IR 05000445/2025004

Integrated Inspection Report 05000445/2025004 and 05000446/2025004

ML26033A024
Person / Time
Site:	Comanche Peak
Issue date:	02/09/2026
From:	Ami Agrawal NRC/RGN-IV/DORS/PBB
To:	Peters K Vistra Operations Company
References
IR 2025004
Download: ML26033A024 (0)

Text

February 09, 2026

SUBJECT:

COMANCHE PEAK NUCLEAR POWER PLANT, UNITS 1 AND 2 -

INTEGRATED INSPECTION REPORT 05000445/2025004 AND 05000446/2025004

Dear Ken Peters:

On December 31, 2025, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Comanche Peak Nuclear Power Plant, Units 1 and 2. On January 29, 2026, the NRC inspectors discussed the results of this inspection with C. Jackson, Site Vice President, and other members of your staff. The results of this inspection are documented in the enclosed report.

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.

If you disagree with a cross-cutting aspect assignment in this report, you should provide a response within 30 days of the date of this inspection report, with the basis for your disagreement, to the U.S. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, DC 20555-0001; with copies to the Regional Administrator, Region IV; 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, Ami N. Agrawal, Chief Reactor Projects Branch B 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:

05000445/2025004 and 05000446/2025004

Enterprise Identifier:

I-2025-004-0005

Licensee:

Vistra Operations Company LLC

Facility:

Comanche Peak Nuclear Power Plant, Units 1 and 2

Location:

Glen Rose, TX

Inspection Dates:

October 1, 2025, to December 31, 2025

Inspectors:

M. Bloodgood, Senior Project Engineer

J. Ellegood, Senior Resident Inspector

J. Freeman, Resident Inspector

Approved By:

Ami N. Agrawal, Chief

Reactor Projects Branch B

Division of Operating Reactor Safety

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated 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

Containment Spray Pump Declared Inoperable due to Misaligned Breaker for a Duration Prohibited by Technical Specifications Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000446/2025004-01 Open/Closed

[H.9] - Training 71152A A self-revealed finding and associated non-cited violation occurred on March 25, 2025, when licensee staff incorrectly racked in a breaker for containment spray pump 2-04. Specifically, on August 12, 2025, containment spray pump 2-04 failed to start for a routine recirculation of the containment spray system. Review by the licensee concluded that the breaker for the pump had not been correctly racked in on March 25, 2025.

Additional Tracking Items

Type Issue Number Title Report Section Status LER 05000446/2025-001-00 Containment Spray Pump Declared Inoperable Due to Misaligned Breaker 71152A Closed

PLANT STATUS

Unit 1 began and ended the inspection period at or near rated thermal power.

Unit 2 began the inspection period at or near rated thermal power. On October 26, 2025, the licensee reduced power to about 65 percent to correct air intrusion into the generator cooling system. The licensee returned to at or near rated thermal power later that day and remained there 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 onsite portions of IPs. The inspectors reviewed selected procedures and records, observed activities, and interviewed personnel to assess licensee performance and compliance with Commission rules and regulations, license conditions, site procedures, and standards.

71111.01 - Adverse Weather Protection

Seasonal Extreme Weather Sample (IP Section 03.01) (1 Sample)

(1) The inspectors evaluated readiness for seasonal extreme weather conditions prior to the onset of seasonal cold weather for the following systems:

• feed system

• steam system

• condensate storage tanks

71111.04 - Equipment Alignment

Partial Walkdown Sample (IP Section 03.01) (2 Samples)

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

(1) Unit 1 and 2, control room AC on October 7, 2025

(2) Unit 1, motor-driven auxiliary feedwater pump train A on October 20, 2025

Complete Walkdown Sample (IP Section 03.02) (1 Sample)

(1) The inspectors evaluated system configurations of the Unit 1 emergency diesel generators during a complete walkdown of the fuel oil, lube oil, jacket water cooling, starting air, intake, and exhaust systems on October 8, 2025

71111.05 - Fire Protection

Fire Area Walkdown and Inspection Sample (IP Section 03.01) (4 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 1, switchgear, central alarm, and HVAC equipment rooms elevation 810'-6" on October 27, 2025

(2) Unit 2, switchgear and radiologically controlled area access elevation 810'-6" on November 4, 2025

(3) Common, fuel handling building elevation 860'-0" on November 12, 2025

(4) Common, fuel handling building elevation 838'-9" and 841'-0" on November 13, 2025

Fire Brigade Drill Performance Sample (IP Section 03.02) (1 Sample)

(1) The inspectors evaluated the onsite fire brigade training and performance during an announced drill on October 14, 2025.

