IR 05000261/2025003
| ML25330A001 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 12/01/2025 |
| From: | Matthew Fannon NRC/RGN-II/DORS/PB2 |
| To: | Basta L Duke Energy Progress |
| References | |
| IR 2025003 | |
| Download: ML25330A001 (0) | |
Text
SUBJECT:
H. B. ROBINSON STEAM ELECTRIC PLANT - INTEGRATED INSPECTION REPORT 05000261/2025003
Dear Laura Basta:
On September 30, 2025, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at H. B. Robinson Steam Electric Plant. On November 17, 2025, the NRC inspectors discussed the results of this inspection with you and other members of your staff. The results of this inspection are documented in the enclosed report.
Due to the temporary cessation of government operations, which commenced on October 01, 2025, the NRC began operating under its Office of Management and Budget-approved plan for operations during a lapse in appropriations. Consistent with that plan, the NRC operated at reduced staffing levels throughout the duration of the shutdown. However, the NRC continued to perform critical health and safety functions and make progress on other high-priority activities associated with the ADVANCE Act and Executive Order 14300. On November 13, 2025, following the passage of a continuing resolution, the NRC resumed normal operations. Due to the 43-day lapse in normal operations, the Office of Nuclear Reactor Regulation granted the Regional Offices an extension on the issuance of the calendar year 2025 inspection reports that should have been issued by November 13, 2025, to December 31, 2025. The NRC resumed the routine cycle of issuing inspection reports on November 13, 2025.
One finding of very low safety significance (Green) is documented in this report. This finding did not involve a violation of NRC requirements.
A licensee-identified violation which was determined to be of very low safety significance is documented in this report. We are treating this violation as a non-cited violation (NCV)
consistent with Section 2.3.2 of the Enforcement Policy.
If you contest the violation or the significance or severity of the violation documented in this inspection report, you should provide a response within 30 days of the date of this inspection report, with the basis for your denial, to the U.S. Nuclear Regulatory Commission, ATTN:
Document Control Desk, Washington, DC 20555-0001; with copies to the Regional Administrator, Region II; the Director, Office of Enforcement; and the NRC Resident Inspector at H. B. Robinson Steam Electric Plant.
If you disagree with a cross-cutting aspect assignment or a finding not associated with a regulatory requirement in this report, you should provide a response within 30 days of the date December 1, 2025 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 II; and the NRC Resident Inspector at H. B. Robinson Steam Electric Plant.
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, Matthew S. Fannon, Chief Projects Branch 2 Division of Operating Reactor Safety Docket No. 05000261 License No. DPR-23
Enclosure:
As stated
Inspection Report
Docket Number:
05000261
License Number:
Report Number:
Enterprise Identifier:
I-2025-003-0021
Licensee:
Duke Energy Progress, LLC
Facility:
H. B. Robinson Steam Electric Plant
Location:
Hartsville, SC
Inspection Dates:
July 01, 2025 to September 30, 2025
Inspectors:
J. Bell, Senior Health Physicist
J. Diaz-Velez, Senior Health Physicist
M. Donithan, Senior Operations Engineer
C. Dorman, Resident Inspector
J. Hickey, Senior Project Engineer
A. Nielsen, Senior Health Physicist
J. Rivera, Health Physicist
J. Vasquez, Construction Project Inspector
A. Wang, Resident Inspector
J. Zeiler, Senior Resident Inspector
Approved By:
Matthew S. Fannon, Chief
Projects Branch 2
Division of Operating Reactor Safety
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at H. B. Robinson Steam Electric Plant, in accordance with the Reactor Oversight Process. The Reactor Oversight Process is the NRCs program for overseeing the safe operation of commercial nuclear power reactors. Refer to https://www.nrc.gov/reactors/operating/oversight.html for more information. A licensee-identified non-cited violation is documented in report section: 71124.0
List of Findings and Violations
Failure to Follow Procedure Results in Electrohydraulic Control System Fluid Inventory Loss and Operator Actions to Conduct a Unit Rapid Power Reduction to Manually Trip the Main Turbine Cornerstone Significance Cross-Cutting Aspect Report Section Initiating Events Green FIN 05000261/2025003-01 Open/Closed
[H.12] - Avoid Complacency 71152A A self-revealed Green finding (FIN) was identified for the licensees failure to follow procedure requirements for periodic venting of air from the contaminate filter recirculation piping for the non-safety related turbine electrohydraulic control (EHC) system. Specifically, operator rounds procedure number R0016, H.B. Robinson Steam Electric Plant Outside Auxiliary Operator Logs, required the contaminate filter vent isolation valve to be closed after being opened to vent any potential buildup of filter gases in the contaminate filter piping. However, because the isolation valve was left partially open resulting in a loss of EHC fluid inventory, control room operators took action to conduct a rapid unit down power to 17.5% and manually trip the main turbine to avoid a potential automatic turbine trip from occurring on low EHC pressure.
