IR 05000298/2025002
| ML25204A090 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 08/11/2025 |
| From: | Douglas Dodson NRC/RGN-IV/DORS/PBC |
| To: | Dia K Nebraska Public Power District (NPPD) |
| References | |
| IR 2025002 | |
| Download: ML25204A090 (1) | |
Text
August 11, 2025
SUBJECT:
COOPER NUCLEAR STATION - INTEGRATED INSPECTION REPORT 05000298/2025002
Dear Khalil Dia:
On June 30, 2025, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Cooper Nuclear Station. On July 7, 2025, the NRC inspectors discussed the results of this inspection with John Dent Jr., Executive Vice President and Chief Nuclear Officer, and other members of your staff. The results of this inspection are documented in the enclosed report.
Two findings of very low safety significance (Green) are documented in this report. Two of these findings involved violations of NRC requirements. We are treating these violations as non-cited violations (NCVs) consistent with Section 2.3.2 of the Enforcement Policy.
If you contest the violations or the significance or severity of the violations 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 Cooper Nuclear Station.
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 Cooper Nuclear Station. 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, Douglas E. Dodson II, Chief Reactor Projects Branch C Division of Operating Reactor Safety Docket No. 05000298 License No. DPR-46
Enclosure:
As stated
Inspection Report
Docket Number:
05000298
License Number:
Report Number:
Enterprise Identifier:
I-2025-002-0004
Licensee:
Nebraska Public Power District
Facility:
Cooper Nuclear Station
Location:
Brownville, NE
Inspection Dates:
April 1, 2025, to June 30, 2025
Inspectors:
G. Birkemeier, Resident Inspector
S. Hedger, Senior Emergency Preparedness Inspector
G. Kolcum, Senior Resident Inspector
L. Moore, Emergency Preparedness Inspector
Approved By:
Douglas E. Dodson II, Chief
Reactor Projects Branch C
Division of Operating Reactor Safety
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at Cooper 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 Perform Evaluations of the Licensee Interface with Offsite Organizations Cornerstone Significance Cross-Cutting Aspect Report Section Emergency Preparedness Green NCV 05000298/2025002-01 Open/Closed
[H.1] -
Resources 71114.05 The inspectors identified a Green finding and associated non-cited violation of 10 CFR 50.54(t)(2), with two examples, for the licensees failure to include an evaluation of the adequacy of the interfaces with State and local governments in a review of emergency preparedness program elements in audit reports Nuclear Independent Oversight (NIOS)
Audit 23-06 and 24-05. Specifically, the licensee failed to include an evaluation of this interface when audit personnel: (1) did not furnish offsite officials with an opportunity to provide their view of the adequacy of the interface to the audit team; and (2) did not conduct an evaluation of feedback that was provided by the State of Kansas.
Failure to Correct Conditions Adverse to Quality for Jacket Water Leakage from an Emergency Diesel Generator Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000298/2025002-02 Open/Closed
[H.12] - Avoid Complacency 71152A The inspectors reviewed a self-revealed Green finding and associated non-cited violation of 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, which requires, in part, that measures shall be established to assure that conditions adverse to quality, such as failures, malfunctions, deficiencies, deviations, defective material and equipment, and nonconformances are promptly identified and corrected. Specifically, since 2011, the licensee failed to correct conditions adverse to quality associated with jacket water leakage on the 1R cylinder for emergency diesel generator 2, which resulted in emergency diesel generator 2 becoming inoperable on January 22, 2025.
Additional Tracking Items
None.
