IR 05000313/2025001
| ML25122A159 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 05/07/2025 |
| From: | John Dixon NRC/RGN-IV/DRP/RPB-D |
| To: | Pehrson D Entergy Operations |
| References | |
| EAF-RIV-2025-0096 IR 2025001 | |
| Download: ML25122A159 (1) | |
Text
May 07, 2025
SUBJECT:
ARKANSAS NUCLEAR ONE - INTEGRATED INSPECTION REPORT 05000313/2025001 AND 05000368/2025001 AND INDEPENDENT SPENT FUEL STORAGE INSTALLATION REPORT 07200013/2025001 AND EXERCISE OF ENFORCEMENT DISCRETION
Dear Doug Pehrson:
On March 31, 2025, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Arkansas Nuclear One. On April 10, 2025, the NRC inspectors discussed the results of this inspection with Mark Skartvedt, General Manager Plant Operations, and other members of your staff. The results of this inspection are documented in the enclosed report.
Four findings of very low safety significance (Green) are documented in this report. Four 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.
The NRC identified a violation of 10 CFR 72.48 and 72.212 associated with Arkansas Nuclear Ones use of the Holtec HI-STORM FW spent fuel storage cask. Enforcement discretion is being granted as authorized by Enforcement Guidance Memorandum (EGM) 25-001, Enforcement Guidance for Dispositioning Noncompliances Related to a General Licensees use of Certain Non-Qualified Spent Fuel Casks (see Agencywide Documents Access and Management System [ADAMS] Accession No. ML24303A436). The NRC will take additional enforcement action if compliance is not restored following the expiration date of this EGM.
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 Arkansas Nuclear One. 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 Arkansas Nuclear One.
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, John L. Dixon, Jr., Chief Reactor Projects Branch D Division of Operating Reactor Safety Docket Nos. 05000313; 05000368; 07200013 License Nos. DPR-51 and NPF-6
Enclosure:
As stated
Inspection Report
Docket Numbers:
05000313, 05000368, and 07200013
License Numbers:
Report Numbers:
05000313/2025001, 05000368/2025001, and 07200013/2025001
Enterprise Identifier:
I-2025-001-0002 and I-2025-001-0110
Licensee:
Entergy Operations, Inc.
Facility:
Arkansas Nuclear One
Location:
Russellville, AR
Inspection Dates:
January 1, 2025, to March 31, 2025
Inspectors:
L. Brookhart, Senior Spent Fuel Storage Inspector
T. DeBey, Resident Inspector
J. Freeman, Spent Fuel Storage Inspector
M. Mondou, Resident Inspector
B. Tindell, Senior Resident Inspector
E. Tinger, Resident Inspector
Approved By:
John L. Dixon, Jr., Chief
Reactor Projects Branch D
Division of Operating Reactor Safety
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at Arkansas Nuclear One, 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 Maintain Acoustic Ceiling Tiles Results in Non-Functional Fire Suppression Sprinklers Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000368/2025001-01 Open/Closed
[H.12] - Avoid Complacency 71111.05 The inspectors identified a Green finding and associated non-cited violation of Unit 2 License Condition 2.C.(3)(b) for the failure to implement and maintain in effect all provisions of the approved fire protection program. Specifically, missing ceiling tiles in the Unit 2 health physics area closet could result in enough heat loss through the ceiling during a postulated fire that the sprinkler could fail to actuate prior to the fire spreading to the area above the ceiling that contains cables important to safe shutdown.
Failure to Maintain Combustible Loading Within Limits Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000313/2025001-02 Open/Closed
[P.2] -
Evaluation 71111.05 The inspectors identified a Green finding and associated non-cited violation of Unit 1 License Condition 2.C.(8) for the failure to maintain in effect all provisions of the approved fire protection program, as specified in the license amendment request dated January 29, 2014, and Procedure EN-DC-161, Control of Combustibles, revision 27. Specifically, transient combustibles in the storage room adjacent to the upper north electrical penetration room exceeded 100 pounds of rubber and plastic, and an hourly fire watch was not posted.
Failure to Monitor the Effectiveness of Maintenance Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000313,05000368/2025001-03 Open/Closed
[H.3] - Change Management 71111.12 The inspectors identified a Green finding and associated non-cited violation of 10 CFR 50.65 (a)(2) and (a)(3) for the failure to demonstrate that the performance or condition of structures, systems, and components are being effectively controlled through the performance of appropriate preventive maintenance; and making adjustments where necessary to ensure that the objective of preventing failures of those structures, systems, and components through maintenance are appropriately balanced against the objective of minimizing unavailability. Specifically, the licensee failed to adequately demonstrate the performance of the Unit 1 decay heat removal system, the Unit 2 instrument air compressors, and failed to conduct an adequate 2023 50.65(a)(3) periodic assessment.
Failure to Establish Proper Risk Management Actions during Switchyard Maintenance Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000313,05000368/2025001-04 Open/Closed
[H.11] -
Challenge the Unknown 71111.13 The inspectors identified a Green finding and associated non-cited violation of 10 CFR 50.65(a)(4) for the failure to manage the increase in risk that may result from proposed maintenance activities. Specifically, the licensee failed to manage the increase in risk associated with planned major switchyard maintenance when they did not station a dedicated operator locally at the alternate AC diesel generator during a period when the diesel could not be started from the normal location in the control room, which was required by Procedure COPD-024, Risk Assessment Guidelines, revision 78.
Additional Tracking Items
Type Issue Number Title Report Section Status URI 05000313,05000368/
2023003-01 Use and Acceptance of the Holtec Canister with the CBS Variant Design Change 60855 Closed EDG EAF-RIV-2025-0096 Enforcement Action EA-25-096: Noncompliance Related to a General Licensees Use of Non-Qualified Spent Fuel Casks (EGM 25-001)60855 Closed NOV 05000368/2023002-03 Failure to Establish Adequate Corrective Actions Resulting in Excessive Instances of Damaged and Broken Internals of the Emergency Feedwater Pump Turbine Steam Admission Check Valves 71111.18 Closed
PLANT STATUS
Unit 1 began the inspection period at full power and remained there for the duration of the inspection period.
Unit 2 began the inspection period at full power. On February 23, 2025, the main generator stator water cooling system temperature controller failed, which caused an automatic generator runback to 38 percent power. The licensee repaired the controller and then returned the unit to full power on February 25, 2025. On March 25, 2025, the licensee reduced power to approximately 50 percent to repair a condenser tube leak. After repairing the leak, operators returned the unit to full power on March 30, 2025. Unit 2 remained at or near full 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
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 cold weather for forecasted temperatures below 10 degrees Fahrenheit, on January 17, 2025.
