ML20337A022

License Renewal Severe Accident Mitigation Alternatives Audit Plan Regarding the North Anna Power Station, Units 1 and 2, Subsequent License Renewal Application (EPID No.: L-2020-SLE-0000) (Docket No.: 50-338 and 50-339)

ML20337A022
Person / Time
Site:	North Anna
Issue date:	12/04/2020
From:	Tam Tran NRC/NMSS/DREFS/ELRB
To:	Stoddard D Virginia Electric & Power Co (VEPCO)
Tam Tran
References
EPID L-2020-SLE-0000
Download: ML20337A022 (6)

Text

December 4, 2020 Mr. Daniel G. Stoddard Senior Vice President and Chief Nuclear Officer Innsbrook Technical Center 5000 Dominion Blvd.

Glen Allen, VA 23060

SUBJECT:

LICENSE RENEWAL SEVERE ACCIDENT MITIGATION ALTERNATIVES AUDIT PLAN REGARDING THE NORTH ANNA POWER STATION, UNIT NUMBERS 1 AND 2, SUBSEQUENT LICENSE RENEWAL APPLICATION (EPID NUMBER: L-2020-SLE-0000) (DOCKET NUMBERS: 50-338 and 50-339)

Dear Mr. Stoddard:

The U.S. Nuclear Regulatory Commission (NRC) staff is reviewing the Virginia Electric and Power Companys subsequent license renewal application for North Anna Power Station, Unit Nos. 1 and 2. The NRC staff plans to conduct an in-office audit of new and significant information related to the severe accident mitigation alternatives, beginning December 9, 2020, by teleconference and online reference portal (Agencywide Documents Access and Management System Accession No. ML20269A465). The audit activities will be conducted in accordance with the audit plan provided in Enclosure 1. The list of audit questions is provided in Enclosure 2.

If you have any questions, please contact me by e-mail at Tam.Tran@nrc.gov.

Sincerely, Tam Tran, Project Manager Environmental Review License Renewal Branch Division of Rulemaking, Environmental, and Financial Support Office of Nuclear Material Safety and Safeguards Docket Nos. 50-338 and 50-339

Enclosures:

As stated cc w/encls: Listserv Tam M.

Tran Digitally signed by Tam M. Tran Date: 2020.12.04 12:20:01 -05'00'

ML20337A022

• via email OFFICE PM:REFS LA:REFS BC:REFS PM:REFS NAME TTran

• AWalker-Smith RElliott TTran DATE 12/01/2020 12/01/2020 12/03/2020 12/04/2020

LICENSE RENEWAL AUDIT PLAN FOR NEW AND SIGNIFICANT INFORMATION RELATED TO THE SEVERE ACCIDENT MITIGATION ALTERNATIVES NORTH ANNA POWER STATION, UNITS 1 AND 2

1. Background By letter dated August 24, 2020 (Agencywide Documents Access and Management Systems (ADAMS) Package Accession No. ML20246G703), Dominion Energy Virginia (Dominion Energy or the applicant), submitted to the U.S. Nuclear Regulatory Commission (NRC or staff) an application to renew the North Anna Power Station, Units 1 and 2 (North Anna), renewed facility operating licenses NPF-4 and NPF-7. The staff is reviewing the information contained in the environmental report (ER) of the license renewal application (LRA) per Title 10 of the Code of Federal Regulations (10 CFR) Part 51.

As part of the staffs review, a severe accident mitigation alternatives (SAMA) audit will be conducted for Surrys Subsequent License Renewal Application (SLRA). This audit is conducted with the intent to gain understanding, to verify information, and to identify information that will require docketing to support the basis of the licensing or regulatory decision.

Specifically, the NRC staff will identify pertinent SAMA information and data and obtain clarifications regarding information provided in the ER.

Per NRC guidance, the NRC staff prepares a regulatory audit plan that provides a clear overview of audit activities and scope, team assignments, and schedule.

2. Audit Bases License renewal requirements are specified in 10 CFR Part 54, Requirements for Renewal of Operating Licenses for Nuclear Power Plants. Licensees are required by 10 CFR 54.23 to submit an ER that complies with the requirements in 10 CFR Part 51, Environmental Protection Regulations for Domestic Licensing and Related Regulatory Functions, as part of the LRA.

Review guidance for the staff is provided in NUREG-1555, Standard Review Plans for Environmental Reviews for Nuclear Power Plants: Supplement 1 - Operating License Renewal.

