ML25335A104
| ML25335A104 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 12/02/2025 |
| From: | Dariusz Szwarc NRC/RGN-III/DORS/RPB3 |
| To: | Hafen S Northern States Power Company, Minnesota |
| References | |
| IR 2025003 | |
| Download: ML25335A104 (0) | |
Text
Shawn Hafen Site Vice President Monticello Nuclear Generating Plant Northern States Power Company, Minnesota 2807 West County Road 75 Monticello, MN 55362-9637
SUBJECT:
MONTICELLO NUCLEAR GENERATING PLANT - INTEGRATED INSPECTION REPORT 05000263/2025003
Dear Shawn Hafen:
On September 30, 2025, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Monticello Nuclear Generating Plant. On November 24, 2025, the NRC inspectors discussed the results of this inspection with M. Neal, Plant Manager, and other members of your staff. The results of this inspection are documented in the enclosed report.
Due to the temporary cessation of government operations, which commenced on October 01, 2025, the NRC began operating under its Office of Management and Budget-approved plan for operations during a lapse in appropriations. Consistent with that plan, the NRC operated at reduced staffing levels throughout the duration of the shutdown.
However, the NRC continued to perform critical health and safety functions and make progress on other high-priority activities associated with the ADVANCE Act and Executive Order 14300.
On November 13, 2025, following the passage of a continuing resolution, the NRC resumed normal operations. However, due to the 43-day lapse in normal operations, the Office of Nuclear Reactor Regulation granted the regional offices an extension on the issuance of the calendar year 2025, third quarter integrated inspection reports normally issued by November 15, 2025, to December 31, 2025. The NRC will resume the routine cycle of issuing inspection reports on a quarterly basis beginning with the calendar year 2025, fourth quarter integrated inspection reports, which will be issued 45 days after the fourth quarter ends on December 31, 2025.
No findings or violations of more than minor significance were identified during this inspection.
December 2, 2025
S. Hafen 2
This letter, its enclosure, and your response (if any) will be made available for public inspection and copying at http://www.nrc.gov/reading-rm/adams.html and at the NRC Public Document Room in accordance with Title 10 of the Code of Federal Regulations 2.390, Public Inspections, Exemptions, Requests for Withholding.
Sincerely, Dariusz Szwarc, Chief Reactor Projects Branch 3 Division of Operating Reactor Safety Docket No. 05000263 License No. DPR-22
Enclosure:
As stated cc w/ encl: Distribution via LISTSERV Signed by Szwarc, Dariusz on 12/02/25
S. Hafen 3
Letter to Shawn Hafen from Dariusz Szwarc dated December 2, 2025.
SUBJECT:
MONTICELLO NUCLEAR GENERATING PLANT - INTEGRATED INSPECTION REPORT 05000263/2025003 DISTRIBUTION:
Rodney Clagg RidsNrrDorlLpl3 RidsNrrPMMonticello RidsNrrDroIrib Resource Jack Giessner Mohammed Shuaibi Diana Betancourt-Roldan John Pelchat Jared Heck Jennifer Dalzell R3-DORS ADAMS Accession Number: ML25335A104
SUNSI Review
Non-Sensitive
Sensitive
Publicly Available
Non-Publicly Available OFFICE RIII NAME DSzwarc:anm DATE 12/02/2025 OFFICIAL RECORD COPY
Enclosure U.S. NUCLEAR REGULATORY COMMISSION Inspection Report Docket Number:
05000263 License Number:
DPR-22 Report Number:
05000263/2025003 Enterprise Identifier:
I2025003-0058 Licensee:
Northern States Power Company, Minnesota Facility:
Monticello Nuclear Generating Plant Location:
Monticello, MN Inspection Dates:
July 01, 2025, to September 30, 2025 Inspectors:
T. Hartman, Senior Resident Inspector B. Edwards, Health Physicist C. Norton, Senior Resident Inspector S. Orth, Senior Health Physicist K. Pusateri, Resident Inspector Approved By:
Dariusz Szwarc, Chief Reactor Projects Branch 3 Division of Operating Reactor Safety
2
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at Monticello Nuclear Generating Plant, in accordance with the Reactor Oversight Process. The Reactor Oversight Process is the NRCs program for overseeing the safe operation of commercial nuclear power reactors. Refer to https://www.nrc.gov/reactors/operating/oversight.html for more information.
List of Findings and Violations No findings or violations of more than minor significance were identified.
Additional Tracking Items None.
3 PLANT STATUS The unit began the inspection period at rated thermal power. On July 28, 2025, in response to the loss of the ventilation system that cools the steam chase, the unit was taken offline.
