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Units 2 and 3 - Integrated Inspection Report 05000336/2025004 and 05000423/2025004
	ML26028A066
Person / Time
Site:	Millstone
Issue date:	01/28/2026
From:	Glenn Dentel; Division of Operating Reactors
To:	Carr E; Dominion Energy
References
	IR 2025004
	Download: ML26028A066 (0)
	v • d • e

January 28, 2026 Eric S. Carr Chief Nuclear Officer and President - Nuclear Operations and Contracted Energy Dominion Energy, Inc.

Innsbrook Technical Center 5000 Dominion Blvd.

Glen Allen, VA 23060-6711

SUBJECT:

MILLSTONE POWER STATION, UNITS 2 AND 3 - INTEGRATED INSPECTION REPORT 05000336/2025004 AND 05000423/2025004

Dear Eric Carr:

On December 31, 2025, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Millstone Power Station, Units 2 and 3. On January 21, 2026, the NRC inspectors discussed the results of this inspection with James Petty, Site Vice President, 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, Glenn T. Dentel, Acting Chief Projects Branch 2 Division of Operating Reactor Safety Docket Nos. 05000336 and 05000423 License Nos. DPR-65 and NPF-49

Enclosure:

As stated cc w/ encl: Distribution via GovDelivery GLENN DENTEL Digitally signed by GLENN DENTEL Date: 2026.01.28 14:34:26 -05'00'

ML26028A066 SUNSI Review Non-Sensitive Sensitive Publicly Available Non-Publicly Available OFFICE RI/DORS RI/DORS RI/DORS NAME BPinson NMentzer GDentel DATE 1/28/2026 1/27/2026 1/27/2026

Enclosure U.S. NUCLEAR REGULATORY COMMISSION Inspection Report Docket Numbers:

05000336 and 05000423 License Numbers:

DPR-65 and NPF-49 Report Numbers:

05000336/2025004 and 05000423/2025004 Enterprise Identifier: I-2025-004-0046 Licensee:

Dominion Energy Nuclear Connecticut, Inc.

Facility:

Millstone Power Station, Units 2 and 3 Location:

Waterford, CT Inspection Dates:

October 1, 2025 to December 31, 2025 Inspectors:

B. Pinson, Senior Resident Inspector D. Antonangeli, Resident Inspector E. Bousquet, Resident Inspector T. Fish, Senior Operations Engineer M. Patel, Senior Operations Engineer B. Dyke, Senior Operations Engineer N. Eckhoff, Health Physicist E. Chen, Reactor Inspector Approved By:

Glenn T. Dentel, Acting Chief Projects Branch 2 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 Millstone Power Station, Units 2 and 3, 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 Unit 2 operated at or near rated thermal power for the entire inspection period.

Unit 3 began the inspection period at rated thermal power. On October 16, 2025, the unit shut down for a planned maintenance outage to address reactor coolant pump seal leakage and returned to rated thermal power on October 28, 2025. On November 4, 2025, the unit lowered power to approximately 75 percent to repair a leak on the cover of service water check valve 3SWP*V705 and returned to rated thermal power on November 5, 2025. 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 on-site 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 prior to the onset of heavy rain and wind on October 10, 2025.

71111.04 - Equipment Alignment Partial Walkdown Sample (IP Section 03.01) (3 Samples)

The inspectors evaluated system configurations during partial walkdowns of the following systems/trains:

(1)

Unit 3, 'A' residual heat removal train during shutdown cooling operations, October 21, 2025 (2)

Unit 3, 'B' train of service water located in the engineered safeguards building, November 5, 2025 (3)

Unit 3, reactor plant component cooling water system components located in the auxiliary building, December 17, 2025

4 71111.05 - Fire Protection Fire Area Walkdown and Inspection Sample (IP Section 03.01) (7 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)

Unit 3, main steam valve building (fire area MSV-1 elevation 24'6", 41', 49'6", and 71'6"), October 1, 2025 (2)

Unit 3, east switchgear room (fire area CB-2 elevation 4'6"), October 2, 2025 (3)

Unit 3, normal switchgear room (fire area SB-1), November 17, 2025 (4)

Unit 2, auxiliary building railroad bay area (fire area A-14B elevation 14'6"),

November 20, 2025 (5)

Unit 3, auxiliary building (fire area AB-1C), elevation 24 foot, November 24, 2025 (6)

Unit 3, cable spreading room (fire area CB-8), November 25, 2025 (7)

Unit 2, intake structure (fire area I-1, zone A), December 11, 2025 71111.06 - Flood Protection Measures Flooding Sample (IP Section 03.01) (1 Sample)

(1)

The inspectors evaluated internal flooding mitigation protections in the:

Unit 2, upper 4160 volt switchgear room, west cable vault, and 480 volt west switchgear room, December 3, 2025.

