Semantic search
| Discovered date | Reporting criterion | Title | Description | LER | |
|---|---|---|---|---|---|
| ENS 57203 | 1 July 2024 13:42:00 | 10 CFR 26.719, FFD Reporting requirements | Positive Fitness for Duty Test | The following information was provided by the licensee via phone and email: At 0942 EDT on July 1, 2024, it was determined that an individual had a confirmed positive test as specified by the fitness-for-duty testing program. The individual's authorization for site access has been terminated. The NRC Resident Inspector has been notified. | |
| ENS 57159 | 3 June 2024 04:51:00 | 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Automatic Actuation of Emergency Feedwater System | The following information was provided by the licensee via phone and email: At 0051 EDT on June 3, 2024, with Unit 3 in Mode 3 at 0 percent power, an actuation of the emergency feedwater system (EFW) occurred as main steam pressure was being lowered as part of reactor coolant system (RCS) cooldown for a planned shutdown. The reason for the EFW auto-start was lowering levels in the 3A and 3B steam generators following loss of the operating main feedwater pump. The main feedwater pump automatically tripped when main steam pressure was lowered below the automatic feedwater isolation system (AFIS) actuation setpoint before AFIS channels were taken to bypass. The 3A and 3B motor driven emergency feedwater pumps automatically started as designed when the low steam generator level signal was received for the 3A and 3B steam generators. This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the EFW system. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. | |
| ENS 57104 | 3 May 2024 11:50:00 | 10 CFR 26.719, FFD Reporting requirements | Controlled Substance Found in Protected Area | The following information was provided by the licensee via email and phone call: At approximately 0750 EDT on 05/03/24, an employee discovered an unopened can of an alcoholic beverage inside a refrigerator located in a common break area inside the protected area. The container label indicates the beverage is 5.3 percent alcohol by volume. The employee immediately reported the discovery to their supervisor and site security. Security took possession of the container and is continuing the investigation. The Resident Inspector has been notified. | |
| ENS 56830 | 3 November 2023 19:30:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Offsite Notification - Press Release | The following information was provided by the licensee via email: A press conference is being held by the Oconee County Sheriff's office today at 1530 EDT in which Duke Energy will be present and may participate regarding the facts pertaining to an event that occurred outside the Oconee Nuclear Power Plant. The NRC Resident Inspector was notified. This is a four-hour report per 10 CFR 50.72(b)(2)(xi) for any event or situation for which a news release is planned or notification to other government agencies has been or will be made which is related to heightened public or government concern. The event is not significant with respect to the health and safety of the public. | |
| ENS 56221 | 14 November 2022 11:30:00 | 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | Reactor Coolant System (RCS) Pressure Boundary Degraded | The following information was provided by the licensee via email: During a scheduled refueling outage, a walkdown inside containment discovered a small amount of boron on the 1B2 Reactor Coolant Pump (RCP) lower bearing temperature instrument. At 0730 EST on November 14, 2022, with Unit 1 in Mode 6, disassembly of the instrument indicated the source of the boron was from a leak in the thermowell. The thermowell is considered part of the reactor coolant system pressure boundary and as such the condition is reportable. Repairs for the condition are in progress. This event is being reported as an eight-hour non-emergency notification per 10 CFR 50.72(b)(3)(ii)(A). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. | |
| ENS 56197 | 1 November 2022 18:33:00 | 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | Reactor Coolant System (RCS) Pressure Boundary Degraded | The following information was provided by the licensee via email: At 1433 EDT on November 1, 2022, it was determined that a single relevant indication in the RCS pressure boundary did not meet the acceptance criteria under ASME, Section XI IWB-3514-2. 'Allowable Planar Flaws.' The condition will be resolved prior to plant startup. This event is being reported as an eight-hour non-emergency notification per 10 CFR 50.72(b)(3)(ii)(A). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. | |
| ENS 55888 | 7 May 2022 03:10:00 | 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Automatic Actuation of Emergency Feedwater | The following information was provided by the licensee via fax: At 2310 EDT on May 6, 2022, with Unit 3 in Mode 3, an actuation of the Emergency Feedwater (EFW) System occurred while entering a planned refueling outage. The reason for the EFW auto-start was a loss of all Main Feedwater (MFDW) Pumps which occurred when the 3A MFDW Pump tripped on steam generator (SG) overfill protection due to high level in the 3B SG. The high level in the 3B SG occurred when a Startup Feedwater Control Valve (3FDW-44) malfunctioned, resulting in excessive feedwater flow to the 3B SG. Investigation and repairs are in progress. Units 1 and 2 were not affected. This event is being reported as an 8-hr non-emergency notification in accordance with 10 CFR 50.72(b)(3)(iv)(A) as a valid actuation of the EFW system. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. | |
| ENS 55750 | 22 February 2022 03:07:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Manual Reactor Trip | The following information was provided by the licensee via fax or email: At 2207 (EST) on 2/21/2022 with Unit 2 in Mode 1 at 68 percent power, the reactor was manually tripped due to lowering water level in the 2A Steam Generator. The trip was not complex with all systems responding normally post-trip. Operators responded and stabilized the plant. Decay heat is being removed by discharging steam to the main condenser using the turbine bypass valves. Units 1 and 3 were not affected. Due to the Reactor Protection System actuation while critical, this event is being reported as a four-hour, non- emergency notification per 10 CFR 50.72(b)(2)(iv)(B). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified."
The following information was provided by the licensee via phone and email: On 2/21/2022, Unit 2 was in Mode 1 increasing reactor power following startup from a forced outage. At 2205 (EST) with Unit 2 at 68 percent power, a feedwater control valve failed to properly control feedwater flow to the 2A Steam Generator and the Integrated Control System initiated an automatic runback. At 2207 (EST), the reactor was manually tripped from 39 percent power due to lowering water level in the 2A Steam Generator. Immediately following the manual reactor trip, an actuation of the Emergency Feedwater System (EFW) occurred. The 2A and 2B Motor Driven Emergency Feedwater (MDEFW) pumps automatically started as designed when the 'low steam generator level' signal was received for the 2A Steam Generator. The trip was not complex with all systems responding normally post-trip. Operators responded and stabilized the plant. Decay heat was removed by discharging steam to the main condenser using the turbine bypass valves. Units 1 and 3 were not affected. Unit 2 was restarted on 2/27/2022 following repairs. Due to the Reactor Protection System actuation while critical, this event was reported on 2/22/2022 as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). Following further evaluation, it was determined that a valid EFW actuation occurred, therefore this event is now also being reported as a late 8-hour non-emergency notification of a valid actuation of the EFW system in accordance with 10 CFR 50.72(b)(3)(iv)(A). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. Notified the R2DO (Miller). | |
| ENS 55800 | 13 February 2022 21:25:00 | 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Emergency Feedwater System Actuation | The following information was provided by the licensee via email and phone: At 1625 (EST) on 2/13/2022, with Unit 2 in Mode 3 at 0 percent power and plant heat up to normal operating temperature in progress, an actuation of the Emergency Feedwater System (EFW) occurred. The reason for the EFW auto-start was lowering water level in the 2A and 2B Steam Generators due to failure of the 2A Main Feedwater Pump to respond as required to maintain Steam Generator water level as Steam Generator pressure increased during plant heat up. The 2A and 2B Motor Driven Emergency Feedwater (MDEFW) pumps automatically started as designed when the 'low steam generator level' signal was received for the 2A and 2B Steam Generators. Following further evaluation, it was determined that a valid EFW actuation occurred, therefore this event is being reported as a late 8-hour non-emergency notification of a valid actuation of the EFW system in accordance with 10 CFR 50.72(b)(3)(iv)(A). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. | |
| ENS 55733 | 5 February 2022 08:57:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Visual Observation of Smoke and Multiple Fire Alarms in the West Penetration Room | The following information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: At 0357 EST on 2/5/22, Oconee Unit 2 declared an Unusual Event due to a multiple fire alarms and visual observance of a smoke filled room in the West Penetration Room (EAL HU 4.1). Unit 2 automatically tripped and entered Mode 3. There was an indication that a release to the environment potentially occurred. Units 1 and 3 remained at 100% power. The Licensee notified the NRC Resident Inspector, the State, and local authorities. Notified DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), and DHS Nuclear SSA (email).
