IR 05000456/2025004
| ML26030A045 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  (NPF-072, NPF-077) |
| Issue date: | 01/30/2026 |
| From: | Dariusz Szwarc NRC/RGN-III/DORS/RPB3 |
| To: | Mudrick C Constellation Energy Generation, Constellation Nuclear |
| References | |
| IR 2025004 | |
| Download: ML26030A045 (0) | |
Text
SUBJECT:
BRAIDWOOD STATION - INTEGRATED INSPECTION REPORT 05000456/2025004 AND 05000457/2025004
Dear Christopher H. Mudrick:
On December 31, 2025, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Braidwood Station. On January 12, 2026, the NRC inspectors discussed the results of this inspection with A. Schuerman, Site Vice President, 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, Dariusz Szwarc, Chief Reactor Projects Branch 3 Division of Operating Reactor Safety Docket Nos. 05000456 and 05000457 License Nos. NPF-72 and NPF-77 Enclosure:
As stated cc w/ encl: Distribution via GovDelivery January 30, 2026 Signed by Szwarc, Dariusz on 01/30/26
Letter to Christopher
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at Braidwood Station, 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
Type Issue Number Title Report Section Status LER 05000456/2025-001-00 LER 2025-001-00 for Braidwood Station, Unit 1,
Over Temperature Delta Temperature due to Lightning Strike 71153 Closed
PLANT STATUS
Unit 1 began the inspection period operating at 89 percent power due to coasting down for a scheduled refueling outage. On October 5, 2025, the unit was taken offline to begin scheduled refueling outage A1R25. On October 22, 2025, the unit achieved criticality. Several hours later, on October 23, 2025, the unit entered Mode 1. The unit reached full power on October 29, 2025.
With the exception of minor reductions in power to support scheduled testing activities and load changes requested by the transmission system dispatcher, the unit remained operating at or near full power for the rest of the inspection period.
Unit 2 began the inspection period operating at full power. With the exception of minor reductions in power to support scheduled testing activities and load changes requested by the transmission system dispatcher, the unit remained operating at or near full power for the entire 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 on-site 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.
REACTOR SAFETY
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 residual heat removal system train A while protected for shutdown cooling during A1R25 the week ending October 11, 2025
- (2) Both trains of the fuel pool cooling system while the core was fully offloaded during A1R25 during the week ending October 11, 2025
71111.05 - Fire Protection
Fire Area Walkdown and Inspection Sample (IP Section 03.01) (2 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) Fire Zone 8.3-1, turbine building, 401' elevation, Unit 1 grade level (NW)during hot work for valve replacement during the week ending October 11, 2025
- (2) Fire Zone 8.5-1, turbine building, 426' elevation, Unit 1 mezzanine floor (SE)during hot work for piping replacement during the week ending October 11, 2025
71111.11Q - Licensed Operator Requalification Program and Licensed Operator Performance
Licensed Operator Performance in the Actual Plant/Main Control Room (IP Section 03.01) (1 Sample)
- (1) The inspectors observed and evaluated various activities involving on-watch operations crews in the main control room on October 5, 2025, during shutdown of Unit 1 for refueling outage A1R25.
