IR 05000369/2025001
| ML25113A049 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 04/30/2025 |
| From: | Robert Williams NRC/RGN-II/DORS/PB1 |
| To: | Pigott E Duke Energy Carolinas |
| References | |
| IR 2025001 | |
| Download: ML25113A049 (1) | |
Text
SUBJECT:
MCGUIRE NUCLEAR STATION - INTEGRATED INSPECTION REPORT 05000369/2025001 AND 05000370/2025001
Dear Edward Pigott:
On March 31, 2025, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at McGuire Nuclear Station. On April 15, 2025, the NRC inspectors discussed the results of this inspection with you 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 II; the Director, Office of Enforcement; and the NRC Resident Inspector at McGuire Nuclear Station.
April 30, 2025 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, Robert E. Williams, Jr., Chief Projects Branch 1 Division of Operating Reactor Safety Docket Nos. 05000369 and 05000370 License Nos. NPF-9 and NPF-17
Enclosure:
As stated
Inspection Report
Docket Numbers:
05000369 and 05000370
License Numbers:
Report Numbers:
05000369/2025001 and 05000370/2025001
Enterprise Identifier:
I-2025-001-0026
Licensee:
Duke Energy Carolinas, LLC
Facility:
McGuire Nuclear Station
Location:
Huntersville, North Carolina
Inspection Dates:
January 01, 2025, to March 31, 2025
Inspectors:
C. Safouri, Senior Resident Inspector
F. Young, Resident Inspector
Approved By:
Robert E. Williams, Jr., Chief
Projects Branch 1
Division of Operating Reactor Safety
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at McGuire Nuclear 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
Failure to Scope Nuclear Service Water Vacuum Breakers into Fourth Interval Inservice Testing Program Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000369,05000370/2025001-01 Open/Closed None (NPP)71111.24 The inspectors identified a Green finding and associated non-cited violation (NCV) of 10 CFR 50.55a(f)(4) when the licensee failed to scope and test nuclear service water (RN) vacuum breaker valves on the chilled water (YC) system (train A: 1RN-90, 1RN-92; train B: 1RN-191, 1RN-193) in accordance with American Society of Mechanical Engineers (ASME) Operation and Maintenance of Nuclear Power Plants (OM) Code (2004 Revision through 2006 Addenda).
Additional Tracking Items
None.
PLANT STATUS
Unit 1 began the inspection period at rated thermal power (RTP). On February 24, 2025, the unit entered coastdown operations for refueling outage M1R30 and ended the inspection period at approximately 84 percent RTP.
Unit 2 began the inspection period at RTP. On March 14, 2025, the unit reduced power to 98 percent RTP to conduct turbine valve movement testing. During testing, Unit 2 throttle valve #4 was procedurally closed but did not re-open as expected. As a result, the licensee reduced power to 73 percent RTP in accordance with procedures to troubleshoot the valve malfunction.
On March 15, 2025, the unit was raised to 85 percent RTP to re-perform turbine valve movement testing. Following successful testing, the licensee raised the unit back to RTP, and it remained at or near RTP 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 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
71111.01 - Adverse Weather Protection
Impending Severe Weather Sample (IP Section 03.02) (1 Sample)
- (1) The inspectors evaluated the adequacy of the overall preparations to protect risk significant systems from impending severe weather during winter storm conditions on January 22, 2025.
71111.04 - Equipment Alignment
Partial Walkdown Sample (IP Section 03.01) (4 Samples)
The inspectors evaluated system configurations during partial walkdowns of the following systems/trains:
- (1) Unit 2 train A and train B auxiliary feedwater (CA) pumps and discharge path to loop B and loop C steam generators on January 24, 2025
- (2) Unit 1 train B spent fuel cooling system on March 7, 2025
- (3) Unit 2 train B residual heat removal (ND) system while train A ND system was out of service for planned maintenance on March 10, 2025
- (4) Pre-outage alignment of Unit 1 and Unit 2 offsite electrical circuits and control room chilled water system on March 27, 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) Fire Area 22: Unit 1 motor generator set room on January 3, 2025
- (2) Fire Area 3: Unit 2 CA pump room area and the auxiliary building fire protection deluge valves and bypass lines on February 3, 2025
- (3) Fire Area 25: auxiliary building ventilation equipment shared area, 767 ft elevation on February 10, 2025
- (4) Fire Area 19 and 20: Units 1 and 2 shared cable spreading room in the auxiliary building on February 21, 2025
Fire Brigade Drill Performance Sample (IP Section 03.02) (2 Samples)
- (1) The inspectors evaluated the onsite fire brigade training and performance during an unannounced fire drill conducted in the Unit 1 lubrication oil purifier on January 31, 2025.