PLANT STATUS
Cooper Nuclear Station began the inspection period at rated thermal power. On April 5, 2025, power was lowered to approximately 65 percent for a planned feedwater flow instrument calibration. The unit returned to rated thermal power on April 5, 2025. On May 17, 2025, power was lowered to approximately 65 percent for planned maintenance on the main condenser waterbox and rod sequence exchange. The unit returned to rated thermal power on May 19, 2025. The unit remained at rated thermal power 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
Seasonal Extreme Weather Sample (IP Section 03.01) (1 Sample)
- (1) The inspectors evaluated readiness for seasonal extreme weather conditions on June 10, 2025, prior to the onset of seasonal high temperatures for the following systems:
- supplemental diesel generator
- service water pumps
71111.04 - Equipment Alignment
Partial Walkdown Sample (IP Section 03.01) (6 Samples)
The inspectors evaluated system configurations during partial walkdowns of the following systems/trains:
(1)
(2)emergency diesel generator 1 following emergency diesel generator 1 jacket water pump failure and restoration on April 17, 2025 emergency diesel generator 2 for extent of condition following emergency diesel generator 2 jacket water pump failure and restoration on April 17, 2025 (3)condensate filter demineralizer 'D' due to reactor coolant system resin intrusion on April 22, 2025 (4)high-pressure coolant injection on May 1, 2025 (5)planned emergency station service transformer maintenance on May 12, 2025 (6)standby gas treatment train A on June 12, 2025
71111.05 - Fire Protection
Fire Area Walkdown and Inspection Sample (IP Section 03.01) (8 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)reactor northeast quad on April 18, 2025 (2)diesel generator building emergency diesel generator 1 on April 21, 2025 (3)diesel generator building emergency diesel generator 2 on April 21, 2025 (4)control room and computer room on April 22, 2025 (5)intake structure on May 14, 2025 (6)control reactor protection system room 1B on May 14, 2025 (7)control corridor battery/switchgear/reactor protection system room 1A on May 14, 2025 (8)transformer yard on May 15, 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 restoration of the startup system safety transformer and associated loads following emergent removal from service on May 3, 2025.
Licensed Operator Requalification Training/Examinations (IP Section 03.02) (1 Sample)
- (1) The inspectors observed and evaluated licensed operator simulator training on May 29, 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)emergency station service transformer maintenance window on May 12, 2025 (2)emergency diesel generator 2 jacket water leakage from 1R head on June 11, 2025 (3)standby gas treatment train A on June 12, 2025 (4)emergency diesel generator 2 failure to start on June 30, 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)emergency diesel generator 2 trip solenoid valve procurement and burn-in testing on June 30, 2025
71111.13 - Maintenance Risk Assessments and Emergent Work Control
Risk Assessment and Management Sample (IP Section 03.01) (4 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)planned maintenance window on reactor equipment cooling on April 7, 2025 (2)planned Yellow risk window for division 1 residual heat removal maintenance on May 8, 2025 (3)planned maintenance on emergency station service transformer on May 12, 2025 (4)planned maintenance window on standby gas treatment train A on June 9, 2025
71111.15 - Operability Determinations and Functionality Assessments
Operability Determination or Functionality Assessment (IP Section 03.01) (8 Samples)
The inspectors evaluated the licensee's justifications and actions associated with the following operability determinations and functionality assessments:
(1)emergency diesel generator 2 failure to start during monthly surveillance on April 3, 2025 (2)reactor equipment cooling SW-V-126 valve leakage on April 8, 2025 (3)reactor equipment cooling service water pipe weld leak repair on April 8, 2025 (4)service water booster pump gland water inlet to pump stuffing box pipe supports on April 28, 2025 (5)reactor equipment cooling tank level on May 12, 2025 (6)emergency station service transformer corona discharge on May 14, 2025 (7)emergency diesel generator 2 jacket water leakage from 1R head on June 11, 2025 (8)standby gas treatment train A on June 12, 2025
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)emergency diesel generator 1 jacket water pump impeller modification on May 14, 2025 (2)emergency station service transformer replacement on May 15, 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) (14 Samples)
(1)emergency diesel generator 2 following failure to start on April 3, 2025 (2)feedwater flow instrumentation software upgrade on April 5, 2025 (3)reactor equipment cooling 'B' train maintenance on April 6, 2025 (4)reactor recirc motor generator 'A' scoop tube lockout on April 6, 2025 (5)condensate filter demineralizer 'G' maintenance on April 7, 2025 (6)emergency diesel generator 1 maintenance and 30-day surveillance following jacket water pump impeller modification on April 12, 2025 (7)residual heat removal service water booster pump 'C' maintenance on April 13, 2025 (8)residual heat removal 'A' heat exchanger maintenance on April 14, 2025 (9)control rod accumulator 38-15 maintenance on May 2, 2025 (10)residual heat removal 'A' maintenance on May 8, 2024 (11)residual heat removal power-operated valve operability test on May 8, 2025 (12)place bus G on emergency station service transformer and return to normal on May 16, 2025 (13)place bus F on emergency station service transformer and return to normal on May 16, 2025 (14)standby gas treatment train A maintenance on June 12, 2024
Surveillance Testing (IP Section 03.01) (4 Samples)
(1)rated conditions reactivity on April 24, 2025 (2)technical specification verification of secondary containment access doors and hatches on May 7, 2025 (3)division 1 air flow test of fan coil unit FC-R-1J on May 7, 2025 (4)division 1 day venting of emergency core cooling system and reactor core isolation cooling injection/spray subsystem piping on May 8, 2025
Inservice Testing (IST) (IP Section 03.01) (1 Sample)
(1)emergency diesel generator 2 monthly testing on April 21, 2025
Diverse and Flexible Coping Strategies (FLEX) Testing (IP Section 03.02) (1 Sample)
- (1) FLEX diesel generator run on May 22, 2025
71114.02 - Alert and Notification System Testing
Inspection Review (IP Section 02.01-02.04) (1 Sample)
- (1) The inspectors evaluated the maintenance and testing of the alert and notification system between May 10, 2023, and May 5, 2025. In addition, the inspectors observed siren testing activities on May 13, 2025.
