IR 05000263/2023001

Integrated Inspection Report 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

May 4, 2023

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, Nguyen, April signing on behalf of Peterson, Hironori on 05/04/23 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: DPR-22 Report Number: 05000263/2023001 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 Enclosure

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.

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)

(2 Samples)

The inspectors evaluated the following temporary or permanent modifications:

(1) Tritium mitigation tank siting for interference with FLEX strategies

(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)

(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) (5 Samples)

(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) (2 Samples)

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 notification (EN) 56236 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 Type Designation Description or Title Revision or

Procedure Date

71111.01 Procedures 1444 Pre and Post Severe Weather Inspection Checklist 21

71111.04 Drawings NF 93493 Monticello Nuclear Generating Plant SW> Supply Line from C

Pump-111D To VEAV14B (Turbine Building)

NH36036 P&ID Condensate & Feedwater 93

(M105)

NH36039 P&ID Condensate & Demineralized Water Storage Systems 101

(M108)

NH36244 Control Rod Hydraulic System P&ID 90

(M118)

NH36245 P&ID Control Rod Hydraulic System 80

(M119)

NX952521 Emergency Service Water Pumps P111A and P111B 77

Procedures B.08.01.0205 EDG Emergency Service Water - System Operation 24

CSOP-PR113 Energy Solutions, Monticello Well Water Demand Demin 01/18/2023

Skid

Ops Man CRD Hydraulic System 17

B.01.0301

Work Orders 7001167100610 Ground Watering Monitoring Well 9 4

7001167100885 Groundwater Monitoring Well 12 4

700117970 Groundwater Remediation 01/18/2023

71111.05 Corrective Action 501000071474 Fire Watch Secured Early 03/19/2023

Documents

Corrective Action 501000070469 EFT/ASDS Phone Issues 02/07/2023

Documents

Resulting from

Inspection

Fire Plans Strategy A.301-C RCIC Room and Appendix R Cable Enclosure 11

Strategy A.301-E HPCI Room - Reactor Building Elevation 896' 9

Strategy A.301-G Fire Zone 1G, CRD Pump Room 5

Strategy A.312-A Lower 4KV Bus Area No. 13 & 15 19

Strategy A.314-A Upper 4KV Bus Area (14 & 16) 18

Inspection Type Designation Description or Title Revision or

Procedure Date

Procedures 4 AWI08.01 Combustible Source Use Permit 16

Strategy A.302-H West Shutdown Cooling Area 10

Strategy A.323-A Fire Zone 23A, Intake Structure Pump Room 15

Strategy A.333 EFT Building Third Floor 12

71111.11Q Corrective Action 501000069765 Heating Boiler Flame Fail 01/10/2023

Documents

Procedures FPOP-ROM02 Shutdown Safety Management Program 18

OPs Man Loss of Heating Boiler 22

C.4B.08.03A

71111.12 Corrective Action 501000044002 11 RHR, Possible Rotor Defects 09/09/2020

Documents 501000056563 11 RHR Pump Testing Frequency 09/30/2021

501000068846 TI4766A Temperature Increasing (11 EDG Lube Oil Cooler 11/29/2022

Outlet Oil Temperature)

501000071215 Motor Labeling Needs Updating 03/08/2023

Drawings NE364044 RHR Pump P202A, ACB 152504 Control 79

NH36247 P&ID Residual Heat Removal System 96

(M121)

NX92168-54 Physical Schematic & Field Connections Model 999 - 11 82

(TS7194) EDG

Procedures 4075PM D20 Battery Charger Preventive Maintenance 8

Work Orders 7000904920020 Alternate 125Vdc Supply from D40 to D21 (PMT/RTS) 01/18/2023

7000940190010, D20 Battery Charger Preventive Maintenance 01/18/2023

20

700097218 11 RHR Motor Replacement 03/11/2023

700116900 Replace TS7194 (11 EDG Immersion Heater Temperature 01/10/2023

Control)

