IR 05000461/2025012
| ML25324A225 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 11/20/2025 |
| From: | Nestor Feliz-Adorno NRC/RGN-III/DORS/ERPB |
| To: | Mudrick C Constellation Energy Generation |
| References | |
| IR 2025012 | |
| Download: ML25324A225 (0) | |
Text
SUBJECT:
CLINTON POWER STATION, UNIT 1 - LICENSE RENEWAL PHASE 1 INSPECTION REPORT 05000461/2025012
Dear Christopher H. Mudrick:
On September 24, 2025, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Clinton Power Station, Unit 1 and discussed the results of this inspection with Norha Plumey 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 inspection reports that should have been issued by November 13, 2025, to December 31, 2025. The NRC resumed the routine cycle of issuing inspection reports on November 13, 2025.
November 20, 2025 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, Néstor J. Feliz-Adorno, Chief Engineering and Reactor Projects Branch Division of Operating Reactor Safety Docket No. 05000461 License No. NPF-62 Enclosure:
As stated cc: Distribution via LISTSERV Signed by Feliz-Adorno, Nestor on 11/20/25
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting a License Renewal Phase 1 Inspection at Clinton Power Station,
Unit 1, 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 71013 - Site Inspection for Plants with a Timely Renewal Application Inspectors completed phase 1 of inspection procedure 71013 for Clinton Unit 1 from September 8 through September 24, 2025, while the plant was shut down for refueling outage C1R21. This allowed the inspectors to evaluate the material condition of components normally inaccessible prior to entry into the period of extended operation and perform inspections associated with aging management programs as described in their license renewal application.
This was the last scheduled outage before the expiration date of the Unit 1 original license on April 17, 2027. Clinton was under timely renewal provisions throughout this inspection.
Therefore, the NRC invoked inspection procedure 71013 instead of 71003. Many license renewal activities encountered during this inspection period were in progress, recently completed, or intended for completion prior to April 2027.
Site Inspection for Plants with a Timely Renewal Application (1 Sample)
- (1) The following aging management programs were evaluated by the team:
- One-Time Inspection, XI.M32
- One-Time Inspection of ASME Code Class 1 Small-Bore Piping, XI.M35
INSPECTION RESULTS
Observation: Selected Methodology for Detecting Aging Effect Not in Alignment with Commitment 71013 Clinton Power Station (CPS) License Renewal Application (LRA), Section A.2.1.21 stated, The One-Time Inspection aging management program is a new condition monitoring program that will be used to verify the system-wide effectiveness of the Water Chemistry (A.2.1.2) program, Fuel Oil Chemistry (A.2.1.20) program, and Lubricating Oil Analysis (A.2.1.26) program, which are designed to prevent or minimize aging to the extent that it will not cause a loss of intended function during the period of extended operation.
The applicants program basis document for One-Time Inspection (OTI) aging management program (AMP), CL-PBD-AMP-XI.M32, Revision 6, Section 3.3 stated, Inspections will be performed by using the appropriate nondestructive examination (NDE) methods, including visual, volumetric, and surface techniques []. Section 3.4 of the AMP stated, The inspection for the reduction of heat transfer will include visual examination (VT-3 or equivalent).
The applicant established CL-AMPBD-OTI, One-Time Inspection Sample Basis Document, Revision 2, to provide basis for determination of the sample size to be inspected and the examination technique, including acceptance criteria that would be effective in managing the aging effect for which the component is examined. In the sample basis document, the Residual Heat Removal (RHR) heat exchanger, 1E12B001A, was selected as one of the samples under Section 3.1.5 for detecting Reduction of Heat Transfer aging effect. However, the applicant stated that this inspection did not involve a visual examination. Rather, the heat transfer capability test conducted in 2018 was used as the alternative methodology to detect the subject aging effect.
The term VT-3 or equivalent was taken directly from NRC guidance in the Generic Aging Lessons Learned (GALL) Report, NUREG 1801, Revision 2. According to the American Society of Mechanical Engineers (ASME) Code, a VT-3 visual examination determines the general mechanical and structural condition of components and supports by visually verifying parameters such as clearances, settings, and physical displacements and by detecting discontinuities and imperfections such as corrosion, wear, erosion, loose or missing parts, debris, and loss of integrity at bolted or welded connections.