Licensed Operator Requalification Training/Examinations (IP Section 03.02) (1 Sample)
- (1) Observation of the performance of a crew of licensed plant operators in the facilitys simulator performing just in time training on October 1, 2025
71111.12 - Maintenance Effectiveness
Maintenance Effectiveness (IP Section 03.01) (4 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) Maintenance effectiveness review of 1RC014A-D, reactor head vent valves following discovery of leakage during refueling outage A1R25
- (2) Maintenance effectiveness review of 0VC43Y, Unit Common, Train A (0A)recirc charcoal absorber bypass damper during the week ending October 25, 2025
- (3) Maintenance effectiveness review of the Unit 2 steam generator PORVs during the weeks ending November 8 and 15, 2025
- (4) Maintenance effectiveness review of 0SX147, Unit Common component cooling heat exchanger outlet valve during the weeks ending December 5 and December 19, 2025
71111.13 - Maintenance Risk Assessments and Emergent Work Control
Risk Assessment and Management Sample (IP Section 03.01) (1 Sample)
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 2 elevated risk while emergency DC bus 212 was cross-tied to Unit 1 for refueling outage A1R25 during the week ending October 11, 2025
71111.15 - Operability Determinations and Functionality Assessments
Operability Determination or Functionality Assessment (IP Section 03.01) (2 Samples)
The inspectors evaluated the licensees justifications and actions associated with the following operability determinations and functionality assessments:
- (1) Evaluation of the operability of ESF (Engineered Safety Feature) Transformer 132X, as documented in action request (AR) 4906585 during the weeks ending October 25 and November 1, 2025
- (2) Evaluation of the operability of the 2B emergency diesel generator (EDG),as documented in AR 4907289 during the weeks ending October 25 and November 1, 2025
71111.20 - Refueling and Other Outage Activities
Refueling/Other Outage Sample (IP Section 03.01) (1 Sample)
- (1) The inspectors evaluated refueling outage A1R25 activities from October 6, 2025, to October 23, 2025
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) (8 Samples)
- (1) Functional and operational testing of the Unit 1 DC-112 125V ESF bus following battery cell replacement during refueling outage A1R25, as documented in Work Order (WO) 5528760
- (2) Functional and operational testing of 1CC9518 after valve replacement during refueling outage A1R25, as documented in WO 5735934.
- (3) Functional and operational testing of the Unit 1 Train B auxiliary feedwater system following maintenance during refueling outage A1R25, as documented in WO 5723897
- (4) Core reload verification following refueling outage A1R25, as documented in WO 5533252
- (5) Low power physics testing following refueling outage A1R25, as documented in WO 5536091
- (6) Functional and operational testing of the Unit 1 Solid State Protection System (SSPS)following maintenance during refueling outage A1R25, as documented in WOs 5566824 and 5588144
- (7) Functional and operational testing of control rod drive system following refueling outage A1R25, as documented in WO 5536100
- (8) Hydraulic pressure testing of the reactor coolant system following refueling outage A1R25 on October 22, 2025
Surveillance Testing (IP Section 03.01) (2 Samples)
- (1) Unit 1 auxiliary feedwater full flow and response time testing, as documented in WO 5549001
- (2) Unit 1 main steam safety valve testing, as documented in WO 5540154
Containment Isolation Valve (CIV) Testing (IP Section 03.01) (1 Sample)
- (1) Local leak rate testing of Unit 1 primary containment isolation valves CC 9518/9438/685 for the reactor coolant pump thermal barrier return, as documented in WO 5232324.
71114.04 - Emergency Action Level and Emergency Plan Changes
Inspection Review (IP Section 02.01-02.03) (1 Sample)
- (1) The inspectors evaluated the following submitted Emergency Action Level and Emergency Plan changes.
- EP-AA-1000, Standardized Radiological Emergency Plan, Revision 34 This evaluation does not constitute NRC approval.
71114.06 - Drill Evaluation
Additional Drill and/or Training Evolution (1 Sample)
The inspectors evaluated sites emergency plan by observing the following emergency response organization (ERO) activities:
- (1) A limited emergency preparedness drill that resulted in a simulated Site Area Emergency event classification on November 10, 2025
OTHER ACTIVITIES - BASELINE
71151 - Performance Indicator Verification The inspectors verified licensee performance indicators submittals listed below:
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) (3 Samples)
The inspectors reviewed the licensees implementation of its corrective action program related to the following issues:
- (1) The inspectors reviewed the corrective actions associated with AR 4901565, high head FLEX pumps high hydraulic fluid temperature
- (2) The inspectors reviewed the corrective actions associated with AR 4424225, 2A CV Pump Significantly Weaker than 2B CV Pump
- (3) The inspectors reviewed the corrective actions associated with AR 4890667, Switchyard Ground Repair
71152S - Semiannual Trend Problem Identification and Resolution Semiannual Trend Review (Section 03.02) (1 Sample)
- (1) The inspectors reviewed the licensees corrective action program to identify potential trends with ground water intrusion in Unit 2 curved wall area that might be indicative of a more significant safety issue.