- (2) The inspectors evaluated the onsite fire brigade training and performance during an unannounced fire drill conducted in the Unit 2 main turbine hydraulic seal oil pump skid on February 7, 2025.
71111.06 - Flood Protection Measures
Flooding Sample (IP Section 03.01) (1 Sample)
- (1) The inspectors evaluated internal flooding mitigation protections in the Unit 1 and Unit 2 turbine building basements on January 3, 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 licensed operator performance in the control room during Unit 2 control rod bank repositioning on March 3, 2025, and Unit 2 main turbine valve movement test on March 14, 2025.
71111.12 - Maintenance Effectiveness
Maintenance Effectiveness (IP Section 03.01) (1 Sample)
The inspectors evaluated the effectiveness of maintenance to ensure the following structures, systems, and components (SSCs) remain capable of performing their intended function:
- (1) Nuclear condition report (NCR) 02535890, periodic 10 CFR 50.65(a)(3) evaluation review covering the period of October 1, 2022, through September 30, 2024 on February 7, 2025
71111.13 - Maintenance Risk Assessments and Emergent Work Control
Risk Assessment and Management Sample (IP Section 03.01) (6 Samples)
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 due to train A emergency diesel generator (D/G) planned safety system unavailability on January 13, 2025
- (2) Unit 2 upper containment airlock door emergent work evaluation on February 6, 2025
- (3) Unit 1 and Unit 2 main control room train A chilled water system compressor refurbishment on February 7, 2025
- (4) Unit 1 elevated risk due to train A containment spray pump planned safety system unavailability on February 10, 2025
- (5) Unit 2 train A D/G room ventilation fan 2A1 motor windmilling backward due to backdraft damper stuck open on February 18, 2025
- (6) Unit 2 elevated risk due to train B D/G planned safety system unavailability and risk-informed completion time program usage on February 24, 2025
71111.15 - Operability Determinations and Functionality Assessments
Operability Determination or Functionality Assessment (IP Section 03.01) (5 Samples)
The inspectors evaluated the licensee's justifications and actions associated with the following operability determinations and functionality assessments:
- (1) NCR 02541438, trend in Unit 2 unidentified leakage negative values due to in-leakage from adjacent systems, on January 23, 2025
- (2) Work request (WR) 20282426, Unit 1 train B nuclear service water (RN) control valve to 1B1 component cooling water pump motor cooler, 1RN-213B, valve body leakage, on January 28, 2025
- (3) WR 20281712, Unit 2 train A ND to safety injection suction motor operated valve, 2NI-334B, unexpected seating profile, on January 30, 2025
- (4) NCR 02544013, train A RN vacuum breakers, 1RN-90 and 1RN-92, as-found set pressure criteria failure, on February 12, 2025
- (5) NCR 02545617, Unit 2 train B D/G ventilation fan 2B1 windmilling backward due to backdraft damper stuck open, on February 27, 2025
71111.18 - Plant Modifications
Temporary Modifications and/or Permanent Modifications (IP Section 03.01 and/or 03.02) (1 Sample)
The inspectors evaluated the following temporary or permanent modifications:
- (1) Procedure revision request 02508961, incorporating instructions for lube oil addition to a running D/G during loss of electrical power
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) (6 Samples)
- (1) OP/1/A/6200/004, ND system operational test following breaker removal and preventive maintenance on Unit 1 train B ND pump supply breaker on January 7, 2025
- (2) PT/1/A/4403/002E, Quarterly valve stroke timing following calibration of Unit 1 train B RN flow control valve, 1RN-190B on January 7, 2025
- (3) PT/2/A/4350/002A, Unit 2 train A D/G operability test following two cylinder head replacements on January 15, 2025