71111.04 - Equipment Alignment
Partial Walkdown Sample (IP Section 03.01) (3 Samples)
The inspectors evaluated system configurations during partial walkdowns of the following systems/trains:
- (1) Unit 1, swing inverter Y-25 during normal inverter maintenance, on January 25, 2025
- (2) Unit 1, turbine-driven emergency feedwater steam supply following severe cold weather, on January 28, 2025
- (3) Unit 2, emergency diesel generator 2K-4B while emergency diesel generator 2K-4A was unavailable due to maintenance, on February 4, 2025
71111.05 - Fire Protection
Fire Area Walkdown and Inspection Sample (IP Section 03.01) (5 Samples)
The inspectors evaluated the implementation of the fire protection program by conducting a walkdown and performing a review to verify program compliance, equipment functionality, material condition, and operational readiness of the following fire areas:
- (1) Unit 2, west dc equipment room, fire zone 2099-W, on January 15, 2025
- (2) Unit 2, emergency diesel generator 2K-4A room, fire zone 2093-P, on February 3, 2025
- (3) Unit 2, health physics corridor, fire zone 2136-I, on February 21, 2025
- (4) Unit 1, upper north electrical penetration room and decontamination room, fire zone 149-E, on March 11, 2025
- (5) Unit 1, upper north piping penetration room, fire zone 79-U, on March 11, 2025
Fire Brigade Drill Performance Sample (IP Section 03.02) (1 Sample)
- (1) The inspectors evaluated the onsite fire brigade training and performance during an announced fire drill in warehouse 3, on March 19, 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) (2 Samples)
- (1) The inspectors observed and evaluated licensed operator performance in the Unit 1 control room during a test of the emergency diesel generator K-4B, on February 2, 2025.
- (2) The inspectors observed and evaluated licensed operator performance in the Unit 2 control room following the automatic generator runback and preparations for power ascension, on February 24, 2025.
Licensed Operator Requalification Training/Examinations (IP Section 03.02) (2 Samples)
- (1) The inspectors observed and evaluated Unit 1 simulator evaluation and continuing training, on January 29, 2025.
- (2) The inspectors observed and evaluated Unit 2 simulator evaluation and continuing training, on January 30, 2025.
71111.12 - Maintenance Effectiveness
Maintenance Effectiveness (IP Section 03.01) (2 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) Units 1 and 2, service water debris management, on March 3, 2025
- (2) Unit 2, auxiliary feedwater leakage into emergency feedwater, on March 17, 2025
71111.13 - Maintenance Risk Assessments and Emergent Work Control
Risk Assessment and Management Sample (IP Section 03.01) (5 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, permanently installed instrument air compressors out of service for planned maintenance, on January 15, 2025
- (2) Unit 1, inverter Y-22 out of service for planned maintenance, on January 24, 2025
- (3) Units 1 and 2, elevated risk due to startup transformer 2 out of service, on January 29, 2025
- (4) Unit 1, elevated risk due to low pressure injection pump P-34B out of service, on February 25, 2025
- (5) Unit 1, elevated risk due to motor-driven emergency feedwater pump out of service, on March 10, 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) Unit 1, penetration room ventilation operability determination due to improperly installed check valves, on January 23, 2025
- (2) Unit 2, main control room fire alarm panel functionality assessment due to de-energization of the main panel, on February 4, 2025
- (3) Unit 1, safety-related instrument air operated valves operability determination due to water intrusion in the air lines, on February 5, 2025
- (4) Unit 2, emergency diesel generator 2K-4A operability determination after unexpected power drop during test, on February 8, 2025
- (5) Unit 2, emergency diesel generator 2K-4A operability determination for jacket water leakage, on March 28, 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) Unit 2, permanent modification of motor-operated steam isolation valve to turbine-driven emergency feedwater pump turbine 2CV-1050-2 from normally open to normally closed, in response to degradation of emergency feedwater steam supply check valve 2MS-39B, on January 16, 2025 Response to cited violation of 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action (CR-ANO-2-2021-02496, CR-ANO-2-2023-01282, and CR-ANO-2-2023-02140):
In October 2024, during Unit 2 refueling outage 2R30, emergency feedwater steam supply check valve 2MS-39B was found degraded. The inspectors determined that the valve had failed in the same manner as was previously documented in NOV 05000368/2023002-03. The licensee implemented a design modification to eliminate the previously identified failure mechanism of the valve.
The inspectors reviewed the licensees response to NOV 05000368/2023002-03 and determined that the reason, corrective actions taken to address the condition adverse to quality, and the date when full compliance was achieved for this violation is adequately addressed and captured on the docket in Status of Actions to Return Arkansas Nuclear One, Unit 2 to Compliance, (ML24340A172), dated December 4, 2024. This NOV is closed.
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) Unit 1, low pressure injection pump P-34A test after preventive maintenance, on January 14, 2025
- (2) Unit 2, service water discharge check valve 2SW-2A test after preventative maintenance, on January 17, 2025
- (3) Unit 1, 480 Volt breaker B-633 for reactor building fan VSF-1D test after replacement, on January 23, 2025
- (4) Units 1 and 2, startup 2 transformer voltage regulator test after preventive maintenance, on January 30, 2025
- (5) Unit 2, upstream atmospheric dump valve isolation 2CV-1052 test after preventive maintenance, on January 31, 2025
- (6) Unit 1, penetration room ventilation train A test after preventive maintenance on check valves, on February 4, 2025
- (7) Unit 2, refueling water tank level instrument test after corrective maintenance for an out-of-tolerance transmitter and signal conditioner, on February 14, 2025
- (8) Unit 1, motor-driven emergency feedwater pump test after preventive maintenance, on March 11, 2025
Surveillance Testing (IP Section 03.01) (3 Samples)
- (1) Units 1 and 2, diesel-driven fire pump P-6B test, on January 7, 2025
- (2) Unit 1, turbine-driven emergency feedwater pump test, on January 22, 2025
- (3) Unit 2, refueling water tank level indication test, on February 13,
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) Unit 2, ingress of steam to motor control center 2B53 room from actuation of downstream atmospheric dump valves, on March 20,
OTHER ACTIVITIES
- TEMPORARY INSTRUCTIONS, INFREQUENT AND ABNORMAL
===60855 - Operation of an ISFSI The inspectors performed a review to close an Unresolved Item regarding the licensees independent spent fuel storage installation (ISFSI) activities.
Operation of an ISFSI===
- (1) In accordance with Inspection Procedure 60855, section 04.03, inspectors performed an in-office follow-up review of unresolved item (URI)05000313,05000368/2023004-03. In accordance with Enforcement Guidance Memorandum (EGM) 25-001, Enforcement Guidance for Dispositioning Noncompliance Related to a General Licensees use of Certain Non-Qualified Spent Fuel Casks, dated February 11, 2025, (ML24303A436), the NRC is exercising enforcement discretion for ANOs failure to request Holtec obtain a Certificate of Compliance amendment prior to loading the CBS variant canister that resulted in a departure from a method of evaluation described in the FSAR used in establishing the design bases.
INSPECTION RESULTS
Unresolved Item (Closed)
Use and Acceptance of the Holtec Canister with the CBS Variant Design Change URI 05000313,05000368/2023003-01 60855
Description:
The inspectors identified an unresolved item (URI) related to design changes on the dry cask storage multi-purpose canisters (MPC) utilized by the licensee. On November 6, 2020, Holtec International, the supplier of HI-STORM FW storage system, performed Engineering Change Order (ECO) 5018-122 and 72.48 design #1498. These evaluations performed a design change to introduce a new MPC basket design to the HI-STORM FW dry storage system, designated as the continuous basket shim (CBS) variant.