Additional Tracking Items
None.
PLANT STATUS
Unit 2 began the inspection period operating at rated thermal power (RTP). On August 15, 2025, the unit was down powered to 37 percent (%) to replace reactor coolant system (RCS)flow transmitters FT-435, FT-425, and FT-426, following FT-435 experiencing degrading output performance beginning August 12, 2025. Following the transmitter replacements, the unit returned to RTP on August 16, 2025. The unit operated at or near RTP for the remainder of the inspection period.
INSPECTION SCOPES
Inspections were conducted using the appropriate portions of the inspection procedures (IPs) in effect at the beginning of the inspection unless otherwise noted. Currently approved IPs with their attached revision histories are located on the public website at http://www.nrc.gov/reading-rm/doc-collections/insp-manual/inspection-procedure/index.html. Samples were declared complete when the IP requirements most appropriate to the inspection activity were met consistent with Inspection Manual Chapter (IMC) 2515, Light-Water Reactor Inspection Program - Operations Phase. The inspectors performed activities described in IMC 2515, Appendix D, Plant Status, observed risk significant activities, and completed on-site portions of IPs. The inspectors reviewed selected procedures and records, observed activities, and interviewed personnel to assess licensee performance and compliance with Commission rules and regulations, license conditions, site procedures, and standards.
REACTOR SAFETY
71111.04 - Equipment Alignment
Partial Walkdown Sample (IP Section 03.01) (2 Samples)
The inspectors evaluated system configurations during partial walkdowns of the following systems/trains:
(1)
'A' residual heat removal (RHR) system while the 'B' RHR system was out-of-service (OOS) for planned maintenance on July 15, 2025 (2)
'B' and 'C' component cooling water (CCW) systems while the 'A' CCW pump was OOS for planned pump inboard bearing replacement on September 15-18, 2025
71111.05 - Fire Protection
Fire Area Walkdown and Inspection Sample (IP Section 03.01) (3 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) RHR pump room (fire zone 27) on July 15, 2025 (2)turbine building elevation 242 (fire zone 25E) on August 8, 2025 (3)turbine building elevation 226 (fire zone 25A) on August 25, 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 unannounced fire drill on September 5, 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 the following risk significant activities:
- planned down power to 99% RTP to conduct 'B' motor driven auxiliary feedwater (MDAFW) pump post-maintenance testing on July 8, 2025
- planned down power to 37% RTP to replace RCS flow transmitters FT-435, FT-425, and FT-426 on August 15, 2025
Licensed Operator Requalification Training/Examinations (IP Section 03.02) (1 Sample)
- (1) The inspectors observed and evaluated a licensed operator as-found simulator exam which included a charging system leak, a control rod drive cooling fan ground fault, multiple chemical and volume control system failures, and a loss of all alternating current power on July 22, 2025.
