IR 05000423/2025010
| ML25217A521 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 08/06/2025 |
| From: | Erin Carfang Division of Operating Reactors |
| To: | Carr E Dominion Energy |
| References | |
| IR 2025010 | |
| Download: ML25217A521 (1) | |
Text
August 6, 2025
SUBJECT:
MILLSTONE POWER STATION UNIT 3 - LICENSE RENEWAL PHASE 2 INSPECTION REPORT 05000423/2025010
Dear Eric Carr:
On July 24, 2025, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Millstone Power Station Unit 3 and discussed the results of this inspection with Alex Trespalacios, 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 (10 CFR) 2.390, Public Inspections, Exemptions, Requests for Withholding.
Sincerely, Erin E. Carfang, Chief Engineering Branch 1 Division of Operating Reactor Safety
Docket No. 05000423 License No. NPF-49
Enclosure:
As stated
Inspection Report
Docket Number:
05000423
License Number:
Report Number:
Enterprise Identifier: I-2025-010-0023
Licensee:
Dominion Energy, Inc.
Facility:
Millstone Power Station Unit 3
Location:
Waterford, CT
Inspection Dates:
July 14, 2025 to July 24, 2025
Inspectors:
J. Ambrosini, Nuclear Engineer
J. Kulp, Senior Reactor Inspector
K. Mangan, Senior Reactor Inspector
S. McClay, Reactor Inspector
J. Tifft, Senior Reactor Inspector
Approved By:
Erin E. Carfang, Chief
Engineering Branch 1
Division of Operating Reactor Safety
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting a License Renewal Phase 2 Inspection at Millstone Power Station Unit 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.
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 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.
OTHER ACTIVITIES
- TEMPORARY INSTRUCTIONS, INFREQUENT AND ABNORMAL
===71003 - Post-Approval Site Inspection for License Renewal
From July 14 to 24, 2025, the NRC conducted a Post-Approval Site Inspection for License Renewal - Phase 2 at Millstone Power Station Unit 3 in accordance with the license renewal inspection program. This inspection took place prior to the period of extended operation (PEO),which will begin on November 25, 2025. Per IMC 2516, the license renewal inspection program is the process used by NRC staff to verify the adequacy of aging management programs (AMPs), Time-Limited Aging Analyses (TLAAs), and other activities associated with an applicants request to renew an operating license of a commercial nuclear power plant beyond the initial licensing period under 10 CFR 54, Requirements for the Renewal of Operating Licenses for Nuclear Power Plants.
Post-Approval Site Inspection for License Renewal===
- (1) License Conditions and Commitments for License Renewal, Implementation of Aging Management Programs and Time-Limited Aging Analyses
There are a total of 37 regulatory commitments linked to the renewed operating license for Millstone Power Station Unit 3, discussed in NUREG-1938, Safety Evaluation Report Related to the License Renewal of Millstone Power Station, Units 2 and 3, issued in October 2005, consisting of the following: 28 commitments related to enhancing existing AMPs; 5 commitments related to implementing new AMPs; 1 commitment related to implementing a new AMP and enhancing an existing AMP; 2 commitments related to TLAA activities; and 1 standalone commitment (not associated with an AMP or TLAA). During the inspection, the team reviewed 33 of these commitments to assess the adequacy and effectiveness of the license renewal program. For each commitment selected, the inspectors reviewed the applicable license renewal program documents, a sample of implementing procedures and records, conducted interviews with licensee staff, and performed walkdowns of structures, systems, and components (SSCs) to verify that the licensee completed the actions necessary to comply with the conditions listed in the renewed facility operating license. For those license renewal action items that were not completed at the time of this inspection, the team verified that there was reasonable assurance that such action items were on track for completion prior to the PEO or in accordance with an established implementation schedule consistent with the license renewal application, the NRC Safety Evaluation Report, and the Updated Final Safety Analysis Report (UFSAR) supplement.
The regulatory commitments selected for the inspection sample are listed below along with the completion status of the item at the time of the inspection. The full description of each commitment is available in the UFSAR supplement for license renewal, as revised, and the NRC Safety Evaluation Report (NUREG-1838).
