ML24155A177

Regulatory Audit in Support of Review of the LAR to Revise Emergency Diesel Generator Frequency and Voltage Ranges for Technical Specification 3.8.1, Surveillance Requirements

ML24155A177
Person / Time
Site:	Vogtle
Issue date:	06/05/2024
From:	John Lamb Plant Licensing Branch II
To:	Coleman J Southern Nuclear Operating Co
References
EPID L-2024-LLA-0031
Download: ML24155A177 (1)

Text

June 5, 2024

Jamie M. Coleman Regulatory Affairs Director Southern Nuclear Operating Co., Inc.

3535 Colonnade Parkway Birmingham, AL 35243

SUBJECT:

VOGTLE ELECTRIC GENERATING PLANT, UNITS 1 AND 2 - REGULATORY AUDIT IN SUPPORT OF REVIEW OF THE LICENSE AMENDMENT REQUEST TO REVISE EMERGENCY DIESEL GENERATOR FREQUENCY AND VOLTAGE RANGES FOR TECHNICAL SPECIFICATION 3.8.1, AC SOURCES

- OPERATING, SURVEILLANCE REQU IREMENTS (EPID L-2024-LLA-0031)

Dear Jamie Coleman:

By letter dated March 20, 2024 (Agencywide Documents and Access Management System (ADAMS) Accession No. ML24080A455), Southern Nuclear Operating Company (SNC, the licensee) submitted a license amendment request (LAR) for Vogtle Electric Generating Plant (Vogtle), Units 1 and 2. The proposed LAR would revise the emergency diesel generator (EDG) frequency and voltage acceptance criteria for Technical Specification (TS) 3.8.1, AC

[alternating current] Sources - Operating, Surveillance Requirements (SRs). The proposed LAR is required to correct a non-conservative TS.

The U. S. Nuclear Regulatory Commission (NRC) staff has identified the need for a regulatory audit to examine SNCs non-docketed information with the intent to gain understanding, verify information, or identify information that will require docketing to support the basis of the licensing or regulatory decision.

The NRC staff will conduct the audit virtually v ia Teams using a licensee-established electronic portal available to NRC staff from approximately J uly 1, through October 31, 2024, with formal audit meetings to be scheduled durin g this period as needed. The NRC staff reserves the right to extend the audit, if necessary. The detailed audit plan is enclosed with this letter.

J. Coleman

If you have any questions, please contact me at (301) 415-3100 or by email at John.Lamb@nrc.gov.

Sincerely,

/RA/

John G. Lamb, Senior Project Manager Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Docket Nos. 50-424 and 50-425

Enclosure:

Audit Plan

cc: Listserv REGULATORY AUDIT PLAN

BY THE OFFICE OF NUCLEAR REACTOR REGULATION

TO SUPPORT THE REVIEW OF THE LICENSE AMENDMENT REQUEST

TO REVISE TS 3.8.1

SOUTHERN NUCLEAR OPERATING COMPANY

VOGTLE ELECTRIC GENERATING PLANT, UNITS 1 AND 2

DOCKET NOS. 50-424, AND 50-425

1.0 BACKGROUND

By letter dated March 20, 2024 (Agencywide Documents and Access Management System (ADAMS) Accession No. ML24080A455), Southern Nuclear Operating Company (SNC, the licensee) submitted a license amendment request (L AR) for Vogtle Electric Generating Plant (Vogtle), Units 1 and 2. The proposed LAR would revise the emergency diesel generator (EDG) frequency and voltage acceptance criteria for Technical Specification (TS) 3.8.1, AC

[alternating current] Sources -Operating, Surv eillance Requirements (SRs). The proposed LAR is required to correct a non-conservative TS.

The NRC staff has identified the need for a regulatory audit to examine the SNCs non-docketed information with the intent to gain understanding, to verify information, or to identify information that will require docketing to support the basis of the licensing or regulatory decision.

The NRC staff from the Office of Nuclear Reactor Regulation (NRR) has initiated its review of the LAR in accordance with NRR Office Instruction LIC-101, License Amendment Review Procedures (ML19248C539).

2.0 REGULATORY AUDIT BASIS

A regulatory audit is a planned license-or regulation-related activity that includes the examination and evaluation of primarily non-docketed information associated with the LAR. An audit is conducted to gain understanding, to verify information, and to identify information that will require docketing to support the basis of a licensing or regulatory decision. An audit will assist the NRC staff in efficiently conducting it s review and gaining insights to the licensees processes and procedures. Information that the NRC staff relies upon to make the safety determination must be submitted on the docket. This audit will be conducted in accordance with NRR Office Instruction LIC-111, Regulatory Audits, Revision 1, dated October 2019 (ML19226A274), with exceptions noted within this audit plan.