71153 - Follow-up of Events and Notices of Enforcement Discretion Event Report (IP Section 03.02) (1 Sample)
The inspectors evaluated the following licensee event reports (LERs):
- (1) LER 05000456/2025-001-00, Over Temperature Delta Temperature Reactor Trip Due to Lightning Strike (ADAMS Accession No. ML25269A165)
The inspectors determined that the cause of the condition described in the LER was not reasonably within the licensees ability to foresee and correct, and therefore was not reasonably preventable. No performance deficiency nor violation of NRC requirements was identified. This LER is Closed.
INSPECTION RESULTS
Observation: Ground Water Intrusion Trend
The inspectors reviewed AR 4899202 for a licensee identified trend in ground water intrusion into the Unit 2 curved wall area, 364' elevation by safety injection (SI) valves. The inspectors reviewed past action requests (ARs), work orders, and procedures and interviewed licensee engineers to ascertain the causes and potential safety impact of the ground water intrusion.
The inspectors determined that the current rate of ground water intrusion does not have an impact on the function of safety-related systems or is the result of degradation of the auxiliary building structure. The licensee has developed long term plans and initiated actions to monitor and address the issue. No findings or violations were identified.
EXIT MEETINGS AND DEBRIEFS
The inspectors verified no proprietary information was retained or documented in this report.
- On January 12, 2026, the inspectors presented the integrated inspection results to A. Schuerman, Site Vice President, and other members of the licensee staff.
- On December 8, 2025, the inspectors presented the emergency preparedness inspection results to A. Nissen, Emergency Preparedness Manager, and other members of the licensee staff.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Miscellaneous
1A RH Protected
for S/D Cooling
A1R25 Equipment List
10/02/2025
1BwGP 100-5
Plant Shutdown and Cooldown
BwOP FC-M1
Operating Mechanical Lineup Unit 1
Procedures
BwOP RH-6
Placing the RH System in Shutdown Cooling
1074183
NRC Questions Regarding 1(2)RC014A-D Head Vent Valves
05/27/2010
266402
External Leakage (1RC014 Sol. Va. Assemblies)
10/23/2004
4414119
01-OSP-A Reactor Head Vent BA
04/05/2021
4516310
MOV 0SX147 - Valve Shaft / Bearing Replacement
08/11/2022
20574
0A VC Charcoal Adsorber Bypass Leakage Results
OOT [Out of Tolerance]
11/30/2023
4896712
0A-VC Charcoal Absorber Leakage Test OOT
09/11/2025
4903195
SOP-A Boric Acid Overflow from Leakby on
1RC014 Valves
10/06/2025
Corrective Action
Documents
4916143
Follow-Up to AR 4516310 for Upcoming 0SX147 Diagnostic
11/20/2025
Engineering
Changes
646516
Evaluate Acceptance of Weak Link Analysis for
Jamesbury 30 Butterfly Valve, 0SX147
Engineering
Evaluations
EQ Binder, EQ-
GEN040
V526 Series Solenoid Valves
Miscellaneous
IST-BRW-PLAN
Inservice Testing Program Fourth Ten Year Interval
03/24/2021
1397268
Task 1, 0FZ-VC023 Hydramotor Replacement PM
05/29/2013
Work Orders
29335
0SX147 Motor Operated Valve Diagnostic Test
2/19/2025
Miscellaneous
25VDC DC-111
and DC-212
Protected
Equipment List
10/07/2025
Procedures
BwOP DC-7-112
25V DC ESF Bus 112 Cross-tie/Restoration
4906585
OSP-R XFMR 132X Cooling Fans Incorrect Safety Level
10/17/2025
Corrective Action
Documents
4907289
2B DG Jacket Water Sightglass Lower than Ops Rounds