After troubleshooting and repairs to the ventilation system on August 1, 2025, the unit began a reactor and plant startup. The unit was placed back online and was returned to rated thermal power on August 2, 2025. On August 7, 2025, the unit began slowly lowering power to approximately 70 percent to address a leaking safety relief valve. On August 13, 2025, power was lowered to 30 percent in an attempt to reseat the valve and then was taken offline for repairs. On August 17, 2025, the unit began a reactor and plant startup. The unit was placed online and returned to rated thermal power on August 18, 2025. On September 19, 2025, the unit was lowered to approximately 85 percent rated thermal power for rod pattern adjustments and returned to rated thermal power. The unit remained at or near rated thermal power for the remainder of the inspection period.
INSPECTION SCOPES Inspections were conducted using the appropriate portions of the inspection procedures (IPs) in effect at the beginning of the inspection unless otherwise noted. Currently approved IPs with their attached revision histories are located on the public website at http://www.nrc.gov/reading-rm/doc-collections/insp-manual/inspection-procedure/index.html. Samples were declared complete when the IP requirements most appropriate to the inspection activity were met consistent with Inspection Manual Chapter (IMC) 2515, Light-Water Reactor Inspection Program - Operations Phase. The inspectors performed activities described in IMC 2515, Appendix D, Plant Status, observed risk significant activities, and completed onsite portions of IPs. The inspectors reviewed selected procedures and records, observed activities, and interviewed personnel to assess licensee performance and compliance with Commission rules and regulations, license conditions, site procedures, and standards.
REACTOR SAFETY 71111.04 - Equipment Alignment Partial Walkdown Sample (IP Section 03.01) (2 Samples)
The inspectors evaluated system configurations during partial walkdowns of the following systems/trains:
(1)
Division I core spray system on August 20, 2025 (2)
Division II residual heat removal service water system on September 10, 2025 71111.05 - Fire Protection Fire Area Walkdown and Inspection Sample (IP Section 03.01) (2 Samples)
The inspectors evaluated the implementation of the fire protection program by conducting a walkdown and performing a review to verify program compliance, equipment functionality, material condition, and operational readiness of the following fire areas:
(1)
Fire zone 200, drywell on August 7, 2025 (2)
Fire zone 19B, essential motor control center (MCC) area on August 27, 2025
4 Fire Brigade Drill Performance Sample (IP Section 03.02) (1 Sample)
The inspectors observed fire brigade drill performance.
(1)
The inspectors evaluated the onsite fire brigade training and performance during an announced fire drill on September 18, 2025.
71111.11Q - Licensed Operator Requalification Program and Licensed Operator Performance Licensed Operator Performance in the Actual Plant/Main Control Room (IP Section 03.01)
(1 Sample)
(1)
The inspectors observed and evaluated licensed operator performance in the control room during a loss of steam chase ventilation and manual scram on July 28, 2025 Licensed Operator Requalification Training/Examinations (IP Section 03.02) (1 Sample)
(1)
The inspectors observed and evaluated licensed operator requalification simulator on August 18, 2025 71111.12 - Maintenance Effectiveness Maintenance Effectiveness (IP Section 03.01) (1 Sample)
The inspectors evaluated the effectiveness of maintenance to ensure the following structures, systems, and components (SSCs) remain capable of performing their intended function:
(1)
Electrical cable vaults for safety-related cables on August 4, 2025 71111.13 - Maintenance Risk Assessments and Emergent Work Control Risk Assessment and Management Sample (IP Section 03.01) (1 Sample)
The inspectors evaluated the accuracy and completeness of risk assessments for the following planned and emergent work activities to ensure configuration changes and appropriate work controls were addressed:
(1)
C safety relief valve leaking requiring emergent down power and shutdown on August 13, 2025
5 71111.15 - Operability Determinations and Functionality Assessments Operability Determination or Functionality Assessment (IP Section 03.01) (3 Samples)
The inspectors evaluated the licensees justifications and actions associated with the following operability determinations and functionality assessments:
(1)
Division I control room ventilation outside air isolation damper did not open during fan start (2)
Small amount of water was found in 12 emergency diesel generator lube oil (3)
High pressure coolant injection steam supply low pressure isolation switch (PS2368B) had abnormal indications 71111.20 - Refueling and Other Outage Activities Refueling/Other Outage Sample (IP Section 03.01) (2 Samples)
(1)
The inspectors evaluated the rising steam chase temperatures forced outage activities from July 28 to August 2, 2025 (2)
The inspectors evaluated the leaking C safety relief valve forced outage activities from August 13 to August 18, 2025.