The following information was provided by the licensee via email: At 0343 EST on February 5th, 2022, with Unit 2 in Mode 1 at 100% power, the reactor automatically tripped due to Reactor Coolant Pump (RCP) Flux/Flow Imbalance caused by the simultaneous trip of all 4 RCPs. The cause of the loss of all RCPs is under investigation. The trip was not complex. There was no inoperable equipment prior to the event that contributed to it. Operations responded and stabilized the plant. Decay heat is being removed by the Reactor Coolant System (RCS) in natural circulation with normal feedwater flow. Due to the Reactor Protection System (RPS) actuation while critical, this event is being reported as a four hour, nonemergency notification per 10 CFR 50.72(b)(2)(iv)(B). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The Licensee notified the State and local authorities. Notified R2DO (Miller)
The following information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: At 0811 EST on 2/5/22, Oconee Unit 2 terminated the notification of unusual event because EAL HU 4.1 criteria were no longer met. Unit 2 remains shutdown in Mode 3. The licensee has notified the State and local authorities and will notify the NRC Resident Inspector. Notified R2DO (Miller), IRD MOC (Gott), NRR EO (Regan), DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email).
The following information was provided by the licensee via email: The follow-up investigation determine that the cause of the trip was determined to be a failed fuse in an undervoltage monitoring circuit for the electrical bus powering the reactor coolant pumps. The trip of the reactor coolant pumps resulted in an automatic reactor trip as designed. The plant responded as expected. There was no fire. The response of the main feedwater system caused an expected increase in temperature in a standby portion of the system which caused the breakdown of the pipe coating producing smoke. There was no release to the environment. The reading of a single instrument was determined to be invalid and other indications supported the conclusion that no release occurred. The following information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The Licensee notified the NRC Resident Inspector, State and local authorities. A media release was issued on 2/5/22. Notified R2DO (Miller), IRD MOC (Gott), NRR EO (Regan). | |
| ENS 55713 | 26 January 2022 15:50:00 | 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor | Required Offsite and Both Onsite Emergency AC Power Paths Inoperable | Licensee provided the following information via email: At 1050 EST on January 26, 2022, it was discovered that the required offsite and the overhead and underground paths of onsite emergency AC power were simultaneously inoperable; therefore this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(A). The overhead path and both required offsite paths were inoperable due to a lockout of the Unit 3 Startup Transformer CT-3. The underground path was made momentarily inoperable as part of aligning an additional offsite power source to Unit 3 to provide defense in depth to a loss of power. The safety function was restored at 1051 EST when the underground path was declared OPERABLE. The offsite power source was restored at 1651 EST. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
The Licensee updated the 3rd paragraph above as follows via email: The safety function was restored at 1051 EST when the underground path was declared OPERABLE. An offsite power source was restored through Transformer CT-5 within 15 minutes. Startup transformer CT-3 was restored and all offsite and the onsite overhead power source were returned to service by 1651 EST. Investigation of the cause of the CT-3 lockout is in progress. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified of this update. | |
| ENS 55638 | 10 December 2021 05:49:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Automatic Reactor Trip | At 0049 EST, on December 10, 2021, with Unit 2 in Mode 1 at 73 percent power, the reactor automatically tripped due to an unknown condition. The trip was not complex, with all systems responding normally post-trip. Operations responded and stabilized the plant. Decay heat is being maintained by discharge steam to the main condenser using the turbine bypass valves. Units 1 and 3 are not affected. The cause of the trip is under investigation. Due to the Reactor Protection System actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)iv)(B). There was no impact to the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. All rods inserted into the core during the trip. The plant is in its normal shutdown electrical lineup maintaining normal operating pressure and temperature. | |
| ENS 55612 | 27 November 2021 10:19:00 | 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Automatic Actuation of the Emergency AC Electrical Power System | At 0519 EST on November 27, 2021, with Unit 2 in Mode 5 at zero percent power, an actuation of the Emergency AC Electrical Power System occurred. The reason for the Emergency AC Electrical Power System auto-start was a lockout of the CT-2 transformer; causing a temporary loss of AC power to the main feeder bus. The Keowee Hydroelectric Units 1 and 2 automatically started as designed when a main feeder bus undervoltage signal was received. This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the Emergency AC Electrical Power System. Additionally, the temporary loss of AC power resulted in a loss of Decay Heat Removal (DHR) that was restored upon power restoration to the main feeder bus. Therefore, this condition is also being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v) for an event or condition that could have prevented fulfillment of a safety function. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. The loss of the CT-2 transformer is under investigation. Main feeder bus power was restored within a minute so no plant heat up occurred as a result of the loss of the decay heat removal system. | |
| ENS 55523 | 14 October 2021 21:27:00 | 10 CFR 26.719, FFD Reporting requirements | Fitness for Duty - Failed Test | At 1727 (EDT) on October 14, 2021, it was determined that a licensed operator failed a test specified by the Fitness-For-Duty (FFD) testing program. The individual's authorization for site access has been terminated. The NRC Resident Inspector has been notified. | |
| ENS 54771 | 10 July 2020 13:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Planned Common Emergency Operations Facility Maintenance | At 0900 EDT hours on 7/10/2020 Duke Energy will undertake planned maintenance activities on the common Emergency Operations Facility (EOF) for Brunswick, Catawba, Harris, McGuire, Oconee, and Robinson nuclear sites. The work includes performance of upgrades to the emergency AC power system and requires the removal of both normal and emergency power to the facility. The work duration is approximately ten (10) days. If a declared emergency were to occur at Oconee, the Alternate EOF would be set up in the Catawba Alternate Technical Support Center (TSC) location as described in implementing procedures. The Emergency Response Organization has been notified that the primary EOF will be unavailable during the upgrade project and to report to the alternate location, if activated. This is an eight-hour, non-emergency notification for a loss of emergency assessment capability. This event is reportable in accordance with 10 CFR 50.72(b)(3)(xiii) because the work activity affects the functionality of an emergency response facility. The NRC Resident Inspector has been notified. | |
| ENS 54661 | 11 April 2020 01:25:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Manual Reactor Trip | At 2125 EDT on April 10, 2020, with Unit 3 in Mode 1 at approximately 32 percent power, the reactor was manually tripped due to a tube leak in the 3F1 feedwater heater. The trip occurred during a planned shutdown for a refueling outage. The trip was not complicated, with all systems responding normally post-trip. Decay heat is being removed by discharging steam to the main condenser using the turbine bypass valves. Units 1 and 2 were not affected. Due to the Reactor Protection System actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. | |
| ENS 54509 | 3 February 2020 14:15:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Emergency Assessment Capability Due to Planned Tsc and Osc Upgrades | At 0915 EST on February 3, 2020, planned upgrades to the Technical Support Center (TSC) and Operations Support Center (OSC) will begin. The work includes upgrades to furniture, carpet, telecommunications, celling tiles, and HVAC vent covers and the installation of new Audio-Visual equipment to include monitors, speakers, and microphones. The work duration is approximately eight weeks. If an emergency is declared requiring TSC and OSC activation during this period, the TSC and OSC will be staffed and activated at the alternate location in accordance with applicable site procedures. The Emergency Response Organization team has been notified of the TSC and OSC planned upgrades and the need to assemble and staff the alternate location during an emergency. This is an eight-hour, non-emergency notification for a planned loss of Emergency Assessment Capability. This event is reportable in accordance with 10 CFR 50.72(b)(3)(xiii) because the work activity affects the functionality of an emergency response facility. There is no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. | |