71111.07A - Heat Exchanger/Sink Performance Annual Review (IP Section 03.01) (1 Sample)

The inspectors evaluated readiness and performance of:

(1)

Unit 2 'A' reactor building component cooling water heat exchanger, including review of eddy current testing from December 2 through December 4, 2025 (Work Order (WO)53203406272) 71111.11A - Licensed Operator Requalification Program and Licensed Operator Performance Requalification Examination Results (IP Section 03.03) (2 Samples)

(1)

The inspectors reviewed and evaluated the Unit 3 licensed operator examination failure rates for the Unit 3 requalification annual operating exams administered October - November 2025 and the Unit 3 biennial written examinations administered November - December 2024.

(2)

The inspectors reviewed and evaluated the licensed operator examination failure rates for the Unit 2 requalification annual operating exam completed on December 12, 2025.

5 71111.11B - Licensed Operator Requalification Program and Licensed Operator Performance Licensed Operator Requalification Program (IP Section 03.04) (1 Sample)

(1)

Biennial Requalification Written Examinations The inspectors evaluated the quality of the Unit 3 licensed operator biennial requalification written examinations administered November - December 2024.

Annual Requalification Operating Tests The inspectors evaluated the adequacy of the Unit 3 annual requalification operating test administered week of October 28, 2025.

Administration of an Annual Requalification Operating Test The inspectors evaluated the effectiveness of the facility licensee in administering requalification operating tests required by Title 10 of the Code of Federal Regulations (10 CFR) 55.59(a)(2) and that the facility licensee is effectively evaluating their licensed operators for mastery of training objectives.

Requalification Examination Security The inspectors evaluated the ability of the facility licensee to safeguard examination material, such that the examination is not compromised.

Remedial Training and Re-examinations The inspectors evaluated the effectiveness of remedial training conducted by the licensee, and reviewed the adequacy of re-examinations for licensed operators who did not pass a required requalification examination.

Operator License Conditions The inspectors evaluated the licensees program for ensuring that licensed operators meet the conditions of their licenses.

Control Room Simulator The inspectors evaluated the adequacy of the facility licensees control room simulator in modeling the actual plant, and for meeting the requirements contained in 10 CFR 55.46.

71111.11Q - Licensed Operator Requalification Program and Licensed Operator Performance Licensed Operator Performance in the Actual Plant/Main Control Room (IP Section 03.01)

(4 Samples)

(1)

The inspectors observed and evaluated licensed operator performance in the Unit 3 control room during solid plant operations, October 16, 2025.

6 (2)

The inspectors observed and evaluated licensed operator performance in the Unit 3 control room during reactor startup operations, October 26, 2025.

(3)

The inspectors observed and evaluated licensed operator performance in the Unit 3 control room during multiple diesel generators starts, as part of a maintenance outage, during the week of November 17, 2025.

(4)

The inspectors observed and evaluated licensed operator performance in the Unit 2 control room during a period of elevated risk due to 'D' service water bay outage, switchyard work, reactor building component cooling water heat exchanger outage, and reactivity manipulations from December 9-10, 2025.

Licensed Operator Requalification Training/Examinations (IP Section 03.02) (4 Samples)

(1)

The inspectors observed and evaluated Unit 3 operator performance in the simulator during just in time training for a unit shutdown, October 15, 2025.

(2)

The inspectors observed and evaluated Unit 3 operator performance in the simulator during just in time training activities related to service water train 'A' isolation, November 4, 2025.

(3)

The inspectors observed and evaluated operator requalification training in the Unit 2 simulator, November 4, 2025.

(4)

The inspectors observed and evaluated licensed operator requalification training in the Unit 3 simulator, December 9, 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)

Unit 3 safety-related dampers 3HVP*MOD26B, 3HVP*MOD23B, 3HVP*MOD26A, and 3HVP*MOD23A, December 31, 2025 Quality Control (IP Section 03.02) (1 Sample)

The inspectors evaluated the effectiveness of maintenance and quality control activities to ensure the following SSC remains capable of performing its intended function:

(1)

ASME Qualifications for replacement service water valve bonnet, SWP*V705, following emergent replacement, November 7, 2025 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)

Unit 2, scheduled yellow risk due to switchyard maintenance requiring north bus outage, October 14, 2025

7 (2)

Unit 3, containment closure due to a short time to boil with the reactor shutdown, October 18, 2025 (3)

