ML22196A197

Request for Relief Request N2-I4-LMT-004 Inservice Inspection Limitations

ML22196A197
Person / Time
Site:	North Anna
Issue date:	07/28/2022
From:	Stephanie Devlin-Gill Plant Licensing Branch II
To:	Stoddard D Southern Nuclear Operating Co
Miller G
References
EPID L-2021-LLR-0088
Download: ML22196A197 (8)

Text

July 28, 2022 Mr. Daniel G. Stoddard Senior Vice President and Chief Nuclear Officer Innsbrook Technical Center 5000 Dominion Blvd.

Glen Allen, VA 23060-6711

SUBJECT:

NORTH ANNA POWER STATION, UNIT NO. 2 - RE: REQUEST FOR RELIEF REQUEST N2-I4-LMT-004 INSERVICE INSPECTION LIMITATIONS (EPID L-2021-LLR-0088)

Dear Mr. Stoddard:

By letter dated December 13, 2021 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML21348A711), as supplemented by letter dated April 25, 2022 (ML22115A175), Virginia Electric and Power Company (VEPCO, Dominion Energy Virginia, the licensee), submitted Relief Request No. N2-14-LMT-004 for the North Anna Power Station, Unit 2 (NAPS2), to the U.S. Nuclear Regulatory Commission (NRC or Commission) for review and approval, pursuant to the requirements of Title 10 of the Code of Federal Regulations (10 CFR), Section 50.55a(g)(6)(i).

Specifically, the requested relief is on the basis that the required examination coverage was impractical due to physical obstructions and limitations imposed by design, geometry, and materials of construction of the subject components.

The NRC staff has reviewed the subject request and concludes, as set forth in the enclosed safety evaluation, that VEPCO has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(g)(5)(iii) and demonstrated that achieving the required examination coverage is impractical for North Anna, Unit 2, for the Fourth Inservice Inspection (ISI) Program Test interval, which ended on December 13, 2020.

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

If you have any questions, please contact the Project Manager, Ed Miller at 301-415-2481 or via e-mail at Ed.Miller@nrc.gov.

Sincerely, Stephanie Digitally signed by Stephanie Devlin-Gill Devlin-Gill Date: 2022.07.28 13:10:34 -04'00' Michael T. Markley, Chief Plant Licensing Branch 2-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-339

Enclosure:

Safety Evaluation cc: Listserv

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION PROPOSED INSERVICE INSPECTION ALTERNATIVE N2-I4-LMT-004 VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION ENERGY VIRGINIA)

NORTH ANNA POWER STATION, UNIT 2 DOCKET NO. 50-339

1.0 INTRODUCTION

By letter dated December 13, 2021, (Agencywide Documents Access and Management System (ADAMS) Accession No. ML21348A711) and supplemented by the letter dated April 25, 2022 (ML22115A175), Virginia Electric and Power Company (the licensee), submitted Relief Request (RR) N2-14-LMT-004 to the U.S. Nuclear Regulatory Commission (NRC) for the fourth Inservice Inspection (ISI) interval at North Anna Power Station, Unit 2 (NAPS2). In RR N2-14-LMT-004, the licensee requested relief from the examination coverage requirements of Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) applicable to certain ASME Code Class 1 and non-class component welds. Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(g)(5)(iii), the licensee requested relief on the basis that achieving the ASME Code-required examination coverage for the subject welds in RR N2-14-LMT-004 is impractical.

2.0 REGULATORY EVALUATION

Pursuant to 10 CFR 50.55a(g)(4), ISI Standards Requirement for Operating Plants, components (including supports) that are classified as ASME Code Class 1, Class 2, and Class 3 must meet the requirements in 10 CFR 50.55a throughout the service life of a boiling or pressurized water reactor. Pursuant to 10 CFR 50.55a(g)(4)(ii), Applicable ISI Code: Successive 120-month Intervals, in-service examination of components and system pressure tests conducted during successive 120-month inspection intervals must comply with the requirements of the latest edition and addenda of the ASME Code incorporated by reference in paragraph (a) of 10 CFR 50.55a 12 months before the start of the 120-month inspection interval or the optional ASME Code Cases listed in NRC Regulatory Guide (RG) 1.147, Inservice Inspection Code Case Acceptability, Revision 20 (ML21181A222), when using ASME Code,Section XI, as incorporated by reference in paragraph (a)(3)(ii) of 10 CFR 50.55a, subject to the conditions listed in paragraph (b) of 10 CFR 50.55a.