| ENS 54465 | 7 January 2020 18:41:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Chill Water System Inoperable | At 1341(EST), on 01/07/20, it was discovered all trains of the Chilled Water System were simultaneously Inoperable; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(D). During this event, the Bravo train chiller was operating in a maintenance run and the temporary chiller was available and placed in service promptly to restore the safety function. The control room area cooling safety function was restored at time 1435 (EST) when one required train was declared Operable. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
The purpose of this notification is to retract a previous report made on January 7, 2020, at 1909 EST (EN#54465). A subsequent evaluation determined that the Bravo train chiller, which was running at the time of the event, would be able to perform its safety function and was operable at the time of the event. Therefore, there was no loss of safety function. The NRC Senior Resident Inspector has been notified. Notified R2DO (Coovert). | |
| ENS 54268 | 11 September 2019 16:48:00 | 10 CFR 26.719, FFD Reporting requirements | Fitness-For-Duty Report Involving a Contract Supervisor | A non-licensed contract supervisor had a confirmed positive for illegal drugs during a random fitness-for-duty test. The individual's authorization for site access has been terminated. The NRC Resident Inspector has been notified. | |
| ENS 53677 | 19 October 2018 04:00:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Turbine Steam Seal Header Pressure Malfunction | On 10/19/18 at 2202 EDT, at 19 (percent) Reactor power, a malfunction of (the) Turbine Steam Seal Header pressure control caused a loss of Condenser vacuum, resulting in an automatic trip of the Main Turbine and a manual reactor trip (RPS Actuation). Just prior to the reactor trip, Emergency Feedwater was manually initiated to mitigate the potential loss of Main Feedwater. Condenser vacuum was recovered after the reactor trip and Main Feedwater remained in operation. Due to the RPS actuation while critical, this event is being reported as a 4-hour non-emergency per 10CFR50.72(b)(2). Also, due to the manual initiation of Emergency Feedwater, this event is also being reported as an 8-hour non-emergency per 10CFR50.72(b)(3). Following the reactor trip, all systems responded as expected with no complications. Emergency feedwater was secured at 2300. Unit 1 is in Mode 3 and stable, continuing to cooldown for a refueling outage. The NRC Resident Inspector has been notified. | |
| ENS 53396 | 10 May 2018 20:17:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Notification of Unusual Event | Unit 3 experienced a loss of AC power while in Mode 6. Power was regained automatically from Keowee via the underground path. Decay heat removal has been restored. Spent fuel cooling has been restored. Emergency procedures (are) in progress. The Licensee notified the senior NRC resident inspector, State of South Carolina and local authorities. The total loss of 4160 volt AC power was for approximately 30 seconds. The unit is refueled and reactor reassembly complete up to bolting on the reactor head. There was no effect on Units 1 and 2. Notified DHS SWO, FEMA Ops Center, FEMA NWC, DHS NICC, and NuclearSSA
At 0530 EDT, Oconee terminated the notification of unusual event on Unit 3. The basis for termination was that offsite power was restored and the plant is now in its normal shutdown electrical lineup. The licensee has notified Oconee and Pickens counties and will be notifying the NRC Resident Inspector. Notified R2DO (Ehrhardt), NRR EO (Miller), IRD MOC (Gott), DHS SWO, FEMA Operations Center, DHS NICC, FEMA NWC (email) and NuclearSSA (email). | |
| ENS 53329 | 13 April 2018 06:27:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Manual Reactor Trip Following Main Feedwater Control Problem | On 4/13/2018 at 0227 (EDT), the Oconee Unit 1 Reactor was manually tripped from 24 percent power due to the inability to control main feedwater flow through the Main Feedwater Control Valves using the Integrated Control System. Due to the RPS actuation while critical, this event is being reported as a 4-hour Non-Emergency per 10 CFR 50.72(b)(2)(iv)(B). Following the reactor trip, multiple Main Steam Relief Valves failed to reseat at the expected pressure. Using procedure guidance, Main Steam Pressure was lowered by 115 psig, resulting in the closing of all Main Steam Relief Valves. All other post-trip conditions are normal and all other systems performed as expected. Unit 1 is currently in Mode 3 and stable. Decay heat is being removed by the steam generators discharging steam to the main condenser using the turbine bypass valves. Units 2 and 3 are not affected by the Unit 1 reactor trip. The licensee notified the NRC Resident Inspector. | |
| ENS 52870 | 24 July 2017 20:38:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Automatic Reactor Trip Due to Load Rejection | At 1638 (EDT) on 7/24/2017, Oconee Unit 3 experienced an automatic reactor trip due to a load rejection when the generator output breakers both tripped open unexpectedly while 525kV switchyard maintenance was being performed. The trip was uncomplicated with all systems responding normally post-trip. Due to the RPS (Reactor Protection System) actuation while critical, this event is being reported as a 4-hour non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). The plant responded normally to the reactor trip, and there was no impact on the health and safety of the public or plant personnel. Operations responded using the Emergency Operating Procedure and stabilized Unit 3 in MODE 3. The NRC Senior Resident Inspector has been notified. Decay heat is removed by discharging steam to the main condenser using the turbine bypass valves. Unit 1 and 2 are not affected. | |
| ENS 52812 | 16 June 2017 20:35:00 | 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Loss of Safety Function Due to Keowee Dam Units Being Declared Inoperable | Keowee Hydro Units (KHU) 1 and 2 were both declared inoperable at 1635 (EDT) on 6-16-17 due to discovery of breaker 1GSC-1 (KHU-1) in the intermediate position, and breaker 2GSC-1 (KHU-2) in the open position. Keowee Hydro Units are required to be operable per TS (Technical Specification) 3.8.1 (AC Sources - Operating), TS 3.8.2 (AC Sources - Shutdown), and TS 3.7.10 (Protected Service Water, applies only to KHU aligned to the Overhead Power Path). All Tech Spec required conditions were entered, and all required actions completed. Both Standby Buses were energized from a Lee Combustion Turbine via an isolated power path at 1715 (EDT) on 6-16-17 in accordance with TS 3.8.1 Condition (I), Required Action (I.1). It has been determined by station personnel that a loss of safety function did occur between 1635 (EDT) (when the Keowee Hydro Units were declared inoperable) and 1715 (EDT) (when the Standby Buses were energized from a Lee Combustion Turbine via an isolated power path). Investigation has determined the cause of breakers 1GSC-1 and 2GSC-1 being out of their required closed position to be inadvertent bumping while performing station work activities. Breakers 1GSC-1 and 2GSC-1 have been reclosed, and both Keowee Hydro Units have been declared operable as of 2351 (EDT) on 6-16-17. The licensee notified the NRC Resident Inspector. | 05000269/LER-2017-001 |
| ENS 52486 | 12 January 2017 19:00:00 | 10 CFR 26.719, FFD Reporting requirements | Fitness-For-Duty Test Positive for Non-Licensed Supervisor | A non-licensed supervisor has been found in violation of the Duke Energy Fitness for Duty Policy during a random fitness for duty test. The individual's access to the plant has been suspended. The licensee has notified the NRC Senior Resident Inspector. | |
| ENS 51770 | 6 March 2016 20:20:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Emergency Declaration Due to Fire/Explosion in the Main Transformer | At 1512 EST, a fire/explosion occurred in the Unit 1 Main Transformer which resulted in a reactor trip. At 1520 EST, the licensee declared a Notification of Unusual Event. Offsite assistance was requested. At 1633 EST, smoke and flame were no longer visible. Fire brigade personnel were applying additional foam to prevent a re-flash. No personnel injuries occurred. Offsite assistance was requested with three local fire departments responding. All rods inserted on the trip. Steam generator feed is by the normal path. The plant is in its normal shutdown electrical lineup. The licensee has notified state and local authorities and the NRC Resident Inspector. Notified DHS SWO, FEMA, and DHS NICC. Notified FEMA NWS and Nuclear SSA via email.
