IR 05000263/2023001
ML23124A108 | |
Person / Time | |
---|---|
Site: | Monticello ![]() |
Issue date: | 05/04/2023 |
From: | Hironori Peterson NRC/RGN-III/DORS/RPB3 |
To: | Domingos C Northern States Power Company, Minnesota |
References | |
IR 2023001 | |
Download: ML23124A108 (1) | |
Text
SUBJECT:
MONTICELLO NUCLEAR GENERATING PLANT-INTEGRATED INSPECTION REPORT 05000263/2023001
Dear Christopher Domingos:
On March 31, 2023, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Monticello Nuclear Generating Plant. On April 13, 2023, the NRC inspectors discussed the results of this inspection with Shawn Hafen, Plant Manager, and other members of your staff.
The results of this inspection are documented in the enclosed report.
No findings or violations of more than minor significance were identified during this inspection.
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, Hironori Peterson, Chief Reactor Projects Branch 3 Division of Operating Reactor Safety Docket No. 05000263 License No. DPR22
Enclosure:
As stated
Inspection Report
Docket Number:
05000263
License Number:
Report Number:
Enterprise Identifier:
I2023001-0061
Licensee:
Northern States Power Company, Minnesota
Facility:
Monticello Nuclear Generating Plant
Location:
Monticello, MN
Inspection Dates:
January 01, 2023 to March 31, 2023
Inspectors:
N. Bolling, Project Engineer
T. McGowan, Resident Inspector
C. Norton, Senior Resident Inspector
K. Pusateri, Resident Inspector
D. Tesar, Senior Resident Inspector
Approved By:
Hironori Peterson, Chief
Reactor Projects Branch 3
Division of Operating Reactor Safety
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 February 6, 2023, the licensee reduced thermal power to 95 percent of rated to perform a control rod pattern adjustment and returned to rated thermal power the same day. On February 27, the licensee reduced thermal power to 95 percent of rated to perform a control rod pattern adjustment and returned to rated thermal power the same day. On March 3, the unit began coast down from rated thermal power with all control rods fully withdrawn and recirculation pumps at maximum speed. On March 18, the licensee reduced power from 95 percent of rated thermal power in coast down to 65 percent of rated thermal power, closed the inboard C main steam isolation valve, and returned to 75 percent of rated thermal power. On March 24, the licensee shutdown the reactor to repair a leak on the control rod drive suction header. On March 30, 2023, the licensee commenced a reactor startup. The unit ended the inspection period at 80 percent of rated thermal power in coast down.
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
71111.01 - Adverse Weather Protection
Impending Severe Weather Sample (IP Section 03.02) (1 Sample)
- (1) The inspectors evaluated the adequacy of the overall preparations to protect risk-significant systems from impending severe weather, winter storm advisory with high winds, icy conditions, and predicted 12 feet snow fall on February 21, 2023.
71111.04 - Equipment Alignment
Partial Walkdown Sample (IP Section 03.01) (5 Samples)
The inspectors evaluated system configurations during partial walkdowns of the following systems/trains:
- (1) Control rod drive (CRD) system suction piping on January 3, 2023
- (2) Emergency diesel generator (EDG) 12, protected train, essential service water subsystem on January 10, 2023
- (3) Division 2 filtration service water (FSW) following pipe replacement on January 19, 2023
- (4) Control rod drive system 12 protected train while CRD pump 11 was isolated and unavailable on January 25, 2023
- (5) Groundwater tritium mitigation system on January 27, 2023
Complete Walkdown Sample (IP Section 03.02) (1 Sample)
- (1) The inspectors evaluated system configurations during a complete walkdown of the control rod drive system on January 18, 2023
71111.05 - Fire Protection
Fire Area Walkdown and Inspection Sample (IP Section 03.01) (8 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 1G, CRD pump room on January 3, 2023
- (2) Fire zone 1E, high pressure coolant injection (HPCI) room on January 3, 2023
- (3) Fire zone 12A, lower 4 KV bus area 13 and 15 on January 5, 2023
- (4) Fire zone 14A, upper 4 KV bus area 14 and 16 on January 5, 2023
- (5) Fire zone 1C, reactor core isolation cooling (RCIC) room on January 5, 2023
- (6) Fire zone 2H, west shutdown cooling area on February 6, 2023
- (7) Fire zone 33, emergency filtration train (EFT) building third floor on February 6, 2023
- (8) Fire zone 23A, intake structure while hot work was in progress on March 22, 2023
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 the plant heating boiler on January 10, 2023.