The GALL Report stated that if the applicant chooses to use an alternative inspection method, a technical justification be provided as an exception to the AMP when submitting their LRA to the NRC. However, the applicant did not request such exception to use the heat transfer capability test as the alternative methodology.
In response, the applicant generated Condition Report (CR) 04896337 to conduct a visual examination of the RHR heat exchanger and revise the sampling basis document to be aligned with the committed inspection methodology.
This was the last scheduled outage before the expiration date of the original operating license on April 17, 2027. Clinton remained under the timely renewal provisions throughout this inspection. As a result, some license renewal activities observed by the inspectors were still in progress, had been recently completed, or were scheduled for completion prior to entering the period of extended operation in April 2027. Because the OTI aging management program is one of the activities identified for completion before the period of extended operation, its completion was not required at the time of this inspection. Therefore, the inspectors noted the issue as an observation.
Observation: Deficiencies in Execution of One-Time Inspection of Reactor Core Isolation Cooling (RCIC) Lube Oil Cooler Tubes 71013 The applicants implementation of the OTI AMP commitments included performing one-time inspections to verify the effectiveness of the applicants Water Chemistry and Lubricating Oil Analysis programs to manage Reduction of Heat Transfer aging effect for material/component combinations exposed to treated water and lubricating oil environments. The applicants sample basis document, CL-AMPBD-OTI, Revision 2, provided the basis for determination of the sample size to be inspected under the OTI AMP commitments. In this document, the Reactor Core Isolation Cooling (RCIC) system Lube Oil Cooler, 1E51C002, was selected as one of the samples to identify whether the subject aging effect was present. Specifically, the inner diameter (ID) side of the RCIC Lube Oil Cooler tubes was selected as a sample component exposed to the treated water environment (Work Order (WO) 05532385-01), and the outer diameter (OD) side of its tubes was selected as a sample component exposed to the lubricating oil environment (WO 05532385-07).
The applicant utilized remote visual examination technique involving a borescope to examine the ID side of the tubes using site-specific procedure ER-CL-700-301, Clinton One-Time Inspection Requirements and Guidelines, Revision 0. The applicant utilized the direct visual examination for the OD side of the tubes using the same procedure. The inspectors reviewed the examination records including the photos and videos taken during the borescope examination and were concerned with the execution of these examinations as illustrated by the following examples.
Example 1:
The visual examination report and the corresponding Issue Report (IR) 04896993 documented that no fouling/degradation was identified in the ID of the Lube Oil Cooler tubes during the examination. However, during review of the examination records, the inspectors noted that one of the tubes displayed a collection of deposits that was not documented in either the examination report or the Inspection Record (IR), nor was it evaluated.
ER-CL-700-301, Attachment 2, One-Time inspection Assessment Guide for Reduction of Heat Transfer, Revision 0, contained acceptance criteria and general guidance for identifying Reduction of Heat Transfer aging effect from fouling. It defined fouling as the accumulation of material on Heat Exchanger (HX) tube surfaces that can impede the transfer of heat, reduce coolant flow, or increase differential pressure (D/P) across HXs. Fouling may occur as macrofouling, microfouling, or scale. It described microfouling as deposits, nominally, for the purpose of this guideline, thought to be on the ID tube surface, comprised nominally of a film of a combination of microorganisms, their associated slime, and entrapped solids.
It described scale as another common form of microfouling, caused by the plating of chemical salts on tube surfaces due to the reduction of solubility of the salts as temperature increases. Either form of microfouling can significantly reduce heat across the tube [].
ER-CL-700-301, Section 4.6.2 stated, Evaluate relevant conditions to the requirements of the individual Aging Management requirements as specified on the applicable attachments. Section 4.6.6 stated, Create an Issue Report (IR) to enter the condition into the Corrective Action Process if age-related degradation is identified. Document any observed age-related degradation and all acceptable and non-acceptable test results. For all examination results identifying suspect indications, discontinuities, and/or flaws that do not meet acceptance criteria, further evaluation is needed in accordance with the Corrective Action Process.
The identified collection of deposits from the examination satisfied the criteria for being documented and evaluated in accordance with the procedure. Additionally, the inspectors noted that the intent of the one-time inspection was, as stated in the applicants OTI AMP, to verify the effectiveness of the Water Chemistry program to manage aging effects for material/component combinations exposed to treated water environment. Since the collection of deposits were identified in the environment where the aging-related degradation was not expected to occur, documenting and evaluating such conditions were important in satisfying the intent of the OTI AMP commitments.