At 1658 EST, the licensee declared an Alert based on EAL Alert A.1. The cause of entry was that the fire damaged an overhead power line that supplies emergency power to all three units at Oconee. Offsite power is still available to all units. At 1708 EST, the fire is declared out. The licensee has notified the NRC Resident Inspector. Notified DHS SWO, FEMA, DHS NICC, USDA, HHS, DOE, and EPA. Notified FEMA NWS, FDA and Nuclear SSA via email.
The licensee made notification of the RPS actuation as a result of the transformer fault. The licensee has notified the NRC Resident Inspector. Notified R2DO (Sykes).
At 2016 EST, the licensee terminated all emergency declarations. The licensee has notified the NRC Resident Inspector. Notified R2DO (Sykes), IRD (Gott), NRR EO (Morris), DHS SWO, FEMA, DHS NICC, USDA, HHS, DOE, and EPA. Notified FEMA NWS, FDA and Nuclear SSA via email. | 05000269/LER-2016-001 |
| ENS 51268 | 27 July 2015 13:56:00 | 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Valid Actuation of Unit 2 Emergency Feedwater System During Startup | At approximately 0956 EDT on July 27, 2015, Oconee Nuclear Station Unit 2 experienced a valid actuation of the Emergency Feedwater System (EFW). At the time of the event, Unit 2 was in Mode 1 at approximately 17% power and increasing with preparations in progress for placing the main turbine on line during a unit startup. The (EFW) actuation was due to a low level on the 2B steam generator, which resulted from failure of 2B Main Feedwater Block Valve 2FDW-40 to automatically open upon demand. All systems operated as expected with no problems observed. Unit 2 is currently stable at approximately 16% power while troubleshooting valve 2FDW-40 (and the 2B Steam Generator level stable at the normal operating level). Units 1 and 3 were unaffected and remain on line and stable at 100% power. Public health and safety were not impacted by this event. This event is being reported as an 8 hour non-emergency in accordance with 10 CPR 50.72(b)(3)(iv) for a valid actuation of the Emergency Feedwater System. The NRC Resident Inspector has been notified. Corrective Action: Troubleshooting of valve 2FDW-40 is on-going. | 05000270/LER-2015-001 |
| ENS 51026 | 30 April 2015 22:40:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Electrical Fault | Unusual Event (4.6.U.1) was declared by the Shift Manager at Oconee Nuclear Station at 1840 EDT on 4/30/15 due to scorched 4160V cable and a hole created in metal connector coming into the top of 1C condensate booster pump motor electrical junction box. Unit 1 experienced a decrease in power to approximately 98.6% power due to the perturbation in condensate flow from the loss of 1C condensate booster pump. Unit 1 is currently stable at 98.6%. 1A condensate booster pump auto-started as expected. Smoke was observed and quickly dissipated. No visible fire or flame was observed. No Fire Brigade response required. The Unusual Event was terminated at 1945 EDT on 4/30/15. The licensee informed state/local agencies and the NRC Resident Inspector and does not plan to issue a press release. Notified other Federal Agencies (DHS SWO, FEMA Ops, FEMA NWC, NICC Watch Officer and NuclearSSA). | |
| ENS 50917 | 23 March 2015 11:17:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Offsite Notification Due to Death of Employee | At approximately 0605 EDT on March 23, 2015, the Oconee Nuclear Station main control room and Security received an emergency call for an employee experiencing a non-work related medical issue. Site first responders were dispatched in conjunction with a request for off-site medical assistance. The individual was transported by ambulance to the Oconee Medical Center and was pronounced dead at 0717 EDT. The individual was outside of the protected area (within the owner controlled area) and no radioactive material or contamination was involved. The cause of death has not been determined. This notification is being made in accordance with 10 CFR 50.72(b )(2)(xi) for situations related to the health of on-site personnel for which a notification to other government agencies has been made. The South Carolina Occupational Safety and Health Administration (SCOSHA) was notified at 0920 EDT. The NRC Resident Inspector has been notified. The licensee notified Pickens County, South Carolina and Oconee County Emergency Managements. | |
| ENS 50781 | 31 January 2015 19:31:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Manual Rps Actuation Due to Oscillations in the Feedwater System | At 1431 EST on 1/31/15, Oconee Unit 3 was manually tripped due to oscillations in the feedwater system in anticipation of an automatic trip. At 1427 EST, Unit 3 began experiencing small feedwater oscillations. Specifically, 3FDW-32, the 3A main feedwater control valve, appeared to be oscillating with corresponding feedwater flow oscillation. Feedwater oscillations continued to grow in magnitude and at 1431 EST a manual trip was directed by the Unit 3 control room supervisor. The shutdown was orderly and the unit is currently stable and in Mode 3 (Hot Standby). Units 1 and 2 were unaffected by the trip and are currently 100% power (Mode 1). Due to the RPS actuation while critical, this event is being reported as a 4-hour non-emergency per 10CFR50.72(b)(2)(iv)(B). Following the reactor trip, a main steam relief valve (MSRV) failed to reseat as expected. Emergency Operating procedure guidance was utilized to reduce main steam system pressure by approximately 80 psig to reseat the valve (valve reseated at 1506 EST). All of the main steam relief valves are now seated. In addition, the 3B condensate booster pump experienced a mechanical seal leak (approximately 4-5 gpm). The pump was subsequently secured at 1447 EST. All other post trip conditions were normal and all other systems performed as expected. Unit 3 is currently in Mode 3 and stable. All rods fully inserted. Main Feedwater is feeding the steam generators and decay heat is being removed to the Main Condenser. The cause of the trip is under investigation. There is no known primary to secondary leakage. The NRC Resident Inspector has been informed. | 05000287/LER-2015-001 Manual Reactor Trip Due to Unacceptable Main Feedwater Flow Control Valve Oscillations |
| ENS 50640 | 25 November 2014 17:12:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Deficiency in Methodology Used for Emergency Core Cooling System Performance Requirements | On Tuesday, November 25, 2014, at 1212 EST, Duke Energy Carolinas, LLC (Duke Energy) reviewed AREVA 10CFR50.46 Notification Letter FAB 14-00631. This letter indicates that a deficiency was discovered in the uranium thermal conductivity models used in the Oconee Nuclear Station Loss of Coolant Accident (LOCA) analysis of record. When the deficiency is corrected, the LOCA Peak Cladding Temperature (PCT) limits may be in excess of 2200 degrees F. 10CFR50.46 paragraph (b) defines the acceptance criteria for the LOCA analysis process. The Oconee licensing basis PCT is evaluated for compliance with the criterion 10CFR50.46(b)(1) and must not exceed a PCT of 2200 degrees F. On October 20, 2014, AREVA recommended actions in the form of reductions in LOCA linear heat rates, which were then translated into reduced axial imbalance limits for the excore and backup incore detector systems. This was done to ensure that Duke Energy operated within 10CFR50.46 limits in the event of a loss of the full incore detector system. The full incore detector system is the primary method for evaluating imbalance and the imbalance limits are unaffected by the reduction in LOCA linear heat rates. The full incore detector system is operable and meets Technical Specification 3.2.2. In addition, the Reactor Protection System (RPS) trip limits for imbalance are not derived from the LOCA analysis and are not affected. When AREVA notified Duke Energy of the deficiency, Duke Energy confirmed that existing administrative limits bound the AREVA recommended actions and as a result, the errors reported have no impact on plant operation or public health and safety. This event affects all three (3) units and is being reported in accordance with 10CFR50.72(b)(3)(ii)(B). Based on 10CFR50.46(a)(3)(ii) criteria, Duke Energy will submit a written report within 30 days. Duke Energy has notified the NRC Senior Resident Inspector. | 05000269/LER-2014-002 |
