ML24047A092

Limited-Scope Audit Report for Buried Piping and External Surfaces AMPs

ML24047A092
Person / Time
Site:	Monticello
Issue date:	02/26/2024
From:	Tyree C NRC/NRR/DNRL/NLRP
To:	Hafen S Northern States Power Company, Minnesota
References
EPID L 2022-SLR-0000
Download: ML24047A092 (8)

Text

February 26, 2024

Mr. 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, UNIT 1 - SECOND LIMITED AGING MANAGEMENT AUDIT REPORT REGARDING THE SUBSEQUENT LICENSE RENEWAL APPLICATION REVIEW (EPID NO. L-2022 -SLR-0000)

Dear Mr. Hafen:

By letter dated January 9, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23009A352), as supplemented by letters dated April 3, 2023 (ML23094A136), June 26, 2023 (ML23177A218), July 11, 2023 (ML23193B026 ), July 18, 2023 (ML23199A154), August 15, 2023 (ML23227A175), August 28, 2023 (ML23240A695), September 5, 2023 (ML23248A474), September 22, 2023 (ML23265A158), October 3, 2023 (ML23276B433), and November 9, 2023 (ML23313A158), Northern States Power Company, Minnesota submitted to the U.S.

Nuclear Regulatory Commission (NRC or staff) an application to r enew the Renewed Facility Operating License No. DPR-22 for Monticello Nuclear Generating Plant (MNGP),

Unit 1.

The NRC co nducted a limited aging management audit from December 4, 2023 - January 4, 2024, in accordance with the audit plan (ML23332A165). The audit was extended 3 weeks beyond the originally planned date to allow for additional interactions between NRC and MNGP staff members. The audit report is enclosed.

S. Hafen

If you have any questions on this matter, please contact Marieliz Johnson, P roject Manager, for the safety review of the MNGP Subsequent License Renewal Application at Marieliz.Johnson@nrc.gov, or Christopher Tyree at Christopher.Tyree@nrc.gov.

Sincerely,

/RA/

Christopher S. Tyree, Project Manager License Renewal Projects Branch Division of New and Renewed Licenses Office of Nuclear Reactor Regulation

Docket No. 50-263

Enclosure:

Audit Report

cc: w/encl.: ListServ

S. Hafen

SUBJECT:

MONTICELLO NUCLEAR GENERATING PLANT, UNIT 1 - SECOND LIMITED AGING MANAGEMENT AUDIT REPORT REGARDING THE SUBSEQUENT LICENSE RENEWAL APPLICATION REVIEW (EPID NO. L-2022-SLR-0000)

DATED: FEBRUARY 26, 2024

DISTRIBUTION:

PUBLIC SLee, NRR/DNRL BSmith, NRR/DNRL LGibson, NRR/DNRL MJohnson, NRR/DNRL BBallard, NRR/DORL DRoth, OGC RidsNrrDnrl Resource RidsNrrPMMonticello Resource

EMAIL:

Max.W.Smith@xcelenergy.com Stephen.Sollom@xcelenergy.com

ADAMS Accession No.: ML24047A092 NRR-106 OFFICE NRR/DNRL: PM NRR/ DNRL: LA NRR/NLRP: PM NAME CTyree KBratcher MJohnson DATE 02/21/2024 02/21/2024 02/22/2024 OFFICE NRR/DNRL: BC NRR/DNRL: BC NAME SBloom LGibson DATE 02/22/2024 02/26/2024 OFFICIAL RECORD COPY

AUDIT REPORT Aging Management Audit

Monticello Nuclear Generating Plant, Unit 1 Subsequent License Renewal Application December 4, 2023 - January 4, 2024

Division of New and Renewed Licenses Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission

Enclosure U.S. NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATION DIVISION OF NEW AND RENEWED LICENSES

Docket No: 50- 263

License No: DPR-22

Licensee: Northern States Power Company, a Minnesota corporation (NSPM)

Facility: Monticello Nuclear Generating Plant (MNGP), Unit 1

Location: Rockville, Maryland

Dates: December 4, 2023 - January 4, 2024

Approved By: Steven D. Bloom, Chief Corrosion and Steam Generator Branch Division of New and Renewed Licenses

Lauren K. Gibson, Chief License Renewal Projects Branch Division of New and Renewed Licenses

Reviewers: Name Organization Brian Allik Corrosion and Steam Generator (NCSG)/New and Renewed Licenses (DNRL)

James Gavula NCSG/DNRL Christopher Tyree License Renewal Projects Branch (NLRP)/DNRL Marieliz Johnson NLRP/DNRL

TABLE OF CONTENTS

AUDIT REPORT.................................................................................................................... TABLE OF CONTENTS......................................................................................................... 1. Background................................................................................................................. 2. Audit Activities............................................................................................................. 3. Supplements to the SLRA........................................................................................... 4. Applicant Personnel Contacted During Audit............................................................... 5. Exit Meeting................................................................................................................

