IR 05000445/2025012

Comprehensive Engineering Team Inspection Report 05000445/2025012 and 05000446/2025012

ML25101A075
Person / Time
Site:	Comanche Peak
Issue date:	04/15/2025
From:	Nick Taylor NRC/RGN-IV/DORS/EB1
To:	Peters K Vistra Operations Company
References
IR 2025012
Download: ML25101A075 (1)

Text

April 15, 2025

SUBJECT:

COMANCHE PEAK NUCLEAR POWER PLANT - COMPREHENSIVE ENGINEERING TEAM INSPECTION REPORT 05000445/2025012 AND 05000446/2025012

Dear Ken Peters:

On March 10, 2025, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Comanche Peak Nuclear Power Plant and discussed the results of this inspection with Hunter A. Schill, 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 2.390, Public Inspections, Exemptions, Requests for Withholding.

Sincerely, Nicholas H. Taylor, Deputy Director 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:

05000445/2025012 and 05000446/2025012

Enterprise Identifier:

I-2025-012-0003

Licensee:

Vistra Operations Company LLC

Facility:

Comanche Peak Nuclear Power Plant

Location:

Glen Rose, TX

Inspection Dates:

January 27, 2025, to March 10, 2025

Inspectors:

D. Bryen, Reactor Inspector

W. Cullum, Senior Reactor Inspector

R. Kumana, Senior Reactor Inspector

B. Nwafor, Reactor Inspector

D. Reinert, Senior Reactor Analyst

A. Saunders, Reactor Inspector

F. Thomas, Reactor Inspector

C. Young, Senior Reactor Analyst

Approved By:

Nicholas H. Taylor, Deputy Director

Division of Operating Reactor Safety

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting a design basis assurance inspection (teams) inspection at Comanche Peak Nuclear Power Plant, 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.

REACTOR SAFETY

===71111.21M - Comprehensive Engineering Team Inspection The inspectors evaluated the following components and listed applicable attributes, permanent modifications, and operating experience:

Structures, Systems, and Components (SSCs) (IP section 03.01)===

(1)2ED2, Unit 2 125 VDC Switchboard

• Final Safety Analysis Report, Technical Specifications, and Technical Specifications bases document

• Visual inspection of configuration and material condition

• Sizing and equipment protection calculation

• Maintenance and testing history

• System health report

(2) BC2ED2-1, Unit 2 Battery Charger

• Final Safety Analysis Report, Technical Specifications, and Technical Specifications bases document

• Visual inspection of configuration and material condition

• Battery and charger sizing calculation

• Maintenance and testing history

• System health report

(3) CP2-CCATST-01, Unit 2 Component Cooling Water Surge Tank

• Component cooling water system piping and instrumentation diagram

• Vendor manual for installation, operation, and maintenance of the surge tank

• System and abnormal operating procedures

• Corrective action program documents

• Visual inspection of the as-built configuration and material configuration (4)1HV8010A, Unit 1 Pressurizer Safety Relief Valve

• Reactor coolant system piping and instrumentation diagram

• Inservice and diagnostic testing procedures and results

• Vendor manual for installation and testing instructions

• Corrective action program documents (5)2-VAAUSE-08, Unit 2 MDAFW Pump 2-02 Room Cooler Fan

• Piping and Instrumentation diagrams

• Vendor documentation

• Preventative maintenance history

• Visual inspection of the component

• Room cooling load calculations

• Corrective actions related to component

(6) CP2-MEDGEE-02, Unit 2 Diesel Generator 2-02

• Visual inspection of the as-built configuration and material condition

• Final Safety Analysis Report, Technical Specifications, and Technical Specifications bases document

• Vendor manuals

• System and abnormal operating procedures

• Maintenance and testing history

• System health report

• Calculations for:

a.

Starting air requirements b.

Water cooling requirements c.

Maximum load d.