71114.03 - Emergency Response Organization Staffing and Augmentation System
Inspection Review (IP Section 02.01-02.02) (1 Sample)
- (1) The inspectors evaluated the readiness of the Emergency Preparedness Organization between May 10, 2023, and May 5, 2025. Inspectors also evaluated the licensee's ability to staff the emergency response facilities in accordance with emergency plan commitments.
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.
- Emergency Plan Implementing Procedure 5.7.20, Protective Action Recommendations, Revision 34
- Emergency Plan Implementing Procedure 5.7.24, Medical Emergency, Revision 43
- Cooper Nuclear Station Emergency Plan, Appendix D - Letters of Agreement, Revision 82 In addition, the inspectors evaluated the 10 CFR 50.54(q) emergency plan change process and practices between May 10, 2023, and May 5, 2025. The evaluations reviewed screenings and evaluations documenting implementation of the process. The reviews of the change process documentation or the emergency plan changes do not constitute NRC approval.
71114.05 - Maintenance of Emergency Preparedness
Inspection Review (IP Section 02.01 - 02.11) (1 Sample)
- (1) The inspectors evaluated the maintenance of the emergency preparedness program between May 10, 2023, and May 5, 2025. The evaluation reviewed evidence of completing various emergency plan commitments, the conduct of drills and exercises, licensee audits and assessments, and the maintenance of equipment important to emergency preparedness.
71114.06 - Drill Evaluation
Additional Drill and/or Training Evolution (1 Sample)
The inspectors evaluated:
- (1) quarterly emergency response organization drill on June 17,
OTHER ACTIVITIES - BASELINE
===71151 - Performance Indicator Verification The inspectors verified licensee performance indicator submittals listed below:
MS06: Emergency AC Power Systems (IP Section 02.05)===
- (1) January 1 through December 31, 2024
MS07: High-Pressure Injection Systems (IP Section 02.06) (1 Sample)
- (1) January 1 through December 31, 2024
MS08: Heat Removal Systems (IP Section 02.07) (1 Sample)
- (1) January 1 through December 31, 2024
MS09: Residual Heat Removal Systems (IP Section 02.08) (1 Sample)
- (1) January 1 through December 31, 2024
MS10: Cooling Water Support Systems (IP Section 02.09) (1 Sample)
- (1) January 1 through December 31, 2024
EP01: Drill/Exercise Performance (DEP) Sample (IP Section 02.12) (1 Sample)
- (1) April 1, 2024, through March 31, 2025 EP02: Emergency Response Organization (ERO) Drill Participation (IP Section 02.13) (1 Sample)
- (1) April 1, 2024, through March 31, 2025 EP04: Emergency Response Facility and Equipment Readiness (ERFER) (IP Section 02.14) (1 Sample)
- (1) January 1, 2025, through March 31, 2025
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)emergency diesel generator 2 jacket water leakage from 1R head on June 11, 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 fire protection transient combustibles that might be indicative of a more significant safety issue.
INSPECTION RESULTS
Failure to Perform Evaluations of the Licensee Interface with Offsite Organizations Cornerstone Significance Cross-Cutting Aspect Report Section Emergency Preparedness Green NCV 05000298/2025002-01 Open/Closed
[H.1] -
Resources 71114.05 The inspectors identified a Green finding and associated non-cited violation of 10 CFR 50.54(t)(2), with two examples, for the licensees failure to include an evaluation of the adequacy of the interfaces with State and local governments in a review of emergency preparedness program elements in audit reports Nuclear Independent Oversight (NIOS)
Audit 23-06 and 24-05. Specifically, the licensee failed to include an evaluation of this interface when audit personnel:
- (1) did not furnish offsite officials with an opportunity to provide their view of the adequacy of the interface to the audit team; and
- (2) did not conduct an evaluation of feedback that was provided by the State of Kansas.