71111.12 - Maintenance Effectiveness
Maintenance Effectiveness (IP Section 03.01) (1 Sample)
The inspectors evaluated the effectiveness of maintenance to ensure the following structures, systems, and components (SSCs) remain capable of performing their intended function:
- (1) Maintenance Rule (a)(3) periodic evaluation from May 1, 2023, to April 30, 2025
[Nuclear Condition Report (NCR) 02557105]
71111.13 - Maintenance Risk Assessments and Emergent Work Control
Risk Assessment and Management Sample (IP Section 03.01) (3 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)elevated risk (Green) during preplanned reactor power maneuver to 99% to conduct testing of the 'B' MDAFW pump on July 8, 2025 (2)elevated risk (Green) during preplanned maintenance on the 'B' RHR pump on July 16, 2025 (3)elevated risk (Green) during preplanned maintenance on the dedicated shutdown diesel generator (DSDG) on August 19, 2025
71111.15 - Operability Determinations and Functionality Assessments
Operability Determination or Functionality Assessment (IP Section 03.01) (3 Samples)
The inspectors evaluated the licensee's justifications and actions associated with the following operability determinations and functionality assessments:
- (1) NCR 2557273, operation of remaining period of current operating cycle with condenser steam dump valve PRV-1324B-2 isolated, review completed on July 25, 2025
- (2) NCR 2565243, investigate 'C' steam generator narrow range level transmitter LT-495 lowering trend identified on August 18, 2025
- (3) NCR 2564542, degraded performance of 'C' loop RCS flow transmitter FT-435 and replacement of similar adversely impacted flow transmitters FT-425 and FT-426, review completed on August 27, 2025
71111.18 - Plant Modifications
Temporary Modifications and/or Permanent Modifications (IP Section 03.01 and/or 03.02) (1 Sample)
The inspectors evaluated the following temporary or permanent modifications:
(1)permanent engineering change (EC) 423306, replacement of 'B' RHR pump casing vent valve RH-781B implemented during the previous refueling outage, review completed on July 31, 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) (4 Samples)
- (1) OST-201-2, MDAFW System Component Test - Train B, following relay and lubrication preventive maintenance activities on July 8, 2025
- (2) OST-013, Weekly Checks and Operations (partial), Section 7.0, Instructions, following replacement of the 'D' deepwell pump relief valve DW-962 using Work Order (WO)
===20591404 on July 17, 2025
- (3) OST-948, DSDG Auto Start Function and Dedicated Shutdown Bus Energization, following 12-year complex maintenance evolution on August 15, 2025
- (4) WO 20744619 instructions for performing PMT following replacement of internal circuit board for 'C' steam generator narrow range level transmitter LT-495 on August 19, 2025 Surveillance Testing (IP Section 03.01)===
- (1) OST-910, Dedicated Shutdown Diesel Generator, on July 2, 2025
- (2) OST-409-1, EDG A Fast Speed Start, on July 30, 2025
- (3) MST-E-125DC-BATT-001, Station Battery A Test, and MST-E-125DC-BATT-002, Station Battery B Test, on September 9, 2025
Inservice Testing (IST) (IP Section 03.01) (1 Sample)
- (1) OST-551-1, RHR Pump A and Components Test, on September 2, 2025
71114.06 - Drill Evaluation
Required Emergency Preparedness Drill (1 Sample)
- (1) The inspectors observed and evaluated an emergency preparedness drill on July 9, 2025. The drill involved a fuel failure followed by a steam generator tube rupture and a subsequent faulted steam generator.
RADIATION SAFETY
71124.01 - Radiological Hazard Assessment and Exposure Controls
Radiological Hazard Assessment (IP Section 03.01) (1 Sample)
- (1) The inspectors evaluated how the licensee identifies the magnitude and extent of radiation levels, identifies the concentrations and quantities of radioactive materials, and assesses radiological hazards.
Instructions to Workers (IP Section 03.02) (1 Sample)
- (1) The inspectors evaluated how the licensee instructs workers on plant-related radiological hazards and the radiation protection requirements intended to protect workers from those hazards.
Contamination and Radioactive Material Control (IP Section 03.03) (2 Samples)
The inspectors observed/evaluated the following licensee processes for monitoring and controlling contamination and radioactive material:
(1)workers exiting the radiologically controlled area (2)licensee survey of potentially contaminated equipment for free release using a whole body counter
Radiological Hazards Control and Work Coverage (IP Section 03.04) (3 Samples)
The inspectors evaluated the licensee's control of radiological hazards for the following radiological work:
(1)removal of Tri Nuc filtration system from spent fuel pool (SFP)
(2)dry cask horizontal storage module inspection activities (3)at-power containment entry for leak inspection High Radiation Area and Very High Radiation Area Controls (IP Section 03.05) (2 Samples)
The inspectors evaluated licensee controls of the following high radiation areas (HRAs) and very high radiation areas (VHRAs):
- (1) SFP skimmer filter housing area (2)containment vessel 61-foot elevation and 'A' reactor coolant pump bay area Radiation Worker Performance and Radiation Protection Technician Proficiency (IP Section 03.06) (1 Sample)
- (1) The inspectors evaluated radiation worker and radiation protection technician performance as it pertains to radiation protection requirements.
