ML13071A634

Relief Request ANO2-ISI-014, from Volumetric and Surface Exam Requirements for Pressure Retaining Welds in Austenitic Stainless Steel, Third 10-Year Inservice Inspection Interval

ML13071A634
Person / Time
Site:	Arkansas Nuclear
Issue date:	03/22/2013
From:	Markley M Plant Licensing Branch IV
To:	Entergy Operations
Kalyanam N
References
TAC ME8269
Download: ML13071A634 (9)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 March 22,2013 Vice President, Operations Arkansas Nuclear One Entergy Operations, Inc.

1448 S.R. 333 Russellville, AR 72802

SUBJECT:

ARKANSAS NUCLEAR ONE, UNIT 2 - REQUEST FOR RELIEF AN02-ISI-014 FROM ASME CODE, SECTION XI, REQUIREMENTS FOR CATEGORY C-F-1 WELDS FOR THE THIRD 10-YEAR INSERVICE INSPECTION INTERVAL (TAC NO. ME8269)

Dear Sir or Madam:

By letter dated March 26, 2012, as supplemented by letter dated February 5, 2013, Entergy Operations, Inc. (the licensee), proposed Request for Relief (RR) No. AN02-ISI*014 (in addition to other RRs) from certain requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (ASME Code), under the provisions of Title 10 of the Code of Federal Regulations (10 CFR), paragraph 50.55a(g)(6)(i), for the third 1O-year inservice inspection (lSI) program for Arkansas Nuclear One (ANO), Unit 2. The ANO, Unit 2, third 10*

year lSI interval ended on March 25, 2010. The licensee extended the third 1O-year lSI interval by 1 year in accordance with ASME Code,Section XI, Paragraph IWA-2430 for the 2R21 (21st) refueling outage.

RR AN02-ISI-014 covers nine Code Class 2 pressure retaining welds in piping, Weld Nos.61-025, 66-014, 55-034A,55-043, 55-057,61-002,61-011,61-021, and 78-056 in examination category C-F-1, Item numbers C5.11 and R1.20.

Specifically, the licensee has stated that it is impractical to obtain essentially 100 percent examination coverage of the subject welds, and to obtain additional coverage would necessitate modification and/or replacement of the component. The licensee has also stated that the examinations performed on the subject areas, in addition to the examination of similar welds contained in the program, would detect generic degradation, if it existed, demonstrating an acceptable level of integrity. The licensee has requested relief from the ASME Code requirements on the basis that obtaining increased examination coverage is impractical and accepting the present examination coverage 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 enclosed safety evaluation, the U.S. Nuclear Regulatory Commission (NRC) staff concludes that due to the geometric configuration of the subject welds at ANO, Unit 2, obtaining the ASME Code-required examination coverage is impractical. The staff further concludes that weld examination coverage that has been achieved provides reasonable assurance of the structural integrity of the subject welds. In summary, the staff concludes that granting relief pursuant to 10 CFR 50.55a(g)(6)(i) is authorized by law and will not endanger life or property or

-2 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. Therefore, the NRC staff grants the licensee's RR AN02-ISI-014, pursuant to 10 CFR 50. 55a(g)(6)(i) for the ANO, Unit 2, third 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.

The NRC staff's safety evaluation is enclosed.

Sincerely, Michael T. Markley, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-368

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 AN02-ISI-014 EXAMINATION REQUIREMENTS FOR CATEGORY C-F-1 WELDS ARKANSAS NUCLEAR ONE, UNIT 2 ENTERGY OPERATIONS, INC.

DOCKET NO. 50-368

1.0 INTRODUCTION

By letter dated March 26, 2012, as supplemented by letter dated February 5, 2013 (References 1 and 2, respectively) Entergy Operations, Inc. (Entergy, the licensee), submitted Request for Relief (RR) No. AN02-ISI-014 (in addition to other RRs) from certain requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (ASME Code), under the provisions of Title 10 of the Code of Federal Regulations (10 CFR),

paragraph 50.55a(g)(6)(;), for the third 1O-year inservice inspection (lSI) program for Arkansas Nuclear One (ANO), Unit 2. The ANO, Unit 2, third 10-year lSI interval ended on March 25, 2010. The licensee extended the third 1O-year lSI interval by 1 year in accordance with ASME Code,Section XI, Paragraph IWA-2430 for the 2R21 (21st) refueling outage.

