|Entered date||Site||Region||Reactor type||Event description|
|ENS 53677||20 October 2018 01:13:00||Oconee||NRC Region 2||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 17:03:00||Oconee||NRC Region 2||B&W-L-LP|
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 06:07:00||Oconee||NRC Region 2||B&W-L-LP||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 19:25:00||Oconee||NRC Region 2||B&W-L-LP||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||17 June 2017 00:32:00||Oconee||NRC Region 2||B&W-L-LP||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.|
|ENS 52486||12 January 2017 18:25:00||Oconee||NRC Region 2||B&W-L-LP||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 16:09:00||Oconee||NRC Region 2||B&W-L-LP|
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.
|ENS 51268||27 July 2015 16:31:00||Oconee||NRC Region 2||B&W-L-LP||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.|
|ENS 51026||30 April 2015 19:38:00||Oconee||NRC Region 2||B&W-L-LP||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 11:16:00||Oconee||NRC Region 2||B&W-L-LP||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 18:00:00||Oconee||NRC Region 2||B&W-L-LP||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.|
|ENS 50640||25 November 2014 16:35:00||Oconee||NRC Region 2||B&W-L-LP||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.|
|ENS 50288||20 July 2014 21:12:00||Oconee||NRC Region 2||B&W-L-LP||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 15:19:00||Oconee||NRC Region 2||B&W-L-LP||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 16:21:00||Oconee||NRC Region 2||B&W-L-LP||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 08:48:00||Oconee||NRC Region 2||B&W-L-LP||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 11:41:00||Oconee||NRC Region 2||B&W-L-LP||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 09:45:00||Oconee||NRC Region 2||B&W-L-LP|
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).
|ENS 49468||23 October 2013 15:02:00||Oconee||NRC Region 2||B&W-L-LP||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||20 August 2013 11:49:00||Oconee||NRC Region 2||B&W-L-LP||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 18:33:00||Oconee||NRC Region 2||B&W-L-LP||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.|
|ENS 49068||24 May 2013 14:47:00||Oconee||NRC Region 2||B&W-L-LP||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.|
|ENS 48789||27 February 2013 14:47:00||Oconee||NRC Region 2||B&W-L-LP||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 17:45:00||Oconee||NRC Region 2||B&W-L-LP|
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 14:37:00||Oconee||NRC Region 2||B&W-L-LP||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 23:28:00||Oconee||NRC Region 2||B&W-L-LP||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 08:35:00||Oconee||NRC Region 2||B&W-L-LP||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 06:22:00||Oconee||NRC Region 2||B&W-L-LP|
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 48030||15 June 2012 16:00:00||Oconee||NRC Region 2||B&W-L-LP||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 47887||2 May 2012 12:18:00||Oconee||NRC Region 2||B&W-L-LP||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 47810||6 April 2012 03:57:00||Oconee||NRC Region 2||B&W-L-LP|
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).
