ML20253A329

Revised License Renewal Commitment Pressurizer Surge Line Weld Inspection Frequency

ML20253A329
Person / Time
Site:	North Anna
Issue date:	09/30/2020
From:	Geoffrey Miller Plant Licensing Branch II
To:	Stoddard D Southern Nuclear Operating Co
Miller G
References
EPID L-2020-LLL-0017
Download: ML20253A329 (6)

Text

September 30, 2020 Mr. Daniel G. Stoddard Senior Vice President and Chief Nuclear Officer Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711

SUBJECT:

NORTH ANNA POWER STATION, UNITS 1 AND 2 - REVISED LICENSE RENEWAL COMMITMENT PRESSURIZER SURGE LINE WELD INSPECTION FREQUENCY (EPID L-2020-LLL-0017)

Dear Mr. Stoddard:

By letter dated March 26, 2020, Virginia Electric and Power Company (Dominion Energy Virginia, Dominion, or the licensee) submitted a document titled Revised License Renewal Commitment Pressurizer Surge Line Weld Inspection Frequency, for the North Anna Power Station (NAPS), Units 1 and 2, to the U.S. Nuclear Regulatory Commission (NRC), for review and approval.

As stated in the March 26, 2020, submittal, Dominion requested approval to revise the inspection frequency of NAPS Units 1 and 2, pressurizer surge line welds from once every 40 months, to once every 10 years. Dominion stated that its proposed inspection interval is applicable to both the first license renewal period as well as subsequent license renewal.

A copy of the related Safety Evaluation is enclosed.

If you have any questions, please contact me at (301) 415-2481, or via email at ed.miller@nrc.gov.

Sincerely,

/RA/

G. Edward Miller, Project Manager Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-338 and 50-339 cc: Listserv

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNITS 1 AND 2 REVISED LICENSE RENEWAL COMMITMENT PRESSURIZER SURGE LINE WELD INSPECTION FREQUENCY

1.0 INTRODUCTION

By letter dated March 26, 2020, (Agency Documents Access and Management System (ADAMS) Accession Nos. ML20090B397), Virginia Electric and Power Company (Dominion Energy Virginia, Dominion, or the licensee) submitted a document titled Revised License Renewal Commitment Pressurizer Surge Line Weld Inspection Frequency, for the North Anna Power Station (NAPS), Units 1 and 2, to the U.S. Nuclear Regulatory Commission (NRC), for review and approval. The licensee had previously submitted its Pressurizer Surge Line Weld Inspection Plan Summary, to the NRC by letter dated July 1, 2014 (ADAMS Accession No. ML14189A129). Dominions July 1, 2014, submittal met its license renewal commitment, documented in NUREG-1766, Safety Evaluation Report Related to the License Renewal North Anna Power Station Units 1 and 2, and Surry Power Station, Units 1 and 2 (ADAMS Accession No. ML030160853), December 2002. Specifically, in its submittal dated July 1, 2014 Dominion stated that it would perform baseline volumetric and surface examinations of the pressurizer surge line welds at the NAPS, Units 1 and 2, prior to entry into the period of extended operation (PEO), and once every 40 months thereafter.

As stated in the licensees submittal dated March 26, 2020, Dominion requested approval to revise the inspection frequency of the NAPS, Units 1 and 2, pressurizer surge line welds from once every 40 months, to once every 10 years. Dominion stated that its proposed inspection interval is applicable to both the first license renewal period as well as subsequent license renewal.