In RR AN02-ISI-014, the licensee requested relief from required volumetric examination coverage of ASME Code,Section XI, Examination Category C-F-1 welds under the ANO, Unit 2, Risk-Informed Inservice Inspection (RI-ISI) Program which was approved in a safety evaluation dated December 29, 1998 (Reference 3), by the Office of Nuclear Reactor Regulation.

Specifically, the licensee has stated that it is impractical to obtain essentially 100 percent examination coverage of the subject welds, and to obtain additional coverage would necessitate modification and/or replacement of the component. The licensee has also stated that the examinations performed on the subject areas, in addition to the examination of similar welds contained in the program, would detect generic degradation, if it existed, demonstrating an acceptable level of integrity. The licensee has requested relief from the ASME Code requirements on the basis that obtaining increased examination coverage is impractical and accepting the present examination coverage 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.

Enclosure

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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 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 inspection interval and subsequent 1O-year inspection 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 inspection interval, subject to the limitations and modifications listed therein. The regulations in 10 CFR 50.55a(g)(5)(iii) state, in part, that 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) of 10 CFR 50.55a state 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 its analysis of the regulatory requirements, the NRC staff concludes that it has the regulatory authority to grant the proposed alternative under 10 CFR 50.55a(g)(6)(i).

The ASME Code of record for the ANO, Unit 2, third 10-year lSI interval program is the 2001 Edition through the 2003 Addenda of Section XI of the ASME Code. ANO, Unit 2, also uses the 1995 Edition through the 1996 Addenda for ultrasonic testing (UT) examination requirements.

3.0 TECHNICAL EVALUATION

3.1 Components for which Relief is Being Reguested Code Class 2 pressure retaining welds in piping, examination category C-F-1, Item numbers C5.11 and R1.20.

Weld No. Item Description 61-025 Safety Injection Header Pipe-toNalve Circumferential Weld  !66-014 Safety Injection Pipe-to-Flued Head Penetration Circumferential Weld i 55-034A Safety Injection Weld-o-Iet-to-Pipe Circumferential Weld I 55-043 Safety Injection Tee-to-Pipe Circumferential Weld J 55-057 Safety Injection Pipe-to-Branch Connection Circumferential Weld i 161-002 Safety Injection Pipe-to-Valve Circumferential Weld I 61-011 Safety Injection Pipe-to-Valve Circumferential Weld I 61-021 Safety Injection Pipe-to-Valve Circumferential Weld I 78-056 Containment Spray Elbow-to-Pipe Circumferential Weld I

- 3 3.2 ASME Code Requirements The Code of record for the ANO-2 third 1O-year inservice inspection (lSI) interval program is the 2001 Edition through the 2003 Addenda of Section XI of the ASME Code. The ANO-2 third 10-year lSI interval ended on March 2S, 2010, but the licensee extended the lSI interval by 1 year in accordance with ASME Code,Section XI, Paragraph IWA-2430 to encompass spring 2011 refueling outage 2R21.

In its letter dated March 26, 2012, the licensee stated, in part, that ASME Section XI, Table IWC-2S00-1, Examination Category C-F-1, "Pressure Retaining Welds in Austenitic Stainless Steel or High Alloy Piping - Inspection Program B":

1) Item CS.11, as allowed by the Risk Informed (RI) process, requires a volumetric examination of circumferential piping welds Nominal Pipe Size (NPS) 4 or larger, as depicted in Figure IWC-2S00-7 and Risk-Informed Inservice Inspection Evaluation Procedure, Electric Power Research Institute (EPRI) Report No. TR-106706, Interim Report, June 1996.