71124.06 - Radioactive Gaseous and Liquid Effluent Treatment
Walkdowns and Observations (IP Section 03.01) (3 Samples)
The inspectors evaluated the following radioactive effluent systems during walkdowns:
(1)environmental and radiological control building exhaust vents, noble gas and tritium sample collection (2)liquid waste discharge pathway, through monitor R-18 (3)lower fuel handling building exhaust vent, noble gas, tritium, particulate, iodine sample collection
Sampling and Analysis (IP Section 03.02) (3 Samples)
Inspectors evaluated the following effluent samples, sampling processes and compensatory samples:
(1)plant vent gaseous monitor, R-14, sample line configuration (2)plant vent gaseous monitor, R-14, compensatory sampling records, 8/12/24 - 8/13/24 (3)liquid waste disposal monitor, R-18, compensatory sampling records, 12/19/24 - 12/23/24
Dose Calculations (IP Section 03.03) (2 Samples)
The inspectors evaluated the following dose calculations:
- (1) gaseous release permit number G-2025-0122 (2)liquid release permit number L-2025-0101
71124.07 - Radiological Environmental Monitoring Program
Environmental Monitoring Equipment and Sampling (IP Section 03.01) (1 Sample)
- (1) The inspectors evaluated environmental monitoring equipment and observed collection of environmental samples.
Radiological Environmental Monitoring Program (IP Section 03.02) (1 Sample)
- (1) The inspectors evaluated the implementation of the licensees radiological environmental monitoring program.
GPI Implementation (IP Section 03.03) (1 Sample)
- (1) The inspectors evaluated the licensees implementation of the Groundwater Protection Initiative (GPI) program to identify incomplete or discontinued program elements.
71124.08 - Radioactive Solid Waste Processing & Radioactive Material Handling, Storage, &
Transportation
Radioactive Material Storage (IP Section 03.01)
The inspectors evaluated the licensees performance in controlling, labeling and securing the following radioactive materials:
(1)radioactive materials stored in the auxiliary building, and the radwaste building
Radioactive Waste System Walkdown (IP Section 03.02) (1 Sample)
The inspectors walked down the following accessible portions of the solid radioactive waste systems and evaluated system configuration and functionality:
(1)accessible components at the radwaste building truck bay area, auxiliary building wastewater demineralization system, waste disposal panel, and condensate filters
Waste Characterization and Classification (IP Section 03.03) (2 Samples)
The inspectors evaluated the following characterization and classification of radioactive waste:
(1)10 CFR Part 61, Station Report for H. B. Robinson Change 101, dated 08/24/2023.
(2)10 CFR Part 61, Station Report for H. B. Robinson Change 105, dated 12/17/2024.
Shipping Records (IP Section 03.05) (3 Samples)
The inspectors evaluated the following non-except radioactive material shipments through a record review:
(1)shipment 23-0048, dry active waste, two 20' Sealand containers, low specific activity (LSA-I), shipped on 07/11/2023.
(2)shipment 25-0021, Spent resin storage tank (SRST) dewatered bead resin, high integrity container (HIC) (Type B(U) Cask), shipped on 05/09/2024.
(3)shipment 25-0011, SRST dewatered bead resin HIC, low specific activity (LSA-II),shipped on 02/20/2025.
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 2 (July 1, 2024, through June 30, 2025)
IE03: Unplanned Power Changes per 7000 Critical Hours Sample (IP Section 02.02) (1 Sample)
- (1) Unit 2 (July 1, 2024, through June 30, 2025)
MS08: Heat Removal Systems (IP Section 02.07) (1 Sample)
- (1) Unit 2 (July 1, 2024, through June 30, 2025)
OR01: Occupational Exposure Control Effectiveness Sample (IP Section 02.15) (1 Sample)
- (1) December 10, 2024, through July 31, 2025 PR01: Radiological Effluent Technical Specifications/Offsite Dose Calculation Manual Radiological Effluent Occurrences (RETS/ODCM) Radiological Effluent Occurrences Sample (IP Section 02.16) (1 Sample)
- (1) December 14, 2024, through August 1, 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)loss of turbine electrohydraulic control (EHC) system fluid inventory resulting in AOP-038, Rapid Downpower, entry and taking the turbine offline (NCR 2557259)
OTHER ACTIVITIES
- TEMPORARY INSTRUCTIONS, INFREQUENT AND ABNORMAL
===60859 - Independent Spent Fuel Storage Installation (ISFSI) License Renewal Inspection 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) 2690, Inspection Program for Storage of Spent Reactor Fuel and Reactor-Related Greater-than-Class C Waste at Independent Spent Fuel Storage Installations (ISFSI) and for 10 CFR Part 71 Transportation Packaging.