Pursuant to 10 CFR 50.55a(g)(5)(iii), ISI Program Update: Notification of Impractical ISI Code Requirements, If the licensee has determined that conformance with a Code requirement is impractical for its facility, the licensee must notify the NRC and submit, as specified in § 50.4, Enclosure

information to support the determinations. Determinations of impracticality in accordance with [10 CFR 50.55a(g)(5)(iii)] must be based on the demonstrated limitations experienced when attempting to comply with the Code requirements during the ISI interval for which the request is being submitted. Requests for relief made in accordance with [10 CFR 50.55a(g)(5)(iii)] must be submitted to the NRC no later than 12 months after the expiration of the initial or subsequent 120-month inspection interval for which relief is sought.

Pursuant to 10 CFR 50.55a(g)(6)(i), Impractical ISI Requirements: Granting of Relief, The Commission will evaluate determinations under paragraph (g)(5) of [10 CFR 50.55a]

that Code requirements are impractical. The Commission may grant such relief and may impose such alternative requirements as it determines are authorized by law, will not endanger life or property or the common defense and security, and are 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 finds 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 Licensee's Proposed Alternative Relief Request N2-14-LMT-004 is for six ASME Code, Class 1 and three non-code class component welds for the fourth 10-year ISI interval. The licensee indicated that, due to original design of these components, it was impractical to meet the ASME Code-required examination volumes for the welds described in RR N2-14-LMT-004. Code conformance would require extensive structural modifications to the components or surrounding structures.

The licensee indicated that it performed the ASME Code required examinations to the maximum extent possible or best effort. Due to physical limitations, there are no viable alternative examination techniques currently available to increase the coverage. Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee requested relief on the basis that achieving the ASME Code required volumetric examination coverage for the subject components in RR N2-14-LMT-004 is impractical.

In addition, the licensee is using ASME Code Case N-460, Alternative Examination Coverage for Class 1 and Class 2 Welds,Section XI, Division 1, which defines essentially 100 percent, as greater than 90 percent coverage of the examination volume or surface area, as applicable.

ASME Code Case N-460 is an NRC-approved alternative that can be used by licensees, as referenced in Regulatory Guide 1.147, Revision 20.

Applicable Code Requirements The welds described in RR N2-14-LMT-004 are governed by the Risk-Informed lnservice Inspection (RI-ISI) Program Plan that was approved by the NRC for NA2 by letter dated January 21, 2011 (ML110050003). The welds are assigned category R-A, Items R1.11, R1.16, and R1.20, and require ultrasonic examination. Three Class 1 welds were classified as Examination Category R-A, Item Numbers R1.11, Elements Subject to Thermal Fatigue, and

three were classified as R1.16, Welds Subject to lntergranular or Transgranular Stress Corrosion Cracking (lGSCC or TGSCC). The non-code-class welds were classified as Examination Category R-A, item number R1.20, Elements Not Subject to a Damage Mechanism, require essentially 100 percent coverage.

Components Covered in Request The welds covered in RR N2-14-LMT-004are described in Table 1. For each component, the limitations were caused by single-sided access, with more access being possible for the carbon steel components. The only recordable indications in any of the welds were caused by geometry.

Table 1: Welds Covered by Relief Request N2-14-LMT-004 Examination Component ASME Code Coverage Materials Item Number Identification Class Obtained R1.11 12050-WMKS-Austenitic to 0109D/14-RC-410/3 1 50 Percent Austenitic Weld R1.11 12050-WMKS- 50 Percent Austenitic to 0103AG/6-RC-416/3A 1 Austenitic weld R1.11 12050-WMKS- 50 Percent Austenitic to 0103AH/6-RC-421/1 1 Austenitic Weld R1.16 12050-WMKS- Austenitic to 50 Percent 1

0103AH/6-SI-416/10 Austenitic Weld R1.16 12050-WMKS- Austenitic to 50 Percent 1

01038N/6-SI-532/19 Austenitic Weld R1.16 12050-WMKS-0113C- Austenitic to 50 Percent 1

1/12-SI-469/8 Austenitic Weld R1.20 12050-WMKS- Carbon Steel to 0102D/6-WFPD-419/ Non-Class Carbon Steel Weld 75 Percent SW-60W (BPL 473)

R1.20 12050-WMKS-0101A- Carbon Steel to 75 Percent 4/32-SHP-457 I SW-8 Non-Class Carbon Steel Weld (BPL 116)

R1.20 12050-WMKS-0101A- Carbon Steel to 75 Percent 4/32-SHP-458/ SW-7 Non-Class Carbon Steel Weld (BPL209)

ASME Code of Record The licensee used the 2004 Edition of ASME Code,Section XI for the Fourth 10-Year ISI Interval, which concluded on December 13, 2020.