2.0 REGULATORY EVALUATION

By letter dated May 29, 2001 (ADAMS Accession No. ML011500496), Dominion submitted a license renewal application for the NAPS, Units 1 and 2. Title 10 of the Code of Federal Regulations (10 CFR) Part 54, Requirements for Renewal of Operating Licenses for Nuclear Power Plants, addresses the requirements for plant license renewal. Pursuant to 10 CFR 54.21, each application for license renewal must contain an integrated plant assessment (IPA) and an evaluation of time limited aging analyses (TLAAs). The plant-specific IPA shall identify and list those structures and components subject to an aging management review and demonstrate that the effects of aging (e.g., cracking, loss of material, loss of fracture toughness, dimensional changes, and loss of preload) will be adequately managed so that their intended functions will be maintained consistent with the current licensing basis (CLB) for the PEO as Enclosure

required by 10 CFR 54.21(a)(3). In addition, 10 CFR 54.21(d) requires that the final safety analysis report (FSAR) supplement for the facility, must contain a summary description of programs and activities for managing the effects of aging and TLAAs for the PEO.

On March 20, 2003 (ADAMS Accession No. ML030710581), NRC issued renewed facility operating licenses to the NAPS Units 1 and 2. The technical basis for NRC staffs review and issuance of the renewed operating facility licenses was documented by NUREG-1766. As stated earlier, NUREG-1766 also documented the licensees commitment regarding future activities to be completed by the licensee, related to the aging management of the NAPS, Units 1 and 2, pressurizer surge line welds.

Pursuant to 10 CFR 54.21(d), Dominions most recent Updated Final Safety Analysis Report (UFSAR) Section 18.3.2.4, and Table 18-1, (Item 24) for NAPS, Units 1 and 2, summarizes the licensees current inspection frequency of the NAPS, Units 1 and 2 pressurizer surge line welds.

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 review and approve the licensees revised inspection frequency for the NAPS Units 1 and 2, pressurizer surge line welds. The scope of this review is limited to the NAPS, Units 1 and 2, revision of the inspection frequency of Dominions previously submitted aging management program for the pressurizer surge line welds, applicable to the PEO.

TECHNICAL EVALUATION 3.1 Summary of Submittal Information By letter dated July 1, 2014, as part of its license renewal commitments, Dominion provided the NRC its inspection plan summary to inspect the pressurizer surge line welds once every 40 months for each of the NAPS, Units 1 and 2. In its current submittal. Dominion stated that when it submitted its inspection plan summary, the once every 40 months inspection frequency was selected because no guidance was available at the time. Dominion further stated that in 2012, Florida Power and Light (FPL) proposed using an inspection frequency of 120 months for its pressurizer surge nozzle welds, based on use of American Society Of Mechanical Engineers Boiler and Pressure Vessel Code (ASME),Section X;, Appendix L, Operating Plant Fatigue Assessment, dated May 16, 2012 for Turkey Point Units 3 and 4 (ADAMS Accession No. ML12152A156). The NRC approved FPLs inspection program by letter dated May 29, 2013 (ADAMS Accession No. ML13141A595). Dominion further noted a similar submittal dated October 29, 2015, for St. Lucie Units 1 and 2 (ADAMS Accession No. ML15314A160), and was approved by the NRC on October 13, 2016 (ADAMS Accession No. ML16235A138). The licensee stated that it performed a flaw evaluation for the NAPS pressurizer surge line welds using the 2013 Edition of ASME Section XI, Appendix L. These evaluations assumed a postulated flaw and used a bounding stress, which demonstrated that the crack growth for a postulated circumferential flaw reached the allowable flaw size after an operating period of 60 years. Dominion included the NAPS Unit 1 and 2, technical report as .

The licensee stated that upon receipt of NRCs approval, the NAPS UFSAR will be revised to reflect the new inspection frequency for the NAPS Units 1 and 2 pressurizer surge line welds.

The scheduling of the welds will be based upon the date of completion of the last weld inspection not to exceed 10 years. The licensee further stated that the proposed inspection frequency for the NAPS Units 1 and 2, pressurizer surge line weld is applicable to both the first

license renewal period (i.e., PEO), as well as subsequent license renewal. The NRC staff will review the program as part of its subsequent license renewal review for NAPS, Units 1 and 2.

