ML092530274

Fourth 10-Year Inservice Inspection Plan - Nondestructive Examination

ML092530274
Person / Time
Site:	North Anna
Issue date:	09/28/2009
From:	Jacqueline Thompson Plant Licensing Branch II
To:	Heacock D Virginia Electric & Power Co (VEPCO)
Sreenivas V.NRR/DORL/LPL2-1 415-2597
References
TAC ME0268, TAC ME0269
Download: ML092530274 (10)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 September 28, 2009 Mr. David A. Heacock President and Chief Nuclear Officer Virginia Electric and Power Company Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711 SUB..IECT:

NORTH ANNA POWER STATION, UNIT NO.1 - FOURTH 10-YEAR INSERVICE INSPECTION PLAN NONDESTRUCTIVE EXAMINATION (TAC NOS. ME0268 AND ME0269)

Dear Mr. Heacock:

By letter dated October 7,2008 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML082880160), as supplemented by letter dated January 30, 2009 (ADAMS Accession No. ML090330392), Virginia Electric and Power Company (the licensee) requested relief from certain requirements of Section XI of the American Society of Mechanical Engineers, Boiler and Pressure Vessel Code (ASME Code), under the provisions of Title 10 of the Code of Federal Regulations (10 CFR), Part 50, Section 50.55a for the fourth 10-year Inservice Inspection (lSI) Interval for North Anna Power Station, Unit No.1. Although the October 7, 2008, letter addresses relief request (RR) NDE-004 on nondestructive examination for Class 1 components regarding preemptive weld overlay on pressurizer dissimilar metal welds, by the letter dated August 24, 2009 (ADAMS Accession No. ML092370690), the licensee withdrew RR NDE-004.

The U.S. Nuclear Regulatory Commission (NRC) staff finds that the proposed alternative and inservice examinations pertaining to weld overlays of the six dissimilar metal welds, provide an acceptable level of quality and safety. Therefore, the NRC staff authorizes the alternative in RR NDE-005 pursuant to 10 CFR 50.55a(a)(3)(i) for the fourth 10-year lSI interval.

The fourth 10-year lSI program for components and component supports is scheduled to be completed by April 30, 2019.

D. Heacock

- 2 All other requirements of the ASME Code,Section XI for which relief has not been specifically requested remain applicable, including a third-party review by the Authorized Nuclear Inservice Inspector. If you have any questions concerning this matter, please contact Dr. V. Sreenivas at (301) 415-2597.

Sincerely, Jon Thompson, Acting Branch Chief Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-338

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 FOURTH 10-YEAR INSERVICE INSPECTION INTERVAL PROGRAM RELIEF NDE-005 FOR PREEMPTIVE WELD OVERLAY ON PRESSURIZER DISSIMILAR METAL WELDS EXAMINATION NORTH ANNA POWER STATION, UNIT NO.1 VIRGINIA ELECTRIC AND POWER COMPANY DOCKET NO. 50-338

1.0 INTRODUCTION

By letter dated October 7, 2008, (Agencywide Documents Access and Management System (ADAMS) Accession No. ML082880160), as supplemented by letter dated January 30, 2009 (ADAMS Accession No. ML090330392),Virginia Electric and Power Company (the licensee),

submitted Relief Request (RR) NDE-005 for its fourth 10-year inservice inspection (lSI) interval for component and component support welds examination at North Anna Power Station Unit 1 (NAPS 1). The licensee requested relief from certain lSI and examination requirements of the American Society of Mechanical Engineers, Boiler and Pressure Vessel Code (ASME Code),

Section XI, lSI program.

Relief Request (RR) NDE-005 of the lSI plan pertains to lSI of weld overlays of six dissimilar metal butt welds (DMW) on the pressurizer that were installed in the third lSI interval in 2007.

By letter dated December 19,2007, the U.S. Nuclear Regulatory Commission (NRC) staff approved the original RR (CMP-022, Revision 1) for the weld overlay design and lSI of the six DMWs (ADAMS Accession No. ML072220228). Relief Request NDE-005 is a continuation of the original RR CMP-022, Revision 1, to be applied in the fourth lSI interval at NAPS 1. By letter dated May 4, 2009 (ADAMS Accession No. ML0912503570), the licensee provided its response to the staff's request for additional inform1tion regarding RR NDE-005.

