IR 05000445/2025010

Biennial Problem Identification and Resolution Inspection Report 05000445/2025010 and 05000446/2025010

ML25356A450
Person / Time
Site:	Comanche Peak
Issue date:	12/30/2025
From:	Wynar C NRC/RGN-IV/DORS/PBB
To:	Peters K Vistra Operations Company
References
IR 2025010
Download: ML25356A450 (0)

Text

December 30, 2025

SUBJECT:

COMANCHE PEAK NUCLEAR POWER PLANT, UNITS 1 AND 2 - BIENNIAL PROBLEM IDENTIFICATION AND RESOLUTION INSPECTION REPORT 05000445/2025010 AND 05000446/2025010

Dear Ken Peters:

On September 26, 2025, the U.S. Nuclear Regulatory Commission (NRC) completed a problem identification and resolution inspection at Comanche Peak Nuclear Power Plant, Units 1 and 2.

On September 25, 2025, the NRC inspectors discussed the results of this inspection with Kassie Mandrell, Regulatory Compliance, 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 1, 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.

The NRC inspection team reviewed the stations problem identification and resolution program to confirm that the station was complying with NRC regulations and licensee standards. The team also evaluated the stations effectiveness in identifying, prioritizing, evaluating, and correcting problems, reviewed licensee audits and self -assessments, and its use of industry and NRC operating experience information. The results of these evaluations are documented in the enclosed report. Finally, the team reviewed the stations programs to establish and maintain a safety-conscious work environment and interviewed station personnel to evaluate the effectiveness of these programs. The team did not identify any issues related to your organizations safety-conscious work environment.

One finding of very low safety significance (Green) is documented in this report. This finding involved a violation of NRC requirements. We are treating this violation as a non-cited violation (NCV) consistent with Section 2.3.2 of the Enforcement Policy.

If you contest the violation or the significance or severity of the violation documented in this inspection report, you should provide a response within 30 days of the date of this inspection report, with the basis for your denial, to the U.S. Nuclear Regulatory Commission, ATTN:

Document Control Desk, Washington, DC 20555-0001; with copies to the Regional Administrator, Region IV; the Director, Office of Enforcement; and the NRC Resident Inspector at Comanche Peak Nuclear Power Plant, Units 1 and 2.

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, Curtis J. Wynar, Team Lead Inspection Programs & Assessment Team Division of Operating Reactor Safety Docket Nos. 05000445 and 05000446 License Nos. NPF-87 and NPF-89

Enclosure:

As stated

Inspection Report

Docket Numbers:

05000445 and 05000446

License Numbers:

NPF-87 and NPF-89

Report Numbers:

05000445/2025010 and 05000446/2025010

Enterprise Identifier:

I-2025-010-0016

Licensee:

Vistra Operations Company LLC

Facility:

Comanche Peak Nuclear Power Plant, Units 1 and 2

Location:

Glen Rose, TX 76043

Inspection Dates:

September 8 to September 26, 2025

Inspectors:

J. Ellegood, Senior Resident Inspector

L. Moore, Emergency Preparedness Inspector

M. Ruffin, Reactor Inspector

C. Speer, Reactor Systems Engineer

Approved By:

Curtis Wynar, Team Lead

Inspection Programs & Assessment Team

Division of Operating Reactor Safety

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting a biennial problem identification and resolution inspection at Comanche Peak Nuclear Power Plant, Units 1 and 2, 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

Failure to Correct a Condition Adverse to Quality Cornerstone Significance Cross-Cutting Aspect Report Section Barrier Integrity Green NCV 05000445,05000446/2025010-01 Open/Closed None 71152B The inspectors identified a finding and associated non-cited violation of 10 CFR Part 50,

Appendix B, Criterion XVI, Corrective Action, for failing to correct a condition adverse to quality related to a release path through the vents of the refueling water storage tank.

Specifically, in 2015, the licensee recognized that the back leakage through the emergency core cooling systems could allow radio-nuclides to be released through vents in the refueling water storage tank. Isolation valves in this release path require leak testing to meet ASME code. As of September 30, 2025, the licensee had not restored compliance which is contrary to the requirements of 10 CFR Part 50, Appendix B, Criterion XVI.

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 - BASELINE

71152B - Problem Identification and Resolution Biennial Team Inspection (IP Section 03.04)

(1) The inspectors performed a biennial assessment of the effectiveness of the licensees Problem Identification and Resolution program, use of operating experience, self-assessments and audits, and safety conscious work environment.