Enclosure

The NRC staff will perform the audit to support its evaluation of whether SNCs LAR can be approved per Title 10 of the Code of Federal Regulations (10 CFR), Section 50.90, Application for amendment of license, construction permit, or early site permit. The NRC staffs review will be informed by NUREG-0800, Standard Review Plan. The audit will assist the NRC staff with understanding the licensees proposed TS 3.8.1 LAR.

3.0 REGULATORY AUDIT SCOPE AND METHODOLOGY

NRCs objectives of the audit are the following:

Gain a better understanding of the detailed calculations, analyses, and bases underlying the LAR and confirm the NRC staffs understanding of the LAR.

Gain a better understanding of plant design features and their implications for the LAR.

Identify any information needed to enable the NRC staffs evaluation of the technical basis used for this application.

Identify any information needed to enable the NRC staffs evaluation of whether the proposed changes challenge design-basis functions or adversely affect the capability or capacity of plant equipment to perform design-basis functions.

Identify questions and requests that may become formal requests for additional information (RAIs) per NRR Office Instruction LIC-115, Processing Requests for Additional Information (ML21141A238).

The NRC staff will audit the technical information and methods that the licensee used to determine the impact on the plant, and the licensees evaluation of defense-in-depth.

4.0 INFORMATION AND OTHER MATERIAL NECESSARY FOR THE AUDIT

The NRC staff will request information and an audi t meeting(s) throughout the audit period. The NRC staff will use an audit items list to identify the information (e.g., methodology, process information, and calculations) to be audited. The NRC staff will provide the final audit items list as an enclosure to the audit summary report, which will be publicly available. The attachment to this audit plan includes the initial audit item s list. Throughout the audit period, the NRC staff will provide SNC with audit questions and audit-related requests so that the licensee can better prepare for audit discussions with NRC staff. Any information accessed through the licensees portal will not be held or retained in any way by NRC staff. The NRC staff requests the licensee to have the requested audit information listed in the audit items list to be readily available and accessible for the NRC staffs review via a Web-based portal.

5.0 TEAM ASSIGNMENTS

The audit team will consist of t he following NRC staff from NRR:

John G. Lamb, Division of Operating Reactor Licensing (DORL)/Plant Licensing Branch 2-1 (LPL2-1)

Khoi Nguyen, Division of Engineering and External Hazards (DEX)/Electrical Engineering Branch (EEEB)

Hari Kodali, DEX/EEEB Tarico Sweat, Division of Safety Systems (DSS)/Technical Specifications Branch (STSB)

Fred Forsaty, DSS/Nuclear Systems Performance Branch (SNSB), and Santosh Bhatt, DSS/SNSB.

6.0 LOGISTICS

To support the review schedule communicated to SNC when the NRC staff accepted the LAR for technical review, audit activities will be performed remotely and virtually using Microsoft Teams, teleconference, and a Web-based portal or other virtual meeting space created by the licensee. The NRC staff information requests and communications with licensee staff will be coordinated through the NRCs licensing project manager.

A desktop audit will take place between July 1, through October 31, 2024. The NRCs licensing project manager will inform the licensee of the entrance and exit meeting dates when they are established. The NRC intends to establish an approximately thr ee-day virtual audit meeting via Microsoft Teams on mutually agreeable dates and times, to discuss information needs and questions arising from the NRCs review of the audited items. The NRC staff may change and/or add audit dates and times, or extend the audit, if necessary. Audit meeting agenda and questions, if needed, will be sent in advance of the audit meeting.

The NRC staff requests the licensee to have the information referenced in Section 4.0 of this audit plan available and accessible for the NRC sta ffs review via an internet-based portal within five days of this audit plan. The NRC staff requests that any supplemental information requested be available and accessible for the NRC staffs review within 5 days of the date of the NRCs notification to the licensee of the new reques ts. The NRCs licensing project manager will inform the licensee via routine communications when the NRC staff no longer needs access to the portal. The NRC staff requests the licensee to no tify the NRCs licensing project manager when an audit item is added to its portal by sending an e-mail to the NRC licensing project manager.