| ENS 50288 | 20 July 2014 23:53:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Small Keowee Hydroelectric Station Oil Discharged to the Keowee River | On 7/20/2014, at 1700 hours EDT, a spill of approximately five (5) gallons of Teresstic 68 lube oil was identified in the Keowee Hydroelectric Station (KHS) tailrace. Teresstic 68 oil is used at the station as an equipment lubricant. The KHS tailrace feeds into the Keowee River that leads into Lake Hartwell. The estimated area of the oil sheen is approximately 30x50 feet and a cleanup response is currently in progress. The cause of the spill was attributed to a faulty oil float switch in the KHS unwatering pump that allowed the oil to spill into the KHS tailrace (Keowee River). South Carolina Department of Health and Environmental Control (SCDHEC) and the National Response Center were notified of the spill on 7/20/2014 at approximately 2002 and 1953 hours (EDT) respectively. This event was determined to be reportable pursuant to 10CFR50.72(b)(2)(xi) due to the notifications to the SCDHEC and the National Response Center. The licensee notified the NRC Resident Inspector. Initial Safety Significance: The oil did not contain any plant produced radiological material and while contained, poses no safety risk with respect to the health and safety of the public. Corrective Action(s): The oil spill sheen is isolated to an approximate 30x50 foot area of the Keowee River. Because the KHS is currently not operating, the water spill area is stagnant, i.e., there is little or no movement of the water containing the oil sheen. The source of the leak has been contained and an investigation is underway to determine the actual cause of the spill. There was no impact on plant operations. The event was entered into the station's corrective action program. | |
| ENS 50093 | 7 May 2014 18:50:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Voluntary Notification to Offsite Government Agencies Due to Leak of Water Containing Low Level Tritium Concentration in Accordance with Nei Initiative 07-07 | A leak containing a low level tritium concentration assumed to be greater than 100 gallons of water, with the potential to reach groundwater, occurred at Oconee Nuclear Station. A water sample indicated that the tritium level was 3150 picocuries per liter; which is less than a quarter of the US Environmental Protection Agency drinking water standard of 20,000 picocuries per liter for tritium. While conducting a transfer from one chemical treatment pond to another, water was observed seeping from the ground at a location near the transfer piping between the ponds. The transfer was terminated and the ground seepage subsided. Actions have been taken to prevent further use of the chemical treatment pond discharge path at this time. Based upon the on-site location and low tritium levels, there is no health or safety impact to the public or employees. Voluntary notification of state and local agencies is being made via the industry groundwater protection initiative; measured tritium levels were below any required notification threshold. Agencies notified: South Carolina Department of Health and Environmental Control, South Carolina Emergency Management, City of Seneca, City of Anderson, Greenville Water System, Oconee County Administration, Pickens County Administration, Anderson County Administration, Oconee County Emergency Management, Pickens County Emergency Management, Greenville County Emergency Management, and Clemson University Utility Services. The licensee notified the NRC Resident Inspector. | |
| ENS 49968 | 28 March 2014 17:00:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Keowee Emergency Power System 13.8Kv Cable May Not Comply with Licensing Basis | Event: In an NRC Component Design Basis Inspection (CDBI) debrief held at 1300 EDT on March 28, 2014, it was stated that a potential non-compliance and unanalyzed condition exists with respect to the design and installation of the Keowee emergency power system 13.8kV power cables associated with the underground power path. The NRC stated that Duke does not have sufficient documentation to support the station's position that the cables comply with the station's licensing basis. In particular, there are questions related to the station's compliance with IEEE-279-1971. This issue has been documented in Duke's corrective action program. Duke has reviewed the design associated with the subject 13.8kV cables and considers the design to be robust. Pending further analysis and/or testing, Duke has made a decision to report this event in accordance with 10 CFR 50.72(b)(3)(ii) as an 'Unanalyzed Condition.' The Oconee NRC Senior Resident Inspector has been notified of the event. Initial Safety Significance: An Immediate Determination of Operability has been performed and concluded the existing system design is adequately robust to address circuit faults. The health and safety of the public and station personnel is not impacted by this event. Corrective Action(s): Corrective actions are being implemented in accordance with Duke's Corrective Action Program. | |
| ENS 49527 | 11 November 2013 10:20:00 | 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | Unit 1 Commenced a Technical Specification Required Shutdown Due to Rcs Leakage | Oconee Nuclear Station identified a small Reactor Coolant System (RCS) pressure boundary leak on ONS (Oconee Nuclear Station) Unit 1 and initiated a Unit 1 shutdown at 0520 hours (EST) on November 11, 2013 in accordance with procedures and Technical Specifications. Visual inspection confirmed the leak is located on the 1B2 loop High Pressure Injection Line. ONS Unit 1 was operating at full power when the leak was identified and a down power to 20% was commenced at 2141 hours (EST) on November 10, 2013 in order to characterize the leak and leak location. The measured RCS leak rate was 0.13 gpm (gallons per minute) at the time of commencing the down power. This issue is reportable per 10 CFR 50.72(b)(2)(i) and 10 CFR 50.72(b)(3)(ii)(A). The NRC Resident Inspector has been notified. This event poses no threat to the public or station employees. Unit 1 entered TS 3.4.13 Condition B at 0520 EST on 11/11/13. This TS requires Unit 1 be in Mode 3 Hot Standby within 12 hours and Mode 5 Cold Shutdown within 36 hours. The generator is currently offline and the licensee anticipates entering Mode 3 at 1000 EST. Unit 1 entered their Abnormal Operating procedures for leak determination at 0442 EST on 11/09/13. | |
| ENS 49511 | 7 November 2013 17:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Technical Support Center Taken Out of Service for Planned Maintenance | Technical Support Center (TSC) out of service due to planned maintenance. This is a non-emergency eight hour notification for a loss of Emergency Assessment Capability. This event is reportable in accordance with 10 CFR 50.72(b)(3)(xiii) because the work activity affects the functionality of an emergency response facility. Planned maintenance activities during the Unit 2 outage on 11/7/2013 will render TSC out of service for approximately 48 hours. The unit 2 work is on electrical equipment that will impact the power supply to the TSC. If an emergency is declared requiring TSC activation during this period, the alternate TSC will be used per existing emergency planning procedures. The NRC Resident Inspector has been notified. This event poses no threat to the public or station employees. | |
| ENS 49471 | 24 October 2013 09:53:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Manual Reactor Trip from Full Power Due to Feedwater System Oscillations | At 0553 EDT on 10/24/2013, Oconee Unit 3 was manually tripped due to oscillations in the feedwater system in anticipation of an automatic reactor trip. At 0549 EDT, Unit 3 began experiencing small feedwater oscillations. The feedwater control system was placed in manual in an attempt to stabilize feedwater flows. Feedwater oscillations continued to grow in magnitude and at 0553 EDT, a manual trip was directed to prevent an automatic reactor trip. Due to an RPS actuation, this event is being reported as a 4 and 8 hour Non-Emergency per 10 CFR 50.72 (b)(2)(iv)(B) and 10 CFR 50.72 (b)(3) Following the reactor trip, four main steam relief valves failed to reseat. Procedure guidance was utilized to reduce main steam system pressure by approximately 30 psig to reseat the main steam relief valves. All main stream relief valves are now reseated. All other post trip conditions were normal and all other systems performed as expected. Unit 3 is currently in Mode 3 and stable. Operations have been stabilized on Unit 3. A post-trip investigation is in progress, per site procedures and directives. The licensee has notified the NRC Resident Inspector.