Licensed Operator Requalification Training/Examinations (IP Section 03.02) (1 Sample)
- (1) The inspectors observed and evaluated crew 4 operations training in preparation for the upcoming refueling outage on January 18, 2023.
71111.12 - Maintenance Effectiveness
Maintenance Effectiveness (IP Section 03.01) (3 Samples)
The inspectors evaluated the effectiveness of maintenance to ensure the following structures, systems, and components (SSCs) remain capable of performing their intended function:
(1)11 EDG immersion heater temperature sensor, TS7194 replaced due to unexpected rise in lube oil cooler outlet temperature
- (2) Division 2 125Vdc battery charger, D20
- (3) Division 1 residual heat removal (RHR) 11 pump motor replaced due to historical vibrations in the alert range (decreased reliability)
71111.13 - Maintenance Risk Assessments and Emergent Work Control
Risk Assessment and Management Sample (IP Section 03.01) (3 Samples)
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) CRD pump 11 with elevated vibrations on January 25, 2023
- (2) Elevated temperatures in steam chase on March 10, 2023
- (3) Aggregate risk associated with multiple residual heat removal service water (RHRSW) deficiencies which potentially impacted system operability on March 26, 2023
71111.15 - Operability Determinations and Functionality Assessments
Operability Determination or Functionality Assessment (IP Section 03.01) (6 Samples)
The inspectors evaluated the licensee's justifications and actions associated with the following operability determinations and functionality assessments:
(1)
===501000070625, safety relief valve 'G' reached 165 degrees Fahrenheit (2)501000070299, unexpected configuration of 10A-K48B 2/3 core height interlock (3)501000070173, evidence of battery cell 29 positive post-seal leakage on battery string 16 (4)501000070634, unexpected annunciator 5A-43, rod block monitor downscale/trouble (5)501000070666, degraded fire barrier (6)501000072235, 11 RHR pump failed to start manually; 501000072261, Fuse 10A-F19A (panel C32) found open
71111.18 - Plant Modifications
Temporary Modifications and/or Permanent Modifications (IP Section 03.01 and/or 03.02)
=
The inspectors evaluated the following temporary or permanent modifications:
- (2) Replacement and modification of the control rod drive pumps' suction line from the condensate system
71111.20 - Refueling and Other Outage Activities
Refueling/Other Outage Sample (IP Section 03.01) (1 Sample)
- (1) The inspectors evaluated forced outage 2301 activities from March 25-30, 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) (4 Samples)
(1)
===025511-IIC2, Emergency Service Water System Leakage Test-Loop 'B,' after FSW pipe replacement, on January 19, 2023
- (2) B.09.1205 G4, Transfer of Reactor Protection System (RPS) Bus Back to Motor Generator (MG) Set B, following B RPS motor generator replacement on January 31, 2023
- (3) Cycling MO2012, RHR division 1 low pressure coolant injection outboard valve, after swapping motor operated valve (MOV) breaker fuses, on March 7, 2023 (4)025505-IA11, 'A' RHRSW Pump and Valve Quarterly Test, for CV1728, RHR 11 heat exchanger RHRSW outlet valve, after maintenance, on March 9, 2023 Surveillance Testing (IP Section 03.01)===
- (1) EDG 11 comprehensive load test on January 9, 2023
- (2) Emergency service water 14 quarterly pump and valve tests on February 3, 2023
- (3) Standby liquid control quarterly pump and valve tests on February 9, 2023
- (4) RHRSW train 'A' quarterly pump and valve tests on March 9, 2023
- (5) RHRSW train 'B' quarterly pump and valve tests on March 24, 2023
Inservice Testing (IST) (IP Section 03.01) (1 Sample)
- (1) IST, Division 2 Filtration Service Water System Test, following pipe replacement, per work order 70010369690070