Example 2:
ER-CL-700-301, Section 4.6.5, stated, If examination regions are identified as access restricted or obstructed, then record the restrictions or obstructions on Attachment 3 One Time Inspection Visual Examination Report or equivalent. During review of the examination records for the OD and ID of the tubes, the inspectors identified that the limitations and obstructions were not properly documented in the examination reports.
For the direct visual examination of the OD of the tubes, the examination report documented that there were no limitations/obstructions. However, the inspector review revealed that not all tubes were accessible due to the physical configuration of the RCIC Lube Oil Cooler tubes. Some of the tubes located on the interior portion of the tube bundle were not accessible due to the limited visual line of access.
For the remote visual examination of the ID of the tubes, the examination report documented that there were no limitations/obstructions. However, interviews with the examiners revealed that there were some limitations associated with the utilized borescope. While each of the 22 tubes had approximately 42 inches of inspectable length from each end excluding the U-bend, the length of the borescope cable was limited such that not all inspectable length was examined. This limitation was not documented in the examination report.
To address both examples, the applicant generated CRs 04898993 and 04898887.
The corrective actions recommended by the applicant under these CRs included:
- (1) determining the characteristics of the identified deposits on the RCIC Lube Oil Cooler tubes and evaluating the condition in accordance with ER-AA-700-301;
- (2) correcting the deficiencies in documentation and recording of the RCIC Lube Oil Cooler tube examination results, restrictions, and/or obstructions;
- (3) conducting extent of condition reviews of the previously performed OTI inspections for completeness in documenting, reporting and evaluating any relevant conditions, and;
- (4) enhancing procedural guidance and future work package instructions for conducting LR visual inspections of heat exchangers.
This was the last scheduled outage before the expiration date of the original operating license on April 17, 2027. Clinton remained under the timely renewal provisions throughout this inspection. As a result, some license renewal activities observed by the inspectors were still in progress, had been recently completed, or were scheduled for completion prior to entering the period of extended operation in April 2027. Because the One-Time Inspection aging management program is one of the activities identified for completion before the period of extended operation, its completion was not required at the time of this inspection. Therefore, the inspectors noted the issue as an observation.
Observation: Inadequate Utilization of NDE Methodology for Detecting Stress Corrosion Cracking 71013 The applicants implementation of the OTI AMP activities included performing one-time inspections of the material/component combinations exposed to a steam, treated water greater than 140 deg F, or Reactor Coolant environment to verify the effectiveness of the Water Chemistry program to manage cracking due to stress corrosion cracking. The applicants sample basis document, CL-AMPBD-OTI, Revision 2, provided the basis for determination of the sample size to be inspected under the OTI AMP commitments. In this document, the Reactor Pressure Vessel (RPV) head ventilation pipe segment 1NB04B and the orifice plate 1B21D332 downstream of the pipe were among the samples selected to detect the cracking aging effect.
The applicants program basis document for the OTI AMP, CL-PBD-AMP-XI.M32, Revision 6, Section 3.3 stated, Inspections will be performed by using the appropriate nondestructive examination (NDE) methods, including visual, volumetric, and surface techniques
[]. Section 3.4 of the AMP stated, The inspection for cracking will include surface examination (magnetic particle or liquid penetrant), visual examination (EVT-1 or equivalent, of disassembled components), or volumetric examination (UT or RT). The applicant utilized the remote visual examination technique involving a borescope for the inner diameter portion of approximately five feet of the 3/4" diameter, Schedule 160, pipe segment 1NB04B (WO 05650022-01) and the orifice plate 1B21D332 (WO 05650028-01).
The inspectors reviewed the examination records and questioned whether the applicants examination was equivalent to EVT-1 or the Enhanced Visual Examination method as stated in the applicants AMP. The GALL Report stated that the description of EVT-1 is found in Boiling Water Reactor Vessel and Internals Project (BWRVIP)-03, Reactor Pressure Vessel and Internals Examination Guidelines (proprietary). BWRVIP-03, Revision 20, Section 2.5 provides a proprietary definition of EVT-1, and Subsection 6.0 contains the proprietary EVT-1 inspection requirements, including the resolution demonstration, as well as camera motion speed and viewing angle criteria.