Independent Spent Fuel Storage Installation (ISFSI) License Renewal Inspection===
- (1) The inspectors reviewed a sample of documents planning and implementing aging management activities, and aging management programs (AMPs) required by the General License Certificate of Compliance (CoC) 72 - 1004 issued for the standardized NUHOMS system and described in the applicable Final Safety Analysis Reports (FSARs).
The inspectors were on-site from July 28-31, 2025. During this time, the inspectors reviewed implementing procedures, observed in-process non-destructive examination of NUHOMS horizontal module storage HSM-10 and dry storage canister RNP-24PTH-L-2B-H201, and conducted interviews with licensee staff to verify that the licensee was implementing the necessary actions to:
- (a) comply with the conditions stipulated in the CoCs; and
- (b) implement the TLAAs and AMPs as described in updated NUHOMS FSARs and associated NRC safety evaluation report.
For those license renewal items that were not completed at the time of this inspection, the team verified that there was reasonable assurance that the items were on track for completion in accordance with an established implementation schedule consistent with the conditions of the CoCs, FSARs, technical specifications, and the NRC safety evaluation report.
INSPECTION RESULTS
Licensee-Identified Non-Cited Violation 71124.06 This violation of very low safety significance was identified by the licensee and has been entered into the licensee corrective action program and is being treated as a non-cited violation, consistent with Section 2.3.2 of the Enforcement Policy.
Violation: 10 CFR Part 20.1302 states, in part, that the licensee shall survey radioactive materials in effluents released to unrestricted areas to demonstrate compliance with the dose limits for individual members of the public in 10 CFR Part 20.1301. Contrary to this, from 2013 to discovery in 2021, the licensee failed to conduct adequate surveys of their offsite liquid effluent releases. Specifically, in 2021, the licensee was notified by the effluent management software vendor of an error in the calculation parameters. The error involved overestimation of the dilution flow for routine liquid releases by a factor ranging from 100 to 1000, which resulted in an underestimation of radioactive effluent concentrations and doses to members of the public. The licensee made the recommended software upgrades and re-evaluated previously reported effluent releases. The revised calculations showed that the releases were still below regulatory limits. The new results were captured as Errata in the 2021 and 2022 annual effluent reports. NCR 2399509 states that the software error also affected Brunswick and Harris nuclear plants.
Significance/Severity: Green. The finding was part of the licensee's effluent release program, but it did not involve any release of radioactive material into the environment that exceeded the dose values in Appendix I to 10 CFR Part 50 and/or 10 CFR 20.1301. It also does not represent a substantial failure of the licensee's effluent monitoring program.
Corrective Action References: NCR 2399509 Failure to Follow Procedure Results in Electrohydraulic Control System Fluid Inventory Loss and Operator Actions to Conduct a Unit Rapid Power Reduction to Manually Trip the Main Turbine Cornerstone Significance Cross-Cutting Aspect Report Section Initiating Events Green FIN 05000261/2025003-01 Open/Closed
[H.12] - Avoid Complacency 71152A A self-revealed Green finding (FIN) was identified for the licensees failure to follow procedure requirements for periodic venting of air from the contaminate filter recirculation piping for the non-safety related turbine electrohydraulic control (EHC) system. Specifically, operator rounds procedure number R0016, H.B. Robinson Steam Electric Plant Outside Auxiliary Operator Logs, required the contaminate filter vent isolation valve to be closed after being opened to vent any potential buildup of filter gases in the contaminate filter piping. However, because the isolation valve was left partially open resulting in a loss of EHC fluid inventory, control room operators took action to conduct a rapid unit down power to 17.5% and manually trip the main turbine to avoid a potential automatic turbine trip from occurring on low EHC pressure.