On September 12, 2023, the NRC issued Inspection Report 07201014/2022-201 (ML23145A175) to Holtec International, identifying three apparent violations associated with design change. The apparent violations, related to 10 CFR 72.48 and 10 CFR 72.146 requirements, are for Holtecs apparent failures to provide adequate bases that the CBS variant did not require a license amendment, failure to ensure the change did not result in a departure from the method of evaluations described in the Final Safety Analysis Report, and failure to establish design control measures commensurate with those applied to the original design. At this time, the NRC has determined there is no immediate safety concern associated with the use of the modified basket design.
On January 25, 2023, the licensee adopted Holtecs CBS ECO/72.48 through the licensees 72.48 program, LBDCR #2022-034, and subsequently loaded the MPC-37-CBS canister during their September 2023 loading campaign.
General licensees are responsible to ensure that each cask they use conforms to the terms, conditions, and specifications of a Certificate of Compliance (CoC) or an amended CoC listed in 72.214 and regulatory requirements in 10 CFR Part 72. Accordingly, pending determination of the final enforcement action to Holtec International associated with the design change, it may be determined that ANO's loading of the dry storage systems did not meet regulatory requirements.
Corrective Action Reference: Condition Report CR-HQN-2023-03197 Enforcement Discretion Enforcement Action EAF-RIV-2025-0096: Enforcement Action EA-25-096: Noncompliance Related to a General Licensees Use of Non-Qualified Spent Fuel Casks (EGM 25-001)60855
Description:
Using the 10 CFR 72.48 change control process, Holtec International (Holtec)made a change to the design of its multi-purpose canisters (casks) that contain spent nuclear fuel inside of a honeycombed fuel basket. Holtec designated the basket design change as the Continuous Basket Shim (CBS) variant, and assessed how the design change from a welded to a bolted shim design impacted the cask structural performance during a hypothetical cask tip-over event. Holtec failed to consider the cumulative impacts from changes made to multiple elements of the method of evaluation (MOE) that were not consistent with the licensing basis. Additionally, Holtec adopted aspects of several different approved MOEs and did not apply these evaluation aspects in the same manner as the original MOE. As such, NRC found Holtec in violation of 10 CFR 72.48 requirements and issued three Severity Level IV violations for:
- (1) implementation of design changes to NRC-approved spent fuel cask systems that resulted in departures from MOEs described in the Final Safety Analysis Report (FSAR);
- (2) failure to maintain adequate evaluations that provided the bases for determining that the design changes did not require a CoC amendment; and,
- (3) not subjecting the changes to design control measures that were commensurate with those applied to the original design (for more information see NRC inspection reports ML23145A175, ML24016A190 (Notice of Violation) and ML24060A214 (Holtecs response to Notice of Violation).
These violations affected 21 general licensees because they had already loaded the noncompliant casks with the CBS variant.
In addition to applying to Holtec, the requirements of 10 CFR 72.48 also apply to the 21 general licensees who had purchased and used the casks discussed above. Specifically, pursuant to 10 CFR 72.48(c), a licensee or certificate holder may make changes to a spent fuel storage cask design without obtaining a CoC amendment so long as those changes meet certain criteria defined in 10 CFR 72.48(c). Under 10 CFR 72.48(c)(2)(viii), if the change would result in a departure from the method of evaluation described in the FSAR (as updated) used in establishing the design bases or in the safety analyses, a general licensee must request that the certificate holder obtain a CoC amendment prior to implementing the proposed change. Accordingly, a general licensee seeking to adopt a change that a CoC holder made to a cask design must perform an evaluation to determine the suitability of the change for itself. Further, 10 CFR 72.48(d)(1) requires a general licensee to maintain records of a change in the cask design made pursuant to 10 CFR 72.48(c). These records must include a written evaluation that provides the bases for the determination that the change does not require a CoC amendment pursuant to 10 CFR 72.48(c)(2). Prior to loading the non-compliant casks obtained from Holtec, 21 general licensees did not identify that Holtecs cask modification (i.e., changing the basket shim from a welded to a bolted design) utilized MOEs that departed from the MOE described in the FSAR (as updated) that was used in establishing the design bases or in the safety analyses. Because of the noncompliant modification, the general licensees were required to request that the CoC holder submit an amendment request to the NRC to comply with 10 CFR 72.48(c)(2). Contrary to this requirement, none of the general licensees requested that the CoC holder submit an amendment request.
Additionally, pursuant to 10 CFR 72.212(b)(3), a general licensee must also ensure that each cask used by the general licensee conforms to the terms, conditions, and specifications of a CoC or an amended CoC listed in 72.214. The casks with the CBS variant did not conform to the CoC due to the changes that the CoC holder made. Consequently, the 21 general licensees who used the casks did not comply with 10 CFR 72.212(b)(3), because the casks did not conform to a CoC or amended CoC when the general licensees loaded them.
Corrective Actions: The licensee followed the guidance actions as described in the Enforcement Guidance Memorandum (EGM) 25-001, Noncompliance Related to a General Licensees Use of Certain Non-Qualified Spent Fuel Casks, dated February 11, 2025, (ML24303A436). The issue was entered into the corrective action program (CAP) and the licensee established actions to restore compliance. These actions included steps to address the cause of the violation and performing a 10 CFR 72.48 evaluation to adopt the tip-over method of evaluation that was authorized by the NRC in Holtec HI-STORM FW System Amendment 7 (ML24199A236).
Corrective Action Reference: Condition Report CR-ANO-C-2023-03879
Enforcement:
Significance/Severity: This violation was dispositioned in accordance with the traditional enforcement process using section 2.3 of the NRCs Enforcement Policy. Consistent with the guidance in section 1.2.6.D of the NRC's Enforcement Manual, if a violation does not fit an example in the enforcement policy violation examples, it should be assigned a severity level:
- (1) commensurate with its safety significance; and
- (2) informed by similar violations addressed in the violation examples. The violation was evaluated to be similar to a Severity Level IV violation in Enforcement Policy section 6.1.d.2.
Violation: Title 10 CFR 72.48(d)(1) requires, in part, that the licensee shall have a written evaluation which provides the bases for the determination that the change does not require a CoC amendment pursuant to 72.48(c)(2).
Title 10 CFR 72.48(c)(2) requires, in part, a general licensee shall request that the certificate holder obtain a CoC amendment, prior to implementing a proposed change, if the change would: (viii) Result in a departure from a method of evaluation described in the FSAR used in establishing the design bases or in the safety analyses.
Title 10 CFR 72.212(b)(3) requires, in part, a general licensee must ensure that each cask used by the general licensee conforms to the terms, conditions, and specifications of a CoC or an amended CoC listed in 72.214.