- (4) SM/0/A/8030/001, "Relief Valve Set Pressure Testing and Adjustment," of Unit 2 turbine driven CA pump suction relief valve, 2CA-128, following relief valve replacement on January 29, 2025
- (5) PT/0/A/4200/002, Standby Shutdown Facility Operability Test, following mechanical and electrical inspection on February 20, 2025
- (6) PT/2/A/4350/017B, Unit 2 train B D/G fuel oil transfer pump performance test following motor replacement on February 27, 2025
Surveillance Testing (IP Section 03.01) (3 Samples)
- (1) PT/2/A/4600/014E, NIS Power Range N-42 Channel Operational Test, on February 3, 2025
- (2) PT/1/A/4200/028A, "Train A Slave Relay Test," Enclosure 13.3, Train 1A Safety Injection (K-611), on February 13, 2025
- (3) PT/2/A/4250/004A, "Turbine Valve Movement Test," on March 14, 2025
Inservice Testing (IST) (IP Section 03.01) (1 Sample)
Diverse and Flexible Coping Strategies (FLEX) Testing (IP Section 03.02) (1 Sample)
OTHER ACTIVITIES - BASELINE
===71151 - Performance Indicator Verification The inspectors verified licensee performance indicators submittals listed below:
IE01: Unplanned Scrams per 7000 Critical Hours Sample (IP Section 02.01)===
- (1) Unit 1 (January 1 through December 31, 2024)
- (2) Unit 2 (January 1 through December 31, 2024)
IE03: Unplanned Power Changes per 7000 Critical Hours Sample (IP Section 02.02) (2 Samples)
- (1) Unit 1 (January 1 through December 31, 2024)
- (2) Unit 2 (January 1 through December 31, 2024)
IE04: Unplanned Scrams with Complications (USwC) Sample (IP Section 02.03) (2 Samples)
- (1) Unit 1 (January 1 through December 31, 2024)
- (2) Unit 2 (January 1 through December 31, 2024)
71152A - Annual Follow-up Problem Identification and Resolution Annual Follow-up of Selected Issues (Section 03.03)
The inspectors reviewed the licensees implementation of its corrective action program related to the following issues:
- (1) NCR 02546228, Unit 1 train B D/G coolant leak at pipe coupling on March 18, 2025
71152S - Semiannual Trend Problem Identification and Resolution Semiannual Trend Review (Section 03.02)
- (1) The inspectors reviewed the licensees corrective action program to identify potential trends in change management of engineering products including engineering changes and interim calculation changes that might be indicative of a more significant safety issue.
INSPECTION RESULTS
Failure to Scope Nuclear Service Water Vacuum Breakers into Fourth Interval Inservice Testing Program Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000369,05000370/2025001-01 Open/Closed None (NPP)71111.24 The inspectors identified a Green finding and associated non-cited violation (NCV) of 10 CFR 50.55a(f)(4) when the licensee failed to scope and test nuclear service water (RN) vacuum breaker valves on the chilled water (YC) system (train A: 1RN-90, 1RN-92; train B: 1RN-191, 1RN-193) in accordance with American Society of Mechanical Engineers (ASME) Operation and Maintenance of Nuclear Power Plants (OM) Code (2004 revision through 2006 addenda).
Description:
On February 10-11, 2025, the licensee performed a 10-year preventive maintenance task associated with replacing and testing 1RN-90 and 1RN-92, under work orders 20631965 and 20631964, respectively. Licensee design document MCTC-1574-RN.V028-01, Valve Design Criteria/Operability Requirements and Compensatory Measures, states:
"1RN90, 1RN92, 1RN191, and 1RN193 are sub-atmospheric pressure relief valves (vacuum breakers) located on the inlet and outlet of the RN/YC heat exchangers (condensers) on each VC/YC Chiller. Their design function is to prevent water column separation under no flow conditions which could potentially result in water hammer of the RN System piping on initiation of flow.
Additionally, according to MCTC-1574-RN.V028-01, in Modes 1-4:
"If 1RN90, 1RN92, 1RN191, or 1RN193 fails any required testing or is incapable of opening, then the respective YC train is inoperable. There are no immediate compensatory actions for assuring train operability."