Duke Energy reviewed NRC Event Number 49471 against NUREG 1022, Rev 3, section 3.2.6, "System Actuation" and determined this event should have been reported only per 10 CFR 50.72 (b)(2)(iv)(B), RPS Actuation (while critical). Thus, Duke Energy is revising NRC Event Number 49471 to remove the 8-hour report criteria 10 CFR 50.72 (b)(2)(iv)(A). The NRC Resident Inspector was notified of this revised report. This update has no effect on safety significance. Notified R2DO (Shaeffer). | 05000287/LER-2013-001 |
| ENS 49468 | 22 October 2013 22:32:00 | 10 CFR 26.719, FFD Reporting requirements | Fitness for Duty Report Involving a Licensed Employee | A licensed employee had a confirmed positive test for alcohol during a random fitness-for-duty test. The employee's access to the plant has been placed on hold. The licensee notified the NRC Resident Inspector. | |
| ENS 49291 | 19 August 2013 18:24:00 | 10 CFR 26.719, FFD Reporting requirements | Non-Licensed Contract Supervisor Had a Confirmed Positive Fitness for Duty Test | A non-licensed contract supervisor had a confirmed positive fitness for duty test. Plant access for the individual has been terminated. The licensee has notified the NRC Resident Inspector. | |
| ENS 49149 | 26 June 2013 14:40:00 | 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Inadvertent Closure of Opposite Train Valve Renders Safety Trains Inoperable | At 1040 (EDT), on June 26, 2013, with the Unit 1B Low Pressure Injection (LPI) and Reactor Building Spray (RBS) trains inoperable for planned maintenance, a motor operated isolation valve (1LP-21) was inadvertently closed, rendering the 1A LPI and RBS trains inoperable. The intended action was to close 1LP-22 in the Unit 1B train. 1LP-21 was closed due to a human error. Unit 1 entered Tech Spec 3.0.3 for both trains of LPI and RBS being inoperable. At 1053, on June 26, 2013, the Unit 1A train of LPI and RBS were restored to operable by opening 1LP-21, and Tech Spec 3.0.3 was exited. Units 1, 2 and 3 were stable at 100% power during and after this event. No other safety or non-safety systems were degraded or lost as a result of this event. The event was determined to be reportable under 10 CFR 50.72(b)(3)(v) A, B, C and D "Event or Condition that Could Have Prevented Fulfillment of a Safety Function. Initial Safety Significance: None. There was no event on-going at the time of discovery that required the Unit 1 LPI and RBS systems to function, and the safety function was restored when the 1A LPI and RBS trains were restored to operability. Although declared inoperable, the Unit 1B LPI and RBS trains were available during the time 1LP-21 was closed. Corrective Actions: The Unit 1A LPI and RBS trains were restored to operable, an event investigation was commenced and the event was entered into the Oconee Corrective Action Program. The licensee notified the NRC Resident Inspector. | 05000269/LER-2013-002 |
| ENS 49068 | 24 May 2013 18:00:00 | 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Heating Ventilation and Air Condition System Inadequately Analyzed for Heat Load | There is no current event in progress at Oconee Nuclear Station (ONS). This notification is (being made) to complete a required 10 CFR 50.72 report that was not made at the time of discovery. During a review of the guidance in NUREG 1022, Rev. 2, ONS recognized conditions that were reported to the NRC in LER 269/2013-001-00 on April 8, 2013, (ADAMS Accession ML13101A307), which met the 8-hour reporting requirements of 10 CFR 50.72(b)(3)(ii)(B) -- 'Unanalyzed Condition,' and 10 CFR 50.72(b)(3)(v)(A,B,C&D) -- 'Event or Condition That Could Have Prevented Fulfillment of a Safety Function,' but were not previously reported per 10 CFR 50.72(b)(3). LER 269/2013-001-00 previously documented Duke Energy's conclusion that emergency power equipment could be adversely impacted by a licensee identified, original design issue involving inadequate analysis of electrical equipment heat loads and weaknesses in the Heating Ventilation and Air Conditioning (HVAC) system design. Nothing in this notification modifies or supplements the information provided in LER 269/2013-001-00. This legacy event notification completes the action required by 10 CFR 50.72(b)(3)(ii)(B) and 10 CFR 50.72(b)(3)(v)(A,B,C&D). The need to perform a 10 CFR 50.72 notification was not recognized during the reportability evaluation. Initial Safety Significance: None. This is a legacy event notification. Oconee's emergency power equipment is currently operable, but nonconforming with Oconee's license. Corrective Action(s): Compensatory measures are in place, and modifications are in progress to address the legacy design issue. The issue of not reporting as required under 10 CFR 50.72(b)(3) is entered into Duke Energy's corrective action program. The Oconee NRC Resident Inspector has been notified. | 05000269/LER-2013-001 |
| ENS 48789 | 27 February 2013 01:30:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Sewage Spill in the Turbine Building That Discharged to the Keowee River | On 2/26/13 at 2030 hrs (EST), a four (4) inch sewage line in the Oconee Nuclear Station turbine building failed. This failure allowed sanitary wastewater to spill into the turbine building basement. An estimated 750 gallons entered into trench drains and traveled to the station sump which discharges into the conventional wastewater system. This conventional wastewater system is discharged to the Keowee River from NPDES (National Pollutant Discharge Elimination System) outfall 002. The discharge of outfall 002 is into the Keowee River below the Keowee Hydro Station. The normal discharge path for sanitary wastewater is to the City of Seneca, South Carolina (SC). South Carolina Department of Health and Environmental Control (SCDHEC) and the Oconee Joint Regional Sewer Authority (OJRSA) were notified of the spill on 2/27/13 at approximately 1358 hrs (EST). Note: SCDHEC requires the reporting of any overflow that reaches waters of the state, for overflows that exceed an estimated 500 gallons that don't reach water, and for any overflow that may cause a public health or environment concern. This event was determined to be reportable pursuant to 10CFR50.72(b)(2)(xi) due to notification of the SCDHEC and OJRSA. Initial Safety Significance: The sewage leak did not contain any plant produced radiological material and due to dilution, this event posed no safety risk with respect with respect to the health and safety of the public. Corrective Actions: The affected portions of the sanitary sewage system has been isolated and an investigation is underway to determine the cause. There was no impact on plant operations, and the cleanup has been completed. The event was entered into the correction action program. The licensee notified the NRC Resident Inspector. | |
| ENS 48770 | 19 February 2013 15:54:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Oconee Alert and Notification System Sirens Out of Service | Event: At 1400 EST on 2/19/2013, Oconee Nuclear Station (ONS) Emergency Preparedness (EP) was notified that the 65 Oconee Alert and Notification System sirens (65 is the total number of sirens within the ONS 10 mile Emergency Planning Zone) were found to be non-functional at 1054 EST during weekly testing on 2/19/2013. Oconee and Pickens County Emergency Management have been notified and will conduct 'Route Alerting' should ONS experience an emergency event that would normally require siren activation for notifying the public. Route Alerting, a method of backup alerting, is an approved FEMA process and is documented in the Emergency-Plan of both counties. Initial Safety Significance: None. A pre-planned alternate process for notifying the public was put in place immediately and will remain in place until siren repair and testing are completed. Corrective Action(s): An investigation is in progress to determine the cause of the siren system failure. Appropriate repairs will be made and testing conducted once the cause is determined. ONS will notify the NRC when the sirens are returned to service. The ONS NRC Resident Inspector has been notified of this issue." The licensee has also notified state authorities and the appropriate county authorities as indicated in the event description.