Unit 3, high risk plans in effect due to isolation of the 'A' train of service water for replacement of a check valve bonnet at power, November 4-5, 2025 71111.15 - Operability Determinations and Functionality Assessments Operability Determination or Functionality Assessment (IP Section 03.01) (7 Samples)

The inspectors evaluated the licensee's justifications and actions associated with the following operability determinations and functionality assessments:

(1)

Unit 2, 'B' emergency diesel generator alarm response procedure entry for jacket water low temperature along with failure of standby jacket water pump to run, October 16, 2025 (2)

Unit 3, 'B' residual heat removal excessive seal leak, October 23, 2025 (Condition Report (CR) 130457)

(3)

Unit 3, functionality assessment associated with leading edge flow meter degraded transducers, November 24, 2025 (4)

Unit 2, non-vital 120 volt power supply, VR-21, to control element assembly control board core mimic panel indication for CEA-47, December 4, 2025 (CRs 1298943, 1306753, and 1306807)

(5)

Unit 2, operability determination and engineering technical evaluation associated with a through-wall flaw on 'A' service water header piping upstream of valve 2-SW-3.2B, December 17, 2025 (CR 1308124)

(6)

Unit 3, steam dump isolation valves found out of position, December 19, 2025 (CR 1309651)

(7)

Unit 2, 'B' emergency diesel generator jacket water cooling system with thermal overload discrepancy in jacket water pump motor, December 23, 2025 71111.20 - Refueling and Other Outage Activities Refueling/Other Outage Sample (IP Section 03.01) (1 Sample)

(1)

The inspectors evaluated reactor coolant pump seal replacement forced outage activities from October 16, 2025, to October 28, 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) (8 Samples)

(1)

Unit 2, replacement of automatic control element drive mechanism (CEDM) timing module for CEDM 68, October 3, 2025 (2)

Unit 3, repair of station blackout air valve, 3BGA-AOV84, October 6, 2025 (WO 53203468036 and CR 1302692)

(3)

Unit 2, post-maintenance testing of 'B' emergency diesel generator standby jacket water cooling pump following thermal overload replacement, October 16, 2025 (WO 53203469358)

8 (4)

Unit 3, 'B' service water strainer inspection and repair, October 17, 2025 (WOs 53203469327 and 53203469499)

(5)

Unit 3, replacement of 'C' reactor coolant pump seal assembly, October 21-22, 2025 (WO 53203461347)

(6)

Unit 3, post-maintenance testing of the 'B' containment air recirculation fan following replacement, October 24, 2025 (7)

Unit 3, post-maintenance operability testing of 'B' emergency diesel generator, November 22, 2025 (WO 53203450180)

(8)

Unit 3, calibration and testing of 'B' chiller temperature switch M33HVK*TS1006B, December 4, 2025 (WO 53203465243)

Diverse and Flexible Coping Strategies (FLEX) Testing (IP Section 03.02) (1 Sample)

(1)

Beyond design basis high capacity pumps 'A' and 'B', annual and semiannual surveillances reviewed, December 2, 2025 71114.06 - Drill Evaluation Additional Drill and/or Training Evolution (1 Sample)

The inspectors evaluated:

(1)

Unit 1 emergency planning drill on December 4, 2025 RADIATION SAFETY 71124.08 - Radioactive Solid Waste Processing & Radioactive Material Handling, Storage, &

Transportation Radioactive Material Storage (IP Section 03.01) (1 Sample)

The inspectors evaluated the licensees performance in controlling, labeling, and securing the following radioactive materials:

(1)

Radioactive materials containers in warehouse 9 and stack yard.

Radioactive Waste System Walkdown (IP Section 03.02) (1 Sample)

The inspectors walked down the following accessible portions of the solid radioactive waste systems and evaluated system configuration and functionality:

(1)

Radioactive liquid processing system Waste Characterization and Classification (IP Section 03.03) (2 Samples)

The inspectors evaluated the following characterization and classification of radioactive waste:

(1)

Unit 2 2R29 dry active waste 2024, L107814-1 (2)

Unit 3 ALPS resin sample, L109562-2

9 Shipping Records (IP Section 03.05) (3 Samples)

The inspectors evaluated the following non-excepted radioactive material shipments through a record review:

(1)

Shipment number 25-055, UN3321, LSA II, dry active waste (2)

Shipment number 25-067, UN3321, LSA II, U3 Carbon/Bead ALPS Resin Liner (3)

Shipment number 25-067, UN3321, LSA II, U3 ALPS Bead/SRT Resin Liner OTHER ACTIVITIES - BASELINE 71151 - Performance Indicator Verification The inspectors verified licensee performance indicators submittals listed below:

MS05: Safety System Functional Failures (SSFFs) Sample (IP Section 02.04) (2 Samples)

(1)