Section 51.53(c)(3)(ii)(L) of 10 CFR states that If the staff has not previously considered severe accident mitigation alternatives for the applicant's plant in an environmental impact statement or related supplement or in an environmental assessment, a consideration of alternatives to mitigate severe accidents must be provided. North Anna provided a SAMA analysis in the 2001 ER for initial license renewal. The ER was reviewed by the NRC in 2003. Thus, the applicants ER must contain any new and significant information of which the applicant is aware (10 CFR 51.53(c)(iv)) and the NRC staff must consider whether such information affects prior generic environmental determinations, reflected in the Category 1 issues in Table B-1.

3. Audit Scope The scope of the SAMA audit is to review the new and significant evaluation as it relates to the SAMA analysis and results as documented in the North Anna SLRA ER and supporting documents.

4. Information and Other Material Necessary for the Audit As described in the list of audit questions (Enclosure 2).

5. Team Assignments Name Responsibility J. Dozier Senior Reliability and Risk Analyst E. Dickson Physical Scientist T. Tran Project Manager

6. Logistics The regulatory audit will begin as an in-office audit (at NRC Headquarter using Microsoft Teams and/or North Anna online reference portal ADAMS Accession No. ML20269A465)) on December 9, 2020. Discussions between the NRC staff and Dominion Energy staff will be held regarding topics and questions identified in Enclosure 2, list of audit questions.

7. Special Requests The NRC staff requests the applicant to make available the license renewal application program basis documentation and other documents as requested for independent searches by the NRCs audit team via the electronic document portal.

8. Deliverables An audit summary report is scheduled to be issued by NRC staff within 90 days from the end of the audit.

LIST OF AUDIT QUESTIONS NORTH ANNA POWER STATION, UNITS 1 AND 2 SUBSEQUENT LICENSE RENEWAL APPLICATION REVIEW IN-OFFICE SEVERE ACCIDENT MITIGATION ALTERNATIVES AUDIT Specific questions to be discussed during the audit:

1.

In the Environmental Report (ER), Dominion indicated that it is following the guidance in Nuclear Energy Institute (NEI) 17-04, Model SLR New and Significant Assessment Approach for SAMA, Revision 1, for providing severe accident mitigation alternatives (SAMA) new and significant information. NEI 17-04 specifies, Further documentation of the new and significant information review is listed in Section 3.5.2. Furthermore NEI 17-04 indicates, Such documentation should be available to the NRC [U.S. Nuclear Regulatory Commission] either in the SLR [Subsequent License Renewal] ER (at the SLR applicant's discretion), or in supplemental information for review via E-document reading room, audit, and RAIs [requests for additional information].

Specifically, the staff would like to briefly discuss the probabilistic risk assessment revisions and changes to the risk models since the 40-to-60-year license renewal application (focusing on changes made at the plant that have significantly reduced or increased risk).

2.

NEI 17-04 Section 3.1 Data Collection specifies:

Use the latest risk models that are available for internal events (including internal flooding) and for each of the external events contributors identified for evaluation in NEI 05-01 [Severe Accident Mitigation Alternatives (SAMA) Analysis Guidance Document, Revision A, November 2005].

NEI 05-01 specifies:

The IPEEE [Individual Plant Examination of External Events] identified the highest risk externally initiated accident sequences and potential means of reducing the risk posed by those sequences. Typically, the following external events were evaluated:

1. Internal fires

2. Seismic events

3. Other external events such as high wind events, external flooding, transportation and nearby facility accidents Explain how Other external events such as high wind events, external flooding, transportation and nearby facility accidents were considered in the North Anna SAMA New and Significant Evaluation? Discuss recommendations to reduce risk due to each of these external events. Page E-4-91 of the Dominion ER provides:

Therefore, if external events were included, the absolute value reduction in maximum benefit (MB) of some SAMAs would be larger; however, there is confidence that the methodology of percentage reduction in MB due to internal events results in a conservative analysis.

Please be prepared to discuss this further at the audit.

4.

Was there any North Anna or other facility external event SAMAs evaluated? If so, briefly describe. If not, indicate the reason why not.

5.

Describe any North Anna power uprates and impacts on risk at North Anna. What was the change in core damage frequency and large early release frequency as a result of any power uprate.

6.

Did Dominion evaluate all of the items in the 2013 Generic Environmental Impact Statement SAMA Summary Table E-19 (including low power, uncertainties, and the Biological Effects of Ionizing Radiation (BEIR) Report)?

7.

Tables E4.15-1 and E4.15-2 of the ER provides the groupings and reduction in maximum benefit of SAMAs. Please be prepared to discuss these results.