• Problem Identification and Resolution Effectiveness: The inspectors assessed the effectiveness of the licensees Problem Identification and Resolution program in identifying, prioritizing, evaluating, and correcting problems. The inspectors also conducted a five-year review of the safety chilled water system. The corrective actions for the following non-cited violations, minor violations, and findings were evaluated as part of the assessment:

NCV 2025001-01, NCV 2025001-02, NCV 2024004-01, NCV 2024004-02, NCV 2024004-03, FIN 2024003-01, FIN 2024003-02, NCV 2024012-01, NCV 2024012-02, NCV 2024012-03, NCV 2024001-01, NCV 2024001-02, NCV 2024001-03, NCV 2023004-01, NCV 2023004-02, FIN 2023004-03, NCV 2023003-01, NCV 2023003-02, NCV 2023401-01, NCV 2023401-02, NCV 2023401-03, NCV 2023401-04, FIN 2023010-01, FIN 2023010-02, NCV 2023010-03, NCV 2023010 04, and NCV 2022004-01.

• Operating Experience: The inspectors assessed the effectiveness of the licensees processes for use of operating experience.

• Self-Assessments and Audits: The inspectors assessed the effectiveness of the licensees identification and correction of problems identified through audits and self-assessments.

• Safety Conscious Work Environment: The inspectors assessed the effectiveness of the stations programs to establish and maintain a safety-conscious work environment.

INSPECTION RESULTS

Assessment 71152B Corrective Action Program Effectiveness Based on the samples reviewed, the inspectors determined that the licensee's corrective action program was adequate and supported nuclear safety.

Problem Identification The team determined that conditions that required generation of a condition report had been identified and entered appropriately into the corrective action program.

However, the team reviewed a condition report documenting three examples of operations staff not entering lower-level human performance issues into the corrective action program in accordance with management expectations. The inspectors documented one observation, Performance of Lower Tier Evaluations, that may relate to identification of common cause issues.

Problem Prioritization and Evaluation The inspectors found that the licensee was adequately prioritizing and evaluating problems.

However, the team noted multiple potential weaknesses in the scope of the sites initiation and performance of lower-level (i.e., non-root cause) evaluations such as equipment failure investigations (EFIs), organizational effectiveness investigations (OEIs), and performance GAP analysis (PGAs). The inspectors documented two observations under Performance of Lower Tier Evaluations and Suitability of Evaluators that may relate to the station's ability to fully evaluate problems. The team further noted one example of a potentially inconsistent treatment of issues related to the evaluation of problems in the sites trending program and documented the observation under Inconsistent Adverse Trend Identification.

Effectiveness of Corrective Actions Overall, the team concluded that the station generally developed effective corrective actions for the problems evaluated in the corrective action program. The station generally implemented these corrective actions in a timely manner, commensurate with their safety significance. However, as part of their review of the resolution of prior issues, the team noted an inconsistently in the sites use of should versus shall in station procedures. This resulted in a corrective action to prevent recurrence that using should when shall may be more appropriate, as documented in the observation "Guidance on Use of Should Verses Shall." Additionally, the team documented the observation related to ongoing challenges at the site for which prior corrective actions have been taken under "Control and Oversight of Vendors.

Finally, in reviewing condition reports, the team did identify one item associated with leakage to the refueling water storage tank during an accident where a condition adverse to quality has not been corrected. The team identified NCV 05000445,05000446/2025010-01, "Failure to Correct a Condition Adverse to Quality," related to this issue.

Assessment 71152B Audits and Self-Assessments The inspectors reviewed a sample of Comanche Peak Nuclear Power Plants self-assessments and audits to assess whether performance trends were regularly identified and effectively addressed. The inspectors also reviewed audit reports to assess the effectiveness of assessments in specific areas. Overall, the inspectors concluded that the licensee had an adequate departmental self-assessment and audit process.

Assessment 71152B Use of Operating Experience The team reviewed a variety of sources of operating experience including Part 21 notifications and other vendor correspondence, NRC generic communications, and publications from various industries. The team determined that, overall, Comanche Peak is adequately screening and addressing issues identified through operational experience that apply to the station, and this information is being evaluated in a timely manner once it is received.