Containment Isolation Valve (CIV) Testing (IP Section 03.01) (1 Sample)
(1)
===025518-IA, Traversing incore probe ball valve quarterly exercise, on February 15, 2023
71114.06 - Drill Evaluation
Drill/Training Evolution Observation (IP Section 03.02)===
The inspectors evaluated:
- (1) Tabletop drill, loss of alternating current (AC) and direct current (DC) power on January 10, 2023
- (2) Licensed operator, crew 3, performed an out-ofthe-box scenario related to emergency action level classification on February 13,
OTHER ACTIVITIES-BASELINE
===71151 - Performance Indicator Verification The inspectors verified licensee performance indicators submittals listed below:
IE01: Unplanned Scrams per 7000 Critical Hours Sample (IP Section 02.01)===
- (1) January 1, 2022 through December 31, 2022 IE03: Unplanned Power Changes per 7000 Critical Hours Sample (IP Section 02.02) (1 Sample)
- (1) January 1, 2022 through December 31, 2022
IE04: Unplanned Scrams with Complications (USwC) Sample (IP Section 02.03) (1 Sample)
- (1) January 1, 2022 through December 31, 2022
71153 - Follow Up of Events and Notices of Enforcement Discretion Event Follow-up (IP Section 03.01)
- (1) During the first quarter 2023, the inspectors evaluated the licensee response to the discovery of tritium in the groundwater between the turbine building and reactor building as described in Event Number:
INSPECTION RESULTS
Observation: Licensee Response to Event Number: 56236 71153 On November 22, 2022, Monticello Nuclear Generating Plant initiated a voluntary communication to the State of Minnesota after receiving analysis results for an onsite monitoring well that indicated tritium activity above the offsite dose calculation manual for reporting as described in the Nuclear Energy Institute Groundwater Protection Initiative (ML101740201) reporting levels. Subsequently, the licensee notified the Nuclear Regulatory Commission (NRC) of the voluntary communication to the State of Minnesota in accordance with NRC reporting requirements contained in Title 10 of the Code of Federal Regulations (10 CFR) 50.72(b)(2)(xi). The NRC made the licensee's notice publicly available as event notification56236 on November 23, 2022. The NRC inspectors independently determined there was no impact on the health and safety of the public, plant personnel, or the environment.
As a follow up to this EN, the inspectors observed and evaluated the licensee's initial response to identify and quantify the source of the tritium leak and identified no performance deficiencies under the Public Radiation Safety Cornerstone. At that time, the inspectors verified the tritiated water was contained onsite, was identified through the groundwater monitoring program, and did not impact drinking water wells used by the community. The inspectors observed and evaluated the development and implementation of the licensee's actions to mitigate the leak by removing the tritiated water released to the ground and identified no performance deficiencies.
On December 29, 2022, the licensee determined that the leak to groundwater was in the gap between the turbine building and the reactor building in the below grade portion of the control rod drive (CRD) suction piping. NRC inspectors reviewed, evaluated, and observed licensee actions to contain the leak and identified no performance deficiencies.
On March 22, 2023, the catchment around the piping failed to contain the leak. Subsequently, on March 24, 2023, the licensee shut down the unit to replace the below grade portion of the carbon-steel CRD suction piping with stainless-steel piping. They also modified the design of the piping penetration to allow for periodic inspections to check for degradation. The inspectors reviewed, evaluated, and observed inperson critical aspects of the pipe replacement, and identified no performance deficiencies.