The ONS Siren control systems were recovered and the ONS Alert and Notification System was retested and fully returned to service as of 1040 EST on 2/20/2013. Oconee and Pickens County Emergency Management Division (EMD), South Carolina EMD, and the ONS NRC Senior Resident Inspector were notified of the return of the systems to service. The systems were restored after correcting issues associated with the computer system for the sirens. An investigation is in progress to determine the cause of the event. R2DO (McCoy) notified. | |
| ENS 48407 | 15 October 2012 10:56:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Area Radiation Monitor Used for Emergency Assessment Failed | At 0656 on 10/15/2012, the Unit 3 Control Room received indication that the area radiation monitor, 3RlA-15 for Unit 3 High Pressure Injection (HPI) Pump Room had faulted. 3RIA-15 is used in the Oconee Emergency Plan Enclosure 4.3 (Abnormal Rad Levels Radiological Effluent) and Enclosure 4.4 (Loss of Shutdown Functions) for declaration of NOUE and/or Alert. Although the loss of a single area radiation monitor is not generally reportable, the loss of 3RIA-15 is conservatively considered as a major loss of emergency assessment capability pending further review of the Oconee Emergency Plan. The loss of 3RIA-15 is being reported per 10 CFR 50.72(b)(3)(xiii). Initial Safety Significance: None. There is no event in progress and the station has implemented an alternate means to monitor area radiation for the Unit 3 HPI Room. Corrective Action(s): Repair and restoration of the affected radiation monitor has been initiated as a high priority work request. An alternate means to monitor Unit 3 HPI Pump Room has been established. The station will notify the appropriate Emergency Response Organization personnel of the loss of 3RIA-15. Corrective actions are in place to review station procedures/processes for improvement relative to reporting requirements of 10 CFR 50.72(b)(3)(xiii). The NRC Resident Inspector has been informed. | |
| ENS 48284 | 6 September 2012 00:06:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Inoperable Accident Radiation Monitors | This is a non-emergency report. No actual event has occurred. At 2006 EDT, on 9/5/2012, Oconee Nuclear Station Operations declared the radiation monitors out of service for Low Gas Unit Vent monitoring (3RIA-45) and High Gas Unit monitoring (3RIA-46) when the Unit 3 Vent Skid lost its internal memory during a monthly PM to replace the filter cartridge. These monitors are used for determination of Emergency Action Levels (EALs) in ALL modes. Oconee Nuclear Station did not initially recognize that criteria for reporting in accordance with 10 CFR 50.72 (b)(3)(xiii) (Major Loss of Emergency Preparedness Capabilities) was met and acknowledge this notification is outside of the eight (8) hour notification window. There is no adverse impact on nuclear safety. Redundant methods for sampling and determination of activity levels were implemented per SLC 16.11.3. This report is submitted based upon a loss of emergency assessment capability in accordance with 50.72(b)(3)(xiii). Redundant methodology was employed (when the inoperable status was recognized). Repair and restoration of the effected radiation monitors was completed at 2145 on 9/6/2012. The NRC Resident Inspector has been informed. | |
| ENS 48265 | 2 September 2012 16:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Planned Outage of Emergency Operations Facility | As part of preparation for the upcoming Democratic National Convention (DNC), contingencies are in place associated with the common Emergency Operations Facility (EOF) for Catawba, McGuire, and Oconee Nuclear Stations. The common EOF is located in Charlotte, NC. Because of the potential for event security to delay staffing of the facility within the prescribed time frame, Duke Energy is implementing its business continuity plan for the EOF during the period from 12:00 PM (noon) on September 2nd until 24:00 (midnight) on September 6th. If a declared emergency were to occur at Oconee Nuclear Station, the EOF would be set up in the Catawba Alternate Technical Support Center (TSC) location. This facility is used as a backup location for the Catawba TSC as specified in station procedures. This report is being made in accordance with 10CFR50.72, criterion (b)(3)(xiii), and in accordance with NUREG-1022, Revision 2, as a condition that may impair the functionality of an Emergency Response Facility. The licensee notified the South Carolina Department of Health and Environmental Control, Pickens County, and Oconee County. The licensee has notified the NRC Resident Inspector. | |
| ENS 48264 | 2 September 2012 02:30:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Radiation Monitor Declared Inoperable | This is a non-emergency report. No actual event has occurred. At 2230 hours EDT, on September 01, 2012, Oconee Nuclear Station Operations determined that the radiation monitor for Low Gas Unit Vent monitoring failed its check source and was declared inoperable. This monitor is used for determination of Emergency Action Levels (EALs) in ALL Modes. Specifically, the criterion states that an Unusual Event should be declared if this radiation monitoring reading reaches 9.35E5 for greater than 60 minutes. This condition was discovered during weekly radiation monitor setpoint determinations. There is no adverse impact on nuclear safety. A redundant method for sampling and determination of activity levels has been implemented per SLC 16.11.3. The same EAL criterion has a redundant determination of Unusual Event classification based on these activity levels. This report is submitted based upon a loss of emergency assessment capability in accordance with 50.72(b)(3)(xiii). The NRC Resident Inspector has been informed. | |
| ENS 47887 | 2 May 2012 14:05:00 | 10 CFR 50.72(b)(3)(xii), Transport of a Contaminated Person Offsite | Potentially Contaminated Individual Transported Offsite | On 5/2/2012 at approximately 0914 hours, a Duke Energy contract worker performing activities in the Unit 3 reactor basement (currently defueled in a planned refueling outage), experienced dizziness and subsequently experienced a loss of consciousness. Upon discovery, the plant emergency medical team was dispatched to aid the individual. The individual soon regained consciousness but was immediately transported, via ambulance, to a local hospital for treatment. Accompanying the individual were two (2) radiation protection and one (1) Duke energy Public Affairs individuals. The individual was transported out of the protected area at approximately 1005 hours. Because the potentially contaminated individual's back could not be surveyed prior to being transported offsite, the individual was considered potentially contaminated. As such, this event is being reported as an 8-hour prompt report pursuant to 10CFR50.72(b)(3)(xii). On 5-2-2012 at approximately 1100 hours, the radiation protection personnel that accompanied the individual to the medical facility reported that the individual was determined not to be contaminated. As a result, no follow-up status report is planned. The licensee notified the NRC Resident Inspector. | |