2) Item R1.20 requires a volumetric examination of circumferential piping welds less than NPS 4, as depicted in Figure IWC-2S00-7 and Risk Informed Inservice Inspection Evaluation Procedure, EPRI Report No. TR-106706, Interim Report, June 1996.

3.3 Licensee's Proposed Alternative No alternative testing is proposed. The licensee stated that it has examined the subject items to the extent practical and will continue to perform pressure testing on the subject areas as required by the ASME Code.

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

During ultrasonic examination of the piping welds listed in Table 1 above, greater than 90% coverage of the required examination volume could not be obtained.

Class 2 piping and components are often designed with welded joints such as nozzle-to-pipe, pipe-to-valve and pipe-to-pump which can physically obstruct a large portion of the required examination volume. For examinations performed after the 10 CFR SO.SSa mandatory implementation date for Appendix VIII of Section XI, and Code coverage percentages reflect what is currently allowed by quali'Fied Appendix VIII techniques. Appendix VIII qualified Performance Demonstration Initiative (POI) procedures have demonstrated that sound beams may potentially be attenuated and distorted when required to pass through austenitic weld metal. Still, the POI qualified methods employ the best available technology for maximizing examination coverage of these types of welds.

Examination was extended to the far side of the weld to the extent permitted by geometry, but this portion of the examination is not included in the reported coverage for welds examined under PDI and Appendix VIII rules.

- 4 These ultrasonic examinations have been performed over the course of the interval to varying code requirements and procedures. Entergy has used the best available and EPRI approved techniques to examine the subject piping welds. To improve upon these examination coverage percentages, modification and/or replacement of the component would be required. Consistent with the ASME Section XI sampling approach, examination of the subject welds, when combined with examinations that have been performed on other welds within the same Examination Category, is adequate to detect generic degradation, if it existed, demonstrating an acceptable level of integrity.

3.5 NRC Staff Evaluation The ASME Code,Section XI, requires essentially 100 percent volumetric examination coverage for Examination Category C-F-1 pressure retaining welds. The NRC staff recognizes that component design or weld configuration can preclude the licensee from obtaining full volumetric examination coverage.

By letter dated February 5, 2013, in response to the NRC staff's request for additional information (RAI) dated September 6, 2012 (Reference 4), the licensee stated, in part, that, The component selection process purposely includes welds that have configurations to fittings such as elbows, tees, valves and nozzles. To remove these components in favor of a non-restricted component, e.g., pipe to pipe, would result in an lSI program selection process that would not be conservative or represent the piping system configurations.

Review of the data sheets indicates that best effort scanning was performed on both sides of the weld joint where accessible and feasible. Generally, it is not feasible to scan from a valve side or branch connection due to material, surface condition, or part geometry.

The NRC staff recognizes that inclusion of these components results in weld examinations with less than essentially 100 percent examination coverage, but concludes that it is appropriate to include such components in an lSI program in order to sample the range of weld configurations that are in the piping system.

In response to the NRC staff's RAI, the licensee provided scale drawings showing the examination coverage, and data for the diameter, wall thickness, and materials of construction of each weld. The staff has reviewed the licensee's drawings and determined the limitations encountered during the performance of the UT examinations generally result from curvature at the transition region from the pipe-to-valve, pipe-to-tee, pipe-to-branch connection, pipe-to-flued head, or pipe-to-weld-o-Iet weld configuration. The staff further determined that the licensee has examined the subject welds to the extent practicable and that it is impractical to perform an essentially 100 percent volumetric examination without redesigning, modifying, and/or replacing the subject components.

The NRC staff has examined the licensee's drawings and the data in Table 1 of the licensee's RAI response dated February 5, 2013, and has considered the examination coverage for each of the nine subject welds. Each of the welds was examined using ASME Code,Section XI,

- 5 Appendix VIII qualified procedures that do not credit scanned volume past the weld centerline.

Eight of the welds,61-025, 66-014, 55-034A,55-043, 55-057,61-002, 61-011, and 61-021, could only be examined from one side due to the curvature of the transition in the weld region.