Description:
The inspectors reviewed NIOS Audit 23-06 and NIOS Audit 24-5, dated September 27, 2023, and September 26, 2024, respectively. Section III: ERO Staffing - State and Local Support describes the audit teams evaluation of the Offsite Agency Interface. The assessments consisted of the following:
- Review of supporting plans and contracts/letters of agreement (LOAs)
- Transmittals of surveys to State and local organizations to ascertain if interfaces with offsite agencies were being effectively maintained
- Review of whether emergency preparedness (EP) procedures and documents were maintained current at offsite agencies Example 1:
The inspectors determined that in the NIOS Audit 23-06, the State of Kansas and Nemaha County were not contacted to provide feedback on the interface with Cooper Nuclear Station.
Specifically, the NIOS Audit 23-06 report outlined the State and local agencies that were supposedly contacted during the audit. However, the licensee was unable to provide evidence that surveys titled, EP Off-Site Interface Survey, were sent out to the State of Kansas and Nemaha County, which were participating organizations outlined in the stations Emergency Plan. Therefore, from September 27, 2023, to September 26, 2024, the date of the next NIOS Audit, the licensee failed to furnish the opportunity for the State of Kansas and Nemaha County to provide feedback on the State and local interface. Review of audit implementing procedure 0-QA-5 showed that the Audit Matrix and Schedule did not contain a list of required State and local governments, from the Emergency Plan, to contact for providing feedback.
Example 2:
The inspectors ascertained that the NIOS Audit 24-5 report did not include an assessment of a State organization interface that was supported by related documentation. Specifically, the report indicated that the interfaces with the State and local agencies were determined to be adequate in total. However, when reviewing copies of the EP Off-Site Interface Surveys, provided back to the licensee with feedback, the inspectors found that the survey received from the State of Nebraska expressed potential issues with the interface with Cooper Nuclear Stations emergency preparedness program staff. The licensee did not acknowledge this feedback received within the report. In addition, the licensee could not provide evidence that this feedback had been assessed to determine whether there were issues with the State and local interface or corrective actions that needed to be addressed. Therefore, from September 27, 2024, to May 29, 2025, the licensee failed to incorporate feedback from the State of Nebraska in determining the adequacy of the interfaces with the State and local agencies. Review of audit procedure 0-QA-5, NIOS Audit Requirements, Frequencies, and Scheduling, did not include guidance on evaluating feedback received from State and local governments.
The inspectors concluded that Cooper Nuclear Station did not conduct an adequate evaluation of the interface between the station emergency preparedness organization and offsite officials, because the evaluation did not provide offsite officials at the State of Kansas and Nemaha County with the opportunity to provide information to the audit team during the 2023 Quality Audit. Additionally, the inspectors concluded that Cooper Nuclear Station did not conduct an adequate evaluation of the interface between the station EP organization and offsite officials because the audit did not provide evidence that feedback from the State of Nebraska was assessed to determine whether the interface was adequate.
Corrective Actions: The licensee entered these issues into the corrective action program.
Corrective Action References: Condition Reports CR-CNS-2025-02361 and CR-CNS-2025-02365
Performance Assessment:
Performance Deficiency: The failure to perform an evaluation for adequacy of the interface with state and local governments in accordance with 10 CFR 50.54(t)(2) was a performance deficiency because the licensee had the ability to foresee and correct this failure.
Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Offsite Emergency Preparedness attribute of the Emergency Preparedness cornerstone and adversely affected the cornerstone objective to ensure that the licensee is capable of implementing adequate measures to protect the health and safety of the public in the event of a radiological emergency. Specifically, the ability to implement adequate measures to protect the health and safety of the public could be affected if communication and coordination problems between the licensee and offsite agencies are not detected and corrected.
Significance: The inspectors assessed the significance of the finding using IMC 0609, Appendix B, Emergency Preparedness SDP. Using Manual Chapter 0609, Significance Determination Process, Attachment 4, Tables 1, 2, and 3 worksheets (effective date October 25, 2024) and the corresponding Appendix B, Emergency Preparedness Significance Determination Process, Attachment 2 (issue date September 22, 2015), the performance deficiency was determined to have very low safety significance (Green) because it was a failure to comply with NRC requirements, was not a loss of planning standard function, and was not a degraded risk significant planning standard function.
Cross-Cutting Aspect: H.1 - Resources: Leaders ensure that personnel, equipment, procedures, and other resources are available and adequate to support nuclear safety. The finding had a cross-cutting aspect in the area of resources associated with human performance because the licensees procedures failed to provide sufficiently detailed instructions on EP program audits. Specifically, Cooper Nuclear Station NIOS Administrative Procedure 0-QA-05 did not provide adequate instruction on how to conduct a review of the State and local government interface.