|ENS 47785||29 March 2012 00:02:00||Oconee||NRC Region 2||B&W-L-LP||On 3/24/12 at 1810 hrs EDT, a four inch sewage line in the turbine building failed. This allowed sanitary wastewater to spill into the turbine building basement. An estimated 100 gallon entered into trench drains and then 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 River Hydro Station. The normal discharge path for sanitary wastewater is to the City of Seneca. South Carolina DHEC (Department of Health and Environmental Control) was notified of the spill on 3/24/12 at 2259 hrs EDT. After further review, this was determined to be reportable under 10CFR50.72(b)(2)(xi)." This event was determined to be reportable at 2150 EDT on 3/28/2012. The event was entered into the corrective action program. There was no impact on plant operations and the cleanup has been completed. The licensee notified the NRC Resident Inspector.|
|ENS 47386||28 October 2011 16:28:00||Oconee||NRC Region 2||B&W-L-LP||The purpose of this report is to notify the NRC of a breach of a package containing a limited quantity of radioactive material. This breach was considered 'breakage' in accordance with Title 49 of the Code of Federal Regulations, Transportation. In accordance with 49 CFR 171.15, Duke Energy contacted the National Response Center at 1350 (EDT) on October 28, 2011, Report Number 993866. The National Response Center then contacted Mecklenburg County, NC, Emergency Management. Although the packaging of the radioactive material was damaged during transportation, the package was transported in an enclosed van. The radioactive material itself has not been released, and the damage did not result in radioactive contamination or any radiation exposure. This event is being reported because notification to other government agencies has been made. The NRC Resident Inspector has been notified.|
|ENS 47382||27 October 2011 15:35:00||Oconee||NRC Region 2||B&W-L-LP||A non-supervisory technician (vendor) had a confirmed positive test for alcohol during a random fitness-for-duty test. Plant access for the individual involved has been terminated. Contact the Headquarters Operations Officer for additional details. The NRC Resident Inspector has been notified.|
|ENS 47156||16 August 2011 09:36:00||Oconee||NRC Region 2||B&W-L-LP||The purpose of this report is to notify the NRC of a fatality involving a contract worker from Duke Energy's Oconee Nuclear Station. At approximately 0600 EDT, the control room was notified of an unconscious individual, located in a non-radiological area outside the protected area. The Medical Emergency Response Team was activated and dispatched to the scene. At 0640, the worker left the site in an ambulance. The individual was pronounced dead at the local hospital. This fatality was the result of a medical emergency and was not occupationally related. Duke Energy is making a notification to the South Carolina Department of Occupational Safety and Health Administration. This ENS notification is in response to a notification to another government agency in accordance with 10CFR50.72(b)(2)(xi). The licensee notified the NRC Resident Inspector.|
|ENS 47080||20 July 2011 20:45:00||Oconee||NRC Region 2||B&W-L-LP||A contractor supervisor had a confirmed positive for alcohol during a random fitness-for-duty test. The contractor's access to the plant has been terminated. Contact the Headquarters Operations Officer for additional details. The licensee informed the NRC Resident Inspector.|
|ENS 46955||13 June 2011 16:04:00||Oconee||NRC Region 2||B&W-L-LP||In Kalsi Engineering Valve and Actuator Program (KVAP) Error Report 2011-02, Kalsi Engineering identified an error in the KVAP software that provides default flow and torque coefficients for ball and plug valves which can affect margin predictions. Communication between Kalsi and Duke Energy personnel confirmed that non-conservative torque values were calculated for select ball valves used at Oconee for containment isolation. As a result of the Kalsi error, the non-conservatively calculated torque values resulted in negative actuator margins, calling into question the actuators' capability to close the valves under all design conditions. Therefore, it has been determined that the KVAP software program error constitutes a defect, reportable under 10CFR21. Four safety-related containment isolation valves in the High Pressure Injection system were impacted, requiring entry into TS 3.6.3, Containment Isolation Valves, on two Oconee units (Units 2 and 3). Unit 1 was shutdown for a refueling outage at the time of this event and the actuator spring was replaced during the outage. The valves on units 2 and 3 required a Notification of Enforcement Discretion (NOED) which occurred on June 2, 2011. Three of the four valves were declared operable on June 10, 2011 and the remaining valve was declared operable the next day. The licensee notified the NRC Resident Inspector.|