Contrary to the above, from September 2023 to February 2025, the licensee failed to maintain records of changes in the spent fuel storage cask design made pursuant to 72.48(c)that include a written evaluation which provided the bases for the determination that the change did not require a CoC amendment. The licensee failed to request that the certificate holder obtain a CoC amendment, prior to implementing a proposed change, if the change would: (viii) Result in a departure from a method of evaluation described in the FSAR used in establishing the design bases or in the safety analyses. Further, the licensee failed to ensure each cask conformed to the terms, conditions, and specifications of a CoC or amended CoC listed in 72.214. Specifically, ANO's 10 CFR 72.48 #1600 revision 0, failed to identify that the CBS variant design change resulted in a departure from a method of evaluation described in the FSAR used in establishing the design bases, failed to request the certificate holder obtain a CoC amendment pursuant to 10 CFR 72.244, and failed to ensure each cask conformed to the terms conditions, and specifications of a CoC or an amended CoC listed in 72.214, prior to using the canisters.
Basis for Discretion: A general licensees loading of a non-compliant Holtec cask (i.e.,
MPC 37-CBS, MPC 89-CBS, MPC 68M-CBS, and MPC 32M-CBS) under the circumstances presented here has been designated as having very low safety significance. The NRC performed an Immediate Safety Determination 4 to confirm that general licensee use of the CBS basket design does not pose a risk to public health and safety, which stated:
A potential consequence of the unapproved design change is a cask tip-over event that results in damaged fuel assemblies. The staff assigned a significance of Severity Level IV (i.e., violations that are less serious, but are of more than minor concern) because Holtecs failure to obtain an amendment is deemed as having very low safety significance (see section 6.1.d.2 of the Enforcement Policy). The staffs safety significance determination is summarized in memorandum, Safety Determination of a Potential Structural Failure of the Fuel Basket During Accident Conditions for the HI-STORM 100 and HI-STORM Flood/Wind Dry Cask Storage Systems (ML24018A085).
In accordance with the NRC Enforcement Policy, section 3.5, Violations Involving Special Circumstances, the NRC may refrain from issuing a violation based on the merits of the case after considering factors such as the clarity of the requirement and associated guidance, as well as other relevant circumstances. The NRC-endorsed industry guidance lacks clarity concerning the level of review required by general licensees of changes made by CoC holders pursuant to 10 CFR 72.48 that include a modified, new, or different MOE. The significant number of general licensees that failed to comply with the applicable regulations in this instance also indicates a lack of clarity. Accordingly, the staff will exercise enforcement discretion for general licensees violations of 10 CFR 72.48 and 10 CFR 72.212 because of the lack of clarity in the guidance.
Since this violation was identified during the discretion period covered by EGM 25-001, the licensee has taken the necessary conditions specified in the EGM to place the issue into their CAP, and taken actions to restore compliance, the NRC is exercising enforcement discretion by not issuing an enforcement action for the violation.
The disposition of this violation closes URI: 05000313,05000368/2023003-01.
Failure to Maintain Acoustic Ceiling Tiles Results in Non-Functional Fire Suppression Sprinklers Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000368/2025001-01 Open/Closed
[H.12] - Avoid Complacency 71111.05 The inspectors identified a Green finding and associated non-cited violation of Unit 2 License Condition 2.C.(3)(b) for the failure to implement and maintain in effect all provisions of the approved fire protection program. Specifically, missing ceiling tiles in the Unit 2 health physics area closet could result in enough heat loss through the ceiling during a postulated fire that the sprinkler could fail to actuate prior to the fire spreading to the area above the ceiling that contains cables important to safe shutdown.
Description:
On February 20, 2025, the inspectors walked down fire zone 2136-I, which includes the Unit 2 health physics area closet. The closet has a single fire suppression sprinkler directly below a noncombustible acoustic lay-in tile ceiling. The inspectors noted that two of the lay-in ceiling tiles were missing. The inspectors notified the control room operators about the missing ceiling tiles and the licensee immediately replaced the ceiling tiles.
The licensee evaluated the functionality of the fire suppression system for the closet and determined that it was nonfunctional during the period that the ceiling tiles were missing. In the event of a fire, the licensee determined that the heat loss through the missing ceiling tiles may not have allowed enough hot gases to collect below the acoustic tile ceiling to melt the fusible sprinkler head. The inspectors noted that there were combustibles directly below the missing ceiling tiles, and video and internet cables passed vertically through the area where the ceiling tiles were missing. Therefore, the inspectors determined that the sprinkler may not suppress a combustible fire in the closet before the fire would spread to the area above the ceiling, where it may affect cables important to safe shutdown.
Corrective Actions: The licensee declared the fire suppression non-functional and subsequently replaced the missing ceiling tiles.
Corrective Action Reference: Condition Report CR-ANO-2-2025-00291
Performance Assessment:
Performance Deficiency: The failure to maintain functionality of the fire suppression sprinkler in the health physics area closet was a performance deficiency. Specifically, missing ceiling tiles could result in enough heat loss through the ceiling during a postulated fire that the sprinkler could fail to actuate prior to the fire spreading to the area above the ceiling that contains cables important to safe shutdown.
Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Protection Against External Factors attribute of the Mitigating Systems cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the licensee failed to ensure the availability and reliability of the fire protection sprinkler in the Unit 2 health physics area closet area so that the sprinklers could mitigate a fire to prevent damage to cables important to safe shutdown above the ceiling tiles.
Significance: The inspectors assessed the significance of the finding using IMC 0609 Appendix F, Fire Protection and Post - Fire Safe Shutdown SDP. Using Inspection Manual Chapter 0609, Appendix F, Attachment 1, Fire Protection Significance Determination Process Worksheets, revised January 1, 2025, the inspectors assigned the finding category of Fixed Fire Protection Systems. Using Inspection Manual Chapter 0609, Appendix F, 2, Degradation Rating Guidance, revised January 1, 2025, the inspectors assumed that the finding had a high degradation because there were no functional sprinklers in the room. In Attachment 1, the inspectors determined that the degraded fixed suppression system could adversely affect the ability of the system to protect equipment important to safe shutdown. Specifically, cables for both trains of safety equipment and control cables for offsite power are in the area above the suspended ceiling and the inspectors determined that a fire could propagate from the room to the area above the suspended ceiling. The plant does have a fire probabilistic risk assessment capable of adequately evaluating the risk associated with the finding, and the licensees risk-based evaluation indicated that the bounding change in core damage frequency was less than 1E-6, and the evaluation result was accepted by a Senior Reactor Analyst. In PSA-ANO2-03, Arkansas Nuclear One Unit 2 Fire Probabilistic Risk Assessment Summary Report NUREG/CR-6850 Task 16, revision 1, the assessment listed fire scenario 2136-I-TN_A in the health physics corridor which assumes an instantaneous full fire zone burnout from a transient combustible fire. The assessment did not credit the suppression system, so this scenario bounds the risk of this finding. The assessment shows that the core damage frequency for a 1-year exposure to this scenario is 8.91E-7, which is less than 1E-6. Therefore, the finding screens to very low safety significance (Green).
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. In the past, the licensee has adequately addressed other missing ceiling tiles in the main area of the Unit 2 health physics area. However, the licensee did not recognize the risk of the missing ceiling tiles in the closet area.