Fuel requirements

• Corrective action program documents

(7) CP1-AFAPTD-01, Unit 1 Turbine-Driven Auxiliary Feedwater Pump

• Final Safety Analysis Report, Technical Specifications, and Technical Specifications bases document

• Normal and abnormal operating procedures

• Maintenance and testing history

• System health report

• Design basis calculations and analyses

• Physical walkdown of the component

• Corrective action program documents

• Vendor manuals

(8) PV-4553, Unit 1, Component Cooling Water Supply Valve to Chiller 1-06

• Final Safety Analysis Report, Technical Specifications, and Technical Specifications bases document

• Normal and abnormal operating procedures

• Maintenance and testing history

• System health report

• Design basis calculations and analyses

• Physical walkdown of the component

• Corrective action program documents

• Vendor manuals

(9) T1EB4, Unit 1, 6.9 kV Feeder Breaker

• Final Safety Analysis Report, Technical Specifications, and Technical Specifications bases document

• Visual inspection of the as-built configuration and material condition

• Component maintenance history

• System health reports

• Corrective action documentation review

• Component maintenance history and corrective action program documents

• Voltage drop calculations

• Electrical drawings

• Vendor manual and plant design drawings (10)1EB4-1, Unit 1, 480-volt Motor Control Center

• Final Safety Analysis Report, Technical Specifications, and Technical Specifications bases document

• Visual inspection of the as-built configuration and material condition

• Reduced voltage calculations

• Visual inspection of spare breakers in warehouse

• Component maintenance history

• System health reports

• Corrective action documentation review

• Electrical drawings

• Vendor manual and plant design drawings

Modifications (IP section 03.02) (4 Samples)

(1) FDA-2021-000005-01-00, Safety Chiller Control Panel Modification

(2) FDA-2023-00009-01-00, Component Cooling Water Heat Exchanger Service Water Relief Valve Replacement

(3) FDA-2023-000003-01-00, Emergency Diesel Generator RUN/STOP Switch Replacement

(4) FDA-2023-000068-01-00, Valve Operator 1-8104-MO Springpack Replacement 10 CFR 50.59 Evaluations/Screening (IP section 03.03) (10 Samples)

(1) EV-TR-2020-009257-1, Unit 1 & 2 Refueling Machine Modification

(2) EV-TR-2019-009785-2, Rod Control Circuit Surge Suppressors Modification

(3) FDA-2021-000003-02-00, Revise Design Basis Documents for Main Steam Line Break Containment Analysis

(4) FDA-2021-000003-01-00, Revise DBD-ME-008 and M1-3007 to Incorporate Revised Loss of Coolant Containment Analyses

(5) FDA-2021-000053-01-00, Approve Shortening Length of Station Service Water Seismic Restraint Bolts

(6) FDA-2023-000018-01-00, Abandon the Loose Parts Monitoring System for both Units 1and 2 due to the Removal of this System from the Licensing Basis

(7) FDA-2021-000054-01-01, Replace in-line Air Filters on the U1 and U2 Power Operated Atmospheric Relief Valves (ARVs)

(8) FDA-2021-000003-01-00, CR-2015-008785 Accept Void in pipe CT-2-013 Unit 2 Train A CT Point 70

(9) FDA-2024-000001-01-00, Adding a Vent Valve in the Discharge Piping of 1-02 CCP

(10) EV-CR-2024-004178-3, Compensatory Action to Manually Run Unit 1 Train B SSW Screen Wash

Operating Experience Samples (IP section 03.04) (3 Samples)

(1) OER-2022-008061, Review of NRC Regulatory Issue Summary 2022-02, "Operational Leakage"

(2) OER-2021-003367, Review of NRC Information Notice 2021-01

(3) PRA Configuration Control Operating Experience Smart Sample (OpESS) 2023/02

INSPECTION RESULTS

Very Low Safety Significance Issue Resolution Process: Question on Diesel Generator Frequency Acceptance Criteria 71111.21 M

This issue is a current licensing basis question and inspection effort is being discontinued in accordance with the Very Low Safety Significance Issue Resolution (VLSSIR) process. No further evaluation is required.