Enforcement:
Violation: Title 10 CFR 50.54(t)(2) requires, in part, that the review of [emergency preparedness] program elements must include an evaluation for adequacy of the interfaces with State and local governments. The results of the review, along with recommendations for improvements, must be documented [and] reported to the licensees corporate and plant management.
Contrary to the above, the licensees review of [emergency preparedness] program elements failed to include an evaluation for adequacy of the interfaces with State and local governments as evidenced by the following examples:
Example 1 Specifically, from September 27, 2023, to September 26, 2024, the review conducted under audit report NIOS 23-06 did not provide the State of Kansas or Nemaha County the opportunity to provide information about the adequacy of their interface with the licensee.
For Example 2:
Specifically, from September 26, 2024, to May 29, 2025, the review conducted under audit report NIOS 24-05 did not provide an evaluation for adequacy of the interface with the State of Nebraska.
Enforcement Action: This violation is being treated as a non-cited violation, consistent with Section 2.3.2 of the Enforcement Policy.
Failure to Correct Conditions Adverse to Quality for Jacket Water Leakage from an Emergency Diesel Generator Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000298/2025002-02 Open/Closed
[H.12] - Avoid Complacency 71152A The inspectors reviewed a self-revealed Green finding and associated non-cited violation of 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, which requires, in part, that measures shall be established to assure that conditions adverse to quality, such as failures, malfunctions, deficiencies, deviations, defective material and equipment, and nonconformances are promptly identified and corrected. Specifically, since 2011, the licensee failed to correct conditions adverse to quality associated with jacket water leakage on the 1R cylinder for emergency diesel generator 2, which resulted in emergency diesel generator 2 becoming inoperable on January 22, 2025.
Description:
Cooper Nuclear Station relies upon two Cooper Bessemer KSV-16 emergency diesel generators for emergency alternating current power. The emergency diesel generator cylinders are cooled by jacket water. Jacket water moves between the head-to-cylinder interface via eight jumper tubes in the liner. Each jumper tube uses two O-rings in series to seal with the head water passages.
The inspectors noted that licensee procedure 7.2.53.3, "Diesel Generator Maintenance,"
Revision 39, requires a 1/4 inch bead of sealant around the base of all head studs (this procedure requirement has existed since 2013), and the 1R cylinder had not received this sealant since the last maintenance performed on the cylinder in 2007. Additionally, the licensee has documented leakage on the 1R cylinder for emergency diesel generator 2 in four condition reports since 2011.
During the emergency diesel generator 2 monthly surveillance run on January 22, 2025, the 1R cylinder head developed a leak that required maintenance. Emergency diesel generator 2 was declared inoperable. The licensee determined that intermittent leakage was between and under the O-rings from jacket water debris buildup, corrosion products, and additive precipitate.
The licensee conducted an apparent cause evaluation in Condition Report CR-CNS-2025-00399 and determined that the apparent cause of the condition was a failed O-ring seal.
Additionally, the licensee determined that the inoperability in 2021 was a missed opportunity to address the cause. Finally, the licensee identified that an extent of condition existed and determined based on a similar intermittent leakage pattern that emergency diesel generator 1 cylinder heads 7R and 8R and emergency diesel generator 2 cylinder heads 5L, 5R, 6R, 7R, and 8R require planned maintenance.
The inspectors noted the licensee previously evaluated a similar leakage failure in April 2021 on the 3R cylinder for emergency diesel generator 2 in Condition Report CR-CNS-2021-02100 and concluded that surface corrosion and debris in O-ring sealing surfaces was due to intermittent leakage past the O-rings from 2005 to 2021.The inspectors also noted that the licensee had observed leakage on the 3R cylinder for emergency diesel generator 2 in three condition reports since 2005. During the monthly surveillance run on April 26, 2021, emergency diesel generator 2 cylinder head 3R developed a leak that required maintenance, and emergency diesel generator 2 was declared inoperable. The 3R cylinder had not received the sealant required by procedure 7.2.53.3 since the last maintenance performed on the cylinder in 1995 was prior to implementation of the requirement. The inspectors noted that the licensee also determined that the sealant was required by procedure but did not directly lead to the 3R cylinder leakage, and the inspectors concluded this was a missed opportunity for the licensee to ensure appropriate corrective actions.
Corrective Actions: The licensee placed the issue into the corrective action program.
Corrective Action References: This issue was entered into the licensees corrective action program as Condition Report CR-CNS-2025-00399.