|ENS 46947||10 June 2011 15:55:00||Oconee||NRC Region 2||B&W-L-LP||Event: During startup of Unit 1 on June 10, 2011, after increasing power to approximately 50 percent, it was noticed that power range nuclear instrumentation was not responding adequately to power imbalance differences. At 0802 EDT, all four channels of Reactor Protective System instrumentation were declared inoperable. TS 3.3.1., Reactor Protective System (RPS) instrumentation, Condition A, B, and C were entered. RPS Channel D was placed in trip per Condition A. Trouble shooting efforts were immediately initiated. Initial Safety Significance: This issue constitutes a loss of safety function because the nuclear overpower flux/flow imbalance trip function of RPS was not operable. Corrective Action(s): Trouble-shooting commenced. A wiring error was identified that affected all four RPS channels. At this time, all four channels have been restored to operability. All conditions of TS 3.3.1, Conditions A, B, and C have been exited as of 1438 EDT hours when all four channels of RPS were restored. The licensee stated that the wiring error is associated with a modification package that was completed during the recent refueling outage. The licensee has notified the NRC Resident Inspector.|
|ENS 46773||21 April 2011 16:57:00||Oconee||NRC Region 2||B&W-L-LP||On (Thursday), 4/21/2011, at 1405 (EDT), Oconee Nuclear Station notified the South Carolina Department of Health and Environmental Control (SCDHEC) that sanitary sewage had been collected and inadvertently discharged without processing through the sanitary sewage system. The event was identified at 0730 (EDT) on 4/21/2011. The suspected cause is plumbing blockage. It is estimated that intermittent discharges over approximately three months resulted in a total discharge of approximately 4500 gallons. The Oconee NRC Senior Resident Inspector was notified. This event notification is being made pursuant to 10 CFR 50.72 (b)(2)(xi) due to notification of SCDHEC. Immediate corrective action was taken to isolate the affected portion of the sanitary sewage system. This event has no significance with respect to the health and safety of the public.|
|ENS 46554||19 January 2011 17:44:00||Oconee||NRC Region 2||B&W-L-LP||Visual inspections with a video probe (fiberscope) were being performed on the inlet/outlet channels and the tubes of a spare HX to verify that no FM was present. However, when performing these inspections, a problem was encountered in that maintenance was unable to disassemble and remove the bonnet from the lower (inlet) pressure seal connector on the HX. Subsequently, on 10/19/10 a fiberscope inspection was performed of the "back side" of the pressure seal bonnet by inserting a fiberscope thru the inlet nozzle access. A foreign object that appeared as a u-shaped piece of thin wire was seen just behind the pressure seal bonnet, laying in the bottom of the body. Due to the inability to disassemble the pressure seal connector, the affected HX was not installed, The FM was retrieved from the spare HX on December 27,2010 and its size and material type confirmed. The "U-shaped" material is type 304 stainless steel and appears to be a metal shaving. It is about 1-1/2" in length if the "u" was stretched out, 3/32" wide and less than 1/64" thick. The HX was intended for use as a Reactor Coolant System Letdown Cooler. It was ordered in 2006 and was supplied by Energy Steel Supply Company (ESSC), Catalog 10 350952, SIN N32389-1, Purchase Order No. DP 19279. Initial Safety Significance: This event has no actual significance since the issue was discovered prior to installation of the component and the component was not installed. However, Part 21 requires evaluation based on the assumption that the component was installed in the as-found condition. On 1/6/2011, Oconee Engineering concluded that, in some low probability scenarios, this FM could constitute a Substantial safety hazard. Per the postulated scenarios, the FM would be flushed out of the cooler when placed in service. A low potential exists that the FM could be trapped in a downstream valve and damage the seat, resulting in leakage. The cooler outlet valve and the next valve in series are containment isolation valves. If the FM caused leakage in one of those valves and the other was affected by a postulated single failure, any resultant leakage would constitute containment leakage. Also, in some event scenarios, unacceptable leakage past the cooler outlet valve seat could render the Oconee Standby Shutdown Facility (SSF) Reactor Coolant Make-up System inoperable. Therefore, Oconee concludes this issue meets the Part 21 definition as a reportable defect. Corrective Action(s): The affected spare cooler was not installed. Subsequently, the FM was removed. A second spare cooler was inspected, no similar FM was found, and the second cooler was installed. The NRC Resident Inspector will be notified.|