71111.24 - Testing and Maintenance of Equipment Important to Risk The inspectors evaluated the following testing and maintenance activities to verify system operability and/or functionality:
Post Maintenance Testing (PMT) (IP Section 03.01) (1 Sample)
(1)
Post maintenance testing after replacement of the C safety relief valve under work order 700118836 on July 31, 2025 Surveillance Testing (IP Section 03.01) (1 Sample)
(1) 0027, Reactor LoLo Level Emergency Core Cooling System (ECCS) Initiation and Hi Level Trip Test and Calibration, on July 1, 2025 Inservice Testing (IST) (IP Section 03.01) (1 Sample)
(1) 025504-IA11, RHR Loop A Quarterly Pump and Valve Test on September 9, 2025
6 RADIATION SAFETY 71124.05 - Radiation Monitoring Instrumentation Walkdowns and Observations (IP Section 03.01) (5 Samples)
The inspectors evaluated the following radiation detection instrumentation during plant walkdowns:
(1)
Area radiation monitor (ARM) (instrument ID A2), east side refuel floor (2)
ARM (instrument ID A7), decontamination area 1001' (3)
ARM (instrument ID B3), turbine building 931' (4)
Continuous air monitor (CAM) (instrument ID AMS4 3), refuel floor (5)
CAM (instrument ID AMS4 8), reactor water clean up (RWCU)
Calibration and Testing Program (IP Section 03.02) (10 Samples)
The inspectors evaluated the calibration and testing of the following radiation detection instruments:
(1)
Mirion AMP100 (instrument ID A10003)
(2)
Mirion AMP100 (instrument ID A10006)
(3)
Canberra ARGOS5AB (instrument ID AZ13)
(4)
FastScan whole body counter (instrument ID Fastscan2)
(5)
Ortec HPGe detector (instrument ID Det-1)
(6)
Perkin Elmer tri-carb liquid scintillation counter (7)
Ludlum model 177 (instrument ID F021)
(8)
Eberline RO20 ion chamber (instrument ID RO083)
(9)
Mirion telepole 2 (instrument ID TP11)
(10)
CAM (Instrument ID AMS4 7)
Effluent Monitoring Calibration and Testing Program Sample (IP Section 03.03) (2 Samples)
The inspectors evaluated the calibration and maintenance of the following radioactive effluent monitoring and measurement instrumentation:
(1)
Reactor building vent wide range gas radiation monitor (Instrument ID RE7859B)
(2)
Water storage transfer building tank inlet radiation monitor (Instrument ID RM7995) 71124.07 - Radiological Environmental Monitoring Program Environmental Monitoring Equipment and Sampling (IP Section 03.01) (1 Sample)
(1)
The inspectors evaluated environmental monitoring equipment and observed collection of environmental samples Radiological Environmental Monitoring Program (IP Section 03.02) (1 Sample)
(1)
The inspectors evaluated the implementation of the licensees radiological environmental monitoring program
7 GPI Implementation (IP Section 03.03) (1 Sample)
(1)
The inspectors evaluated the licensees implementation of the Groundwater Protection Initiative (GPI) program to identify incomplete or discontinued program elements OTHER ACTIVITIES - BASELINE 71151 - Performance Indicator Verification The inspectors verified licensee performance indicators submittals listed below:
MS06: Emergency AC Power Systems (IP Section 02.05) (1 Sample)
(1)
Unit 1 (July 1, 2024, through June 30, 2025)
MS07: High Pressure Injection Systems (IP Section 02.06) (1 Sample)
(1)
Unit 1 (July 1, 2024, through June 30, 2025)
MS08: Heat Removal Systems (IP Section 02.07) (1 Sample)
(1)
Unit 1 (July 1, 2024, through June 30, 2025)
INSPECTION RESULTS No findings were identified.
EXIT MEETINGS AND DEBRIEFS The inspectors verified no proprietary information was retained or documented in this report.
On November 24, 2025, the inspectors presented the integrated inspection results to M. Neal, Plant Manager, and other members of the licensee staff.
On August 7, 2025, the inspectors presented the radiation safety inspection results to S. Hafen, Site Vice President, and other members of the licensee staff.