Commitments (by number):
- Commitment #1. Battery Rack Inspection Program: The existing inspection program will be modified to include those battery racks that require monitoring for license renewal, but are not already included in the program.
a. Status: Complete.
- Commitment #2. Battery Rack Inspection Program: Implementing procedures will be modified to include loss of material as a potential aging effect and to provide guidance on the inspection of items (such as anchorages, bracing and supports, side and end rails, and spacers), which contribute to battery rack integrity or seismic design of the battery racks.
a. Status: Complete.
- Commitment #3. Buried Pipe Inspection Program: A baseline inspection of the in-scope buried piping located in a damp soil environment will be performed for a representative sample of each combination of material and protective measures.
a. Status: Complete.
- Commitment #4. Buried Pipe Inspection Program: The maintenance and work control procedures will be revised to ensure that inspections of buried piping are performed when the piping is excavated during maintenance or for any other reason.
a. Status: Complete.
- Commitment #5. Electrical Cables and Connectors Not Subject to 10 CFR 50.49 Environmental Qualification Requirements: The Electrical Cables and Connections Not Subject to 10 CFR 50.49 Environmental Qualification Requirements program will be established.
a. Status: Complete.
- Commitment #6. Electrical Cables and Connectors Not Subject to 10 CFR 50.49 Environmental Qualification Requirements: Fuse holders meeting the requirements will be evaluated prior to the PEO for possible aging effects requiring management. The fuse holder will either be replaced, modified to minimize the aging effects, or this program will manage the aging effects. The program (if needed for fuse holders) will consider the aging stressors for the metallic clips.
a. Status: Complete.
- Commitment #7. Electrical Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements Used in Instrumentation Circuits: Procedures will be developed to employ an alternate testing methodology to confirm the condition of cables and connectors in circuits that have sensitive, low level signals and where the instrumentation is not calibrated in situ.
a. Status: Complete.
- Commitment #8. Fire Protection Program: A baseline visual inspection will be performed on a representative sample of the buried fire protection piping and components, hose internal surfaces are exposed to raw water, to confirm there is no degradation.
a. Status: Complete.
- Commitment #9. Fire Protection Program: Testing a representative sample of fire protection sprinkler heads or replacing those that have been in service for 50 years will be included in the Fire Protection Program.
a. Status: Complete.
- Commitment #10. General Condition Monitoring Program: The procedures and training for personnel performing General Condition Monitoring inspections and walkdowns will be enhanced to provide expectations that identify the requirements for the inspection of aging effects.
a. Status: Complete.
- Commitment #11. Inaccessible Medium Voltage Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements: Engineering will identify testing requirements, as necessary, to confirm the condition of the cable insulation for inaccessible medium voltage cables that are exposed to significant voltage and have been submerged. Any tests performed will be proven tests for detecting deterioration of the insulation due to wetting. If cables have become submerged during the PEO, Engineering will evaluate to determine the appropriate testing, as necessary, to be performed during the corresponding ten-year interval.
a. Status: Complete.
- Commitment #12. Infrequently Accessed Areas Inspection Program: The Infrequently Accessed Areas Inspection Program will be established.
a. Status: Complete.
- Commitment #13. ISI Program: Reactor Vessel Internals: Millstone will follow the industry efforts on reactor vessel internals regarding such issues as thermal or neutron irradiation embrittlement (loss of fracture toughness), void swelling (change in dimensions), stress corrosion cracking (Primary Water Stress Corrosion Cracking (PWSCC) and Irradiation Assisted Stress Corrosion Cracking (IASCC)), and loss of pre-load for baffle and former-assembly bolts and will implement the appropriate recommendations resulting from this guidance.
a. Status: Complete.
- Commitment #14. ISI Program: Reactor Vessel Internals: Augmented inspection of the Millstone Unit 3 core barrel hold-down spring will be performed. In particular, the inspection will detect gross indication of loss of preload as an aging effect.
a. Status: This commitment was eliminated by the licensee. The Materials Reliability Program (MRP-227-1-A) identified a concern with loss of hold-down spring preload for springs made of Type 304 stainless steel and required examination to determine changes in spring dimensions. Millstone Unit 3s core barrel hold-down spring is made of Type 403 stainless steel and is not susceptible to relaxation per guidance provided in MRP-227-1-A and examination is not required.