Licensee Reason for Request Due to the original design of these components the licensee stated that it was not possible to obtain essentially 100 percent of the ASME Code-required examination coverage for volumetric examinations for the subject piping welds. Obtaining the required inspection volume would require extensive structural modifications to the components or surrounding structures.

3.2 NRC Staff Evaluation The NRC staff has evaluated RR N2-14-LMT-004 pursuant to 10 CFR 50.55a(g)(6)(i). The NRC staffs evaluation focused on: (1) whether a technical justification exists to support the determination that the ASME Code requirement is impractical; (2) that imposition of the Code required examinations would result in a burden to the licensee; and (3) that the licensees proposed alternative (accepting the reduced inspection coverage in this case) provides reasonable assurance of structural integrity and leak tightness of the subject welds. The NRC staff finds that if these three criteria are met that the requirements of 10 CFR 50.55a(g)(6)(i)

(i.e., granting the requested relief 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) will also be met.

Impracticality of Compliance As described in the submittal, the physical limitations that prevented the licensees ultrasonic testing (UT) to achieve essentially 100 percent coverage of the ASME Code-required volume were the configurations that limited the examinations to one side of the weld. The NRC staff confirmed that the weld configurations prevented the licensee to scan from both sides. As shown in the sketches the subject components have access limitations which resulted in reduced volumetric examination coverage. The staff finds that due to these geometric limitations associated with the aforementioned welds, it was impractical to meet the ASME Code-required essentially 100 percent volumetric examination coverage for the subject welds during its fourth 10-year ISI Interval.

Burden of Compliance Obtaining essentially 100 percent coverage would require extensive modification or replacement of components with a design that would allow full examination from both sides of the weld. The NRC staff finds that replacing or reconfiguring the components of the subject welds is the only reasonable means to achieve dual sided coverage of these welds and that replacement or reconfiguration of the components constitutes a burden on the licensee.

Structural Integrity and Leak Tightness From reviews of the relief requests, the NRC staff verified that:

The welds were examined using the appropriate equipment, ultrasonic modes of propagation, probe angles, frequencies, and scanning directions to obtain maximum coverage; The coverage was calculated in a reasonable manner; The personnel and UT procedures utilized for the volumetric examination were qualified as required by the regulation;

The coverage was limited by physical limitations or access (i.e., the configuration of one side of the weld did not permit access for scanning);

No unacceptable indications were identified.

The volumetric examinations were performed using UT, which facilitated volumetric coverage of the weld joint at the root area located at the inner diameter of the components. The UT examinations were performed using personnel, equipment, and procedures qualified in accordance with ASME Code,Section XI, Appendix VIII as implemented by the Performance Demonstration Initiative (PDI). If there were to be any active aging degradation in the weld joint, it likely would have been identified in the PDI qualified UT examinations.

Although the ASME Code-required coverage could not be obtained, the UT employed provided full volumetric coverage from the near side of the welds, which also facilitated some limited volumetric coverage for the weld materials on the opposite (far) side of these welds. Therefore, the staff concluded that the licensee had demonstrated its capability of adequately monitoring aging degradation using single sided UT examinations for these welds.

Based on the coverage obtained for the subject components, the extent of the examinations, and considering the licensees coverage for the accessible portions of these welds, it is reasonable to conclude that, had significant flaws been present in these welds, some evidence of unacceptable flaws would have been detected by the licensee.

Therefore, the NRC staff finds that the volumetric examinations performed to the extent possible provide a reasonable assurance of structural integrity and leak tightness of the subject welds.

Compliance with the ASME Code requirements for these welds would be a burden on the licensee.

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 NRC staff concluded that the examinations performed to the extent practical provide reasonable assurance of structural integrity of the subject components. Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(g)(5)(iii). Therefore, the NRC staff grants relief from the ASME Code examination requirements for the welds included in RR N2-14-LMT-004 for North Anna Power Station, Unit 2 for the fourth 10-year ISI interval. 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: S. Cumblidge, NRR Date: July 28, 2022

ML22196A197 *Via SE Input OFFICE NRR/DORL/LPL2-1/PM NRR/DORL/LPL2-1/LA NRR/DNRL/NPHP/BC NRR/DORL/LPL2-1/BC GEMiller MMitchell* MMarkley NAME KGoldstein (SDevlin-Gill for)

DATE 7/26/2022 07/21/2022 7/14/2022 7/28/2022 OFFICE NRR/DORL/LPL2-1/PM NAME GEMiller DATE 7/28/2022