71111.11A - Licensed Operator Requalification Program and Licensed Operator Performance Requalification Examination Results (IP Section 03.03)

(1) The inspectors reviewed and evaluated the licensed operator examination failure rates for the requalification annual operating exam administered on October 30, 2025.

71111.11Q - Licensed Operator Requalification Program and Licensed Operator Performance Licensed Operator Requalification Training/Examinations (IP Section 03.02)

(1) The inspectors observed and evaluated a simulator training session on October 21, 2025. The scenario started at 100 percent power and the crew responded to various plant transients including loss of main condenser vacuum, reactor coolant pump high vibrations, reactor failed to trip from control room, faulted steam generator (primary side), and reactor coolant system leak.

71111.12 - Maintenance Effectiveness

Maintenance Effectiveness (IP Section 03.01) (3 Samples)

The inspectors evaluated the effectiveness of maintenance to ensure the following structures, systems, and components (SSCs) remain capable of performing their intended function:

(1)sitewide radiation monitors due to multiple failures

(2) Unit 2, safety chiller 2-06 failure on August 14, 2025

(3) Unit 2, auxiliary power diesel generators 3-year maintenance on October 16, 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) Unit 1, diesel generator 1-01

71111.13 - Maintenance Risk Assessments and Emergent Work Control Risk Assessment and Management Sample (IP Section 03.01)

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 1, elevated risk due to inoperable turbine-driven auxiliary feedwater pump on October 9, 2025

(2) Unit 1, elevated risk during train B charging system valve repair on October 29, 2025

71111.15 - Operability Determinations and Functionality Assessments Operability Determination or Functionality Assessment (IP Section 03.01)

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

(1)control room HVAC with non-functional damper X-20 not operating in manual or automatic (2)pressurizer heaters with failed breaker

71111.18 - Plant Modifications

Temporary Modifications and/or Permanent Modifications (IP Section 03.01 and/or 03.02) (2 Samples)

The inspectors evaluated the following temporary or permanent modifications:

(1)repair of circulating water screen wash (2)main feed pump disabling of over-thrust trip

===71111.24 - Testing and Maintenance of Equipment Important to Risk The inspectors evaluated the following testing and maintenance activities to verify system operability and/or functionality:

Post-Maintenance Testing (PMT) (IP Section 03.01)===

(1) Unit 2, diesel generator 2-01 fuel oil pressure sensing line repair on October 9, 2025

(2) Unit 2, auxiliary power diesel generators triennial maintenance load bank testing conducted by vendor with licensee oversight on October 17, 2025

(3) Unit 1, solenoid replacement on steam supply for the turbine-driven auxiliary feedwater pump on October 21, 2025 4)

Unit 1, motor-driven auxiliary feedwater pump 1-01 run after oil change and pump/motor alignment on December 9, 2025

(5) Unit 1, feedwater pump 1A temperature converter adjustments on December 17, 2025

Surveillance Testing (IP Section 03.01) (3 Samples)

(1) Unit 1, residual heat removal pump 1-01 periodic flow verification using Procedure OPT-203A on December 8, 2025

(2) Unit 1, nuclear instrument N-32 calibration check of intermediate range detector on December 10, 2025

(3) Unit 1, control room ventilation north intake radiation detector 5895B operational test on December 16, 2025

Inservice Testing (IST) (IP Section 03.01) (1 Sample)

(1) Unit 2, residual heat removal pump 1-01 periodic flow verification using Procedure OPT-203B on November 6, 2025

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

(1)biennial maintenance on flex Pettibone forklift on November 10,

2025 OTHER ACTIVITIES - BASELINE

===71151 - Performance Indicator Verification The inspectors verified licensee performance indicators submittals listed below:

MS08: Heat Removal Systems (IP Section 02.07)===

(1) Unit 1, October 1, 2024, through September 30, 2025

(2) Unit 2, October 1, 2024, through September 30, 2025

MS10: Cooling Water Support Systems (IP Section 02.09) (2 Samples)

(1) Unit 1, October 1, 2024, through September 30, 2025

(2) Unit 2, October 1, 2024, through September 30, 2025

BI01: Reactor Coolant System (RCS) Specific Activity Sample (IP Section 02.10) (2 Samples)

(1) Unit 1, October 1, 2024, through September 30, 2025

(2) Unit 2, October 1, 2024, through September 30, 2025

BI02: RCS Leak Rate Sample (IP Section 02.11) (2 Samples)

(1) Unit 1, October 1, 2024, through September 30, 2025

(2) Unit 2, October 1, 2024, through September 30, 2025

===71152A - Annual Follow-up Problem Identification and Resolution Annual Follow-up of Selected Issues (Section 03.03) (1 Samples and 1 Partial)

The inspectors reviewed the licensees implementation of its corrective action program related to the following issues:

(1) Failure of Unit 2 containment spray pump as documented in LER 05000446/2025-001-00 Inspectors reviewed the licensee's actions and documentation related to the Unit 2 containment spray pump inoperability starting on March 25, 2025. Inspectors reviewed the subsequent breaker restoration and associated LER with this event. The licensee identified the issue as an improper breaker racking, corrected the breaker position, conducted an extent of condition review, and entered the issue into their corrective action program. This LER is closed and an NCV is documented in this report.

(2) Unplanned inoperability of safety chiller as documented in LER 05000446/2025-002-00 (Partial Sample)

Inspectors reviewed the licensee's actions and documentation related to the 2-06 safety chiller inoperability between August 13 and August 27, 2025. Inspectors reviewed the subsequent equipment restoration and the associated LER with this event. The licensee conducted a leak test, identified, and corrected the source of the leak and entered this into their corrective action program.

71152S - Semiannual Trend Problem Identification and Resolution Semiannual Trend Review (Section 03.02)===

(1) The inspectors reviewed the licensees quality assurance audits to verify identified issues were included in the corrective action program and to determine if any trends were identified that might be indicative of a more significant safety issue. The audit reports documented several examples of administrative errors none of which were more than minor.

OTHER ACTIVITIES

- TEMPORARY INSTRUCTIONS, INFREQUENT AND ABNORMAL

92709 - Licensee Strike Contingency Plans Licensee Strike Contingency Plans

(1) On December 5, 2025, at midnight, the contract with the International Brotherhood of Electrical Workers expired. In preparation for a potential strike, the NRC inspectors evaluated the adequacy of the licensees contingency plan. The inspectors assessed the adequacy of the plan's post-strike staffing levels, staff qualifications, safety conscious working environment, and site access in meeting operational and security requirements.

INSPECTION RESULTS

Containment Spray Pump Declared Inoperable due to Misaligned Breaker for a Duration Prohibited by Technical Specifications Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000446/2025004-01 Open/Closed

[H.9] - Training 71152A A self-revealed finding and associated non-cited violation occurred on March 25, 2025, when licensee staff incorrectly racked in a breaker for containment spray pump 2-04. Specifically, on August 12, 2025, containment spray pump 2-04 failed to start for a routine recirculation of the containment spray system. Review by the licensee concluded that the breaker for the pump had not been correctly racked in on March 25, 2025.

Description:

On August 12, 2025, operations staff attempted to start containment spray pump 2-04 to recirculate water to obtain a chemistry sample. The pump did not start so the licensee declared containment spray train B inoperable. Inspection of the breaker did not identify any material deficiencies and cycling of the breaker appeared normal. However, an operator performed a visual inspection of the breaker and reported the trip push button was not flush with the breaker face and the locking collar was not fully engaged. The as-found condition was indicative of a breaker not being in the fully racked in position. A review of logs revealed that the pump had run successfully on July 15, 2025. Further review identified the breaker had been racked in on March 25, 2025. The licensee concluded that auxiliary contacts in the breaker dropped out after several breaker cycles. Had the breaker been properly racked in in accordance with the Procedure SOP-609B, 6900 Volt Switchgear, the auxiliary contacts would not have dropped out. The licensee concluded that the status of the auxiliary contacts removed confidence that the breaker would have functioned following a seismic event or other mechanical shock; therefore, containment spray train B had been inoperable since March 25, 2025.