Description:

The inspectors identified an issue of concern associated with the performance of Technical Specification (TS) Surveillance Requirement (SR) 3.8.1.11 on May 19, 2023, for the 2-02 diesel generator (DG).

The inspectors reviewed the licensees record of the surveillance test and noted that the licensee had recorded the lowest observed output frequency as 59.8 Hz as read by the licenses Data Acquisition System (DAS). This was below the technical specification acceptance criteria of 59.9 Hz. At the time of the test, the licensee evaluated the data and stated that the test results were acceptable based on the average frequency being above 59.9 Hz.

The inspectors noted that SR 3.8.1.11 requires that the DG:

4. maintains steady state frequency >

= 59.9 Hz and <= 60.1 Hz, and 5. supplies permanently connected, and auto-connected shutdown loads for >= 5 minutes.

Furthermore, the TS Bases state the following:

The specified minimum and maximum frequencies of the DG are 59.9 Hz and 60.1 Hz, respectively. These values are equal to +/- 0.1 Hz of the 60 Hz nominal frequency and are based on DG control system capabilities.

The inspectors were unable to confirm whether the licensee had fully evaluated the capability of all supported safety related loads (e.g. pumps, valves, and other equipment) to perform their safety functions at a steady state frequency below 59.9 Hz.

The inspectors questioned whether the licensee had appropriately reviewed and evaluated the surveillance test data. The inspectors reviewed the available data and discovered a total of seven frequency transients between 59.9 to 59.8 Hz, each of very short duration (i.e. less than one second), in the first five minutes after load sequencing was complete. The licensees evaluation did not describe all of the identified frequency transients.

After discussing the identified concerns with the inspectors, the licensee performed an additional evaluation and determined that the specific transients that occurred during the test would not have impacted the operability of any of the supported safety related loads or adversely impact the safety analysis.

Based on the licensees conclusions, the inspectors do not have a current safety concern with the transients that were observed during this specific test. However, an unresolved question remained as to whether the specific transients observed during the test constituted a failure to meet the surveillance requirement as described in the current licensing basis.

Licensing Basis: The licensee believes that short duration frequency transients outside the band do not represent a failure to maintain steady-state frequency >= 59.9 Hz and <= 60.1 Hz. The licensee also referenced statements in the technical specification bases that discuss short transients.

The inspectors determined that the licensing basis is not explicit as to whether or not the definition of steady state includes any transients during the surveillance test, or whether the requirement to supply connected loads for five minutes also implies that the frequency must be maintained wholly within the specified band for five minutes. The discussions of transients in the bases are explicitly tied to voltage and load, and do not address changes in frequency. Those discussions are also tied to other surveillance requirements and do not explicitly address SR 3.8.1.11.

After considering all available information, the inspectors were unable to conclude whether the practice of allowing short frequency transients outside the specified steady state acceptance criteria for this surveillance test was consistent with the current licensing basis. Also, the inspectors were not able to determine whether either similar or more limiting frequency transients could be considered acceptable for future tests. The inspectors determined that this issue met the criteria for the Very Low Safety Significance Issue Resolution Process because:

• The inspection staff has not been able to conclude that the issue of concern is a violation after considering licensee provided supporting information and relevant information developed during the inspection process.

• The specific condition surrounding the issue of concern cannot have any potential to be Greater than Green.

• The resources required to resolve the current licensing basis question would not effectively and efficiently serve the Agencys mission.

Significance: For the VLSSIR process, the inspectors screened the issue of concern through IMC 0609, Appendix A and determine the issue of concern would likely be Green had a performance deficiency been identified.

Technical Assistance Request: No Technical Assistance Request was processed for this issue.