- Commitment #15. Inservice Inspection Program: Systems, Components and Supports Steam Generator Structural Integrity: Millstone will follow the industry efforts investigating the aging effects applicable to nickel-based alloys (i.e., PWSCC in Alloy 600 base metal and Alloy 82/182 weld metals) and identifying the appropriate aging management activities and will implement the appropriate recommendations resulting from this guidance.
a. Status: Complete.
- Commitment #18. Structures Monitoring Program: The implementing procedures will be modified to include American Concrete Institute (ACI)349.3R-96, "Evaluation of Existing Nuclear Safety-Related Concrete Structures" and American National Standards Institute (ANSI)/American Society of Civil Engineers (ASCE) 11-90, "Guideline for Structural Condition Assessment of Existing Buildings," as references and as input documents for the inspection program.
a. Status: Complete.
- Commitment #19. Structures Monitoring Program: The Structures Monitoring Program and implementing procedures will be modified to include all in-scope structures.
a. Status: Complete.
- Commitment #20. Structures Monitoring Program: Groundwater samples will be taken on a periodic basis, considering seasonal variations, to ensure that the groundwater is not sufficiently aggressive to cause the below-grade concrete to degrade.
a. Status: Complete.
- Commitment #21. Structures Monitoring Program: The Structures Monitoring Program and implementing procedures will be modified to alert the appropriate engineering organization if the structures inspections identify that medium voltage cables in the scope of license renewal have been submerged.
a. Status: Complete.
- Commitment #22. Structures Monitoring Program: The maintenance and work control procedures will be revised to ensure that inspections of inaccessible areas are performed when the areas become accessible by such means as excavation or installation of shielding during maintenance or for any other reason.
a. Status: Complete.
- Commitment #23. Tank Inspection Program: Appropriate inspections of sealants and caulking used for moisture intrusion prevention in and around aboveground tanks will be performed.
a. Status: Complete.
- Commitment #24. Tank Inspection Program: Non-destructive volumetric examination of the in-scope inaccessible locations, such as the external surfaces of tank bottoms, will be performed prior to the PEO. Subsequent inspections will be performed on a frequency consistent with scheduled tank internals inspection activities.
a. Status: Complete.
- Commitment #25. Tank Inspection Program: The security diesel fuel oil tank and diesel fire pump fuel oil tank are in-scope for license renewal and will be included on the respective Tank Inspection Program inspection plan.
a. Status: Complete.
- Commitment #26. Changes will be made to maintenance and work control procedures to ensure that inspections of plant components and plant commodities will be appropriately and consistently performed and documented for aging effects during maintenance activities.
a. Status: Complete.
- Commitment #28. Inservice Inspection Program: Systems, Components and Supports: For potentially susceptible Cast Austenitic Stainless Steel (CASS)materials, either enhanced volumetric examinations or a unit or component specific flaw tolerance evaluation (considering reduced fracture toughness and unit specific geometry and stress information) will be used to demonstrate that the thermally-embrittled material has adequate fracture toughness in accordance with NUREG-1801 Section XI.M12.3.
a. Status: Complete.
- Commitment #30. Closed-Cycle Cooling Water System: A baseline visual inspection will be performed of the accessible areas of the shell side (including accessible portions of the exterior side of the tubes) of one:
i. Millstone Unit 2 Reactor Building Closed Cooling Water heat exchanger, ii. Millstone Unit 2 Emergency Diesel Generator Jacket Cooling Water heat exchanger, and iii. Millstone Unit 3 Emergency Diesel Generator Jacket Cooling Water heat exchanger.
a. Status: Complete.
- Commitment #31. Work Control Process: Using the Work Control Process, a baseline inspection for the loss of material due to selective leaching will be performed on a representative sample of locations for susceptible materials by visual, mechanical or other appropriate methods prior to entering the PEO.
a. Status: Incomplete. Some license renewal action items have not been completed. Specifically, the licensee plans on completing inspections of a representative sample of locations for susceptible materials prior to entering the PEO but had not completed all locations at the time of the NRC inspection. Based on the review of licensee actions completed at the time of this inspection and the administrative controls in place to track the pending actions, the inspectors determined that there was reasonable assurance that the licensee would complete the necessary actions to meet Commitment #31.