8 DOCUMENTS REVIEWED Inspection Procedure Type Designation Description or Title Revision or Date 501000102168 Pipe Clamp Bolt Askew on ESW Motor Cooling Water for 11 Core Spray Pump 08/20/2025 501000102194 Leak at Threaded Cap After RHR-47 08/20/2025 501000102212 Motor Cooling Pipe Not Fully Insulated 08/20/2025 Corrective Action Documents Resulting from Inspection 501000102863 Rust at Base of Seismic Support 09/10/2025 NH-36248 P&ID Core Spray System 91 Drawings NH-36664 P&ID RHR Service Water & Emergency Service Water Systems 98 2119 Plant Prestart Checklist Core Spray System 10 71111.04 Procedures 2154-23 RHR Service Water System Prestart Valve Checklist 37 A.3-15-E Diesel Oil Pump House Fire Drill Guide 09/18/2025 Strategy A.3-100 MNGP Symbols 4
Strategy A.3-19-B Fire Zone 19-B, Essential MCC Area (No. 142 & 143 931' Elevation) 14 71111.05 Fire Plans Strategy A.3-200 Fire Zone 200, Drywell 3
Control Room vs. Simulator Status for LOR Cycle 25D 0
Miscellaneous MT-LOR-CPE-015S 2024 CPE Scenario 2 2
C.5-1100 RPV Control 12 71111.11Q Procedures C.5-1300 Secondary Containment Control 13 Corrective Action Documents Resulting from Inspection 501000105630 MOV Set Screw Not Retained 11/25/2025 Drawings NF-74413 Underground Services of Div. II Cable Raceway System 80 Engineering Evaluations Condition Evaluation 01494332-02 Evaluation of Safety-Related Cables Within Cable Vaults 02/02/2016 EWI-08.19.01 Cable Condition Monitoring Program 10 71111.12 Procedures FP-PE-CBL-01 Cable Condition Monitoring Program 5
Workweek 2532 Schedule 08/12/2025 71111.13 Miscellaneous Monticello Forced Outage Schedule 08/12/2025
9 Inspection Procedure Type Designation Description or Title Revision or Date 501000101167 VD-9216A Didnt Open on V-EAC-14A Start 07/23/2025 501000103217 Small Amount of Water Found in 12 Emergency Diesel Generator [Lube] Oil (501000103217) 09/22/2025 Corrective Action Documents 501000103237 High Pressure Coolant Injection Turbine Steam Supply Low Pressure Isolation Switch (PS-23-68B)
Abnormal Indications (501000103237) 09/22/2025 NH-170037 Main Control Room CRV/EFT System 84 Drawings NX-8292-12-1 HPCI System Shutdown 81 B.08.13-01 Control Room Heating and Ventilation and Emergency Filtration Train 11 71111.15 Procedures B.08.13-02 Control Room Heating and Ventilation and Emergency Filtration Train 12 Reactivity Maneuvering Steps for C SRV Down Power 08/08/2025 Miscellaneous MT Forced Outage Schedules 08/12/2025 2167 Plant Startup 112 2204 Plant Shutdown 85 2300 Reactivity Adjustment 29 71111.20 Procedures C.5-1100 RPV Control 12 501000100820 NRC ID: Station Log Error 07/10/2025 501000105520 Log Entries Not Corrected 11/21/2025 Corrective Action Documents Resulting from Inspection 501000105571 NRC Identified: Log Entry Incorrect 11/24/2025 0027 Reactor Lo-Lo Level ECCS Initiation and Hi Level Reactor Core Isolation Cooling/High Pressure Coolant Injection (RCIC/HPCI) Turbine Trips Trip Unit Test and Calibration Procedure 32 Procedures 0255-04-IA-1-1 RHR Loop A Quarterly Pump and Valve Test 101 71111.24 Work Orders 700118836 RV-2-71C - Changeout SRV per 4280-PM 07/31/2025 71124.05 Corrective Action Documents Resulting from Inspection 501000101641 ARM Detector Cans Marked Confusingly 08/05/2025 5829 REMP Air Sampler Calibration 07/24/2025 71124.07 Calibration Records 5829 REMP Air Sampler Calibration 04/30/2025
10 Inspection Procedure Type Designation Description or Title Revision or Date 7320 Monticello Meteorological Station Calibration Procedure 06/23/2025 501000101628 NRC Observation on 2023, 2024 AREORs 08/05/2025 501000101699 NRC Question on 2024 ARERR MW Data 08/07/2025 501000101734 Spring MET PM Failed Wind Criteria 08/07/2025 501000101738 NRC Question-M-9 Downstream River Sample 08/07/2025 Corrective Action Documents Resulting from Inspection 501000101760 NRC Observation: REMP Air Sampler Cal 08/07/2025 Procedures FP-CY-GWPP-01 Fleet Groundwater Protection Program 10 MSPI Basis Document 15 MSPI Basis Document 16 MSPI Derivation Reports; Emergency AC, High Pressure Injection, Heat Removal; Unavailability Index; Unit 1 07/01/2024 -
06/30/2025 MSPI Derivation Reports; Emergency AC, High Pressure Injection, Heat Removal; Unreliability Index; Unit 1 07/01/2024 -
06/30/2025 MSPI Derivation Reports; Emergency AC, High Pressure Injection, Heat Removal; Performance Limit Exceeded (PLE); Unit 1 07/01/2024 -
06/30/2025 MSPI Margin Reports 07/01/2024 -
06/30/2025 71151 Miscellaneous PI Summary - MS06-08, 3Q24-2Q25 07/18/2025