Corrective Action Reference: CR-2025-000805

EXIT MEETINGS AND DEBRIEFS

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

• On March 10, 2025, the inspectors presented the Comanche Peak Comprehensive Engineering Team Inspection results to Hunter A. Schill, Plant Manager and other members of the licensee staff.

DOCUMENTS REVIEWED

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

16435-EEB-005

Voltage drop in D.C. Control Circuits for Class 1E 6.9 KV

SWGR

004

2-ME-0042

Minimum Allowable Service Water Flow to the Diesel

Generator

2-9222189-000

CPNPP EDG ETAP Dynamic Calculation

DBD-ME-302

Safeguards Building Ventilation System

DBD-ME-311

Safety Chilled Water System

EE-1E-2ED2-2

25V DC Distribution Panel, CP2-ECDPED-04 (2ED2-2)

Bus Based Calculation

EE-EDG-LOAD-

UNIT-2

Unit 2 EDG Loading Calculation

EE-VP-U1-1E

Unit 1 Class 1E Voltage Profile

005

IMT-CA-EQ-0482-

MS10

Service Water Pump Supplemental Calculation

ME-CA-0000-

20

Air Operated Valve Capability Evaluation

ME-CA-0000-

5487

Turbine Driven Auxiliary Feedwater Pump Design

Performance Limit for Inservice Testing

ME-CA-0206-

3147

Auxiliary Feedwater Flow Distribution Evaluation on Turbine

Driven Overspeed

ME-CA-0215-

4054

Diesel Generator Fuel Oil Storage Requirements and Tank

Level Process Set Points

MEB-156

Diesel Generator Fuel Oil Day Tank Technical Specification

Volume

Calculations

MES-071

Operation of Emergency Diesel Generators Without Full

Service Water Flow to JW Heat Exchanger

71111.21M

Corrective Action

Documents

(CR)

24-006866, 2021-008062, 2023-000980, 2018-004603,

2018-004701, 2025-000492, 2021-003196, 2022-008146,

25-000517, 2017-012024, 2023-002718, 2023-002788,

2008-000640, 2024-004178, 2020-002396, 2021-007320,

22-002920, 2022-007252, 2021-007748, CR-2010-

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

005563, CR-2013-006604, CR-2013-008405, CR-2015-

004077, CR-2023-003723, CR-2023-004582, CR-2023-

008360, CR-2024-006967

Corrective Action

Documents

Resulting from

Inspection

(CR)