3.2 NRC Staff Technical Evaluation The NRC staff reviewed the NAPS, Units 1 and 2, Revised License Renewal Commitment Pressurizer Surge Line Weld Inspection Frequency, to determine if the inspection frequency would be adequate in managing the effects of aging so that the components intended functions would be maintained consistent with the CLB during the PEO, in accordance with 10 CFR 54.21(a)(3). The NRC staff notes that all ASME Code,Section XI, Inservice Inspection (ISI) and 10 CFR 50.55a requirements continue to apply during the term of a renewed license, unless a relief request is submitted by the licensee and subsequently approved by NRC staff in accordance with 10 CFR 50.55a. The NRC staff noted that the proposed inspection frequency (i.e., once every 10 years) for surface and volumetric examinations is consistent with the ASME Code,Section XI, examinations for reactor coolant piping.

During its review, the NRC staff noted that the licensee performed the flaw evaluation for the NAPS pressurizer surge line welds using the 2013 Edition of ASME Section XI, Appendix L, Operating Plant Fatigue Assessment. The NRC staff further notes the 2013 Edition of ASME Section XI is endorsed by reference in 10 CFR 50.55a, and includes Appendix L without any conditions.

As part of its the review the NRC staff verified that the values for the material properties, dimensions, design temperatures, thermal transients, and pressures used for the NAPS pressurizer surge line flaw tolerance evaluation matched the UFSAR provided values for the two units. By letter dated September 3, 2020 (ADAMS Accession No. ML20252A220), the licensee confirmed that the baseline examinations for the NAPS Units 1 and 2 had been completed (N1R25 - fall 2016 and N2R26 - spring 2018, respectively). Those examinations confirmed that there were no recordable indications present on the pressurizer surge line welds.

Based on the above, the NRC staff confirmed that the revised inspection frequency would provide an acceptable level of safety. This was, in part, because the projected growth rate for a postulated crack to challenge the leak tightness of the pressurizer surge line exceeds 60 years of operation. The 10-year inspection interval proposed by the licensee provides reasonable assurance that indications, if they are present, will be detected before they become unacceptable indications. Therefore, the NRC staff concludes that Dominion has demonstrated that the effects of aging for the NAPS Units 1 and 2 pressurizer surge line welds will be adequately managed so that the intended function(s) will be maintained consistent with the CLB for the PEO, as required by 10 CFR 54.21(a)(3).

4.0 CONCLUSION

The NRC staff reviewed the NAPS, Units 1 and 2, Revised License Renewal Commitment Pressurizer Surge Line Weld Inspection Frequency. Based on its review, the NRC staff concludes that there is reasonable assurance that the license will manage the aging effects of the pressurizer surge line welds for the NAPS, Units 1 and 2, through the implementation of the revised proposed inspection frequency. Therefore, the NRC staff approves the licensees request to extend the inspection interval from 40 months to 10 years for NAPS, Units 1 and 2.

The licensee may inspect these welds based upon the date of completion of the last weld inspection not to exceed 10 years during the PEO.

Principal Contributor: Roger Kalikian Date: September 30, 2020

SUBJECT:

NORTH ANNA POWER STATION, UNITS 1 AND 2 - REVISED LICENSE RENEWAL COMMITMENT PRESSURIZER SURGE LINE WELD INSPECTION FREQUENCY (EPID L-2020-LLL-0017) DATED SEPTEMBER 30 2020 DISTRIBUTION:

PUBLIC LPL2-1 File Copy RidsAcrs_MailCTR Resource RidsNrrDorlLpl2-1 Resource RidsNrrLAKGoldstein Resource RidsNrrPMNorthAnna Resource RidsRgn2MailCenter Resource ADAMS Accession No. ML20253A329 *via e-mail OFFICE NRR/DORL/LPL2-1/PM* NRR/DORL/LPL2-1/LA* NRR/DORL/LPL2-1/BC*

NAME GEMiller* KGoldstein* MMarkley*

DATE 09/23/2020 09/10/2020 09/29/2020 OFFICE NRR/DRL/NPHP/BC* NRR/DORL/LPL2-1/PM*

NAME MMitchell* GEMiller*

DATE 09/23/2020 09/30/2020