Unrelated to the licensee's actions in response to the aforementioned leak, while reviewing the design basis for the most recent license extension, the NRC inspectors identified a performance deficiency for the licensees failure to include the below grade portion of the CRD suction piping in the Underground Piping and Tank Integrity (UPTI) Program. Had the below grade portion of the CRD piping been included in the UPTI program, the piping would have been coated or wrapped for protection and periodically inspected for degradation. The NRC inspectors determined this was a minor performance deficiency because it
- (1) could not be viewed as a precursor to a significant event,
- (2) if left uncorrected, did not have the potential to lead to a more significant safety concern, and
- (3) was not associated with any reactor oversight program cornerstone attributes.
EXIT MEETINGS AND DEBRIEFS
The inspectors verified no proprietary information was retained or documented in this report.
On April 13, 2023, the inspectors presented the integrated inspection results to Shawn Hafen, Plant Manager, and other members of the licensee staff.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Procedures
1444
Pre and Post Severe Weather Inspection Checklist
NF 93493
Monticello Nuclear Generating Plant SW> Supply Line from
Pump-111D To VEAV14B (Turbine Building)
C
NH36036
(M105)
NH36039
(M108)
P&ID Condensate & Demineralized Water Storage Systems
101
NH36244
(M118)
Control Rod Hydraulic System P&ID
NH36245
(M119)
P&ID Control Rod Hydraulic System
Drawings
NX952521
Emergency Service Water Pumps P111A and P111B
B.08.01.0205
EDG Emergency Service Water - System Operation
CSOP-PR113
Energy Solutions, Monticello Well Water Demand Demin
01/18/2023
Procedures
Ops Man
B.01.0301
CRD Hydraulic System
7001167100610
Ground Watering Monitoring Well 9
7001167100885
Groundwater Monitoring Well 12
Work Orders
700117970
Groundwater Remediation
01/18/2023
Corrective Action
Documents
501000071474
Fire Watch Secured Early
03/19/2023
Corrective Action
Documents
Resulting from
Inspection
501000070469
EFT/ASDS Phone Issues
2/07/2023
Strategy A.301-C
RCIC Room and Appendix R Cable Enclosure
Strategy A.301-E
HPCI Room - Reactor Building Elevation 896'
Strategy A.301-G
Fire Zone 1G, CRD Pump Room
Strategy A.312-A
Lower 4KV Bus Area No. 13 & 15
Fire Plans
Strategy A.314-A
Upper 4KV Bus Area (14 & 16)
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
AWI08.01
Combustible Source Use Permit
Strategy A.302-H
West Shutdown Cooling Area
Strategy A.323-A
Fire Zone 23A, Intake Structure Pump Room
Procedures
Strategy A.333
EFT Building Third Floor
Corrective Action
Documents
501000069765
Heating Boiler Flame Fail
01/10/2023
FPOP-ROM02
Shutdown Safety Management Program
Procedures
OPs Man
C.4B.08.03A
Loss of Heating Boiler
501000044002
RHR, Possible Rotor Defects
09/09/2020
501000056563
RHR Pump Testing Frequency
09/30/2021
501000068846
TI4766A Temperature Increasing (11 EDG Lube Oil Cooler
Outlet Oil Temperature)
11/29/2022
Corrective Action
Documents
501000071215
Motor Labeling Needs Updating
03/08/2023
NE364044
RHR Pump P202A, ACB 152504 Control
NH36247
(M121)
P&ID Residual Heat Removal System
Drawings
NX92168-54
(TS7194)
Physical Schematic & Field Connections Model 999 - 11
Procedures
4075PM