Enforcement:
Violation: Arkansas Nuclear One, Unit 2 License Condition 2.C.(3)(b) states, in part that the licensee shall implement and maintain in effect all provisions of the approved fire protection program that comply with 10 CFR 50.48(a) and 10 CFR 50.48(c), as specified in the license amendment request dated December 17, 2012. The license amendment request dated December 17, 2012, Attachment A, section 3.9.1, Fire Suppression System Code Requirements, states that the licensee evaluated NFPA 13 code compliance in the referenced CALC-ANO2-FP-09-00007, ANO Code Compliance Report for NFPA 13 1980 Edition, revision 1. CALC-ANO2-FP-09-00007 states, in part, that sprinkler deflectors are located no more than 11 inches below the noncombustible acoustic lay-in tile ceiling.
Contrary to the above, as of February 20, 2025, the licensee failed to maintain in effect all provisions of the approved fire protection program as specified in the license amendment request dated December 17, 2012, and CALC-ANO2-FP-09-00007. Specifically, the licensee failed to maintain the sprinkler deflectors no more than 11 inches below the noncombustible acoustical lay-in tile ceiling in the health physics area because excessive lay-in tiles were missing.
Enforcement Action: This violation is being treated as a non-cited violation, consistent with section 2.3.2 of the Enforcement Policy.
Failure to Maintain Combustible Loading Within Limits Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000313/2025001-02 Open/Closed
[P.2] -
Evaluation 71111.05 The inspectors identified a Green finding and associated non-cited violation of Unit 1 License Condition 2.C.(8) for the failure to maintain in effect all provisions of the approved fire protection program, as specified in the license amendment request dated January 29, 2014, and Procedure EN-DC-161, Control of Combustibles, revision 27. Specifically, transient combustibles in the storage room adjacent to the upper north electrical penetration room exceeded 100 pounds of rubber and plastic, and an hourly fire watch was not posted.
Description:
On March 11, 2025, the inspectors discovered transient combustibles in the storage room of fire zone 149-E, which is made up of the upper north electrical penetration room, decontamination room, and storage room. According to the licensees fire probabilistic risk assessment, this fire zone has one of the highest fire risks for Unit 1.
The inspectors determined that the combustibles in the storage room of fire zone 149-E exceeded the evaluated permanently stored combustibles per Calculation CALC-85-E-0053-50, Fire Area B-1 Combustible Loading Evaluation, revision 11.
The inspectors further determined that the amount of transient combustibles in the storage room required an hourly fire watch per Procedure EN-DC-161, Control of Combustibles, revision 27, Attachment 1, ANO - COMBUSTIBLE CONTROL ZONES. The procedure states, in part, that if transient combustibles exceed 100 pounds of combustibles such as rubber and plastic in fire zone 149-E, then an hourly fire watch shall be posted. However, an hourly fire watch had not been initiated until the inspectors notified the control room about the transient combustibles.
In 2022, the licensee identified that combustible loading in the same storage room had been exceeded and wrote Condition Report CR-ANO-1-2022-00776. The licensee evaluated the condition and initiated an action to place more metal cabinetry in the storage room.
Procedure EN-DC-161 permits the licensee to store combustibles in closed noncombustible containers like a metal cabinet without a transient combustible permit and fire watch, but it does not allow for permanently increasing the amount of stored combustibles in a fire area without evaluation. The inspectors determined that the additional metal cabinets increased the amount of available storage in fire zone 149-E, and therefore increased the combustibles stored in the storage room without evaluating the combustible loading. Even with the additional metal cabinets, the transient combustible limits in the room were exceeded without an hourly fire watch. Therefore, the inspectors determined that the licensee failed to appropriately evaluate the issue to address the cause of the condition. As a result, the excessive combustibles were placed back in the storage room until identified by the inspectors.
Corrective Actions: The licensee declared the fire suppression inoperable, initiated a fire watch for the area, and removed the excessive combustibles.
Corrective Action Reference: Condition Report CR-ANO-1-2025-00360
Performance Assessment:
Performance Deficiency: The failure to maintain the combustible loading within limits or initiate a transient combustible permit for the storage area adjacent to the upper north electrical penetration room was a performance deficiency. Specifically, the licensee stored significantly more than the allowed combustible loading in this fire zone.
Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Protection Against External Factors attribute of the Mitigating Systems cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the fire loading was not within the combustible loading analysis limits.
Significance: The inspectors assessed the significance of the finding using IMC 0609 Appendix F, Fire Protection and Post - Fire Safe Shutdown SDP. Using IMC 0609, Appendix F, Attachment 1, Fire Protection Significance Determination Process Worksheets, revised January 1, 2025, the inspectors assigned the finding category of Fire Prevention and Administrative Controls. Using Inspection Manual Chapter 0609, Appendix F, Attachment 2, Degradation Rating Guidance, revised January 1, 2025, the inspectors determined that the finding had a low degradation because the storage room did not have low flashpoint combustible liquids, self-heating materials such as oily rags, evidence of recent smoking, or an unapproved heat source. In Attachment 1, the inspectors determined that the finding screened to Green due to the low degradation rating.
Cross-Cutting Aspect: P.2 - Evaluation: The organization thoroughly evaluates issues to ensure that resolutions address causes and extent of conditions commensurate with their safety significance. Specifically, the licensee identified excessive combustible loading in the same storage room in 2022, but instead of evaluating the fire zone for an increase in the combustible limits or other corrective actions to limit transient combustibles in the storage area, the licensee placed additional metal cabinets in the fire zone to store combustibles.
Enforcement:
Violation: Arkansas Nuclear One, Unit 1 License Condition 2.C.(8) states, in part, that the licensee shall implement and maintain in effect all provisions of the approved fire protection program that comply with 10 CFR 50.48(a) and 10 CFR 50.48(c), as specified in the license amendment request dated January 29, 2014. The license amendment request dated January 29, 2014, Attachment A, section 3.3.1.2, Control of Combustible Materials, states, in part, that combustible storage or staging areas are designated and limits established on the types and quantities of stored materials in accordance with Procedure EN-DC-161.
Procedure EN-DC-161, Control of Combustibles, revision 27, Attachment 1, ANO - COMBUSTIBLE CONTROL ZONES, states, in part, that if transient combustibles exceed 100 pounds of Class A combustibles, such as rubber and plastic, in fire zone 149-E, Upper North Electrical Penetration Room, Decontamination Room, Storage Room, then an hourly fire watch shall be posted.
Contrary to the above, as of March 11, 2025, the licensee failed to maintain in effect all provisions of the approved fire protection program, as specified in the license amendment request dated January 29, 2014, and Procedure EN-DC-161. Specifically, transient combustibles in the storage room of fire zone 149-E exceeded 100 pounds of rubber and plastic and an hourly fire watch was not posted.
Enforcement Action: This violation is being treated as a non-cited violation, consistent with section 2.3.2 of the Enforcement Policy.