Specs
10/20/2025
Engineering
Changes
645974
TCCP to Allow the Use of 132X Transformer Without Forced
Air Cooling Fans Available - 1AP13E
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Engineering
Evaluations
BRW-E-2025-012
Remove Power from Cooling Fans to Transformer 132X
Procedures
BwOP DG-3
Filling the Diesel Generator Jacket Water System
4905391
A1R25 Source Range Response Not Verified
10/14/2025
Corrective Action
Documents
4905733
A1R25 Core Reload - FM Discovered in Cavity
10/14/2025
1BwGP 100-5
Plant Shutdown and Cooldown
Procedures
BwOP RH-6
Placing the RH System in Shutdown Cooling
4902164
DPM AF Leak 1D SG Flow Instrument Flange During
10/01/2025
4906995
OSP-R LLRT for 1CC9438 and 1CC9518 in WARNING
Range
10/18/2025
4907143
OSP-X 1PA09J Permissive Test Switch Dirty Contacts
10/19/2025
Corrective Action
Documents
4907149
TD-1 in 1PA09J Degraded
10/19/2025
1BwHSR 3.8.4.2-
2
Unit One 125 Volt ESF Batter Charger 112 Capacity Test
1BwOS TRM
2.7.a.1
Unit One Auxiliary Feedwater Diesel Prime Mover
Performance Surveillance
1BwOSR 3.1.7.1
Digital Rod Position Indication (DRPI) Operability Checkout
1BwOSR 3.3.1.4-
Unit One SSPS, Reactor Trip Breaker, and Reactor Trip
Bypass Breaker Surveillance (Train B)
1BwOSR 3.7.5.4-
Unit One Diesel Driven Auxiliary Feedwater Pump
Surveillance
1BwOSR 3.8.9.1
Unit One 125V DC Bus Division 111/112 Operability
Surveillance
1BwOSR
5.5.8.AF-3B
Group A IST Requirements for Unit 1 Diesel Driven
Auxiliary Feedwater Pump
1BwOSR
5.5.8.AF-4A
Unit One Comprehensive Testing (IST) Requirements
for 1A Auxiliary Feedwater Pump
1BwOSR
5.5.8.AF-4B
Unit One Comprehensive Testing (IST) Requirements
for 1B Auxiliary Feedwater Pump
BwMP 3305-003
Main Steam Safety Valve Testing Using Setpoint Verification
Device
Procedures
BwVS 500-6
Low Power Physics Test Program
Work Orders
28760
Unit One 125V ESF Battery Charger 112 Capacity Test
10/11/2025
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
28761
PMT 1DC04E Functional Check per 1BwOSR 3.8.9.1
10/11/2025
5536091
Low Power Physics Test Program with Dynamic Rod Worth
Measurement
10/22/2025
5536100
DRPI Operability Checkout
10/22/2025
5539209
U1 AF Diesel Prime Mover Performance Surveillance
10/20/2025
5539633
Unit 1 SSPS, Rx BRKR, RX Trip BRKR Train A
10/20/2025
5540154
MSSV Operability Test
10/02/2025
5549001
Unit 1 AF Pumps Comprehensive Full Flow Test and
Equipment Response Time
10/01/2025
5553418
Perform A Full PM On Reactor Trip Breaker
10/19/2025
5588144
Unit 1 SSPS, Reactor Breaker, Reactor Trip Bypass Breaker
Train B
10/20/2025
23897
1B AF Pump Monthly Surveillance Run
10/20/2025
5735934
1CC9518 LLRT Failure
10/19/2025
Calculations
Evaluation No.:
24-49
§50.54(q) Program Evaluation Assessment Review for
Standardized Radiological Emergency Plan Revision 34
2/28/2025
EPA-400/R-
17/001
PAG Manual: Protective Action Guides and Planning
Guidance for Radiological Incidents
01/2017
Miscellaneous
EPID L-2018-
LLA-0045
Issuance of Amendments to Revise the Emergency
Response Organization Staffing Requirements
03/21/2019
Exelon Nuclear Standardized Radiological Emergency Plan
Procedures
Standardized Radiological Emergency Plan
Miscellaneous
None
Braidwood SED [Site Emergency Director] Qualifying Drill
25
11/10/2025
4813791
U2 Leak Rate Deviation Action Level III Exceeded
10/31/2024
4814330
U2 Leak Rate Deviation Action Level II, Improved Leakage
11/01/2024
4815076