Corrective Actions: The licensee racked the breaker in correctly and verified operability of the pump. The licensee provided training for operators on proper breaker racking.

Corrective Action References: Condition Report CR-2025-004252

Performance Assessment:

Performance Deficiency: The licensee's failure to follow procedures for racking in the breaker was a performance deficiency that led to inoperability of the Unit 2 containment spray train B system. Specifically, Procedure SOP-603B, 6900 V Switchgear, provides instruction on proper methods to rack in a breaker. Contrary to these instructions, the licensee did not rack in the breaker correctly per procedure.

Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Human Performance attribute of the Mitigating Systems cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the containment spray train B system was inoperable between March 25 and August 12, 2025.

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 reviewed the issue using Exhibit 2. Because the containment spray train B system was inoperable longer than the technical specification allowed outage time, the inspectors concluded a detailed risk evaluation was needed. A senior reactor analyst performed the detailed risk evaluation and determined that the finding was of very low safety significance (Green). The containment spray system for Comanche Peak, Unit 2, is designed to limit post-accident pressure and temperature in containment and to remove iodine after an accident. It provides little mitigation capability for preventing core damage. The analyst qualitatively considered the increase in core damage frequency (CDF) from internal events from the unavailability of the containment spray pump to be of very low safety significance.

For mitigation of large early release frequency (LERF), the analyst referred to Table 4.1, Containment-Related Systems, Structures, and Components Considered for LERF Implications, from Manual Chapter 0609, Appendix H, Containment Integrity Significance Determination Process, to determine that containment spray systems for pressurized water reactors impact late containment failure and source terms, but not LERF. Therefore, the analyst considered the increase in LERF to be of very low safety significance. To address the degraded capability of the containment spray pump for seismic events from March 25 to August 12, 2025, the analyst reviewed the seismic hazard for the site and determined that it was minimal. The initiating event probability of the most frequent seismic events for the site during the exposure period was 5.2E-6, which when combined with any post seismic event plant configurations make any contribution from seismic events to CDF and LERF to be characterized as having very low safety significance. The analyst qualitatively considered that combining these risk inputs would result in the increases in CDF and LERF to still be of very low safety significance. This characterization of significance is consistent with the licensees quantitative results run on their PRA model.

Cross-Cutting Aspect: H.9 - Training: The organization provides training and ensures knowledge transfer to maintain a knowledgeable, technically competent workforce and instill nuclear safety values. Licensee corrective actions addressed proper breaker racking techniques and performance expectations.

Enforcement:

Violation: Title 10 CFR 50, Appendix B, Criterion V, states, "Activities affecting quality shall be prescribed by documented instructions, procedures, or drawings, of a type appropriate to the circumstances and shall be accomplished in accordance with these instructions, procedures, or drawings. Instructions, procedures, or drawings shall include appropriate quantitative or qualitative acceptance criteria for determining that important activities have been satisfactorily accomplished." Contrary to this requirement, on March 25, 2025, licensee staff failed to follow Procedure SOP-609B, 6900 Volt Switchgear, for racking in the breaker on Unit 2 containment spray train B pump 2-04 which led to inoperability of containment spray system train B.

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

EXIT MEETINGS AND DEBRIEFS

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

• On January 29, 2026, the inspectors presented the integrated inspection results to C. Jackson, Site Vice President, and other members of the licensee staff.

DOCUMENTS REVIEWED

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

Power Point Slides for Comanche Peak Winter Readiness

25

71111.01

Miscellaneous

Winter Readiness Permanent Scaffold/Tent Frames

Corrective Action

Documents

Resulting from

Inspection

Condition Reports

CR-2025-005816

SOP-304A-AF-

V01

Train A MDAFW Pump Lineup

SOP-609A-DG-

C01

Train A DG Control Switch Lineup

SOP-609A-DG-

V01

Train A DG Air System Valve Lineup

SOP-609A-DG-

V02

Train B DG Air System Valve Lineup

SOP-609A-DG-

V04

Train A DG Valve Lineup

SOP-609A-DG-

V05

Train B DG Valve Lineup

SOP-609A-DG-

V06

Train B DG Valve Lineup

SOP-610A-DO-

V01

Train A Valve Lineup

71111.04

Procedures

SOP-802

Control Room Ventilation System

FPI-304A

Fire Preplan Instruction Manual for Unit 1 Switchgear,

Central Alarm, and HVAC Equipment Rooms Elevation 810'