Assessment 71152B Safety Conscious Work Environment The team conducted safety-conscious work environment interviews with 20 employees from different disciplines that included maintenance, operations, security, engineering, and long term contractors. The purpose of these interviews were:

(1) to evaluate the willingness of the licensee staff to raise nuclear safety issues, either by initiating a condition report or by another method,

(2) to evaluate the perceived effectiveness of the corrective action program at resolving identified problems, and

(3) to evaluate the licensee's safety-conscious work environment (SCWE). The team also observed interactions between employees during routine performance improvement review group meetings. The team interviewed the employee concerns program manager and reviewed a sample of case files that may relate to safety-conscious work environment. The team found that the licensee had a safety-conscious work environment where individuals felt free to raise concerns without fear of retaliation and all individuals indicated that they would not hesitate to raise safety concerns through at least one of the several means available at the station.

Failure to Correct a Condition Adverse to Quality Cornerstone Significance Cross-Cutting Aspect Report Section Barrier Integrity Green NCV 05000445,05000446/2025010-01 Open/Closed None 71152B The inspectors identified a finding and associated non-cited violation of 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, for failing to correct a condition adverse to quality related to a release path through the vents of the refueling water storage tank.

Specifically, in 2015, the licensee recognized that the back leakage through the emergency core cooling systems could allow radio-nuclides to be released through vents in the refueling water storage tank. Isolation valves in this release path require leak testing to meet ASME code. As of September 30, 2025, the licensee had not restored compliance which is contrary to the requirements of 10 CFR Part 50, Appendix B, Criterion XVI.

Description:

In 1991, the NRC issued Information Notice 91-56 to inform licensees of the potential for radioactive leakage to atmosphere from vented tanks. The information notice addressed leakage past isolation valves in the emergency core cooling system during the sump recirculation phase following an accident. In 2015, Comanche Peak evaluated this information notice and determined that Comanche Peak was vulnerable to radio-nuclide release via vents in the refueling water storage tank. Analysis by Westinghouse supported a leak rate of 8 gallons per minute (gpm) to remain within limits of 10 CFR Part 100 for offsite dose as well as General Design Criteria 19 for control room dose. However, the licensee has yet to develop a test methodology to validate the valves leakage support this bounding value.

The licensee determined that per the inservice testing program, the valves would require periodic testing to validate leakage remained below 8 gpm. Despite awareness of this issue, for 10 years, the licensee has not resolved this condition.

The licensee has developed plans to address this condition via a new test procedure to be implemented in the 2026 refueling outages.

Corrective Actions: The licensee evaluated the condition under condition report CR-2015-004916. The licensee determined there was reasonable assurance that the valves remained operable.

Corrective Action References: Condition Report CR-2025-005550

Performance Assessment:

Performance Deficiency: The licensee's failure to develop and implement a test methodology for valves that would limit leakage to the refueling water storage tank from the containment sump, as required by the inservice testing program, was a performance deficiency. The licensee identified the condition in 2015 but has not corrected this condition adverse to quality.

Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Configuration Control attribute of the Barrier Integrity cornerstone and adversely affected the cornerstone objective to provide reasonable assurance that physical design barriers protect the public from radionuclide releases caused by accidents or events. The licensee failed to recognize back leakage could result in an increase in offsite and control room dose.

Significance: The inspectors assessed the significance of the finding using IMC 0609, Appendix A, The Significance Determination Process (SDP) for Findings At-Power. The inspectors determined the finding screened as Green using Exhibit 3 of IMC 0609.

Specifically, the inspectors determined that the finding could result in a bypass of containment; however, insufficient evidence existed to conclude an actual open pathway exists.

Cross-Cutting Aspect: None

Enforcement:

Enforcement Action: This violation is being treated as a non-cited violation, consistent with Section 2.3.2 of the Enforcement Policy.

Observation: Inconsistent use of "should" versus "shall" 71152B The inspectors noted that current licensee procedures in effect for the use of should vs.

shall are inconsistent. Licensee procedure FLT-AS-0040, "Fleet Procedure and Work Instruction Use and Adherence," includes these definitions:

2. 4.27 Should - A term denoting a recommendation: Although the word should" is a

recommendation, when used in a procedure step, it is an expectation that should statements will normally be performed as written. Should procedural statements do not have to be performed if special circumstances make them impractical or undesirable and do not require procedure revision to not perform.