Performance Assessment:
Performance Deficiency: The licensee failed to adequately identify, evaluate, and correct conditions adverse to quality in accordance with 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, associated with 1R cylinder for emergency diesel generator 2.
Specifically, since 2011, the licensee failed to correct conditions adverse to quality associated with jacket water leakage on the 1R cylinder for emergency diesel generator 2, which was identified four different times and resulted in emergency diesel generator 2 inoperability on January 22, 2025.
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, failure to correct an adverse condition associated with equipment performance for debris buildup between and under O-rings on the 1R cylinder head to liner interface, made the emergency diesel generator 2 inoperable on January 22, 2025.
Significance: The inspectors assessed the significance of the finding using Inspection Manual Chapter 0609 Appendix A, "The Significance Determination Process for Findings At-Power."
The inspectors screened the finding using Exhibit 2, "Mitigating Systems Screening Questions." The inspectors determined that the finding had very low safety significance (Green) because, the finding is not a deficiency affecting the design or qualification of a mitigating SSC; the degraded condition does not represent a loss of the probabilistic risk assessment (PRA) function of a single train technical specification (TS) system for greater than its TS allowed outage time; the degraded condition does not represent a loss of the PRA function of one train of a multi-train TS system for greater than its TS allowed outage time; the degraded condition does not represent a loss of the PRA function of two separate TS systems for greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />; the degraded condition does not represent a loss of a PRA system and/or function as defined in the PRIB or the licensee's PRA for greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />; and the degraded condition does not represent a loss of the PRA function of one or more non-TS trains of equipment designated as risk-significant in accordance with the licensee's maintenance rule program for greater than 3 days.
Cross-Cutting Aspect: H.12 - Avoid Complacency: Individuals recognize and plan for the possibility of mistakes, latent issues, and inherent risk, even while expecting successful outcomes. Individuals implement appropriate error reduction tools. Specifically, the organization did not address the latent leakage conditions as they were discovered, and the licensee did not consider the extent of the conditions and their causes following 2021 operability impacts, which resulted in the performance deficiency and continued acceptance of intermittent leakage between and under the O-rings from jacket water debris buildup, corrosion products, and additive precipitate.
Enforcement:
Violation: Title 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, requires, in part, that measures shall be established to assure that conditions adverse to quality, such as failures, malfunctions, deficiencies, deviations, defective material and equipment, and nonconformance's are promptly identified and corrected.
Contrary to the above, since 2011, measures were not established to assure that conditions adverse to quality, such as failures, malfunctions, deficiencies, deviations, defective material and equipment, and nonconformances were promptly identified and corrected. Specifically, since 2011, the licensee failed to correct jacket water leakage on the 1R cylinder for the emergency diesel generator 2, a condition adverse to quality, which caused emergency diesel generator 2 inoperability on January 22, 2025.
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 May 29, 2025, the inspectors presented the EP program inspection results to Khalil Dia, Site Vice President, and other members of the licensee staff.
- On July 7, 2025, the inspectors presented the integrated inspection results to John Dent Jr., Executive Vice President and Chief Nuclear Officer, and other members of the licensee staff.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