Description:
On June 7, 2025, the control room operators received an alarm from the EHC fluid reservoir (tank) indicating that level had lowered to its lowest level alarm setpoint of 7.625 inches, which automatically locked out the start of the second non-running B EHC pump. The operators recognized that two other lowering reservoir level alarms, set at 17.25 inches and 11.75 inches, were not received as expected. Immediate actions were taken to monitor for lowering EHC system pressure and auxiliary operators (AOs) were dispatched to the EHC system skid. The AOs reported that large amounts of EHC fluid was spilled on the floor around the skid, but the source of the leakage could not be readily identified at the time.
In addition, due to the wetted conditions around the EHC reservoir area, the AOs could not safely access the upper platform panel containing the local reservoir level indicator to confirm the amount of reservoir level lost. Based on the available information that suggested a large EHC leak existed, the operators decided to commence a rapid unit down power to 17.5% and manually trip the main turbine to preclude a potential automatic trip from occurring on low EHC system pressure. The unit down power and main turbine removal from service evolutions were conducted successfully without incident.
Subsequent licensee investigations revealed there was approximately 35 gallons of fluid lost from the EHC reservoir. Since normal operating level in the reservoir was typically approximately 20 inches (or 132.5 gallons of fluid), a loss of 35 gallons from the normal reservoir level would result in a reservoir level of approximately 15 inches. The licensees troubleshooting of the level alarm malfunctions identified that most likely the 7.625-inch alarm prematurely actuated due to excessive system vibration as the reservoir lost inventory and the 17.25-inch 11.75 alarms failed to actuate due to a physical mechanical interference found between a level circuitry wire with the moving components associated with the level switch device.
The licensees investigation into the source of the EHC system leakage identified the leakage was from the contaminate filter vent valve EH-65, which had been manipulated by an AO approximately two hours prior to receipt of the initial reservoir low level alarm. This 1/4-inch petcock style, 90-degree manual ball valve was opened as part of the weekly AO rounds for venting the contaminate filter to remove any potential buildup of filter gases. The licensee conducted extensive mechanical testing of the as-found condition of EH-65 and determined that it could not have malfunctioned or vibrated open. Based on the amount of fluid inventory lost and valve flowrate testing, it was concluded that the AO left EH-65 partially open following the venting activity. The inspectors reviewed AO rounds procedure number R0016, H.B. Robinson Steam Electric Plant Outside Auxiliary Operator Logs. The instructions for venting the EHC system contaminate filter directed the AO to open EH-65 when oil flow is seen, close EH-65. Since EH-65 does not have a travel stop in the open or close directions, confidence in positioning the valve to the full close position would rely on ensuring the handle was 90-degrees from the direction of pipe flow in either direction. Based on review of the licensees investigations and testing, the inspectors agreed with the licensees conclusion that EH-65 was most likely left out of the proper closed orientation position during the operator rounds venting activity which allowed the EHC fluid leakage.
Corrective Actions: The licensee refilled the EHC reservoir and conducted extensive leak testing to identify any other potential sources of leakage. The EHC reservoir mercury level switches were replaced, the wiring interference issue corrected, and subsequent testing confirmed restoration of proper reservoir switch operation. A pipe plug was installed downstream of vent valve EH-65 to provide an extra leak isolation barrier from the contaminate filter until a more robust vent valve could be installed that was designed with a hard stop to provide positive indication of full closure. Also, the AO involved in leaving EH-65 partially open was removed from rounds duties until remediation training could be administered.
Corrective Action References: NCR 2557259
Performance Assessment:
Performance Deficiency: The failure to follow operator rounds procedure number R0016, H.B. Robinson Steam Electric Plant Outside Auxiliary Operator Logs, requiring closure of vent valve EH-65 following venting of the EHC system contaminate filter was a performance deficiency that was within the licensees ability to foresee and prevent.
Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Human Performance attribute of the Initiating Events cornerstone and adversely affected the cornerstone objective to limit the likelihood of events that upset plant stability and challenge critical safety functions during shutdown as well as power operations. Specifically, the loss of fluid inventory from the EHC reservoir due to the partially open vent valve resulted in operator actions to conduct a rapid unit down power to 17.5% and manually trip the main turbine to prevent a potential automatic turbine trip from occurring.
Significance: The inspectors assessed the significance of the finding using IMC 0609 Appendix A, The Significance Determination Process (SDP) for Findings At-Power. The inspectors determined the finding was of very low safety significance (Green) because it did not cause a reactor trip AND the loss of mitigation equipment relied upon to transition the plant from the onset of a trip to a stable shutdown condition.