The definitions in procedure FLT-AS-0040 can be interpreted to allow individual performers to self-determine that a should step need not be performed. However, licensee procedure STA-202, "Station Writers Guide," provides the following definitions:

1. Shall - Used for absolute requirements (normally reserved for regulatory requirements

or commitments). If a commitment is to achieve a desired result all procedure steps that describe the process to achieve that result do not have to be shall steps; if the step explicitly meets the commitment, use shall.

2. Should - Used to indicate firm Comanche Peak Nuclear Power Plant management

expectations. Deviation is a departure from the norm and requires supervisory concurrence. This should be noted in writing which may include logs, procedures, work orders, memos, etc.

3. May - Used to indicate a permissive action. Neither a requirement nor a

recommendation.

Procedure STA-202 explicitly requires supervisory concurrence on the determination if a should step need not be performed. This difference could lead to procedures being written or personnel using them in a way that allows for steps to not be performed at the individual performer's discretion when instead supervisory approval would be appropriate.

Observation: Trend in Oversite of Vendors 71152B Over multiple years, the licensee has failed to provide sufficient oversite of vendor performance. This has led to multiple examples where vendor performance has led to findings, plant transients or injury. Examples include:

2. T3000 upgrade to the main feed pump controls where the current output did not

match the current range on the servo

4. Incomplete or inaccurate information provided by a vendor regarding the ability to

replace components at power While the site has tried to address vendor oversite and improve vendor performance, actions to date have not been successful.

Observation: Performance of Lower Tier Evaluations 71152B Procedure STI-421.02, Issue Report Reviews, Revision 7, Step 6.4.10 and 6.5.2, only requires the station to consider performing lower tier evaluations (i.e., non-root cause) such as equipment failure investigations (EFIs), organizational effectiveness investigations (OEIs),and performance GAP analysis (PGAs), for consequential events. Consequential events are defined in 4.1.10 as things such as engineered safety feature actuation signals, reactor transients, outage delays, etc. This high threshold may deter the station from addressing programmatic or organizational issues before they become significant.

The team reviewed two examples of problems identified by the station where lower tier evaluations were not procedurally required or performed, but where doing so may have provided the station the opportunity to better characterize the true extent of the conditions to address them before they may potentially become more significant.

1. NCV 2023010-03 documented failure to promptly correct a significant condition

adverse to quality following failure of a centrifugal charging pump main lubricating oil pump. This modification was a regulatory commitment that remained uncorrected for 8 years.

a.

the station's subsequent evaluation corrected the issue and identified six additional uncorrected regulatory commitments b.

although the additional conditions were corrected, the station did not perform any evaluation of the organizational or programmatic issues that resulted in leaving issues uncorrected for an extended period

2. CR-2024-004832 and TR-2024-007034 documented a situation where operations

personnel did not initiate issue reports for lower-level human performance errors in accordance with management expectations.

a.

the station took action to provide a standing order, training, and other communications to emphasize the expectation to initiate issue reports when appropriate.

b.

no organizational or programmatic review evaluation was performed to see if groups other than Operations were also not initiating issue reports when appropriate Observation: Suitability of Evaluators 71152B For lower tier, non-root cause investigations, the stations corrective action program procedures do not specify qualification, training, or experience requirements for the investigator or other considerations for who is performing the investigation. The assignment of these investigators is at the discretion of the Corrective Action Program Coordinator, with no clarifying requirements, guidance, or expectations on the skills, experience, or suitability of the investigator. The only direct guidance in this area is to consider identification of a mentor/mentee in the Organizational Effectiveness Investigation pre-job checklist.

While qualifications/suitability of these investigators is not a regulatory requirement, this is a potential weakness in the corrective action program for performing these investigations as it leaves the experience/suitability of the investigators largely up to management discretion with little guidance for their selection.

Observation: Inconsistent Adverse Trend Identification 71152B CR-2023-001495 identified an adverse trend per procedure STI-400.01, "Performance Monitoring Process," for repeated low nitrogen accumulator pressures associated with main steam isolation valves 2-01 and 2-03. In contrast, similar recurring low nitrogen accumulator pressure conditions for feedwater isolation valves 1-02 and 1-03 were documented in CR-2025-001347 and CR-2025-003158. The feedwater isolation valve nitrogen pressures were not identified as an adverse trend by the sites trending program.