D20 Battery Charger Preventive Maintenance
7000904920020
Alternate 125Vdc Supply from D40 to D21 (PMT/RTS)
01/18/2023
7000940190010,
20
D20 Battery Charger Preventive Maintenance
01/18/2023
700097218
RHR Motor Replacement
03/11/2023
Work Orders
700116900
Replace TS7194 (11 EDG Immersion Heater Temperature
Control)
01/10/2023
Miscellaneous
Tagout: 1CRD 11
CRD BEARING
RPLC (2)
P201A Rotate Pump Shaft by Hand
01/25/2023
B.02.0405
Procedures
C.51300
Secondary Containment Control (Mode 1, 2, 3)
Work Orders
7001184320050
P201A, Manually Rotate
01/25/2023
Corrective Action
501000070173
Battery Positive Post Seal Leakage
01/26/2023
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
501000070265
G SRV Reached 165 Degrees F
01/29/2023
501000070299
Unexpected Configuration 10A-K48B
01/30/2023
501000070634
Unexpected Annunciator 5A-43
2/11/2023
Documents
501000070666
Degraded Fire Barrier Found
2/14/2023
FPOP-OL01
Operability
Ops Man
B.05.01.0201
Power Range Neutron Monitoring System
Ops Man
B.05.01.0205
Power Range Neutron Monitoring System-System Operation
Procedures
Ops Manual
C.53502
Drawings
SKND1700513
CRD Pump Suction Modification
601000004190
Modify Penetration for CRD Suction Line
Engineering
Changes
ECR 419001
CRD3"-6B Penetration
3185
Anchor Control Record
8053
Penetration Sealing and Visual Inspection
813604
Secondary Containment Work Control Checklist
Procedures
QF1786
Temporary Facilities/Material Storage and Parking
Authorization
Work Orders
7001178910020
Replace Piping Segment Per ECR 601000004190
Drawings
P&ID M115,
NH36241
Nuclear Boiler Steam Supply System
0081
Control Rod Drive Scream Insertion Time Test
013707A
Reactor Steam Supply Valves Leak Rate Testing
25507-IA2
Main Steam Isolation Valve Functional Checks Test
Ops Man D.205
Underwater Vacuum Operation
Procedures
QF 1819
Foreign Material Recovery Plan
501000070720
TIP 11 Stroke Time Out of Band
2/16/2023
Corrective Action
Documents
501000071206
SW221 and SW211 Failed Check Test
03/09/2023
018701A
Emergency Diesel Generator 11 / ESW 11 Comprehensive
Pump and Valve Tests
25502-III
SBLC Quarterly Pump and Valve Tests
Procedures
25505-IA11
'A' RHRSW Quarterly Pump and Valve Tests
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
25511-IIC2
Emergency Service Water System Leakage Test-Loop B
25511-III4
ESW Quarterly Pump and Valve Tests
66, 67
25518-IA
TIP Ball Valve Quarterly Exercise
1399
ECCS Pump Motor Cooler Flush
B.09.1205 G4
Transfer of RPS Bus B Back to MG Set B
7000405710020
Replace Line Fuses (Breaker B3335)
7000728450040
CV1728, PMT
7000991630020
P202B/MTR, Swap Motor
7000991630050
RHR Pump Pre-Service Test
7000991630070
MT Replace Division 2 FSW Pipe
700103969
Replace Division 2 FSW Pipe
70011454850
EFT Emergency Service Water Division 2 Parent
Work Orders
7001149600010
'A' RHRSW Quarterly Pump and Valve Tests
03/09/2023
SEG# RQSS191
RPV Flood
Miscellaneous
Tabletop 22B
5790102-02
Monticello Event Notification Form
5790102-02A
Monticello Event Notification Report Form Instructions
Procedures
A.2807
Off-Site Dose Assessment Protective Action
Recommendations
QF0445
Unplanned Scrams per 7000 Critical Hours, Monthly
Submission Forms (January - December 2022)
71151
Miscellaneous
QF0445
Unplanned Scrams/Complications, Monthly Submission
Forms (January - December 2022)
18