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, inspectors determined that the most likely cause of the failure to follow procedure error was the lack of self-checking and attention to detail which is related to implementing appropriate error reduction tools for routine tasks.
Enforcement:
Inspectors did not identify a violation of regulatory requirements associated with this finding.
EXIT MEETINGS AND DEBRIEFS
The inspectors verified no proprietary information was retained or documented in this report.
- On November 17, 2025, the inspectors presented the integrated inspection results to Laura Basta and other members of the licensee staff.
- On July 31, 2025, the inspectors presented the radiation protection baseline inspection results to George Curtis, Plant General Manager, and other members of the licensee staff.
- On September 11, 2025, the inspectors presented the ISFSI license renewal inspection results to Brenda Hayes, Nuclear Support Services Manager, and other members of the licensee staff.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Corrective Action
Documents
ISFSI License Renewal (Aging Management) Inspection
Areas
7/31/2025
60859
Procedures
PTIP-11184-10.1
Implementing Non-Destructive Examination Procedure
Revision 1
Residual Heat Removal System
Rev. 85
Procedures
Component Cooling Water System
Rev. 83
CSD-RNP-PFP-
AB2-0226-001
Auxiliary Building ELEV 226 Pre-Fire Plan
Rev. 3
CSD-RNP-PFP-
TB2-0226-001
Unit 2 Turbine Building Elev 226 Pre-Fire Plan
Rev. 5
Fire Plans
CSD-RNP-PFP-
TB2-0242-001
Turbine Building Elev 242 Pre-Fire Plan
Rev. 4
AD-FP-ALL-1520
Transient Combustible Control
Rev. 3
AD-FP-ALL-1522
Duties of a Compensatory Fire Watch
Rev. 4
AD-OP-ALL-0207
Fire Brigade Administrative Controls
Rev. 7
AD-TQ-ALL-0086
Fire Brigade and Hazmat Training
Rev. 7
Response to Fire Event
Rev. 18
CSD-RNP-PFP-
SOGS-001
Fire Brigade Standard Operating Guidance
Rev. 1
Fire Protection Systems Minimum Equipment and
Compensatory Actions
Rev. 40
Procedures
OMM-002
Fire Protection Manual
Rev. 59
AD-OP-ALL-1000
Conduct of Operations
Rev. 26
Procedures
Maneuvering the Plant When Greater Than 25% Power
Rev. 75
Procedures
AD-EG-ALL-1210
Rev 5
AD-OP-ALL-0210
Operational Risk Management
Rev. 4
AD-WC-ALL-
200
On-Line Work Management
Rev. 22
AD-WC-ALL-
240
On-Line Risk Management Process
Rev. 6
Procedures
CSD-WC-RNP-
240-00
Rev. 1
Procedures
AD-OP-ALL-0105
Rev. 9
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Procedures
AD-EG-ALL-1132
Preparation and Control of Engineering Changes
Rev. 30
Procedures
PLP-033
Post-Maintenance Testing (PMT) Program
Rev. 70
Corrective Action
Documents
ALARA Plan R2R34-0101 exceeded original dose estimate
by greater than 25%
Corrective Action
Documents
Resulting from
Inspection
PRR 02563412
Enhancement to procedure AD-RP-ALL-0007 for free
release of potentially contaminated material using whole
body counter
Procedures
AD-RP-ALL-0007
Control of Radioactive Material
Rev 4
Corrective Action
Documents
Licensee notified of error in effluent management software
Corrective Action
Documents
Resulting from
Inspection
Documents licensee identified violation
Corrective Action
Documents
Resulting from
Inspection
Tree Limb in Close Proximity to APAC-5
Document not vaulted within 90
day requirement
Spent Resin Transfer to HIC Exceeded Dose Estimate
Corrective Action
Documents
NOS Audit: Missing QA Records for Rad. Material
Shipments
AD-EG-ALL-1217
Mitigating System Performance Index (MSPI)
Rev. 3
71151
Procedures
AD-PI-ALL-0700
Performance Indicators
Rev. 7
AD-PI-ALL-0100
Corrective Action Program
Rev. 31
Procedures
AD-PI-ALL-0106
Cause Investigation Checklists
Rev. 11