IR 05000263/2025003
| 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
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 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
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.
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
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
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,
RADIATION SAFETY
71124.05 - Radiation Monitoring Instrumentation
Walkdowns and Observations (IP Section 03.01)===
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
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
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) 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.
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
Drawings
NH-36664
P&ID RHR Service Water & Emergency Service
Water Systems
2119
Plant Prestart Checklist Core Spray System
Procedures
2154-23
RHR Service Water System Prestart Valve Checklist
A.3-15-E
Diesel Oil Pump House Fire Drill Guide
09/18/2025
Strategy A.3-100
MNGP Symbols
Strategy A.3-19-B
Fire Zone 19-B, Essential MCC Area
(No. 142 & 143 931' Elevation)
Fire Plans
Strategy A.3-200
Fire Zone 200, Drywell
Control Room vs. Simulator Status for LOR Cycle 25D
Miscellaneous
MT-LOR-CPE-
015S
24 CPE Scenario 2
C.5-1100
RPV Control
Procedures
C.5-1300
Secondary Containment Control
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
Engineering
Evaluations
Condition
Evaluation
01494332-02
Evaluation of Safety-Related Cables Within Cable Vaults
2/02/2016
EWI-08.19.01
Cable Condition Monitoring Program
Procedures
FP-PE-CBL-01
Cable Condition Monitoring Program
Workweek 2532 Schedule
08/12/2025
Miscellaneous
Monticello Forced Outage Schedule
08/12/2025
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
Drawings
NX-8292-12-1
HPCI System Shutdown
B.08.13-01
Control Room Heating and Ventilation and Emergency
Filtration Train
Procedures
B.08.13-02
Control Room Heating and Ventilation and Emergency
Filtration Train
Reactivity Maneuvering Steps for C SRV Down Power
08/08/2025
Miscellaneous
MT Forced Outage Schedules
08/12/2025
2167
Plant Startup
2
204
Plant Shutdown
2300
Reactivity Adjustment
Procedures
C.5-1100
RPV Control
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
27
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
Procedures
255-04-IA-1-1
RHR Loop A Quarterly Pump and Valve Test
101
Work Orders
700118836
RV-2-71C - Changeout SRV per 4280-PM
07/31/2025
Corrective Action
Documents
Resulting from
Inspection
501000101641
ARM Detector Cans Marked Confusingly
08/05/2025
29
REMP Air Sampler Calibration
07/24/2025
Calibration
Records
29
REMP Air Sampler Calibration
04/30/2025
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
20
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
MSPI Basis Document
MSPI Basis Document
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