7.0 SPECIAL REQUESTS

The NRC requests access to requested documents and information through a Web-based portal that allows the NRC staff and contractors to a ccess documents over the Internet. The following conditions associated with the online portal must be maintained while the NRC staff and contractors have access to the online portal:

The online portal will be password-protect ed. A separate password will be assigned to each member of the NRC staff and NRC contractors participating in the audit.

The online portal will prevent the NRC participants from printing, saving, downloading, or collecting any information directly from the online portal.

Conditions of use of the online portal will be displayed on the login screen and will require acknowledgment by each user.

Username and password and/or other Web-based portal access information should be provided directly to members of the NRC staff and c ontractors as needed. The NRC licensing project manager will provide the licensee with names and contact information of the NRC staff and contractors participating in the audit. All other communications should be coordinated through the NRC project manager.

8.0 DELIVERABLES

The NRC staff will develop any RAIs, as needed, via NRR Office Instruction LIC-115 and issue such RAIs separately from audit-related co rrespondence. The NRC staff will issue an audit summary report prior to completing its review of the LAR.

Initial Audit Items List

Item # Audit Item Methodology for establishing the proposed emergency diesel generator (EDG) 1 voltage and frequency tolerances. If a calculation for these tolerances exists, a copy of such calculation should be available for auditing. [EEEB]

EDG fuel consumption and EDG loading calculations against the EDG voltage and 2 frequency variations. [EEEB]

In Section 3.0 of the LAR, SNC concluded that Motor-Operated Valve (MOV) performance is not affected by the proposed EDG voltage and frequency ranges.

Provide the following:

a. A sample calculation for MOV performance and for other motor driven loads such as fans, pumps, HVAC heaters,120 V AC etc., as applicable.

3 b. A sample calculation for MOV or an evaluation, if exists, that evaluates the impact of the proposed change to the following:

MOV motor speed MOV inertia MOV voltage Pump output pressure and differential pressure on the MOV. [SNSB]

Section 3 of LAR states that, The performance of the required equipment is dependent on the EDG voltage and frequency.

a-In this Section it is stated that, review of surveillance test data over the past three years provides assurance that the revised voltage and frequency limits 4 will be achievable. Provide evaluation for this conclusion.

b-Provide the present Surveillance Uncertainty analysis.

c-How the plant EDG reliability is analyzed for future extended period; for example, the next 5 fuel reload cycles?

[SNSB]

To reduce stress and wear on diesel engines, some manufacturers recommend that the starting speed of EDGs be limited, that warm-up be limited to a designed lower speed, and that EDGs be gradually accelerated to synchronous speed prior to 5 loading. What are the manufacturer recommendations for the Vogtle, EDGs in support of this condition? Provide the plant procedures in support of possible EDG failure due to stress. [SNSB]

Provide the analysis that evaluates the performance of the Vogtle, Units 1 and 2, containment spray pump, that generates revised minimum and maximum test curves 6 to account for the effects of steady state EDG voltage and frequency variations, as well as evaluating flow and pressure measurement uncertainties. [SNSB]

Provide the Spent Fuel Pit Pumps available margin to cover the EDG degradation 7 uncertainty. [SNSB]

Item # Audit Item

Section 3.0 of the LAR discusses the emergency core cooling systems (ECCS) and Containment Spray pump evaluation. Per Section 2.1 of WCAP-17308-NP-A, the total pump head uncertainty is calculated at discrete flow rates as a function of the combined uncertainties for frequency, voltage, and various other measurements including flow and pressure.

8 Provide evaluation of the following ECCS pumps for the overspeed and overvoltage conditions to show sufficient margins remain to accommodate pump speed increase:

(a) Residual Heat Removal (RHR) pumps (b) Containment Spray pumps (c)

Residual Heat Removal Service Water (RHRSW) and (d) the pumps listed under Miscellaneous Equipment powered from the DGs in the LAR. [SNSB]

9

10

11

12

13

14

15

ML24155A177 NRR-106 OFFICE NRR/DORL/LPLII-1/PM NRR/DORL/LPLII-1/LA NRR/DEX/EEEB/BC NRR/DSS/SNSB/BC NAME JLamb KGoldstein WMorton (SRay for) PSahd (RBeaton for)

DATE 05/29/2024 06/05/2024 06/05/2024 06/05/2024 OFFICE NRR/DORL/LPLII-1/BC NRR/DORL/LPLII-1/PM NAME MMarkley JLamb DATE 06/05/2024 06/05/2024