|ENS 46544||14 January 2011 17:19:00||Oconee||NRC Region 2||B&W-L-LP||This report is being made per paragraphs 50.73(a)(1) and 50.73(a)(2)(iv)(A) to address an actuation of the Emergency Feedwater (EFW) System on Oconee Unit 3 on 11/18/10 while moving the 3A Motor Driven EFW Pump (MD EFWP) control switch from position 'Auto 1' to 'Auto 2.' EFW is a system named in 50.73(a)(2)(iv)(B). The 3A MD EFWP was inadvertently started during operation of the control switch in the Oconee Unit 3 Control Room. The start signal was a manual start when the operator moved the control switch beyond the intended position. The functioning/behavior of the MD EFWP control switch and human error are being investigated in the site corrective action program. This is considered an INVALID signal with respect to 50.73(a)(2)(iv)(A). The manual start only affected the 3A MD EFWP. On 11/18/10, a Unit 3 startup from a refueling outage was in progress. Unit 3 was in Mode 3. While performing a step in OP/3/A/1102/001 (Controlling Procedure for Unit Startup), the Operator inadvertently started 3A MD EFWP when positioning 3A MD EFWP control switch from position 'Auto 1' to 'Auto 2.' Specific Information Required per NUREG 1022: (a) The specific train(s) and system(s) that were actuated: The specific train(s) and system(s) that were actuated was the 3A MD EFWP and the A train of EFW. The 3B MD EFWP and the Turbine Driven EFW Pump were not affected by this event. (b) Whether each train actuation was complete or partial: The manual actuation was considered complete (i.e. all necessary components responded to the start signal to provide EFW to the Steam Generator (SG). The A train control valve (3FDW-315) was open, as expected for the evolutions in progress. This allowed EFW to reach the SG. C) Whether or not the system started and functioned successfully: The 3A MD EFWP and train started and operated successfully until secured by Operations personnel. Initial Safety Significance: None, there was no significant transient. Corrective Action(s): EFDW was secured within approximately one minute by placing 3A MD EFWP control switch in the Auto 2 position. This event has been entered into the site corrective action program for resolution. The licensee notified the NRC Resident Inspector.|
|ENS 46526||8 January 2011 17:06:00||Oconee||NRC Region 2||B&W-L-LP||At 1400 on Saturday, January 8, 2011, Oconee Unit 1 initiated a shutdown required by Technical Specification (TS) 3.6.3, 'Containment Isolation Valves.' Unit 1 experienced an unexpected partial closure of letdown line containment isolation valve 1HP-5 during Engineered Safeguards (ES) Channel 2 on-line testing. 1HP-5 reopened when power was restored. Unit 1 entered TS 3.6.3, CONDITION A at 0148 on 1/8/11. Unit 1 entered TS 3.6.3, CONDITION D at 0548 on 1/8/11. TS 3.6.3, CONDITION D requires Unit 1 to be in mode 3 by 1748 on 1/8/11, and in mode 5 by 1748 on 1/9/11. An updated notification will be provided if the TS CONDITION is exited prior to Unit 1 reaching mode 5. An investigation is in progress to determine the cause of the unexpected partial closure of 1HP-5. All safety systems required for safe shutdown are operable and the electrical lineup is normal. The licensee is evaluating any potential impact of this event on Unit 2 and Unit 3. There is no estimate for the completion of the investigation at this time. The NRC Resident Inspector has been notified.|
|ENS 46375||29 October 2010 09:39:00||Oconee||NRC Region 2||B&W-L-LP||On October 28, 2010, Duke Energy completed a reportability determination which concluded that a defect associated with four inch by four inch tube steel with one-half inch wall thickness is reportable under Part 21. The tube steel was procured safety-related from Mackson, Inc. on May 26, 2010. Receipt of the material occurred on June 14, 2010. During construction of the Protected Service Water (PSW) ductbank elevated cable raceway, Craft reported a longitudinal crack in the tube steel, approximately four feet in length, adjacent to a raceway fabrication weld. The crack was located in the manufacturer's longitudinal seam weld in the tube steel. Follow-up investigation and laboratory evaluation revealed that the structural steel tubing in question contains surface breaking