The NRC staff has evaluated the licensee's RR and determined that the proposed alternative provide an acceptable level of quality and safety for NDE-005, pursuant to Title 10 of the Code of Federal Regulations (10 CFR), Part 50, Section 50.55a(a)(3)(i) for the fourth 10-year lSI interval scheduled to be completed by April 30, 2019.

ENCLOSURE

- 2 2.0 REGULATORY REQUIREMENTS According 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 In-service 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 in-service 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 and subject to Commission approval. The applicable edition of the Code for NAPS-1, 4th 10-year lSI interval, which began May 1, 2009, is the 2004 Edition of the ASME Code,Section XI with no addenda.

As stated in 10 CFR 50.55a(a)(3), the NRC may allow for alternatives to the requirements from paragraph (g)(4) of the regulations that are stated above if (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.

3.0 TECHNICAL EVALUATION

3.1 Request for Relief NDE-005, Pertaining to lSI of weld overlays of six DMW on the pressurizer 3.1.1 System/Components for which Alternative is Requested

1. Weld No. SW-51, 14-inch RCS Safe-End Reducer-To-Surge Nozzle Weld, Category B-F; and adjacent Pipe-to-Safe-End Reducer Weld No. 39, Category B-J. (Pipe Identifier 14-RC-10-2501 R-Q1).

2. Weld No. SW-30, 6-inch Safe-End-to-Safety Nozzle-Weld, Category B-F; and adjacent Elbow-to-Safe-End Weld No. 21, Category B-J (Pipe Identifier 6-RC-38-1502-Q1).

3. Weld No. SW-31, 6-inch Safe-End-to-Safety Nozzle-Weld, Category B-F; and adjacent Elbow-to-Safe-End Weld No. 17, Category B-J (Pipe Identifier 6-RC-39-1502-Q1).

4. Weld No. SW-38, 6-inch Safe-End-to-Safety Nozzle-Weld, Category B-F; and adjacent Elbow-to-Safe-End Weld No. 25, Category B-J (Pipe Identifier 6-RC-37-1502-Q 1).

5. Weld No. SW-64, 6-inch Safe-End-to-Relief Nozzle-Weld, Category B-F; and adjacent 6X4 Concentric Reducer-to-Safe-End Weld No. 30, Category B-J (Pipe Identifier 4-RC-34-1502-Q1).

6. Weld No. SW-71, 4-inch Safe-End-to-Spray Nozzle-Weld, Category B-F; and.adjacent Pipe-to-Safe End Weld No. 11, Category B-J (Pipe Identifier 4-RC-15-1502-Q1).

- 3 3.1.2 ASME Code Requirements The following paragraphs of the ASME Code,Section XI, are applicable to the affected DMWs listed above.

1. The ASME Code,Section XI, 2004 Edition, paragraph IWA-2232, requires that the ultrasonic volumetric examination of welds be performed in accordance with Appendix I which in turn requires that the examinations be performed in accordance with Supplement 11 of Appendix VIII of the ASME Code,Section XI.

2. The ASME Code,Section XI, 2004 Edition, paragraph IWB-2500, specifies the extent, frequency, and acceptance criteria for examinations of the welds, but does not provide requirements for structural overlay welds.

3. The ASME Code,Section XI, 2004 Edition, paragraph IWB-2430, specifies requirements for the examinations of supplemental welds, if unacceptable indications are identified as the result of the required examinations.

3.1.3. Basis For Alternative The licensee stated that DMWs, primarily consisting of Alloy 82/182 weld metal are used in pressurized-water reactor construction to connect stainless steel pipe and safe-ends to reactor vessel nozzles, which are generally constructed of carbon or low alloy ferritic steel. Operating experience has shown that DMWs are susceptible to primary water stress-corrosion cracking (PWSCC), especially in components sUbjected to higher operating temperatures, such as the pressurizer.