0-CNS-FAP-WM-
016
Seasonal Reliability
Procedures
2.2.99
Supplemental Diesel Generator System
Corrective Action
Documents
CR-CNS-
25-01449, 2025-01518, 2025-02020, 2025-02295,
25-02303, 2025-02761
0-CNS-06
Site Risk Significance Standards
0-CNS-WM-104
On-line Risk Assessment
2.0.3
Conduct of Operations
108
2.2.33A
High-Pressure Coolant Injection Operations
Procedures
2.2.5
Condensate Filter Demineralizer System
Work Orders
CNS-FP-211
CNS-FP-215
CNS-FP-218
CNS-FP-219
CNS-FP-224
CNS-FP-225
CNS-FP-226
CNS-FP-227
CNS-FP-228
CNS-FP-229
CNS-FP-230
CNS-FP-236
CNS-FP-237
CNS-FP-247
CNS-FP-249
CNS-FP-256
CNS-FP-266
CNS-FP-268
CNS-FP-344
Fire Plans
CNS-FP-383
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
CNS-FP-384
0-Barrier-Control
Control Building
0-Barrier-Misc
Miscellaneous Buildings
Procedures
0-Barrier-Reactor
Reactor Building
Corrective Action
Documents
CR-CNS-
25-02182
2.0.3
Conduct of Operations
109
2.2.18.1
4160 V Auxiliary Power Distribution System
2.4PC
Primary Containment Control
5.3EMPWR
Emergency Power During Modes 1, 2, or 3
Procedures
5.8
Emergency Operating Procedures (EOPs)
Corrective Action
Documents
CR-CNS-
2011-010473, 2025-00399, 2025-01449, 2025-02295,
25-02303, 2025-02761
Procedures
6.2DG.101
Diesel Generator 31 Day Operability Test (IST)(Div 2)
Work Orders
WO 210671, 5406490, 5406491, 5406492, 5406493,
5410600, 5410601, 5444268, 5488476, 5502406,
5588872
Corrective Action
Documents
CR-CNS-
25-01756, 2025-01758, 2025-02295, 2025-02303
Miscellaneous
RHRA-1-RHRA,
Week 2518
Protected Equipment Tagout
0-CNS-06
Site Risk Significance Standards
0-CNS-WM-104
On-line Risk Assessment
Procedures
0-PROTECT-EQP
Protected Equipment Program
Calculations
NEDC 91-223
Gland Water Piping to the SWBP's Piping Analysis
4C1
Corrective Action
Documents
CR-CNS-
24-03366, 2025-00399, 2025-01449, 2025-02284,
25-02295, 2025-02303, 2025-02761
Burns & Roe 2006,
Sheet 4
Cooper Nuclear Station Flow Diagram Control Building
Service Water System
Drawings
Energy Steel
Drawing
1" 150# SW Valve No. 70-18-2 HO
Work Orders
WO 5502406, 5537914, 5591232
Corrective Action
CR-CNS-
2015-05924, 2025-01826
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Documents
Engineering
Changes
6039780
Emergency Station Service Transformer Replacement
08/23/2019
Corrective Action
Documents
CR-CNS-
25-01791, 2025-01820, 2025-02761
CM 5496273
PM 5500948
Reactivity Anomalies
ECCS - Operating
Reactor Pressure Vessel Water Inventory Control
RCIC System
Miscellaneous
0.31MOV
Motor Operated Valves
2.2.69.3
RHR Suppression Pool Cooling and Containment Spray
6.1HV.603
Air Flow Test of Fan Coil Unit FC-R-1J (Div 1)
6.1MISC.503
Day Venting of ECCS and RCIC Injection/Spray
Subsystem Piping (Div 1)
6.1RHR.101
RHR Test Mode Surveillance Operation (IST) (Div 1)
6.1RHR.201
RHR Power Operated Valve Operability Test (IST)(Div 1)
6.1SGT.301
SGT Operability Test/Off Gas Flow Monitor Channel
Functional Test IST (Div 1)
6.1SGT.501
SGT A Carbon Sample, Carbon Adsorber and HEPA
Filter In-Place Leak Test, And Components Leak Test
(Div 1)
6.2DG.101
Diesel Generator 31 Day Operability Test (IST)(Div 2)
6.EE.610
Off-Site, AC Power Alignment
6.REAC.602
Reactivity Anomaly Follow
Procedures
6.SC.701
Technical Specification Verification of Secondary
Containment Access Doors and Hatches
Work Orders
WO 5449963, 5488476, 5490144, 5494327, 5496723,
5497596, 5497887, 5500230, 5500965, 5502275,
5502406, 5502734, 5502735, 5502745, 5536927,
5541162, 5551274, 5556672, 556671-5-0180, 556671-5-
20, 5570318, 5577662, 5588872, 5591233-1, 5591358,
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
5591806
Corrective Action
Documents
Resulting from
Inspection
CR-CNS-
25-02335, 2025-02358
A Prompt Alert and Notification System Design Report for
the Cooper Nuclear Station
24 ANS Annual Full-Functional Test Records
09/18/2024
December 2024 ANS Semi-Monthly Testing Records
2/27/2024
Miscellaneous
EPDG #2,
C-4,
Revision 10
Semi-Annual Alert Notification System Sign and
Evacuation Map Verification, December 3, 2024
2/03/2024
EPDG #2
C-1
Semi-Monthly Alert and Notification System Siren Testing