In addition, several of the components, welds61-025, 61-002,61-011, and 61-021, also contained cast austenitic stainless steel (CASS) for which an Appendix VIII examination procedure does not exist. The licensee stated that the examinations were performed with the best available technology for maximizing coverage and that best effort scanning was performed from both sides of the weld jOint where accessible and feasible. Although the entire required volume of each weld was examined from a single side, 100 percent examination coverage could not be credited due to the limitations of the qualification procedure. The licensee stated that none of the Category C-F-1 welds has an identified degradation mechanism. Based on the above, the staff concludes that the licensee has performed the UT examination to the extent possible and has obtained single-sided examination coverage for these welds. The staff concludes that significant service-induced degradation would have likely been detected with the UT examination performed and, therefore, the staff accepts the examinations performed.

The volumetric examination coverage of the remaining weld,78-056, was 84 percent due to UT transducer lift-off at the weld toe. The NRC staff notes that the licensee was able to completely scan the inside diameter (ID) surface from two directions but was not able to examine essentially 100 percent of the volume of the weld due to the lift-off. The staff concludes that the high examination coverage, particularly at the ID surface, would have revealed an indication if significant service-induced degradation had occurred, and, therefore, concludes that the extent of examination of this weld to be acceptable.

In summary, the NRC staff concludes that achieving essentially 100 percent volumetric examination is impractical for the subject welds due to the geometric configuration or materials of construction. Based on the examination coverage obtained, it is reasonable to conclude that evidence of significant service-induced degradation would have been detected by the examinations performed. Therefore, the staff concludes that the proposed alternative 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.

4.0 CONCLUSION

Based on the above, the NRC staff concludes that, due to the geometric configuration of the sUbject welds at ANO, Unit 2, obtaining the ASME Code-required examination coverage is impractical. The staff further concludes that weld examination coverage that has been achieved provides reasonable assurance of the structural integrity of the subject welds. The staff concludes 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 giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility. Therefore, the MRC staff grants the licensee's request for relief, AN02-ISI-014, pursuant to 10 CFR 50.55a(g)(6)(i) for the ANO, Unit 2, third 10-year lSI interval.

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.

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5.0 REFERENCES

1. Pyle, S. L., Entergy Operations, Inc., letter to U.S. Nuclear Regulatory Commission, "Requests for Relief from American Society of Mechanical Engineers (ASME)Section XI Volumetric and Surface Examination Requirements - Third 10-Year Interval," dated March 26, 2012 (Agencywide Documents Access and Management System (ADAMS)

Accession No. ML12086A293).

2. Pyle, S. L., Entergy Operations, Inc., letter to U.S. Nuclear Regulatory Commission, "Response to Request for Additional Information Request for Relief AN02-ISI-014,"

dated February 5, 2013 (ADAMS Accession No. ML13037A049).

3. Hannon, J. N., U.S. Nuclear Regulatory Commission, letter to C. R. Hutchinson, Entergy Operations, Inc., "Safety Evaluation by the Office of Nuclear Reactor Regulation, Proposal to Use ASME Code Case N-578 as an Alternative to ASME Code Section XI, Table IWX-2500," dated December 29,1998 (ADAMS Legacy Accession Nos.

9901050347 and 9901050353).

4. Kalyanam, N., U.S. Nuclear Regulatory Commission, electronic mail to Robert Clark, Entergy Operations, Inc., RAI on Request for Relief No. AN02-ISI-014," dated September 6,2012 (ADAMS Accession No. ML12250A756).

Principal Contributor: J. Wallace Date: March 22, 2013

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. Therefore, the NRC staff grants the licensee's RR AN02-ISI-014, pursuant to 10 CFR 50.55a(g)(6)(i) for the ANO, Unit 2, third 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.

The NRC staff's safety evaluation is enclosed.

Sincerely, IRA by CFLyon forI Michael T. Markley, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-368

Enclosure:

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

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