This inconsistent treatment of similar issues affecting comparable equipment types across different systems was discussed with the licensee. In discussions about the issue, Comanche Peak staff indicated that management discretion is utilized in the adverse trend identification process and that their actions are consistent with site trending program requirements. The inspectors agreed with this assessment. However, such discrepant treatment represents a potential weakness in the trending program, as it may undermine the consistency and objectivity of adverse trend identification and could result in missed opportunities for programmatic corrective action.

EXIT MEETINGS AND DEBRIEFS

The inspectors verified no proprietary information was retained or documented in this report.

• On September 25, 2025, the inspectors presented the inspection results to Kassie Mandrell, Regulatory Compliance, and other members of the licensee staff.

DOCUMENTS REVIEWED

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

Condition Reports

CR-YYYY-

NNNNNN

2015-004916, 2021-000740, 2021-003228, 2022-002409,

22-007980, 2022-008146, 2023-000066, 2023-000249,

23-000276, 2023-000807, 2023-000954, 2023-000957,

23-001039, 2023-001272, 2023-001495, 2023-001637,

23-001785, 2023-001787, 2023-001788, 2023-002559,

23-002882, 2023-002970, 2023-003297, 2023-004164,

23-004231, 2023-005015, 2023-005016, 2023-006974,

23-007836, 2023-008540, 2024-000642, 2024-001448,

24-001805, 2024-002170, 2024-002297, 2024-002390,

24-002785, 2024-002808, 2024-002953, 2024-003033,

24-003964, 2024-004832, 2024-004861, 2024-005058,

24-005443, 2024-005464, 2024-005559, 2024-006240,

24-006395, 2024-006698, 2024-006853, 2024-007145,

24-007331, 2024-007708, 2024-007809, 2024-007897,

24-007898, 2025-000136, 2025-000394, 2025-000581,

25-000821, 2025-001009, 2025-001347, 2025-001528,

25-001914, 2025-002287, 2025-003158, 2025-003165,

25-003994

71152B

Corrective Action

Documents

Tracking Reports

TR-YYYY-

NNNNNN

23-000015, 2023-000238, 2023-000453, 2023-000457,

23-000495, 2023-000565, 2023-000807, 2023-000886,

23-000944, 2023-001039, 2023-001238, 2023-001438,

23-001440, 2023-001442, 2023-001502, 2023-001622,

23-001711, 2023-001712, 2023-001750, 2023-001850,

23-002148, 2023-002252, 2023-002782, 2023-003039,

23-003849, 2023-004241, 2023-004243, 2023-005389,

23-006138, 2023-006168, 2023-006806, 2023-006812,

24-000072, 2024-000535, 2024-000602, 2024-000684,

24-000701, 2024-000744, 2024-001129, 2024-001782,

24-001999, 2024-002053, 2024-002554, 2024-003448,

24-003796, 2024-003939, 2024-003947, 2024-004001,

24-004286, 2024-005014, 2024-005043, 2024-006171,

24-007832, 2025-000257, 2025-000616, 2025-000721,

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

25-000808, 2025-001277, 2025-001561, 2025-002669,

25-003834

FLT-AS-BP200

Employee Concerns and Employee Protection

STA-114

Employee Concerns and Employee Protection

STA-421

Control of Issue Reports

STA-422

Corrective Actions Program

STA-429

Human Performance Program

STA-677

Preventative Maintenance Program

STA-744

Maintenance Effectiveness Monitoring Program

STA-744.01

Maintenance Rule Event Review Guide

STA-744.02

Scope of SSC's In The Maintenance Rule Program

STI-400.01

Performance Monitoring Process

STI-421.01

Initiation of Issue Reports

STI-421.02

Issue Report Reviews

STI-422.01

Operability Determination and Functionality Assessment

Program

STI-422.03

Performance Coaching and Investigations

STI-422.06

Performing Root Cause Analyses

Procedures

STI-429.02

Event Review Process

EVAL-2022-006

Fire Protection

EVAL-2022-007

Work Management Maintenance Radiation

EVAL-2023-001

Emergency Preparedness

EVAL-2023-002

Maintenance and Technical Training

EVAL-2024-001

Procurement and Inventory Management

EVAL-2024-002

Chemistry-Enviro-Radwaste

EVAL-2024-005

Maintenance Processes

Self-Assessments

EVAL-2025-002

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