71111.13 Miscellaneous Tagout: 1CRD 11 P201A Rotate Pump Shaft by Hand 01/25/2023

CRD BEARING

RPLC (2)

Procedures B.02.0405 Main Steam 41

C.51300 Secondary Containment Control (Mode 1, 2, 3) 19

Work Orders 7001184320050 P201A, Manually Rotate 01/25/2023

71111.15 Corrective Action 501000070173 16 Battery Positive Post Seal Leakage 01/26/2023

Inspection Type Designation Description or Title Revision or

Procedure Date

Documents 501000070265 G SRV Reached 165 Degrees F 01/29/2023

501000070299 Unexpected Configuration 10A-K48B 01/30/2023

501000070634 Unexpected Annunciator 5A-43 02/11/2023

501000070666 Degraded Fire Barrier Found 02/14/2023

Procedures FPOP-OL01 Operability 22

Ops Man Power Range Neutron Monitoring System 7

B.05.01.0201

Ops Man Power Range Neutron Monitoring System-System Operation 31

B.05.01.0205

Ops Manual Containment Spray 21

C.53502

71111.18 Drawings SKND1700513 CRD Pump Suction Modification 01

Engineering 601000004190 Modify Penetration for CRD Suction Line 0

Changes ECR 419001 CRD3"-6B Penetration 1

Procedures 3185 Anchor Control Record 12

8053 Penetration Sealing and Visual Inspection 39

813604 Secondary Containment Work Control Checklist 21

QF1786 Temporary Facilities/Material Storage and Parking 1

Authorization

Work Orders 7001178910020 Replace Piping Segment Per ECR 601000004190 7

71111.20 Drawings P&ID M115, Nuclear Boiler Steam Supply System 91

NH36241

Procedures 0081 Control Rod Drive Scream Insertion Time Test 80

013707A Reactor Steam Supply Valves Leak Rate Testing 43

25507-IA2 Main Steam Isolation Valve Functional Checks Test 44

Ops Man D.205 Underwater Vacuum Operation 36

QF 1819 Foreign Material Recovery Plan 0

71111.24 Corrective Action 501000070720 TIP 11 Stroke Time Out of Band 02/16/2023

Documents 501000071206 SW221 and SW211 Failed Check Test 03/09/2023

Procedures 018701A Emergency Diesel Generator 11 / ESW 11 Comprehensive 56

Pump and Valve Tests

25502-III SBLC Quarterly Pump and Valve Tests 69

25505-IA11 'A' RHRSW Quarterly Pump and Valve Tests 90

Inspection Type Designation Description or Title Revision or

Procedure Date

25511-IIC2 Emergency Service Water System Leakage Test-Loop B 9

25511-III4 14 ESW Quarterly Pump and Valve Tests 66, 67

25518-IA TIP Ball Valve Quarterly Exercise 22

1399 ECCS Pump Motor Cooler Flush 12

B.09.1205 G4 Transfer of RPS Bus B Back to MG Set B 34

Work Orders 7000405710020 Replace Line Fuses (Breaker B3335) 0

7000728450040 CV1728, PMT 4

7000991630020 P202B/MTR, Swap Motor 5

7000991630050 12 RHR Pump Pre-Service Test 2

7000991630070 MT Replace Division 2 FSW Pipe 0

700103969 Replace Division 2 FSW Pipe 1

70011454850 EFT Emergency Service Water Division 2 Parent 0

7001149600010 'A' RHRSW Quarterly Pump and Valve Tests 03/09/2023

71114.06 Miscellaneous SEG# RQSS191 RPV Flood 0

Tabletop 22B Loss of AC and DC Power 0

Procedures 5790102-02 Monticello Event Notification Form 47

5790102-02A Monticello Event Notification Report Form Instructions 2

A.2807 Off-Site Dose Assessment Protective Action 29

Recommendations

71151 Miscellaneous QF0445 Unplanned Scrams per 7000 Critical Hours, Monthly 18

Submission Forms (January - December 2022)

QF0445 Unplanned Scrams/Complications, Monthly Submission 18

Forms (January - December 2022)

2