Failure to Monitor the Effectiveness of Maintenance Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000313,05000368/2025001-03 Open/Closed
[H.3] - Change Management 71111.12 The inspectors identified a Green finding and associated non-cited violation of 10 CFR 50.65 (a)(2) and (a)(3) for the failure to demonstrate that the performance or condition of structures, systems, and components are being effectively controlled through the performance of appropriate preventive maintenance; and making adjustments where necessary to ensure that the objective of preventing failures of those structures, systems, and components through maintenance are appropriately balanced against the objective of minimizing unavailability. Specifically, the licensee failed to adequately demonstrate the performance of the Unit 1 decay heat removal system, the Unit 2 instrument air compressors, and failed to conduct an adequate 2023 50.65(a)(3) periodic assessment.
Description:
The inspectors reviewed maintenance rule documentation for structures, systems, and components (SSCs) in the plant, and noted that the licensee no longer tracked or evaluated unavailability for SSCs not covered by the NRCs Mitigating Systems Performance Indicators (MSPIs). The inspectors also noted that the licensees maintenance rule program had re-defined maintenance preventable functional failures to the complete failure of a safety function. For example, the station would have to experience a station blackout (a total loss of offsite power and onsite emergency power) to evaluate a maintenance preventable functional failure of the emergency diesel generators.
The inspectors reviewed the licensees maintenance rule program document, Procedure EN-DC-204, Maintenance Rule Scope and Basis, revision 9, and noted that it had been significantly revised. The inspectors asked if the licensee had evaluated the revision to ensure compliance with 10 CFR 50.65. The licensee replied that the revision had not been evaluated for compliance with 10 CFR 50.65, but still followed the guidance of NUMARC 93-01, Industry Guideline for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants, revision 4f. The NRC endorsed NUMARC 93-01, revision 4f, with clarifications, in Regulatory Guide 1.160, Monitoring the Effectiveness of Maintenance at Nuclear Power Plants, revision 4, as a method to comply with 10 CFR 50.65. However, the inspectors noted that portions of the licensees program did not follow the intent of the guidance in NUMARC 93-01. Regulatory Guide 1.160, section 1.13, states that Licensees may use methods other than those provided in NUMARC 93-01 to meet the requirements of the Maintenance Rule. The NRC will inspect the implementation of these methods on a plant-specific basis. Therefore, the inspectors reviewed the licensees implementation of 10 CFR 50.65 on a plant-specific basis and used the NUMARC 93-01 guidance for reference.
The inspectors identified the following two examples of the licensees failure to demonstrate that the performance or condition of an SSC is being effectively controlled through the performance of appropriate preventive maintenance, such that the SSC remains capable of performing its intended function, in accordance with 10 CFR 50.65(a)(2).
The inspectors reviewed the equipment performance of the Unit 1 decay heat removal system and determined that the licensee failed to adequately demonstrate the equipment performance. During the Unit 1 2024 refueling outage, Unit 1 decay heat removal suction isolation valve, CV-1410, failed to fully open. The licensee determined the valve failed to fully open due to breaker B6255 upper mechanical interlock associated with the reversing contactor used for valve closure would not spring return to its normal position. The maintenance rule performance criteria for the decay heat removal system is no functional failures. A functional failure is defined as the inability or failure to remove decay heat on demand. With the valve closed, the entire decay heat system suction is isolated from the reactor coolant system, which resulted in a functional failure of the decay heat removal system. The licensees maintenance rule evaluation credited operator action to manually open the valve locally, but the inspectors determined that the valve was not capable of performing its intended function as specified in 10 CFR 50.65(a)(2), which was to open from the control room. The inspectors determined that the licensee had not demonstrated that the performance or condition of decay heat removal is being effectively controlled through the performance of appropriate preventive maintenance, such that decay heat removal remains capable of performing its intended function.
The inspectors reviewed another case where the licensee used compensatory measures so an SSC would be able to perform its intended function. Specifically, the licensee has used temporary coolers to mitigate high temperature trips of the Unit 2 instrument air compressors for an extended time. The licensee has classified the instrument air system as risk significant because it appears in the top 90 percent of cutsets contributing to the core damage frequency, specifically for Large Early Release Frequency. Therefore, the licensee monitors the performance of the individual Unit 2 instrument air compressors. The inspectors determined that if a compensatory measure is required for the system or component to continue to function, then the system or component has failed to perform its intended function, which may be due to inappropriate preventive maintenance. In this case, the instrument air compressors performance continued to degrade and the licensee placed them in monitoring under 10 CFR 50.65(a)(1) in 2024 due to compressor trips. However, the temporary coolers were in use for years prior, and the licensee failed to evaluate whether the compressors needed additional preventive maintenance. The inspectors determined that the licensee had not demonstrated that the performance or condition of the instrument air compressors were being effectively controlled through the performance of appropriate preventive maintenance, such that the instrument air compressors remain capable of performing their intended function.
Additionally, the inspectors contrasted the requirements of 10 CFR 50.65(a)(3) with the licensees Procedure EN-DC-204, Maintenance Rule Scope and Basis, revision 9, and found that the licensee currently only evaluates unavailability against performance criteria for SSCs covered by the NRCs MSPI or potentially for systems with goals per 50.65(a)(1). The licensee was not using any other methods to evaluate unavailability of other SSCs. In contrast, the inspectors noted that 10 CFR 50.65(a)(3) applies to all in-scope SSCs, not just those in MSPI or those treated per 50.65(a)(1).
In 2023, the licensee issued a 10 CFR 50.65(a)(3) required periodic evaluation without evaluating the unavailability of non-MSPI systems, and therefore, the inspectors concluded that the licensee had not evaluated whether adjustments were necessary to balance reliability and unavailability during that evaluation period, as discussed in 10 CFR 50.65(a)(3).
Corrective Actions: The licensee reviewed their program for compliance and initiated actions to revise the program to address gaps. For the equipment conditions discussed above, the licensee placed the Unit 1 decay heat removal system in monitoring, per 10 CFR 50.65(a)(1),and the licensee had already placed the Unit 2 instrument air system in monitoring. The licensee plans to perform a periodic evaluation per 10 CFR 50.65(a)(3) in 2025 that addresses the balance of reliability and unavailability of non-MSPI systems.
Corrective Action References: Condition Reports CR-HQN-2024-00965, CR-HQN-2024-01160
Performance Assessment:
Performance Deficiency: The licensees failure to adequately monitor the effectiveness of maintenance for all required SSCs was a performance deficiency. Specifically, the licensee failed to evaluate failures and the unavailability of SSCs within scope of the maintenance rule.
Therefore, the licensee failed to ensure that preventive maintenance was appropriate for those SSCs.
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, the inspectors determined the licensee failed to evaluate failures and unavailability of all SSCs within scope of maintenance rule to ensure that preventive maintenance adequately ensured the availability and reliability of those SSCs.