- Commitment #32. Work Control Process: A review of the Work Control Process inspection opportunities for each material and environment group, supplemental to the initial review conducted during the development of the License Renewal Application (LRA), will be performed. Baseline inspections will be performed for the material and environment combinations that have not been inspected as part of the Work Control Process.
a. Status: Complete.
- Commitment #33. Electrical Cables Not Subjected to 10 CFR 50.49 Environmental Qualification Requirements Used in Instrumentation Circuits: Calibration results for cables tested in situ will be reviewed to detect severe aging degradation of the cable insulation. The initial review will be completed prior to entering the PEO and will include at least 5 years of surveillance test data for each cable reviewed. Subsequent reviews will be performed on a period not to exceed 10 years.
a. Status: Complete.
- Commitment #34. Inaccessible Medium Voltage Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements: The in-scope cables in Unit 3 duct lines number 929 (Station Blackout Diesel to Unit 3 4.16kV Normal Switchgear) and number 973 (Reserve Station Service Transformer 3RTX-XSR-B to 6.9kV Normal Switchgear Bus 35A, 35B, 35C and 35D) will be tested to demonstrate that water treeing will not prevent the cables from performing their intended function.
a. Status: Complete.
- Commitment #35. Inaccessible Medium Voltage Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements: In addition to the testing specified in Commitment #33, a representative sample of in-scope medium voltage cables will be tested to demonstrate that water treeing will not prevent the cables from performing their intended function.
a. Status: Complete.
- Commitment #36. Millstone Unit 2 and 3 will complete the Severe Accident Mitigation Alternatives (SAMA) evaluation of the capability to flash the Diesel Generator field in the event of extended loss of DC power with a loss of offsite power. If this SAMA is cost beneficial (i.e., can be accomplished without a hardware modification), a Severe Accident Management Guideline (SAMG)addressing this mitigation strategy will be developed.
a. Status: Complete.
- Commitment #37. Inservice Inspection Program: Systems, Components and Supports: The pressurizer spray head assembly will be either replaced or inspected utilizing the best currently available (at the time of inspection)techniques for detecting cracking resulting from SCC.
a. Status: Complete.
- (2) Newly Identified Structures, Systems, and Components
- The team discussed with the licensees staff their evaluations of newly identified SSCs to determine on a sampling basis compliance with the provisions of 10 CFR 54.37(b). The team reviewed licensee evaluations performed for newly identified structures within the scope of license renewal to verify that the aging management review was performed in accordance with 10 CFR 54.37. The team also reviewed a list of plant modifications performed from the time the license renewal application was submitted to the time the renewed operating license was issued, to identify any potentially new SSCs that would have been subject to aging management review at the time the NRC was reviewing the license renewal application. Additionally, the team reviewed a sample of licensee procedures to verify that adequate guidance was provided to ensure that SSCs within the scope of 10 CFR 54.37(b) were identified, evaluated, and reported.
- (3) Description of Aging Management Programs in the UFSAR Supplement
As part of the review of implementation activities for the selected AMPs, the team reviewed the corresponding UFSAR sections to verify that the program descriptions were consistent with the license renewal application and the corresponding section of the NRC Safety Evaluation Report. The team reviewed three versions of the UFSAR supplement for license renewal as follows:
- The team reviewed the UFSAR supplement submitted with the license renewal application, as revised, to identify the program attributes and future inspection activities that were originally relied upon for the approval of the renewed operating license.
- The team reviewed the revision of the UFSAR submitted to the NRC pursuant to the requirements in 10 CFR 50.71(e)(4) following the issuance of the renewed operating license to verify that the UFSAR supplement for license renewal was included with the UFSAR as required by the condition of the renewed operating license.
- The team reviewed the latest revision of the UFSAR supplement for license renewal to verify that the program attributes and inspection activities were consistent with the AMPs as originally approved by the NRC and subsequent revisions performed under the provisions of 10 CFR 50.59. The team also verified that any changes caused by the inclusion of newly identified SSCs were included in the UFSAR supplement.