FPI-304B

Fire Preplan Instruction for Unit 2 Switchgear and RCA

Access Elevation 810'

FPI-603

Fire Preplan Instruction Manual for Fuel Handling Building

Elevation 838' and 841'

71111.05

Procedures

FPI-604

Fire Preplan Instruction Manual for Fuel Handling Building

Elevation 860'

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

71111.11A

Miscellaneous

71111.11A

Table 03.03-1

Results Table for Annual Exams

2/31/2025

LER 2025-002-00

Safety Chiller Inoperable due to Failure of Copper

Refrigerant Fittings

10/14/2025

RR119083

Diesel Generator Transmitter

04/12/2023

RR121254

Diesel Generator Wire

08/23/2023

RR127380

Diesel Generator Thermostat Element

09/30/2024

RR129678

Diesel Valve, Guide and Gasket

03/19/2025

71111.12

Miscellaneous

RR58908

Diesel Generator Terminals and Splices

2/10/2009

Guarded Equipment Posting Log

10/8/2025

71111.13

Miscellaneous

Guarded Equipment Management Posting

10/29/2025

Corrective Action

Documents

Condition Reports

CR-2024-007611, CR-2025-004666

71111.15

Corrective Action

Documents

Resulting from

Inspection

Condition Reports

CR-2025-005406

Corrective Action

Documents

Condition Reports

CR-2025-004149, Unit 1 Manual Reactor Trip Due to Loss of

Both Main Feedwater Pumps

09/24/2025

59SC-2025-

000008-02-01

Screen Wash Piping Temporary Modification 50.59 Screen

08/26/2025

71111.18

Engineering

Evaluations

FDA-2025-

000039-01

Disable Trips for the Unit 1 MFP Per Attached Drawings

09/26/2025

Corrective Action

Documents

Condition Reports

CR-2025-00529, 1EDG 1-02 Fuel Oil Return Line Leak

10/02/2025

OPT-203A

Operations Testing Manual for Residual Heat Removal

System

OPT-203B

Operations Testing Manual for Residual Heat Removal

System

OPT-203B

Residual Heat Removal System

OPT-216A

Remote Shutdown Operability Test

Procedures

SOP-103A

Chemical and Volume Control System

24-232147

71111.24

Work Orders

24-268113

N-32 Intermediate Range Detector Verification

2/10/2025

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

25-838308

2-510571

2-528165

Margin Reports for Cooling Water Systems and Heat

Removal Systems

2/08/2025

71151

Miscellaneous

Unit 1 and 2 Dose Equivalent Iodine Analysis Results for

10/01/2024 through 09/30/2025

CR-2025-004252

CR-2025-004292, Safety Chiller 2-06 Trip

Corrective Action

Documents

Condition Reports

CR-2025-004448, Safety Chiller Lowering Refrigerant

Pressure

71152A

Procedures

SOP-603B

6900v Switchgear

Condition Reports

CR-2025-1735

Corrective Action

Documents

Tracking Reports

TR-2025-1706

EVAL-2025-001

Training-Operations-Maintenance and Technical

03/20/2025

EVAL-2025-002

Fitness for Duty Audit

04/28/2025

MS-C-2025-03-01

Operations Audit

05/19/2025

MS-C-25-03-

18/20

Audit of Access Authorization/PADs and Fitness for Duty

04/28/2025

MS-C-25-05-19

Physical Security Program and Cyber Security Program

07/02/2025

MS-C-25-07-13

Audit of Training

08/21/2025

MS-C-25-09-09

Audit of Maintenance. Work management, Special

Processes, Measuring and Test Equipment and Material

Control

10/17/2025

71152S

Miscellaneous

MS-C-25-10-07

Audit of Radiation Protection-Rad Waste

On Shift Staffing Plan for Strike Contingency

2/04/2025

2709

Miscellaneous

CPNPP, Vistra Strike Contingency Plan

08/05/2019