During the NAPS 1 fall 2007 refueling outage, the licensee installed full structural preemptive weld overlays (PWOLs) on the subject six DMWs located on the pressurizer. Due to their proximity, the PWOLs also were extended across the adjacent stainless steel pipe/fitting/elbow to-safe-end weld. Repair/replacement activities associated with PWOLs are required to address examination techniques and procedure requirements. Comprehensive and generic NRC approved criteria are not currently available for application of PWOL repairs to DMWs. In addition, the ASME Code,Section XI, or associated Code Cases, do not provide approved industry requirements/criteria for examination of the PWOL, but do provide criteria for the examination of the overlaid welds.

As part of this repair/replacement activity performed in the fall of 2007, NAPS 1 committed, in part, to perform an ultrasonic volumetric inservice examination of 25 percent of the PWOL welds once every 10 years. Specific alternative examination requirements were included in the third interval request for relief, CMP-022, Revision 1, approved by the NRC for the application of the overlays. These alternative examination requirements are also applicable to the performance of the associated fourth interval examination commitments. Therefore, NAPS 1 requested approval to use the applicable alternatives in the fourth interval and requests the proposed alternative shall be met in lieu of all other examination requirements.

The licensee stated that nondestructive examination methods shall be in accordance with IWA-2200 of the ASME Code,Section XI, except as specified in RR NDE-005.

-4 Nondestructive examination personnel shall be qualified in accordance with IWA-2300.

Ultrasonic examination procedures and personnel shall be qualified in accordance with Appendix VIII, Supplement 11.

3.1.4 Proposed Alternatives to Supplement 11, Appendix VIII, 2001 Edition of Section XI The licensee stated that the ultrasonic examination of the installed PWOLs and the first inservice examination, were performed in accordance with the ASME Code,Section XI, 1989 Edition with compliance to the 1995 Edition, including Addenda through 1996, Appendix VIII, Supplement 11, with the alternatives used for complying with the current requirements of the Performance Oemonstration Initiative (POI) Program. The ultrasonic vOlumetric examinations in the fourth interval will be performed in accordance with the requirements of ASME Section XI, 2001 Edition, Appendix VIII, Supplement 11. The requirements to be used in the fourth interval are essentially the same as those used in the third interval; therefore, the same alternatives to comply with the current requirements of the POI are proposed.

The proposed alternative paragraphs were part of the POI protocol that qualified the examination procedures and personnel who performed the pre-service and inservice examinations in the third inspection interval. To change the basis of the POI, qualification may cause the qualification performed to support the initial examinations to no longer be acceptable.

Requalification of the POI may be necessary. Based on the current positions of the POI in implementing the requirements, it may be difficult to meet the original protocol as presented in the 2001 Edition. The licensee believes that implementation of the 2001 Edition of Section XI,

Appendix VIII, Supplement 11, modified as requested, is consistent with current industry practice and provides an acceptable level of quality and safety.

3.1.5. Proposed Additional Alternatives to Examination Requirements of Section XI (a) Examination Requirements (1) As a minimum, 25 percent of the subject welds shall be examined ultrasonically during the fourth lSI interval.

(2) The weld overlay examination volume in Fig. 2 of Relief Request (\\JDE-005, shall be ultrasonically examined to determine if any new or existing cracks have propagated into the upper 25 percent of the base material or into the overlay. The angle beam shall be directed perpendicular and parallel to the piping aXis, with scanning performed in four directions.

(3) The inservice examination acceptance standards of Table IWB-3514-2 of the ASME Code,Section XI, shall be met for the weld overlay. If the acceptance criteria of Table IWB-3514-2 cannot be met, the acceptance criteria of IWB-3600 shall be met for the weld overlay. Cracks in the outer 25 percent of the base metal shall meet the design analysis requirements of, Crack Growth and Oesign.

(4) If inservice examinations reveal crack growth or new cracking which meet the acceptance criteria of IWB-3514, IWB-3600, the weld overlay examination volume shall be reexamined during the first or second refueling outage following discovery of the growth or new cracking.

- 5 (5) For weld overlay examination volumes with unacceptable indications according to paragraph (a)(3) above, the weld overlay shall be removed, including the original defective weld, and the item shall be corrected by a repair/replacement activity in accordance with IWA-4000 of the ASME Code,Section XI.

