI of Nuclear Power Plant Components," to the extent practical within the limitations of design, geometry, and materials of construction of the components.

Enclosure

However, 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 licensee 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.

Based on analysis of the regulatory requirements, the NRC staff concludes that regulatory authority exists to authorize the proposed alternative pursuant to 10 CFR 50.55a(a)(3).

3.0 TECHNICAL EVALUATION

3.1 ASME Code Component Affected and Applicable Code Edition and Addenda ASME Code,Section XI, Class 1, RPV shell-to-flange welds:

Category I Item Description Weld Number B-A I B1.30 Shell-to-Flange Weld 7-442 (Unit 1)

B-A I B1.30 Shell-to-Flange Weld 7-201 (Unit 2)

The DCPP Unit 1 third 10-year lSI interval began on January 1, 2006, and is nominally scheduled to end May 6, 2015. The Unit 2 DCPP Unit 2 third 10-year lSI interval began on July 1, 2006, and is nominally scheduled to end March 12, 2016.

The DCPP Units 1 and 2 third 10-year interval lSI program plan is based on the ASME Code,Section XI, 2001 Edition with 2003 Addenda. ASME Code Section XI, 2001 Edition without Addenda applies to ultrasonic test (UT) examinations performed per ASME Code Section XI, Appendix VIII requirements.

3.2 Applicable Code Requirements (As Stated)

ASME Code,Section XI, Table IWB-2500-1, Category B-A, Item B1.30, requires that RPV shell-to-flange welds be volumetrically examined once during each lSI interval. ASME Code,Section XI, Subsection IWA-2232, requires that the UT examination of reactor pressure vessel (RPV) shell-to-flange welds to be performed per the requirements of ASME Code,Section V, Article 4, as supplemented by Appendix I of Section XI. The examination volume extent is identified in the ASME Code,Section XI, Figure IWB-2500-4, "Shell-To-Flange Weld Joint."

3.3 The Licensee's Proposed Alternative and Basis for Use As stated by the licensee in letter dated December 18, 2013:

Pursuant to 10 CFR 50.55a(a)(3)(i), PG&E requests authorization to use the alternate requirements of ASME Code,Section XI, 2001 Edition with no Addenda, Appendix VIII, Supplements 4 and 6, as amended by 10 CFR 50.55a

and implemented by the PDJ for examination of the shell-to-flange weld when examined from the vessel shell. The Appendix VIII requirements will be implemented in lieu of ASME Code,Section XI, IWA-2232 that requires UT examination of the RPV shell-to-flange weld to be in accordance with ASME Code,Section V, Article 4, as supplemented by Appendix I of Section XI.

The proposed alternate ASME Code,Section XI, Appendix VIII requirements were established to improve the effectiveness of UT examinations by means of a rigorous, item-specific, performance demonstration. The performance demonstration process verifies the capability of personnel, procedures, and equipment to detect and characterize flaws that could be detrimental to the structural integrity of the RPV. Since implementation, this process has shown improved performance as compared to the prescriptive requirements of ASME Code,Section V, Article 4.

NRC report, NUREG/CR-7165, Revision 2, "The Technical Basis Supporting ASME Code,Section XI, Appendix VIII: Performance Demonstration for Ultrasonic Examination Systems,"

May 2013 (ADAMS Accession No. ML13144A107}, states, in part, that: "There is clear evidence that the performance demonstration requirements adopted by Section XI of the ASME Code for Boiler and Pressure Vessels has resulted in a positive impact on the reliability of ultrasonic examinations that are performed on piping and pressure vessels ... "

Further, as stated by the licensee in letter dated December 18, 2013:

Although an ASME Code,Section XI, Appendix VIII qualified [examination]

process is not required for the examination of the reactor vessel shell-to-flange welds, the use of the Appendix VIII, Supplements 4 and 6 process for detection and sizing of flaws in this weld has been shown to exceed the performance of the ASME Code Section V, Article 4 prescriptive examination process.

3.4 NRC Staff Evaluation The licensee proposed to use an examination that will be performed using examination procedures, personnel, and equipment qualified in accordance with ASME Code,Section XI, Appendix VIII, Supplements 4 and 6, as modified by 10 CFR 50.55a. This ASME Code,Section XI, Appendix VIII qualified examination would be used in lieu of the requirements of the ASME Code,Section V, Article 4. ASME Code,Section XI, Appendix VIII is a performance-based UT qualification method and has proven to be at least as effective as the prescriptive requirements of ASME Code,Section XI, Appendix Ill. Performance-based UT requires that detailed criteria be used for performance demonstration tests. The results for the tests are compared against statistically developed screening criteria. The tests are performed on representative mockups containing flaws similar to those found in operating plants, and demonstrate the effectiveness of UT personnel and procedures.

The 2001 Edition through the 2003 Addenda of the ASME Code,Section XI, IWA-2232 states, "Ultrasonic examination shall be conducted in accordance with Appendix 1." The ASME Code,Section V, Article 4 provides a prescriptive process for qualifying UT of procedures and the

scanning requirements for examinations. The UT performed to ASME Code Section V, Article 4 uses detailed criteria for setting up and calibrating equipment, calculating coverage and detecting indications. The capability of an ASME Code,Section V, Article 4, UT examination is demonstrated with calibration blocks made from representative material containing holes and notches.

In lieu of ASME Code,Section V, Article 4, the procedures, equipment, and personnel qualified to ASME Code,Section XI, Appendix VIII have shown a high probability of flaw detection, and have increased the reliability of examinations of weld configurations within the scope of the PDI program as documented in NRC report NUREG/CR-7165, Revision 2. Therefore, the NRC staff concludes that the proposed alternative will provide an acceptable level of quality and safety and meets the requirements as set forth in 10 CFR 50.55a(a)(3)(i).

4.0 CONCLUSION

As set forth above, the NRC staff concludes that in lieu of the ASME Code,Section V, Article 4, the procedures, equipment, and personnel qualified to the ASME Code,Section XI, Appendix VIII requirements have proven to be at least as effective as the prescriptive requirements of ASME Code,Section XI, Appendix Ill. The NRC staff has determined that the alternative examinations described in request for alternative NDE-SFW-13 provides an acceptable level of quality and safety. Therefore, the NRC staff authorizes the use of alternative NDE-SFW-13 pursuant to 10 CFR 50.55a(a)(3)(i) for the DCPP, Units 1 and 2 for the duration of the third 10-year lSI interval, nominally scheduled to end on May 6, 2015, and March 12, 2016, respectively.

All other ASME Code,Section XI requirements for which relief was not specifically requested and authorized in the subject proposed alternative remain applicable, including third-party review by the Authorized Nuclear In-service Inspector.

Principal Contributor: Stephen Cumblidge, NRR Date: September 16, 2014

E. Halpin All other ASME Code,Section XI requirements for which relief was not specifically requested and authorized in the subject proposed alternative remain applicable, including third-party review by the Authorized Nuclear In-service Inspector.

If you have any questions, please contact the Diablo Canyon Project Manager, Balwant Singal, at 301-415-3016 or via e-mail at Balwant.Sinqal@ nrc.qov.

Sincerely, IRA/

Eric R. Oesterle, Acting Chief Plant Licensing Branch IV-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-275 and 50-323

Enclosure:

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