Report for the Aging Management Audit Monticello Nuclear Generating Plant, Unit 1 Subsequent License Renewal Application Aging Management Regulatory Audit

1. Background

By letter dated January 9, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23009A352), as supplemented by letters dated April 3, 2023 (ML23094A136), June 26, 2023 (ML23177A218), July 1 1, 2023 (ML23193B026),

July 18, 2023 (ML23199A154), August 15, 2023 (ML23227A175), August 28, 2023 (ML23240A695), September 5, 2023 (ML23248A474), September 22, 2023 (ML23265A158), October 3, 2023 (ML23276B433), November 9, 2023 (ML23313A158),

and November 30, 2023 (ML23334A147), Northern States Power Company, Minnesota (NSPM or the applicant) submitted to the U.S. Nuclear Regulatory Commission (NRC or staff) an application to renew the Renewed Facility Operating License No. DPR -22 for Monticello Nuclear Generating Plant (MNGP), Unit 1. The staff is reviewing this application in accordance with the guidance in NUREG-2192, Standard Review Plan for Review of Subsequent License Renewal Applications for Nuclear Power Plants, (SRP-SLR).

Following review of Xcel Energy Subsequent License Renewal Application (SLRA) Supplement 4 dated July 18, 2023 (ML23199A154), Response to Request for Additional Information Set 3 dated September 22, 2023 (ML23265A158), Response to Request for Additional Information Round 2 - Set 1 dated November 9, 2023 (ML23313A158) related to SLRA Section B.2.3.27, Buried and Underground Piping and Tanks, the staff conduct ed a limited audit to review the applicants evaluations and supporting bases for its conclusions in the SLRA supplement and RAI responses related to the following topics: (1) Buried and Underground Piping and Tanks program, and (2) External Surfaces Monitoring of Mechanical Components program.

2. Audit Activities

Several calls were held during the audit with the applicant so that the staff could ask questions to better understand the appropriateness of using the inspection quantities and frequencies in GALL-SLR Report Table XI.M41-2 given: (a) plant specific operating experience involving severe external corrosion of underground piping at MNGP; and (b) the deviation from GALL SLR Report guidance at MNGP with respect to providing external coatings for underground piping. The staff was also looking for more information on underground stainless steel piping in the radwaste system and inspections of the underground off-gas piping or vault.

In addition, the staff asked for information on all the in-scope systems that have below grade piping going between the reactor and turbine buildings and justifications for any of the piping that is not designated in the applicable aging management evaluation tables with an underground environment. The staff was seeking information regarding the restricted access for any of the above piping, as it relates to the use of the GALL-SLR specified scope of program program element of the External Surfaces Monitoring of Mechanical Components program for inspection of below grade piping.

Discussions were also held on the current walkdown guidance in MNGPs External Surfaces Monitoring of Mechanical Components program for any in-scope systems containing below

grade piping going between the reactor and turbine buildings, as it relates to whether there is a need to include an enhancement to the program for performing the visual inspections of these components.

At the conclusion of the audit the applicant proposed a commitment to inspect a sample of pipes in the vicinity of the seismic gap that are located below or near the maximum elevation of the water table at least once during the 6-year period before the subsequent period of operation (SPEO) and once every 6-years or 3 fueling outages after SPEO has been entered. The applicant also proposed to inspect a sample of the below-grade pipes within the scope of the External Surfaces Monitoring of Mechanical Components AMP that are located in the seismic gap space between the reactor and turbine buildings 10 years following the initial inspection that was performed prior to the SPEO. The staff found the inspection intervals to be acceptable and the applicant included these commitments as enclosure 5 and 6 of Supplement 8 (ML24012A051).

3. Supplements to the SLRA

After discussions with the applicant, the NRC staff reviewed draft Enclosures 5 and 6 that were included into SLRA Supplement 8 dated January 11, 2024 (ML24012A051). The staff will document its review of this information and resolution of the issues in the SE.

4. Applicant Personnel Contacted During Audit

Xcel Energy Benjamin Alkhas Matthew Sears Max Smith Paul Young Peter Kissinger Stephen Sollom Toutseng Hawj

Enercon Ian Miller Jeff Gromatzky Joanne Aleksick Molly OSullivan Reene Gambrell Richard Pearson

5. Exit Meeting

An exit meeting was held with the applicant on January 4, 2024, to discuss the results of the regulatory audit.