(b) Additional Examinations If inservice examinations reveal an unacceptable indication according to paragraph (a)(3) above, crack growth into the weld overlay design thickness, or axial crack growth beyond the specified examination volume, additional weld overlay examination volumes equal to the number scheduled for the current inspection period shall be examined prior to being returned to service. If additional unacceptable indications are found in the second sample, a total of 50 percent of the total population of weld overlay examination volumes shall be examined prior to operation. If additional unacceptable indications are found, the entire remaining population of weld overlay examination volumes shall be examined prior to return to service.

The proposed alternative requirements of the request will allow the initial program established for the PWOLs to continue into the fourth interval. This set of alternatives establish an examination program for the subject welds in the fourth inspection interval that is consistent with the requirements established at the time the PWOLs were approved for the fall of 2007. As was established by their initial approval, these alternatives used in conjunction with the remaining requirements of Section XI provide an acceptable level of quality and safety.

3.1.6 Duration of the Proposed Relief Request The licensee requested that RR NDE-005 be approved for the duration of the fourth 10-year lSI interval.

3.2 Staff Evaluation By letter dated January 3,2007, and as supplemented by letters dated March 13, May 16, June 15, July 25, and October 1, 2007, the licensee submitted RR CMP-022, Revision 1, for the weld overlay design to be applied to the six subject DMWs on the pressurizer at NAPS 1.

By letter dated December 19,2007, the NRC staff approved the weld overlay design and installation for the third lSI interval, including the requirements for the ambient temperature temper bead welding process, stress analyses, crack growth calculations, acceptance, pre service and in-service examinations, and POI alternative.

Relief Request NDE-005 is a continuation of RR CMP-022, Revision 1. The PWOLs have already been installed on the subject DMWs on the pressurizer in accordance with RR CMP-022, Revision 1, in 2007. The licensee also has performed acceptance and pre service examinations of the overlaid DMWs after overlay installation in 2007. Therefore, for RR NDE-005, the NRC staff will not repeat the same safety evaluation for RR CMP-022, Revision 1, as shown in the December 19,2007, letter.

Instead, the NRC staff focused its evaluation of RR NDE-005 on the in-service examination requirements of the overlaid DMWs. The staff evaluated the differences between RRs NDE-005 and CMP-022, Revision 1. The NRC staff also evaluated NDE-005 to ensure that it satisfies the

- 6 requirements of Code Case N-504-3 and Appendix Q of the ASME Code,Section XI, in accordance with 10 CFR 50.55a.

Code Case N-504-3 of the ASME Code,Section XI, allows the use of weld overlay repair by deposition of weld reinforcement on the outside surface of the pipe. NRC Regulatory Guide 1.147, Revision 15, requires Nonmandatory Appendix Q of the ASME Code,Section XI, be used when using Code Case N-504-3.

Section liLA of RR NDE-005 states that procedures and personnel qualified to ASME Code,Section XI, Appendix VIII, Supplement 11, as modified by Attachment 1 of RR NDE-005 will be used in the IS inspection. Supplement 11 is for the examination of wrought stainless steel piping and weld overlays. The NRC staff requested that the licensee provide a description of the base material, weld/butter material, and overlay material to determine whether the materials in the DMWs are applicable under Supplement 11. In the May 4, 2009, letter, the licensee identified the materials as follows:

Pressurizer nozzles are made of low alloy steel SA-508, Class 2 (P-No. 3 Group No.3).

Safe-end-to-nozzle weld and buttering are made of Alloy 82/182 (F-No. 43). Safe ends are (P-l'Jo. 8) wrought stainless steel SA-182, Grade F316L. The surge line, safety line elbows, relief line reducer, and spray line pipe are made of wrought seamless stainless steel (P-No. 8) and welds are stainless steel (A-NO.8). The weld overlay used ERNiCrFe-7 (Alloy 52) or ERNiCrFe-7A (Alloy 52M) weld material.

The NRC staff finds that these material specifications are consistent with the material specifications in the original NRC-approved RR CMP-022, Revision 1; therefore, they are acceptable to be covered under Supplement 11 of Appendix VIII to the ASME Code,Section XI.