The as-found vacuum relief set pressure acceptance range for 1RN-90 and 1RN-92 was 9.5 - 10.1 psig (vacuum). However, 1RN-90 lifted at 4.974 psig and 5.115 psig; 1RN-92 lifted at 7.42 psig and 6.33 psig. In response to the failed as-found testing results for 1RN-90 and 1RN-92, although these valves did not meet the requirements for operability per MCTC-1574-RN.V028-01, the licensee concluded operability was maintained since the lift setpoint drifted in a conservative manner such that the valves would have opened at a lower setpoint and maintained their design function of protecting against water column separation and water hammer.
The inspectors reviewed the preventive maintenance and calibration practices associated with these valves. From March 1, 2014, to March 1, 2025, the licensee was within their fourth interval of inservice testing (IST), where the IST program code of record was ASME OM Code (2004 revision through 2006 addenda). These valves were removed from the IST program in May 1999 and were not incorporated into the IST program for the fourth interval.
Additionally, on March 19, 2014, the preventive maintenance replacement/refurbish frequency was changed from 20 years to 10 years.
ASME OM Code (2004 Edition), ISTA-1100, Scope, states:
Section IST establishes the requirements for preservice and inservice testing and examination of certain components to assess their operational readiness...
apply to...
- (a) pumps and valves that are required to perform a specific function in shutting down a reactor to the safe shutdown condition, in maintaining the safe shutdown condition, or in mitigating the consequences of an accident; (b)pressure relief devices that protect systems or portions of systems that perform one or more of these three functions....
As a result, these vacuum breakers were required to be tested per ISTC-5230 and Appendix I-1380, which requires "All Classes 2 and 3 vacuum relief valves shall be tested every 2 years, unless performance data suggest the need for a more appropriate test interval."
Corrective Actions: On January 2, 2025, the licensee incorporated 1RN-90, 1RN-92, 1RN-191, and 1RN-193 into the IST program for the fifth interval. Additionally, the licensee approved a preventive maintenance change to test these valves from ten years to two years.
Corrective Action References: Nuclear condition report 02539507
Performance Assessment:
Performance Deficiency: The failure to incorporate IST program testing requirements during the fourth interval for these safety-related vacuum breakers, specifically 1RN-90, 1RN-92, 1RN-191, and 1RN-193, as required by 10 CFR 50.55a(f)(4), was a performance deficiency.
Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Equipment 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, regardless of the final operability or functionality, the as-found condition resulted in reasonable doubt about the equipments reliability, which reduced assurance in the equipments availability and reliability and required the licensee to revise assumptions to maintain operability.
Significance: The inspectors assessed the significance of the finding using IMC 0609 Appendix A, The Significance Determination Process (SDP) for Findings At-Power. Using Exhibit 2, Section A, the inspectors determined the finding to be of very low safety significance, Green, because it did not represent a loss of the probabilistic risk assessment function of any of the components.
Cross-Cutting Aspect: Not Present Performance. No cross-cutting aspect was assigned to this finding because the inspectors determined the finding did not reflect present licensee performance.
Enforcement:
Violation: 10 CFR 50.55a(f)(4), Inservice Testing Standards Requirement for Operating Plants, requires Throughout service life of a pressurized water-cooled nuclear power facility, pumps and valves that are within the scope of the ASME OM Code must meet the inservice test requirement set forth in the ASME OM Code. ASME OM Code (2004 Edition), ISTA-1100, Scope, states the requirements for preservice and inservice testing and examination of certain components to assess their operational readiness... apply to...
- (a) pumps and valves that are required to perform a specific function in shutting down a reactor to the safe shutdown condition, in maintaining the safe shutdown condition, or in mitigating the consequences of an accident;
- (b) pressure relief devices that protect systems or portions of systems that perform one or more of these three functions....
Contrary to the above, from March 1, 2014 to January 2, 2025, the licensee failed to scope and test 1RN-90, 1RN-92, 1RN-191, and 1RN-193 safety-related vacuum breakers per ASME OM Code.
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 April 15, 2025, the inspectors presented the integrated inspection results to Edward Pigott and other members of the licensee staff.
THIRD PARTY REVIEWS Inspectors reviewed the Nuclear Safety Review Board (NSRB) reports that were issued on July 11, 2024, and January 7, 2025.
