ML24137A279

Audit Summary for License Amendment Request to Revise Technical Specification 3.8.6, Battery Parameters, Surveillance Requirement 3.8.6.6

ML24137A279
Person / Time
Site:	Monticello
Issue date:	06/03/2024
From:	Ballard B Plant Licensing Branch III
To:	Hafen S Entergy Operations
References
EPID L-2023-LLA-0038
Download: ML24137A279 (1)

Text

June 3, 2024

Shawn Hafen Site Vice President Northern States Power Company

- Minnesota Monticello Nuclear Generating Plant 2807 West County Road 75 Monticello, MN 55362

SUBJECT:

MONTICELLO NUCLEAR GENERATING PLANT - AUDIT

SUMMARY

FOR LICENSE AMENDMENT REQUEST TO REVISE TECHNICAL SPECIFICATION 3.8.6, BATTERY PARAMETERS, SURVEILLANCE REQUIREMENT 3.8.6.6 (EPID L-2023-LLA-0160)

Dear Shawn Hafen:

By letter dated November 10, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23317A122), Northern States Power Company, a Minnesota Corporation (NSPM, the licensee), doing business as Xcel Energy, submitted a license amendment request (LAR) for the Monticello Nuclear Generating Plant to the U.S. Nuclear Regulatory Commission (NRC). Specifically, the proposed amendment revises Technical Specification 3.8.6, Battery Parameters, Surveillance Requirement 3.8.6.6, acceptance criteria for 125-volt direct current (VDC) batteries.

To support its review, by letter dated February 14, 2024 (ML24036A004), the NRC staff notified the licensee that they would conduct a regulatory audit from February 26, 2024, to March 8, 2024, through an online portal (also known as electronic portal, Certrec Portal, electronic reading room) established by NSPM. Due to the volume and complexity of calculations, and the need for clarifying information, the virtual audit was extended and concluded on April 3, 2024. The results of the re gulatory audit were used by the NRC staff to finalize requests for additional information, which were issued by email dated May 10, 2024 (ML24131A080). The regulatory audit summary is enclosed with this letter.

S. Hafen

If you have any questions, please contact me at 301-415-0860 or via e-mail at Brent.Ballard@nrc.gov.

Sincerely,

/RA/

Brent T. Ballard, Project Manager Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Docket No. 50-263

Enclosure:

Regulatory Audit Summary

cc: Listserv REGULATORY AUDIT

SUMMARY

REGARDING LICENSE AMENDMENT REQUEST TO

REVISE TECHNICAL SPECIFICATION 3.8.6, "BATTERY PARAMETERS"

SURVEILLANCE REQUIREMENT 3.8.6.6

NORTHERN STATES POWER COMPANY

MONTICELLO NUCLEAR GENERATING PLANT

DOCKET NO. 50-263

1.0 BACKGROUND

By letter dated November 10, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23317A122), Norther n States Power Company, a Minnesota Corporation (NSPM, the licensee), doing business as Xcel Energy, submitted a license amendment request (LAR) for the Monticello Nuclear Generating Plant (Monticello).

The proposed amendment revises Technical Specification 3.8.6, Battery Parameters, Surveillance Requirement 3.8.6.6, acceptance criteria for 125-volt direct current (VDC) batteries.

The U. S. Nuclear Regulatory Commission (NRC) staff performed a preliminary review of the LAR and determined that a regulatory audit would assist in the timely completion of the review.

An audit plan was provided to the licensee on February 14, 2024 (ML24036A004), which provided the list of requested documents and other details pertaining to the audit. The purpose of the audit was to gain an understanding of the information needed to support the NRC staffs licensing decision regarding the LAR and to develop requests for additional information (RAIs),

if necessary. The information submitted in suppo rt of the LAR is under final review, and any additional information needed to support the LAR review will be formally requested by the NRC staff using the RAI process.

2.0 REGULATORY AUDIT BASES

A regulatory audit is a planned license or regulation-related activity that includes the examination and evaluation of primarily non-docketed information. The 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 a licensing or regulatory decision. Performing a regulatory audit is expected to assist the NRC staff in effi ciently conducting its review and gaining insights to the licensees processes and procedures. Inform ation that the NRC staff relies upon to make the safety determination must be submitted on the docket.

This regulatory audit is based on the following regulatory requirements and guidance:

Title 10 of the Code of Federal Regulations, section 50.63, Loss of All Alternating Current Power.

Enclosure

The Monticello Updated Safety Analysis Report, Principal Design Criteria (PDC),

specifically:

o PDC 1.2.1.a, General Criteria, o PDC 1.2.6, Plant Electrical Power, o PDC 1.2.10, Separation of Safety Systems, o PDC 1.2.11, Class I Equipment and Structures.

IEEE [Institute of Electrical and Electronics Engineers] Standard 450-1995, IEEE Recommended Practice for Maintenance, Testing, and Replacement of Vented Lead-Acid Batteries for Stationary Applications.