2BwOSR 3.4.13.1 Exceeds Deviation Action Levels II & III
11/04/2024
4817516
U2 RCS Leak Rate Action Level I Exceeded
11/14/2024
4818974
U2 Leak Rate Deviation Action Level II
11/21/2025
20205
U2 RCS Leak Rate Action Level II Exceeded
11/27/2024
25260
U2 RCS Leak Rate Exceeds Deviation Action Level III
2/20/2024
71151
Corrective Action
Documents
4836504
U1 RCS Leak Rate Reached Deviation Action Level I
2/11/2025
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
4863515
U1 Hand Calculation Leak Rate Values Action Level III
05/06/2025
4864195
U1 Hand Calculation Leak Rate Values Action Level II
05/08/2025
4888910
U1 RCS Leak Rate Action Level II Exceeded
08/06/2025
4890073
U1 RCS Leak Rate Exceeded Deviation Action Level I
08/13/2025
4890306
U1 RCS Leak Rate Deviation Action Level I Exceeded
08/13/2025
2713661
Review of IST Surveillance Test Results
09/08/2016
4394374
2A CV Pump D/P Less Than 2390 PSID
01/07/2021
24225
2A CV Pump Significantly Weaker than 2B CV Pump
05/18/2021
4682881
0BwOS FX-12 PCRA
06/06/2023
22420
Long Term FLEX Pump Storage Strategy
2/08/2023
4872335
0C High Head FLEX Pump Trip
06/11/2025
4890477
0FX02PC C High Head FLEX Pump Still Overheating
08/14/2025
Corrective Action
Documents
4901565
0FX02PC High Head FLEX Pump High Hydraulic Fluid Temp
09/29/2025
BRW-16-0001-E
Evaluation of the Effects of Emergency Diesel Generator
(EDG) Voltage and Frequency Variations on
Safety-Related Equipment Powered by EDGs
Report PP-CV-1
IST Eval PP-CV-1 2CV01PA
Report PP-CV-15
IST Eval PP-CV-15 CV01ASME Qtrly
11/19/2019
Report PP-CV-3
IST Eval PP-CV-3
Engineering
Evaluations
Report PP-CV-5
IST Evaluation PP-CV-05 2CV01PA
10/24/2009
Miscellaneous
None
CV Pump Performance Trending Data from 4th Qtr. 2022
thru 4th Qtr. 2025
10/27/2025
0BwOS FX-12
FLEX Pump Full Flow Test Surveillance
0BwOS FX-9
FLEX Pump Flow Surveillance
2BwOSR
5.5.8.CV-4A
Group A IST Requirements for 2A Centrifugal Charging
Pump (2CV01PA) and Check Valve 2CV8480A Stroke Test
2BwOSR
5.5.8.CV-4B
Group A IST Requirements for 2B Centrifugal Charging
Pump (2CV01PB) and Check Valve 2CV8480B Stroke Test
2BwOSR
5.5.8.CV-8
Comprehensive Inservice Testing (IST) Requirements for
Unit 2 Charging Pumps and Safety Injection System
Charging Check Valve Stroke Test
Procedures
Diverse and Flexible Coping Strategies (FLEX), Spent Fuel
Pool Instrumentation (SFPI), and Hardened Containment
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Vent System (HCVS) Program Document
CC-BR-118-1001
Site Implementation of Diverse and Flexible Coping
Strategies (FLEX) And Spent Fuel Pool Instrumentation
Program
4447069
Groundwater Intrusion Near 2SI8811A Needs Attention
09/17/2021
4701562
Groundwater Below 2SI8811A
09/10/2023
4742830
Ground Water Seeping in Around 2SI8811A Crosses CA
2/04/2024
4895612
Water Beneath U2 SI Can Valves Due to Clogged Catch
Basin
09/05/2025
Corrective Action
Documents
4899202
Trend in 2SI Penetration In-Leakage
09/19/2025
5195853
Groundwater In-Leakage Walkdown / Inspection - U2
Auxiliary Building 364' Penetration Area
07/08/2023
292795
Unit 2 - Area 7 Maintenance Rule Inspection_Aux Bldg 364
2/17/2025
Work Orders
5403593
Groundwater Below 2SI8811A
10/13/2024
4887138
OTDT Channel Investigation - U1 Reactor Trip
07/30/2025
4887148
1MS147B MCR Monitor Light is Dual Instead of Red
07/30/2025
Corrective Action
Documents
4887512
W/O 5642969 Switchyard Ground Grid Testing to be
Pulled Up
07/30/2025