- (4) Changes to License Renewal Commitments and the UFSAR Supplement for License Renewal
- As part of the review of license renewal commitments, AMPs, and TLAAs described in this report, the inspectors reviewed license renewal commitment change documents to verify the licensee followed the guidance in Nuclear Energy Institute (NEI) 99-04, Guidelines for Managing NRC Commitment Changes, for any change to the commitments, including their elimination. The team verified on a sampling basis that the licensee properly evaluated, reported, and approved where necessary, changes to license renewal commitments listed in the UFSAR in accordance with 10 CFR
INSPECTION RESULTS
No findings were identified.
EXIT MEETINGS AND DEBRIEFS
The inspectors verified no proprietary information was retained or documented in this report.
- On July 24, 2025, the inspectors presented the License Renewal Phase 2 Inspection results to Alex Trespalacios, Plant Manager, and other members of the licensee staff.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
71003
Corrective Action
Documents
Resulting from
Inspection
296809
296822
296882
296890
Engineering
Evaluations
ETE-MP-2021-
28
Inservice Inspection Program: Millstone Unit 3 Reactor
Vessel Internals License Renewal Aging Management
Program (MP-LR-4711)
Revision 1
Miscellaneous
Applicants Environmental Report - Operating License
Renewal Stage, Millstone Power Station Units 2 and 3,
Dominion Nuclear Connecticut. Docket No. 50-336, License
No. DPR-65, Docket No. 50-423, License No. NPF-49
January
2004
Bolting Integrity Aging Management Program Notebook
06/10/2025
Alloy 600 Aging Management Program
05/19/2025
Inaccessible Medium Voltage Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements Aging
Management Program Notebook
05/27/2025
Inservice Inspection Program: Containment Inspections
Aging Management Program Notebook
05/28/2025
19.6-37
Letter from Leslie
- N. Hartz to NRC, Millstone Power Station
Units 2 and 3, Response to Request for Additional
Information License Renewal Applications (Serial No.: 04-
398
08/13/2004
B.2.18
Electrical Cables and Connectors Not Subject to 10 CFR 50.49 Environmental Qualification Requirements Aging
Management Program Notebook
05/27/2025
B2.1.1
Battery Rack Inspection Aging Management Program
Notebook
06/05/2025
B2.1.10
Fire Protection Aging Management Program Notebook
06/05/2025
B2.1.11
Flow Accelerated Corrosion Aging Management Program
Notebook
06/12/2025
B2.1.12
Fuel Oil Chemistry Aging Management Program Notebook
06/02/2025
B2.1.13
General Condition Monitoring Activities Aging Management
06/04/2025
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Program Notebook
B2.1.15
Infrequently Accessed Areas Inspection Program Aging
Management Program Notebook
06/04/2025
B2.1.17
Inservice Inspection Program: Reactor Vessel Internals
Aging Management Program Notebook
06/17/2025
B2.1.18
Inservice Inspection Program: Systems, Components and
Supports Aging Management Program Notebook
06/12/2025
B2.1.19
Inspection Activities: Load Handling Cranes and Devices
Aging Management Program Notebook
05/29/2025
B2.1.20
Reactor Vessel Surveillance Program Aging Management
Program Notebook
06/17/2025
B2.1.21
Service Water System (Open-Cycle Cooling Aging
Management Program Notebook
06/04/2025
B2.1.22
Steam Generator Structural Integrity Aging Management
Program Notebook
05/13/2025
B2.1.23
Structures Monitoring Aging Management Program Notebook 05/28/2025
B2.1.24
Tank Inspection Program Aging Management Program
Notebook
06/04/2025
B2.1.25
Work Control Process Aging Management Program
Notebook
06/04/2025
B2.1.3
Boric Acid Corrosion Aging Management Program Notebook
B2.1.4
Buried Piping Aging Management Program Notebook
06/12/2025
B2.1.5
Chemistry Control for Primary Systems Aging Management
Program Notebook
06/02/2025
B2.1.6
Chemistry Control for Secondary Systems Aging
Management Program Notebook
06/02/2025
B2.1.7
Closed-Cycle Cooling Water Aging Management Program
Notebook
06/02/2025
B2.1.9
Electrical Cables Not Subject to CFR 50.49 Environmental
Qualification Requirements Used in Instrumentation Circuits
Aging Management Program Notebook
06/17/2025
MP3-UCR-2021-
008
Deletion of MPS3 FSAR Chapter 19 Commitment 14
Revision 0