EPDG #2
C-6
Annual Fixed Siren Maintenance
Procedures
EPDG #2,
C-5
Annual Full-Cycle Sounding of Alert and Notification
System Sirens
Quarterly ERO Call-In Test, September 11, 2023
09/25/2023
Quarterly ERO Call-In Test, December 18, 2023
2/20/2023
Quarterly ERO Call-In Test, March 18, 2024
03/20/2024
Quarterly ERO Call-In Test, June 19, 2024
06/24/2024
Quarterly ERO Call-In Test, August 11, 2024
09/03/2024
Quarterly ERO Call-In Test, December 17, 2024
2/19/2024
Miscellaneous
Quarterly ERO Call-In Test, June 19, 2023
06/21/2023
Procedures
EPDG #2,
E-3
Quarterly ERO Call-In Test
Miscellaneous
50.54(q)
Screen/Evaluations
23-23 ANSDR, 2025-26 (EC 23-004), 2024-67 (TCC
5436164), 2024-64 (NBI-TR-89, Reactor Vessel Metal
Flange Temp Recorder Replacement), 2024-63 (Kaman
Watchdog Timer Removal), 2024-62 (Temp. Power for
ANS Batteries Radio Building), 2023-37 (Site Work
Practices), 2023-36 (Appendix D - Letters of Agreement),
23-29 (ERO-OSC RP Pool Personnel), 2023-24
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
(Medical Emergency), 2023-22 (Terminate Midwest
Medical LOA/Replace with Peru Rescue, 2023-20
(SEMA/Atchison County SNOT line changes), 2023-16
(SAG Refresher), 2023-14 (Protective Action
Recommendations), 2023-27 (Emergency Classification
Process), 2023-40 (State of Kansas LOA)
Procedures
50.54(q) Procedure
Administrative Procedure 0.29.4, Other Regulatory
Reviews
09/07/2022
Corrective Action
Documents
CR-CNS-
2018-04709, 2023-02329, 2023-02352, 2023-03823,
24-00053, 2024-00332, 2024-00725, 2024-00812,
24-00837, 2024-00863, 2024-01553, 2024-01839,
24-01950, 2024-01992-CA-001, 2024-02000, 2024-
2025, 2024-02133, 2024-02153, 2024-02338, 2024-
2364, 2024-02530, 2024-02727, 2024-02805, 2024-
03055
Corrective Action
Documents
Resulting from
Inspection
CR-CNS-
25-02361, 2025-02365, 2025-02366
8-Year Cycle, Exercises and Drills
Watchbill Scenario 2023-04 Team 4
February 20, 2024, Team 2 & D Drill
NIOS Audit 24-05, "Emergency Preparedness (EP)
Program"
NIOS Audit 23-06, "Emergency Preparedness (EP)
Program"
KLD TR-24-1432
24 Population Update Analysis
08/07/2024
Miscellaneous
Letters of
Agreement
Nebraska State Patrol (13 November 2024), Nebraska
City Volunteer Fire Department (12 October 2021),
Nemaha County Hospital (31 May 2011), NEMA,
Nebraska DHHS, NPPD (21 Dec 2018)
0-CNS-LI-102
Corrective Action Process
08/07/2024
0-CNS-EP-202
Equipment Important to Emergency Preparedness
Procedures
0-CNS-WMS-100
Work Order Generation, Screening, and Classification
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
EPDG #2
F-11
Work Orders
Work Order
Numbers
262225, 5539277, 5551208, 5551209, 5535923,
5516499, 5564215, 5546093
0-EP-04
Emergency Preparedness Simulator Scenario-based
Testing
2.4RXLVL
RPV Water Level Control Trouble
Procedures
5.3EMPWR
Emergency Power during Modes 1, 2, or 3
September 2024, Alert and Notification System PI
Documentation and Data Review Form
December 2024, Alert and Notification System PI
Documentation and Data Review Form
April 2024, Drill and Exercise Performance (DEP), PI
Documentation and Data Review Form
September 2024, Drill and Exercise Performance (DEP),
PI Documentation and Data Review Form
November 2024, Drill and Exercise Performance (DEP),
PI Documentation and Data Review Form
December 2024, Drill and Exercise Performance (DEP),
PI Documentation and Data Review Form
February 2025, Drill and Exercise Performance (DEP), PI
Documentation and Data Review Form
June 2024, ERO Drill Participation, PI Documentation and
Data Review Form
September 2024, ERO Drill Participation, PI
Documentation and Data Review Form
December 2024, ERO Drill Participation, PI
Documentation and Data Review Form
Miscellaneous
March 2024, ERO Drill Participation, PI Documentation
and Data Review Form
71151
Procedures
0-CNS-LI-114
Regulatory Performance Indicator Process
Corrective Action
Documents
CR-CNS-
25-00399
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Corrective Action
Documents
CR-CNS-
2011-01452, 2018-02460, 2018-06108, 2019-00673,
2019-01490, 2020-02467, 2020-04510, 2020-04590,
22-04313, 2022-05335, 2024-03799, 2024-03819,
24-03856, 2024-04115, 2024-04371,