flaws located along the centerline of the seam weld which are attributable to lack of fusion that occurred during tubing manufacture. Additional testing of samples from the same heat of material indicated that the seam weld flaw depth varied with some localized areas reaching depths of at least 40 percent through the wall thickness prior to raceway fabrication welding. According to documents received from the supplier, during dedication, the supplier performed chemical, physical and 100 percent visual exam in accordance with their accepted dedication procedures for ASTM A500 for Grade B material. However, the supplied product did not conform to the requirements of ASTM A500 in that the longitudinal butt joint was not welded across its thickness (Reference ASTM A500, Section 6.2). Duke Energy will provide follow-up written notification within 30 days pursuant to Part 21.21(d)(3)(ii). Initial Safety Significance: None. The defective tube steel utilized in the PSW structure was not placed into service. Tube steel sections of the same heat of material not used in pre-fabrication efforts were scrapped. Those installed were cut out or evaluated for acceptability by Engineering. The failure of this weld significantly impairs the structural properties of the hollow structural section. The generic implications associated with the potential to use these structural members in various nuclear safety-related applications at this site and at other stations results in a substantial safety hazard were it to remain uncorrected. Corrective Action(s): 1. Notified supplier, Mackson, Inc. 2. Re-worked all uses of the defective structural tube steel. 3. Developed additional, required testing for safety -related tube steel. The supplier (Mackson, Inc) indicated to Oconee that no other nuclear power plants have received this type of tube steel from Mackson. Oconee also has concluded that the condition is confined to only one heat of the tubing used onsite. All the tube steel of this heat has been either disposed of, removed, or verified acceptable. The licensee has notified the NRC Resident Inspector.|
|ENS 46167||11 August 2010 13:04:00||Oconee||NRC Region 2||B&W-L-LP|
While repairing a control room alarm panel, a screw was dropped. This appears to have caused a breaker (3D1B-27) to trip, which caused a loss of greater than 50% of the control room alarm panels. A team is being assembled to develop trouble shooting plan to restore alarm panels. Enhanced plant monitoring is being put in place until alarm panels are restored. Approximately half of the control room annunciators are locked in and/or non-functional. The licensee notified the NRC Resident Inspector. Notified DHS (Hill), FEMA (Heyman), DOE (Yates), HHS (Baker) and USDA (Shaffer).
At 2130 EDT, Unit 3 exited from the UNUSUAL EVENT based on returning to service greater than 50% of alarm panels. Compensatory measures are in place for the alarm panels which have no audible signal. The licensee notified appropriate state and local agencies. The licensee also notified the NRC Resident Inspector. Agencies that the licensee notified included South Carolina and North Carolina warning points, the South Carolina Emergency Management Agency and the Oconee and Pickens County Emergency Management Agencies. Notified R2DO (Desai), NRR EO (Nelson), IRD Manager (Gott), DHS ( Gates), FEMA (Blankenship), DOE (Bailey), HHS(Grimes) and USDA (Timmons).
|ENS 46159||7 August 2010 18:47:00||Oconee||NRC Region 2||B&W-L-LP||At 1451 on 8/7/2010, Oconee Unit 1 initiated a manual reactor trip from approximately 17% power due to indicated vibrations on 1A1 and 1A2 reactor coolant pumps (RCP) reaching the high vibration trip criteria. All systems responded normally following the reactor trip. Unit 1 is currently stable in MODE 3. An investigation is in progress to determine the cause of the elevated reactor coolant pump vibrations. All control rods fully inserted on the trip. Decay heat is being removed via the turbine bypass valves to the main condenser. Steam generator water level is being maintained with main feedwater. There is no evidence that the PORVs or safety valves lifted. The plant is in its normal shutdown electrical lineup. There were no indications on the loose parts monitor except for the RCP high vibration. There was no affect on units 2 or 3. The licensee notified the NRC Resident Inspector.|