24-007688, 2025-000322, 2025-000755, 2025-000537,

25-000741, 2025-000755, 2025-000454, 2025-000455,

25-000456, 2025-000457, 2025-000458, 2025-000460,

25-000461, 2025-000463, 2025-000479, 2025-000492,

25-000517, 2025-000544, 2025-000545, 2025-000617,

25-000789, 2025-000813, 2025-000491, 2025-000772,

25-000774, 2025-000790, 2025-000805, 2025-000806,

25-000818

1SB12K110-D001

sh. 7

Shaft Displacement Function diagram individual level

CP-0435-001

AC Motor Control Centers

018

DBD-EE-041

480 V and 120 V AC Electrical Power Systems

2

DDELE E1-0004

Sheet. A

6.9 KV Auxiliaries One line Diagram Safeguard Buses

CP-33

DDVEN 076-

09089E-01C

Elementary Diagram Safety Chiller CP1-CHCICE-06

CP-4

DDVEN_51B5897

Body 30 Actuator 657-B-U Spec A Diaphragm Actuated

Control Valve

D

E1-0005 Sht. A

480V Auxiliaries One Line Diagram Safeguards Buses

CP-23

e1-0009 Sht. B

Containment And Diesel Generator Safeguard 480 V MCCs

One line Diagram

000

E1-0031 Sheet

019

6.9 KV Switchgear Bus 1EA2 TRANSF T1EB4 Feeder BKR

Schematic Diagram

CP-3

E2-0137 Sht. -

Core Cooling Monitoring System Core Exit Thermocouple

Rack CP2-EIPRCI-10

M1-0229

Flow Diagram Component Cooling Water System

CP-26

M2-0215 Sheet G

Flow Diagram Diesel Fuel Oil Piping CP2-MEDGEE-02

CP-12

M2-02229

Flow Diagram Component Cooling Water System

M2-0302

Flow Diagram - Ventilation Safeguards and Electrical Area

Drawings

M2-2250 Sht. 04A

Instrumentation & Control Diagram Reactor Coolant System

Channel 3611, 3612, 0001/0050

000

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

SK-0000-23-

000018-01-00

SK-0001, SK-0005, SK-0006, SK-0007, SK-0008, SK-0009,

SK-0010, SK-0012, SK-0013, SK-0014, SK-0015 SK-0018,

SK-0019, SK-0020, SK-0021, SK-0022, SK-0023, SK-0026,

SK-0027, SK-0028, SK-0029 Drawings

SK-0002-22-

000041-01-00

DIESEL GENERATOR AIR COMPRESSOR 3 TAG CP1-

MECAED-03

000

SK-0003-22-

000041-01-00

Protective Device Setting 480 V Safeguard Buses

000

SK-0004-22-

000041-01-00

Safeguards And Auxiliary Buildings Safeguard 480V MCCs

One Line Diagram

000

SK-0005-22-

000041-01-00

MCC 1EB4-4

000

SK-0006-22-

000041-01-00

MCC 1EB2-

000

DBD EE-078

Loose Parts Monitoring System Design Basis Document

DCA 89328

Component Cooling Water Surge Tank Partition Opening

Sizing

ECE-1.06-F10

Engineering Risk/Rigor Assessment

ECE-5.08-F3

Commercial Change Package

ECE-5.21-06

Testing of Digital Systems and Devices

001

EPID-L-2020-

TOP-0054

PWROG - Regulatory Relaxation for PWR Loose-Part-

Detection Systems

FDA-2000-

001852-03-00

Safety Chiller Timing Relay Replacement

FDA-2021-

000053-01

Design Equivalent Change Package

FDA-2021-

000054-01

Replace in-line air filters on the U1 and U2 Power Operated

Atmospheric Relief Valves (ARV's)

FDA-2021-

000064-01-00

2-TE-0016 is non-functional. Disable 2-TE-0016 by lifting

wires in the core exit thermocouple rack CP2-EIPRCI-10

000

FDA-2022-

000041-01-00

Replace NEMA size 3 starter with NEMA size 2 starter

000

Engineering

Changes

FDA-2022-

000050-01-00

Prepare a Temporary Modification to block the Thrust Trip

on the Unit 1 TG

000

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

FDA-2023-

000003-01-00

Replace existing Emergency Diesel Generator RUN/STOP

switch with new model

FDA-2023-

000009-01

Component Cooling Water Heat Exchange Station Service

Water Relief Valve Replacement

FDA-2023-

000018-01-00

Abandon the Loose Parts Monitoring System for both Units

1and 2 due to the removal of this system from the Licensing

Basis

09/20/2023

STA-707-4

Applicability Determination for a reduced thread

engagement on certain bolted connections.

23102-C-003

Tornado Missiles Analysis - Terry Turbine Flash Tank

System Steam Exhaust Stacks

2CP-PT-30-01B

Emergency Diesel Generator Train B

59SC-2021-

000064-01-00

50.59 Screen

000

ER-ME-021

NNS Piping Classification Practices

ER-ME-109

Evaluation of Safety-Related Pump Degradation Issues

EV-TR-2022-

007252-2

Unit 1 Turbine Thrust Bearing Software Trip Block (FDA-

22-000050-01 R. 0)

000

EV-TR-2022-

007252-5

Unit 2 Turbine Thrust Bearing Software Trip Block (FDA-

22-000050-02 )