3.0 AUDIT ACTIVITIES AND SCOPE

By letter dated February 14, 2024 (ML24036A004), the NRC staff issued an audit plan. The original audit duration was from February 26, 20 24, to March 8, 2024. The NRC audit team held an entrance meeting with NSPM on February 26, 2024. Due to the volume and complexity of calculations, and the need for clarifying information, the virtual audit was extended and concluded on April 3, 2024. The audit was performed via online portal and there were no person-to-person interactions between the audit team and the licensee. Therefore, there was no need for a formal exit briefing. The NRC staff conducted this audit under the guidance provided in the Nuclear Reactor Regulation Office Instruction LIC-111, Regulatory Audits, Revision 1 (ML19226A274).

The audit team reviewed documentation and calculations that provide the technical support for the LAR. The NRC staffs audit focused on the following subjects:

The 125 VDC battery sizing calculations that have been revised.

The NRC staff provided four audit questions with items for NSPM to clarify. NSPM posted answers to these questions to the online portal. The audit questions are included in section 4.0 of this audit summary.

4.0 DOCUMENTS AND FILES REVIEWED

No. Audit Item 1 NSPM Calculation No.02-179, Revision 4, MNGP 125 Volt Div. I Battery Calculation 2 NSPM Calculation No.02-192, Revision 4, MNGP 125 Volt Div. II Battery Calculation

No. Audit Item 3 Licensee response to audit question 1 (question copied below):

According to Section 7.1 (pdf page 26 of 1165) of the 125 VDC Division 1 Battery Calculation, Attachment S (pdf page 1051) provides an overview of each specific scenario and the composite scenario.

The Attachment S provides scenarios with following time-steps:

(1) 23 time-steps (pdf pages 1052-1053)

(2) 29 time-steps (pdf pages 1054-1055)

(3) 31 times-steps (pdf pages 1056-1058)

(4) 61 time-steps (pdf pages 1059-1062)

The titles of the above four scenarios are missing. Please confirm that the titles are similar to ones provided in the Division 2 Battery Calculation Attachment S: (1) SBO Scenario, (2) SBLOCA Scenario, (3) LBLOCA Scenario, and (4) Composite Scenario.

4 Licensee response to audit question 2 (question copied below):

Attachment L (pdf pages 951-955) shows 17 load periods considered for the Cell Sizing Worksheet. Attachment M (pdf pages 955-956) provides Load Profile for Battery D1. Please explain how the load periods in Attachment L and load profile in Attachment M were developed considering various scenarios shown in question 1.

5 Licensee response to audit question 3 (question copied below):

Monticello TS SR 3.8.4.3, Note 1 states: The modified performance discharge test SR 3.8.6.6 may be performed in lieu of SR 3.8.4.3 (battery service test).

According to the LAR, the proposed revised TS SR 3.8.6.6 states:

Verify battery capacity is:

90% of the manufacturers rating for 250 VDC batteries 80% of the manufacturers rating for 125 VDC batteries when subjected to a performance discharge test or a modified performance discharge test.

Please provide the 125 VDC battery load profile(s) for (1) battery service test which would be considered for SR 3.8.4.3, and (2) performance discharge test, or a (3) modified performance test for SR 3.8.6.6. Also, explain how these test profiles were developed considering the 17 load periods considered in Attachment L, and the load profile provided in Attachment M of the battery sizing calculations.

No. Audit Item 6 Licensee response to audit question 4 (question copied below):

In response to audit Question 3 (3.3), for the #11, 125 VDC Battery, the Minimum Test Voltage is considered as 105 V for all load test steps. However, for the #12, 125 VDC Battery, the Minimum Test Voltage is considered as varying between 109.1 V and 106.8 V for the various load steps - with a footnote to 106.8 V stating: Terminal voltage required to satisfy the Service Test is 105.455.

Please explain why the minimum test voltage is considered as varying for Battery #12, and constant 105 V for Battery #11 for various load steps. Also, explain how the varying minimum test voltage is determined.

The licensee responses to the staff audit questions provided clarifications to the battery sizing calculations and the LAR. The NRC staff did not remove non-docketed information from the online portal.

5.0 AUDIT TEAM

The NRC audit team included the following:

Brent Ballard, Project Manager - Brent.Ballard@nrc.gov Kayleh Hartage, Electrical Engineer - Kayleh.Hartage@nrc.gov Vijay Goel, Senior Electrical Engineer - Vijay.Goel@nrc.gov Robert Elliot, Senior Safety and Plant Systems Engineer - Robert.Elliott@nrc.gov

6.0 RESULTS OF THE AUDIT

As a result of the audit, the NRC staff gained a better understanding of the licensees calculations supporting the LAR. RAIs were issued to the licensee on May 10, 2024 (ML24131A080). The licensee is scheduled to provide a response to the RAIs by June 10, 2024.

ML24137A279 OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NRR/DEX/EEEB/BC NAME BBallard SRohrer WMorton DATE 5/13/2024 5/16/2024 5/16/2024 OFFICE NRR/DORL/LPL3/BC NRR/DORL/LPL3/PM NAME JWhited BBallard DATE 5/31/2024 6/3/2024