The proposed inservice examination requirements are similar to the examination requirements of Section XI, Appendix Q, for lSI. One of the requirements in RR NDE-005 is for ultrasonic examination of overlays during the first or second refueling outage following installation. The NRC staff asked the licensee to discuss whether such examinations have been performed or plans to do so in the fourth lSI interval. In the May 4, 2009, letter, the licensee responded that the overlay, for the subject DMWs were installed in 2007, and examinations of these overlaid DMWS were completed during the spring 2009 outage for NAPS 1. Examinations in the fourth interval will be performed in accordance with RR NDE-005. The NRC staff finds that the licensee has inspected the overlaid DMWs in accordance with the requirements of the NRC approved Relief Request CMP-022, Revision 1. The NRC staff finds that the inservice examination requirements in RR NDE-005 are consistent with that of CMP-022, Revision 1, and Appendix Q of the ASME Code,Section XI. The NRC staff also finds that the licensee has followed the examination requirements of NDE-005 during the fourth lSI interval in performing the first lSI of the subject DMWs.

Section III.B.(a)(3) of Relief Request NDE-005 states that, "... The inservice examination acceptance standards of Table IWB-3514-2 shall be met for the weld overlay. If the acceptance criteria of Table IWB-3514-2 cannot be met, the acceptance criteria of IWB-3600 shall be met for the weld overlay. Cracks in the outer 25% of the base metal shall meet the design analysis requirements of Attachment 2, Crack Growth and Design... " According to the Electric Power Research Institute report, MRP-139, "Primary System Piping Butt Weld Inspection and Evaluation GUide," the weld overlay material must be resistant to pressurized water stress

- 7 corrosion cracking (PWSCC). The NRC staff asked the licensee to address acceptance criteria in case PWSCC occurs in the weld overlays.

In its May 4, 2009, letter, the licensee responded that if flaw growth in the weld overlay occurs and the acceptance standards of Table IWB-3514.2 cannot be met, a determination will be made to show if the flaw is not PWSCC. If the cause is determined to be PWSCC, or the cause of the flaw cannot be determined, NAPS will repair the flaw and will not use IWB-3600 of ASME Code,Section XI, to accept these types of flaws. The NRC staff finds that the licensee's response is acceptable because the proposed acceptance criteria to disposition the flaws in the weld overlays are consistent with the NRC staff position in that IWB-3600 of the ASME Code,Section XI, cannot be used to allow PWSCC in the weld overlay.

The NRC staff finds that the inservice examinations of the subject overlaid DMWs in RR NDE-005 are acceptable because they satisfy the requirements of Code Case N-504-3 and Appendix Q of the ASME Code,Section XI. The NRC staff also finds that RR NDE-005 is consistent with the NRC-approved RR CMP-022, Revision 1, and the licensee has performed the first lSI of the overlaid DMWs.

4.0 CONCLUSION

On the basis of its review, the NRC staff has determined that RR NDE-005 will provide an acceptable level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(a)(3)(i), the NRC staff authorizes the use of RR NDE-005 for the full structural PWOL of DMWs on the pressurizer surge line, safety valve, and relief valve nozzles at NAPS 1. The effective period of NDE-005 is the fourth 1O-year lSI interval at NAPS 1.

All other ASME Code,Section XI requirements for which relief was not specifically requested and approved in this relief request remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector Principal Contributor: John C. Tsao, DCI/CPNB Date: September 28,2009

D. Heacock

- 2 All other requirements of the ASME Code,Section XI for which relief has not been specifically requested remain applicable, including a third-party review by the Authorized Nuclear Inservice Inspector. If you have any questions concerning this matter, please contact Dr. V. Sreenivas at (301) 415-2597.

Sincerely, IRA!

Jon Thompson, Acting Branch Chief Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-338

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• b>y memo da e t d OFFICE NRRlLPL2-1/PM NRRlLPD2-1/LA NRRlDCI/BC NRRlLPL2-1/(A)BC NAME VSreenivas (KCotton for)

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.IThompson DATE 09/22/09 09/25/09 8/03/09 09/28/09 OFFICIAL RECORD COPY