Inspectors reviewed the World Association of Nuclear Operators (WANO) Peer Review Report that was issued on March 6, 2025.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Procedures
RP/0/B/5700/027
Severe Weather Protection
Calculations
MCC-1435.00-00-
0041
NFPA 805 Transition Risk-Informed, Performance-Based
Fire Risk Evaluations
Corrective Action
Documents
Resulting from
Inspection
Nuclear Condition
Report(s)
2541142
Fire Plans
CSD-MNS-PFP-
AB-0767-001
Auxiliary Building Elevation 767 Pre-Fire Plan
Fire Plans
CSD-MNS-PFP-
TB1-0739-001
U1 Turbine Building Elevation 739 Pre-Fire Plan
Fire Plans
CSD-MNS-PFP-
TB2-0760-001
U2 Turbine Building Elevation 760 Pre-Fire Plan
Miscellaneous
Scenario 22 - Lube Oil Purifier
Miscellaneous
Scenario 13 - Unit 2 LG Skid
Procedures
PT/2/A/4250/004A
Turbine Valve Movement Test
Corrective Action
Documents
Nuclear Condition
Report(s)
2543235, 02546803, 02545617
Corrective Action
Documents
Resulting from
Inspection
Nuclear Condition
Report(s)
2545606, 02545654
Procedures
AD-MN-ALL-0015
Nuclear Station Scaffold Erection, Tracking, and Dismantling
Procedures
AD-OP-ALL-0201
Protected Equipment
Procedures
AD-OP-ALL-0212
Risk Informed Completion Time Program Calculations
Procedures
PT/2/A/4200/020A
Airlock Operability Test
Work Orders
Work Request(s)
283562, 20283402, 20283639, 20283640, 20283641
Corrective Action
Documents
Nuclear Condition
Report(s)
2546803
Procedures
PT/2/A/4150/001B
Reactor Coolant Leakage Calculation
Work Orders
20638587
Work Orders
Work Request(s)
283562, 20283402, 20283639, 20283640, 20283641
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Corrective Action
Documents
Nuclear Condition
Report(s)
2498709
Procedures
AP/2/A/5500/07
Loss of Electrical Power
046
Procedures
MP/0/A/7400/071
Nordberg Diesel Engine Lube Oil Removal, Replacement,
and Replenishment
016
Corrective Action
Documents
Nuclear Condition
Report(s)
2547464, 02539507, 02541410, 02543786, 02544013
Drawings
MC-1783-03.01
C/D Solid State Protection Sys Output Cab-Left Side Train A
Drawings
MCEE-138-00.22
E/D A B Non Ess Sply Isol Vlv 1RN42A
Drawings
MCEE-138-00.67
E/D Unit 1A.B. Vent Sys Return Isol Vlv 1RN299A
Drawings
MCFD-1574-
2.00
Flow Diagram of Nuclear Service Water System - RN
Drawings
MCM 1205.10-66
Vacuum Relief Valve (1RN280, 1RN90, 1RN191, 1RN92,
1RN193)
Drawings
MCM 1399.08-
0086 005
Safeguards Test Cabinet
Drawings
MCM 1399.08-
0092.027
SSPS Output Relay
00Q
Miscellaneous
Fourth Ten-Year Inservice Testing Interval - McGuire
Nuclear Station
Miscellaneous
2006100
Preventive Maintenance Identification - 1RN90, 1RN92,
1RN191, 1RN193
Miscellaneous
CSD-EG-MNS-
20.001
Fifth Ten-Year Inservice Testing Interval - McGuire Nuclear
Station
Miscellaneous
MCTC-1574-
RN.V028-01
Valve Design Criteria/Operability Requirements and
Compensatory Measures - 1RN90, 1RN92, 1RN191,
1RN193
Procedures
IP/0/A/2001/004A
5HK Air Circuit Breaker Inspection and Maintenance
017
Procedures
MP/0/A/7400/009
MP/0/A/7400/009 - Nordberg Diesel Engine Cylinder Head
Removal and Installation
043
Procedures
MP/0/A/7600/140
Vacuum Relief Valve Testing
Work Orders
2062965, 02165651, 02165652, 20631964, 20631965,
20677184, 20691468, 20648769, 20671106, 20671682,
20676815, 20689552
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Corrective Action
Documents
Nuclear Condition
Report(s)
2481429
Work Orders
20617519, 20663393, 20715473, 20657294, 20663398
Corrective Action
Documents
Nuclear Condition
Report(s)
2533290, 02530005, 02533047, 02533842, 02533859,
2537288, 02538965, 02534723