Significance: The inspectors assessed the significance of the finding using IMC 0609 Appendix A, The Significance Determination Process (SDP) for Findings At-Power. The finding was determined to be of very low safety significance (Green) because it:
- (1) did not represent a deficiency affecting the design or qualification of a mitigating SSC;
- (2) did not represent a loss of the PRA function of a single train TS system;
- (3) did not represent an actual loss of the PRA function of one train of a multi-train TS system for more than its TS allowed outage time or;
- (4) two separate safety systems for more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />;
- (5) did not represent a loss of a PRA system and/or function as defined in the PRIB or the licensees 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
- (6) did not represent a loss of a PRA function of one or more non-TS trains of equipment designated as risk-significant in accordance with the licensees maintenance rule program for greater than 3 days.
Cross-Cutting Aspect: H.3 - Change Management: Leaders use a systematic process for evaluating and implementing change so that nuclear safety remains the overriding priority.
When the maintenance rule program was changed in 2021, the licensee did not ensure that unintended consequences were avoided. Specifically, the licensee did not independently verify that the intent of the regulatory guidance was met so that the program would comply with the regulation.
Enforcement:
Violation: Title 10 CFR 50.65(a)(2) requires, in part, that monitoring as specified in paragraph (a)(1) is not required where it has been demonstrated that the performance or condition of a structure, system, or component is being effectively controlled through the performance of appropriate preventive maintenance, such that the structure, system, or component remains capable of performing its intended function.
Title 10 CFR 50.65(a)(3) requires, in part, that adjustments shall be made where necessary to ensure that the objective of preventing failures of structures, systems, and components through maintenance is appropriately balanced against the objective of minimizing unavailability of structures, systems, and components due to monitoring or preventive maintenance.
Contrary to the above, prior to December 31, 2024, the licensee failed to demonstrate the performance or condition of structures, systems, and components is being effectively controlled through the performance of appropriate preventive maintenance and make adjustments where necessary to ensure that the objective of preventing failures of those structures, systems, and components through maintenance is appropriately balanced against the objective of minimizing unavailability. Specifically, the licensee failed to adequately demonstrate the performance of appropriate preventive maintenance of Unit 1 decay heat removal system and Unit 2 instrument air compressors. In addition, the licensee failed to evaluate in 2023 the 50.65(a)(3) periodic assessment whether the unavailability of SSCs, other than MSPI systems, was appropriately balanced against the objective of preventing failures.
Enforcement Action: This violation is being treated as a non-cited violation, consistent with section 2.3.2 of the Enforcement Policy.
Failure to Establish Proper Risk Management Actions during Switchyard Maintenance Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000313,05000368/2025001-04 Open/Closed
[H.11] -
Challenge the Unknown 71111.13 The inspectors identified a Green finding and associated non-cited violation of 10 CFR 50.65(a)(4) for the failure to manage the increase in risk that may result from proposed maintenance activities. Specifically, the licensee failed to manage the increase in risk associated with planned major switchyard maintenance when they did not station a dedicated operator locally at the alternate AC diesel generator during a period when the diesel could not be started from the normal location in the control room, which was required by Procedure COPD-024, Risk Assessment Guidelines, revision 78.
Description:
Between January 27 and 29, 2025, the licensee performed planned switchyard maintenance associated with the startup transformer 2, the shared off-site power source between Unit 1 and Unit 2. The licensee assessed the transformer maintenance to include periods of major switchyard maintenance throughout the 3 days. Procedure COPD-024, Risk Assessment Guidelines, revision 078, defines major switchyard maintenance, in part, as activities that include heavy equipment movement or use in the switchyard or removal/restoring to service major switchyard components or transmission lines.
During this maintenance period, on January 29, 2025, the licensee declared the alternate AC (AAC) diesel generator non-functional due to an unexpected loss of the station blackout diesel link. This link allows the operators to remotely start the AAC diesel generator from the Unit 2 control room. With the blackout diesel link lost, the operators would need to start the AAC diesel generator locally from the AAC diesel generator building.
Procedure COPD-024 provides instructions to operators and scheduling personnel for assessing and managing risk in accordance with 10 CFR 50.65(a)(4). COPD-024, 10, Switchyard Maintenance Guidelines, requires that during major switchyard maintenance a dedicated operator must be stationed at the AAC diesel generator if the AAC diesel generator cannot be started from the control room. A locally stationed dedicated operator, not a designated operator, would be required to ensure the AAC diesel generator could be started and loaded to greater than 3135 kW within 10 minutes.
Since major switchyard maintenance was planned and the AAC diesel generator was non-functional, the inspectors walked down the AAC diesel generator building to see if the required dedicated operator was stationed, but they did not find an operator stationed in the area. The licensee told the inspectors that a designated operator had been identified to start the AAC diesel if needed, but the designated operator was not required to be stationed at the AAC diesel generator building; which could prevent the 10-minute loading requirement from being met. The period of major switchyard maintenance ended soon after the inspectors performed their walkdown, so a dedicated operator was no longer required. There was an approximately 5-hour time period of major switchyard maintenance where a dedicated operator was not stationed locally at the AAC diesel generator.
Corrective Actions: The licensee placed the issue into their corrective action program and are performing an analysis to determine why a dedicated operator was not stationed.
Corrective Action Reference: Condition Report CR-ANO-C-2025-00161
Performance Assessment:
Performance Deficiency: The licensees failure to properly manage the risk associated with switchyard maintenance activities was a performance deficiency. Specifically, the licensee failed to station a dedicated operator to locally start the AAC diesel generator if needed during a period of major switchyard maintenance when the diesel generator was unable to be started from the Unit 2 control room.
Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Protection Against External Factors attribute of the Mitigating Systems cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the inspectors determined the licensee failed to manage the risk by not stationing a dedicated operator at the AAC diesel generator during a time when major switchyard maintenance was planned and the AAC diesel was unable to be started from its normal location, which could affect the availability of the AAC diesel generator.
Significance: The inspectors assessed the significance of the finding using IMC 0609 Appendix K, Maintenance Risk Assessment and Risk Management SDP, due to the finding involving the licensees assessment and management of risk. A regional senior reactor analyst bounded the Incremental Core Damage Probability (ICDP) by determining the change in core damage frequency if the AAC diesel generator was completely unavailable. This resulted in a bounding ICDP of 1.1E-8 for Unit 1 and 2.7E-9 for Unit 2. Since the AAC diesel generator was still available but had a designated operator instead of the required dedicated operator, the ICDP would be more than a magnitude lower than the bounding ICDP case. In accordance with Flowchart 2 of Appendix K, the significance of the finding was determined to be of very low safety significance (i.e., Green) because the ICDP for both units were not greater than 1.0E-6.
Cross-Cutting Aspect: H.11 - Challenge the Unknown: Individuals stop when faced with uncertain conditions. Risks are evaluated and managed before proceeding. Specifically, the licensee did not stop during an unexpected condition and evaluate how operator actions needed to change when the AAC diesel generator could not be operated from the control room during the period of major switchyard maintenance.
Enforcement:
Violation: Title 10 CFR 50.65(a)(4) requires, in part, that before performing maintenance activities, the licensee shall assess and manage the increase in risk that may result from the proposed maintenance activities.