000

EV-TR-2022-

00752

Unit 1 Turbine Thrust Bearing Software Trip Block

000

Engineering

Evaluations

ODMI 7252

Turbine Shaft Displacement Instrumentation

2

System Health Report - Component Cooling Water

10/02/2024

23-MS-81

Emergency Fan Coil Units Specification

05/02/1988

ASME B&PV

Code,Section III,

Division 1

Rules for Construction of Nuclear Power Plant Components,

Subsection NF, Component Supports 1974 Edition

07/01/1974

CP-0007-002

HMTA 6 Stage Turbine Driven Auxiliary Feedwater Pump

CP-0081-001

Vendor Manual for Air Handling Units

DBD-EE-040

6.9kV Electrical Power System

DBD-ME-011

Diesel Generator Sets

DBD-ME-215

Diesel Generator Fuel Oil Storage and Transfer System

Miscellaneous

DBD-ME-311

Safety Chilled Water System

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

OER-2022-

008061

Operating Experience Report

11/9/2022

ABN-401

Main Turbine Malfunction

015

ABN-502

Component Cooling Water System Malfunctions

ALM-4000A

Digital Alarms

009

CHM-160

Diesel Fuel Oil Testing Program

CLI-650

Determination of Specific Gravity

COP-610

General Use Diesel Fuel Oil

CPES-S-1062G

Fastener Substitution and Heli-Coil Specification

ECE 5.08

Standard Design Process

004

ECE-2.15

Risk and Reliability Functions

ECE-5.05

Design Drawings And Special Documents

EOP-0.0A-R9-

P10

Emergency Response Guidelines for Reactor Trip or Safety

Injection

MSM-C0-8811

Fischer Globe Valve Designs EC, EAC, ES, and EAS

OPT-435B

Train B Integrated Test Sequence

OPT-453B

Train A Safeguards Slave Relay K644 Actuation Test

R&R-PN-004

Auxiliary Feedwater Water

R&R-PN-017A

Electric Power-1E 6.9kV and 480V

R&R-PN-017B

118VAC & DC Electric Power

R&R-PN-019

Safety Chilled Water

SOP-502B

Component Cooling Water System

STA 707

CFR 50.59 And 10 CFR 72.48 Reviews

23

STA-202

Nuclear Generation Procedure Change Process

STA-602

Temporary Modifications and Transient Equipment

Placements

20

STA-661

Non-Plant Equipment Storage and Use Inside Seismic

Category I Structures

STA-716

Modification Process

033

STI-422.01

Operability Determination and Functionality Assessment

Program

STI-606.01

Work Control Process

013

Procedures

STI-744.09

Structural Monitoring Inspection Guide

Inspection

Procedure

Type

Designation

Description or Title

Revision or

Date

STI-762.02

Risk Managed Technical Specifications - PRA Model

Configuration Control

TSP-503

Emergency Diesel Generator Reliability Program

Work Orders

(WO)

2-006525, 22-547416, 5975767, 22-361464, 22-361458,

5969916, 5125742, 5224954, 5232843, 5232850, 5557839,

5975767, 22-510374, 5593235, 5919995, 24-256522,

4839825, 4913384, 22-448167, 5887235, 5418666,

257170, 5689999, 21-956016, 22-223464, 4778777,

5364176, 5366151, 5847411, 5257170, 5418666, 5887235,

2-394284, 22-431814, 23-390933, 4778777, 5364176,

5366151, 5847411, 22-212685, 22-490334, 21-838956, 22-

27484, 24-546221, 4841076, 22-196613, 22-399074, 22-

24820, 23-473363, 24-449951, 5977516, 21-436153, 21-

570063, 21-701940, 21-702083, 21-880674, 21-880992, 22-

111618, 22-133497, 23-48416, 21-796720, 23-173976,

5661748, 23-178513, 5155927, 5895942, 23-178513, 21-

28466, 23-828438, 4039380, 5364746, 22-1204