During their review, the inspectors found no documentation indicating that the licensee performed the required resolution demonstration checks in accordance with BWRVIP-03, Subsection 6.0. Additionally, the observed borescope camera motion during the examination did not appear to satisfy the Subsection 6.0 criteria. These attributes were important in providing reasonable assurance that the employed examination methodology was capable of detecting stress corrosion cracking on the surface of the inspected components.
Further review of the WO instructions and the referenced site-specific procedure ER-CL-700-301, Revision 0, revealed that the guidance lacked direction for establishing equivalence to EVT-1. Although the procedure required remote visual aids to provide resolution equivalent to direct visual examination, it did not define what would constitute equivalency to EVT-1. It also lacked guidance on acceptable camera motion speed and viewing angles. The WO instructions likewise did not address these attributes.
In response, the applicant re-performed the remote visual examination of pipe 1NB04B.
The applicant indicated that the re-examination consisted of:
- (1) the borescopes resolution demonstration at the accessible viewing angle and distance equivalent to the EVT-1 method prior to the inspection, and
- (2) the cameras motion speed that met the EVT-1 method.
The applicant generated CR 04900092 to evaluate the procedural guidance and future work package instructions for conducting the license renewal visual inspections under the EVT-1 equivalence guidelines. Additionally, the CR requested surface examination of orifice plate 1B21D332, which was a preferred method for detecting the cracking aging effect.
This was the last scheduled outage before the expiration date of the original operating license on April 17, 2027. Clinton remained under the timely renewal provisions throughout this inspection. As a result, some license renewal activities observed by the inspectors were still in progress, had been recently completed, or were scheduled for completion prior to entering the period of extended operation in April 2027. Because the One-Time Inspection aging management program is one of the activities identified for completion before the period of extended operation, its completion was not required at the time of this inspection. Therefore, the inspectors noted the issue as an observation.
EXIT MEETINGS AND DEBRIEFS
The inspectors verified no proprietary information was retained or documented in this report.
- On September 24, 2025, the inspectors presented the License Renewal Phase 1 Inspection results to Norha Plumey and other members of the licensee staff.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
04896993
LR 1E51C002 Visual Inspection Results
09/12/2025
04897793
LR - 1E51C002 LO CLR UT Degradation Rate Does Not
Support PEO
09/14/2025
Corrective Action
Documents
04898362
LR-C1R22 Alternate Inspections Needed for XI.M32 OTI
09/16/2025
04896337
NRC ID - Misalignment Between AMP PBD and SBD for
09/09/2025
04898887
NRC ID Gaps on RCIC Oil Cooler LR OTI Documentation
09/18/2025
04898993
NRC ID: Gaps Noted in LR OTI Analysis of Visual
Examination
09/18/2025
Corrective Action
Documents
Resulting from
Inspection
04900092
NRC ID: LR 71003 Gap in OTI Visual Exam Performance
09/23/2025
BWR Vessel and Internals Project, Reactor Pressure Vessel
and Internals Examination Guidelines
CL-AMPBD-OTI
One-Time Inspection Sample Basis Document
CL-PBD-AMP-
XI.M32
One-Time Inspection
Miscellaneous
CL-PBD-AMP-
XI.M35
One-Time Inspection of ASME Code Class 1 Small-Bore
Piping
25-UT-014
UT Calibration/Examination for Component ID BW-38
09/17/2025
25-UT-025
UT Calibration/Examination for Component ID 1-MS-3-10
09/18/2025
NDE Reports
25-UT-04
UT Erosion/Corrosion Examination for RCIC Lube Oil Cooler
Shell
09/14/2025
Service Water Heat Exchanger Inspection Guide
License Renewal One-Time Inspection Program
Procedures
ER-CL-700-301
Clinton One-Time Inspection Requirements and Guidelines
05532385-01
ES-LR-RCIC LO CLR (1E51C002) Visual Inspection for
Tube Fouling
09/12/2025
05532385-07
ES-LR-RCIC LO CLR (1E51C002) Visual Inspection for
Loss of Material
09/12/2025
05650022-01
MM-LR Perform OTI/Visual Examination on 1NB04B 3/4
Pipeline
09/16/2025
71013
Work Orders
05650028-01
MM-LR Perform OTI/Visual Examination on 1B21D332
09/16/2025
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Orifice