| ENS 48030 | 23 April 2012 00:58:00 | 10 CFR 50.73(a)(1), Submit an LER | Keowee Hydro Power Station Automatically Started Based on an Invalid Signal | At 1958 (EDT) on 4/22/2012, Oconee emergency power (Keowee Hydro Station Units 1 and 2) automatically started based upon an invalid signal. In progress at the time was the Unit 3 Keowee Emergency Start Channel B Isolations section of the Unit 3 Engineered Safety Features Actuation System Replacement Modification procedure. A step in this procedure provided direction for a jumper to be connected between links B-13 and B-14. However, this jumper was placed between links A-13 and A-14, which caused the start of the Keowee units. During the period the jumpers were inadvertently installed, the Keowee units remained operable and available to supply emergency power to Units 1, 2, and/or 3. Both Keowee units were shutdown from the inadvertent emergency start actuation and the emergency start signal was reset per procedure at 0156 (EDT) hours on 4/23/2012. The cause for the misplaced jumper was determined to be a human performance error by the technicians. As required per NUREG 1022, Rev.2 the following information is provided: (a) The specific train(s) and system(s) that were actuated: In this event, both Keowee Hydro Units 1 and 2 actuated because of the emergency start signal being generated by Channel A. (b) Whether each train actuation was complete or partial: The automatic actuation of the Keowee units was completed. (c) Whether or not the system started and functioned successfully: No problems or issues were identified with the performance of the Keowee Hydro Units in response to the emergency start. Therefore this condition is being reported for Oconee 1, 2, and 3 as an invalid actuation under 10 CFR 50.73 (a)(2)(iv)(A), which allows NRC notification via telephone per 10 CFR 50.73(a)(1). Corrective Actions: - Work was stopped on the Unit 3 Engineered Safety Features Actuation System Replacement Modification procedure; - Immediate investigation was conducted to determine the impact of the jumper activity as well as development of a recovery plan; and - The jumper was removed from links A-13 and A-14 and the Keowee units were shutdown. The NRC Resident Inspector was informed. | |
| ENS 47810 | 6 April 2012 02:38:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Standby Shutdown Facility (Ssf) Not Analyzed for All Operating Conditions | On 3/29/2012 Duke Energy identified that unanalyzed conditions exist for SSF mitigated events since associated thermal and hydraulic analyses do not consider all initial operating conditions, especially lower operating modes and lower decay heat. Specifically there are four (4) conditions where the SSF is not currently analyzed: 1. SSF operating at less than 525 degrees F and less than normal operating pressure (approximately 2155 psig), 2. SSF operation before four (4) Effective Full Power Days (EFPDs), 3. SSF reactor coolant make up at low Reactor Coolant System (RCS) pressure. 4. A reactor trip from less than 85 percent power and less than 579 degrees F. On 4/4/2012, an immediate determination of operability concluded that for the first three (3) conditions the SSF was operable but degraded/nonconforming (OBDN). For the 4th issue, there was reasonable assurance that 1% delta k/k shutdown margin would be maintained if T average. remained above 500 degrees F. Based on a lack of analysis and an increased likelihood of reducing T average. below 525 degrees F during a 72 hour event, the SSF was declared OBDN with a separate operability determination required to validate the Unit 3 power coastdown and end of life T average. reduction analysis. Until additional analysis is performed, the SSF is inoperable on any unit where the power level is reduced below 85 percent. A second operability determination for Unit 3 concluded that the SSF will maintain greater than or equal to 525 degrees F with an initial power level of 70 percent and a 570 degree F T average. The SSF will be declared inoperable on Unit 3 if power is reduced to less than 70 percent. Seventy percent was chosen as a conservative value to ensure the unit stayed inside the bounds of existing analyses. Unit 3 is currently at approximately 85 percent power and reducing power at approximately 1 percent per day in preparation for the Unit 2 end of core 26 refueling outage. For Unit 3, the SSF is OBDN based on preliminary calculation results. On 4/5/2012, due to a worsening component cooling water system leak on Unit 2, it was necessary to bring the unit down to Mode 3 to implement repairs. Upon down power, when Unit 2 transitioned below 85 percent power, the ability of the SSF to perform its design function, in consideration of the information above, could not be confirmed and the SSF was declared inoperable for Unit 2. Currently, there is no conclusive information that would support SSF operability while Unit 2 is below 85 percent power. As such, this event is being conservatively reported under 50.72(b)(3)(ii)(B), 'The nuclear plant being in an unanalyzed condition that significantly degrades plant safety.' Due to their current power levels, this condition does not affect Units 1 and 3. Initial Safety Significance: Until confirmed by analysis, the lack of decay heat may result in an initial over cooling of the RCS and potentially an interruption of natural circulation or inadequate shutdown margin. Consequently, the SSF was declared inoperable. Corrective Action(s): Additional analyses are being completed to reestablish SSF operability to bound the unanalyzed entry conditions. The NRC Resident Inspector has been informed.
Update to ENS Notification Number 47810: ENS Notification number 47810 identified an unanalyzed condition for Oconee Unit 2. This update includes Oconee Units 1, 2 and 3 because the condition of the SSF affects all three units during certain plant conditions. The Standby Shutdown Facility (SSF) serves as a backup for existing safety systems. Currently the events that rely upon the SSF for mitigation are unanalyzed on Units 1 and 2 when the power level is reduced below 85 percent and on Unit 3 when the power level is reduced below 70 percent, or for any unit operating with less than 4 Effective Full Power Days (EFPDs) at 100% full power since its most recent shutdown. Since the SSF events are unanalyzed for these conditions and until further analysis and evaluation can be completed, Duke Energy is conservatively calling the SSF inoperable when in these conditions. For these conditions, this event is being reported for Oconee Units I, 2, and 3 under 50. 72(b )(3)(ii)(B), that is, the nuclear plant being in an unanalyzed condition that significantly degrades plant safety. Based on current analyses, the SSF will be declared inoperable, and action statements entered on Units 1 or 2 if power is reduced below 85% power and on Unit 3 if power is reduced below 70% power, or for any unit operating with less than 4 EFPDs since its most recent shutdown. Initial Safety Significance: Until confirmed by analysis or evaluation, the lack of decay heat may result in an initial over cooling of the RCS and potentially fail the various acceptance criteria of the events required to be augmented by the SSF. Consequently, the SSF will be declared inoperable for the conditions stated above. Unit 3 is being shut down for a routine refueling outage. Units 1 and 2 continue to operate at 100% power with no problems. Corrective Action(s): Additional evaluations are being completed to establish whether the existing analyses are applicable to the conditions outside of which they were performed and, if not, there is a reasonable assurance that successful mitigation can be accomplished with the existing procedure. If not, further licensing action may be required. These evaluations were initiated on April 4, 2012, and are ongoing. The licensee has notified the NRC Resident Inspector. Notified the R2DO (Kathleen O'Donohue). | 05000269/LER-2012-001 |