Contrary to the above, on January 29, 2025, the licensee failed to manage the risk that may result from the proposed maintenance activities. Specifically, risk management actions specified by COPD-024 were not taken to station a dedicated operator at the AAC diesel generator during a time when major switchyard maintenance was planned and the AAC diesel generator was unable to be started from its normal location in the Unit 2 control room.
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 that no proprietary information was retained or documented in this report.
- On April 10, 2025, the inspectors presented the ISFSI closure of URI and use of EGM inspection results to Mark Skartvedt, General Manager Plant Operations, and other members of the licensee staff.
- On April 10, 2025, the inspectors presented the integrated inspection results to Mark Skartvedt, General Manager Plant Operations, and other members of the licensee staff.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Corrective Action
Documents
CR-ANO-
C-2023-03879
03/19/2025
60855
Engineering
Evaluations
LBDCR 2024-017
Issue Revision 4 of the HI-STORM FW 72.212 Evaluation
Report
2/19/2025
Corrective Action
Documents
CR-ANO-
C-2018-00050, C-2022-03586, C-2022-03607, C-2023-
00026
OP-1104.039
Plant Heating and Cold Weather Operations
Procedures
OP-2106.032
Unit Two Freeze Protection Guide
Corrective Action
Documents
CR-ANO-
1-2025-00120
C-294
Auxiliary Building Pipe Restraints
Drawings
M-204
Piping & Instrument Diagram EFW Pump Turbine
Miscellaneous
STM 2-31
OP-1107.003
Inverter and 120V Vital AC Distribution
Procedures
OP-2104.036
Emergency Diesel Generator Operations
106
Calculations
CALC-85-E-0053-
Fire Area B-1 Combustible Loading Evaluation
Corrective Action
Documents
CR-ANO-
1-2022-00776
ANO Prefire Plan (Unit 1)
Fire Plans
ANO Prefire Plan (Unit 2)
Miscellaneous
Arkansas Nuclear One - Unit 1 and Unit 2 FHA
Control of Hot Work and Ignition Sources
Control of Combustibles
Fire Brigade Drills
Procedures
OP-2104.032
Unit 2 Fire Protection System Operations
Corrective Action
Documents
CR-ANO-
1-2024-00286, 1-2024-01469
2503
Cycle 2503 Excess RCS Leakage
Miscellaneous
250303
AOP-High Activity in RCS/AOP-Loss of Charging Simulator
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
OP-1104.036
Emergency Diesel Generator Operation
Procedures
OP-1203.039
Excess RCS Leakage
Work Orders
WO 210912, 54233222
Corrective Action
Documents
CR-ANO-
1-2006-01346, 2-2004-01033, 2-2015-02878, 2-2018-02165,
C-2018-00299, C-2025-00197
Work Orders
WO 25878, 509786
Corrective Action
Documents
CR-ANO-
C-2015-04147
0447-1P-7B
Unit 1 Protected Train for P-7B Outage
03/10/2025
STM 1-32
Electrical Distribution
Miscellaneous
STM 2-48
Arkansas Nuclear One Unit 2 System Training Manual
Instrument Air
COPD-024
Risk Assessment Guidelines
Procedures
On-Line Risk Assessment
Work Orders
WO 53003073, 54029007, 54029147, 54092974
Corrective Action
Documents
CR-ANO-
1-2023-01013, 1-2025-00154, 1-2025-00160, 1-2025-00900,
2-2023-00199, 2-2024-01868, 2-2025-00206, 2-2025-00269,
2-2025-00385
E-253, Sheet 1
Schematic Diagram Penetration Room Ventilating System
M-121-FC-OC2,
Sheet 1
Mission Duo-Check ASA 25 Series Valve Installation
Drawings
M-264, Sheet 1
P&ID Ventilation System Air Flow Containment Penetration
Room
Engineering
Changes
Engineering Input to Operability for CR-ANO-2-2024-1868
10/19/2024
ULD-1-SYS-23
ANO Unit 1 Penetration Room Ventilation System
Miscellaneous
ULD-2-SYS-01
ANO-2 Emergency Diesel Generator System
OP-1104.043
Penetration Room Ventilation System
OP-1411.184
Cleaning and Inspection of Penetration Room Ventilation
OP-2104.036
Emergency Diesel Generator Operations
106
Procedures
OP-2203.009
Fire Protection System Annunciator Corrective Action
Work Orders
WO 53008310, 54028802, 54139080
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Corrective Action
Documents
CR-ANO-
2-2024-01748
Engineering
Changes
Evaluation to Support 2CV-1050-2 Normally Closed
CALC-91-E-0099-
ECP PEAK TEMP and INVENTORY LOSS ANALYSIS
Calculations
CALC-92-D-
21-01
Voltage Settings for Offsite SU Number 1, 2, and 3
Regulators
Corrective Action
Documents
CR-ANO-
1-2022-01736, 1-2024-00891, 1-2025-00016, 1-2025-00022,
1-2025-00085, 1-2025-00097, 1-2025-00140, 1-2025-00165,
2-2024-00742, 2-2024-02515, 2-2025-00090, 2-2025-00236,
2-2025-00249
Drawings
E-2723, Sheet 1
Refueling Water Tank 2T-3 Level
Engineering
Changes
Documentation of Baseline for ANO2 Reference Values for
IST Components
ER-ANO-2002-
285-000
Service Water Boundary Valve Leakage Criteria
Engineering
Evaluations
ER-ANO-2004-
0548-000
Change Voltage Taps for Start-Up #2 Transformer
1-25-001
U1 Mech Dept PIF
Miscellaneous
TDC213 0010
OA/FA Outdoor Step Voltage Regulator
OP-1104.032
Fire Protection Systems
OP-1104.033
OP-1104.043
Penetration Room Ventilation System
OP-1106.006
Emergency Feedwater Pump Operation
2
OP-1107.001
Electrical System Operations
136
OP-1411.019
Diesel Driven Fire Pump Lubrication and Inspection
OP-1411.184
Cleaning and Inspection of Penetration Room Ventilation
OP-2107.001
Electrical System Operations
141
OP-2304.269
Unit 2 Plant Protection System RWT Instrumentation
Calibration
OP-2305.005
Valve Stroke and Position Verification
Procedures
OP-2305.034
Service Water Boundary Valve Test
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
OP-5120.410
Check Valve Disassembly and Inspection
OP-5120.417
In Place Testing of the Unit 1 Penetration Room Filtration
Systems
Work Orders
WO 00589238, 53003073, 53006542, 53006547, 53033986,
53034929, 54028802, 54029147, 54172681, 54200225,
243666
Regulatory Performance Indicator Technique/Data Sheet
Narrative Logs
71151
Miscellaneous
Regulatory Assessment Performance Indicator Guideline
Corrective Action
Documents
CR-ANO-
1-2024-02226, 1-2024-02233, 2-2018-04226, 2-2018-04336,
2-2025-00300
OP-1015.002
Decay Heat Removal and LTOP System Control
OP-1102.001
Plant Heatup and Precritical Checklist
OP-1104.012
Breathing Air System
Procedures
OP-3305.001
Category E/Locked Component Log
6