|ENS 45690||9 February 2010 09:57:00||Oconee||NRC Region 2||B&W-L-LP||Event Description: Ground water monitoring wells were installed on the Oconee site and initially sampled in 2008 in support of the Nuclear Energy Institute (NEI) Ground Water Protection Initiative (NEI 07-07). As part of an on-going investigation, a number of new monitoring wells have been installed and additional wells are in progress at Oconee. On February 8, 2010, Oconee was notified by the Duke Energy Environmental Lab that samples taken on January 26, 2010, from monitoring wells GM-7R and GM-7DR displayed tritium levels of 24,400 pCi/l and 35,400 pCi/l respectively, triggering the communication protocol of the NEI initiative. The threshold for initiating the communication protocol is 20,000 pCi/l. There is no public or plant worker risk associated with the GM-7R and GM-7DR well samples. Wells GM-7R and GM-7DR are not drinking water sources and therefore, there is no potential dose to the public or plant workers. Samples from surrounding monitoring wells indicate that tritium in ground water has not migrated off the plant site. Duke is continuing to investigate the source of tritium in wells GM-7R and GM-7DR. Tritium levels in samples from the remaining wells are below the communication protocol threshold. The licensee plans to notify the South Carolina DHEC state officials and local stakeholders of the sample results. Initial Safety Significance: There is no safety significance due to the tritium identified in ground water at Oconee. The subject wells are not drinking water sources, and there is no indication tritium has migrated off the Oconee site in the ground water. Corrective Action(s): The source of tritium in the ground water at Oconee is not understood at this time. Duke is continuing an investigation to identify the source and implement a corrective action plan. The licensee will issue a press release and has informed the NRC Resident Inspector.|
|ENS 45180||1 July 2009 16:19:00||Oconee||NRC Region 2||B&W-L-LP|
On 5-19-09 ONS (Oconee Nuclear Station) Unit 3 was in Mode 3 during startup from a refueling outage. At 1609 EDT the 3A Motor Driven Emergency Feedwater Pump (MDEFWP) unexpectedly started when the control switch was placed in the AUTO2 position as part of system alignment prior to unit startup. Investigation found that the impulse line for the hydraulic oil pressure switch on the operating 3A Main Feedwater Pump was clogged, causing sensed pressure to read below setpoint. Repositioning the control switch enabled the 3A MDEFWP auto start circuitry, which immediately actuated due to the pre-existing false low pressure indication. Several other redundant indications validated that the pressure signal to the pressure switch was false and that actual hydraulic oil pressure remained above the pressure switch setpoint. Although the pressure switch did see low pressure in the impulse line, the actuation is considered invalid since the signal was based on a false reading that did not represent actual plant conditions. Therefore this report is being made under 10 CFR 50.73(a)(1) and 50.73 (a)(2)(iv)(A). Per NUREG-1022, Rev. 2 the following information is requested:
A) The specific train(s) and system(s) that were actuated. 3A Motor Driven Emergency Feedwater Pump (MDEFWP) which feeds the 3A Steam Generator (SG).
B) Whether each train actuation was complete or partial. The train actuation was considered complete. The pump started per the signal and operated as required/expected in response to the signal. This pump is the only component in the train which receives a specific signal as part of the actuation circuitry.
C) Whether or not the system started and functioned successfully. The 3A MDEFWP started and the system functioned successfully. The EFW control valve (3FDW-315) is set to control at 30 inches (SG startup level) versus 25 inches for Main Feedwater control. Therefore the SG level increased and the train then controlled at approximately 30 inches while an investigation determined the reason for the actuation (as explained above). The 3A MDEFWP was stopped at 2050 EDT and returned to normal status. Initial Safety Significance: Due to low feedwater demand at the time, there was little impact on the unit. Since the SG level was maintained above the normal control system setpoint, Main Feedwater flow was automatically reduced to compensate for the EFW flow. The 3A MDEFWP and associated pressure switch/actuation circuit were declared inoperable during pump shutdown and restoration to normal. Corrective Action(s): After troubleshooting identified the clogged impulse line, it was isolated and cleared. The 3A MD EFWP and the associated pressure instruments were returned to service. The licensee notified the NRC Resident Inspector.
|ENS 45088||21 May 2009 23:09:00||Oconee||NRC Region 2||B&W-L-LP||Event: Oconee Unit 3 Reactor Protection System (RPS) actuation due to Anticipatory Trip. At 2015 hrs on 5-21-2009, Oconee Nuclear Station Unit 3 experienced a RPS actuation due to an anticipatory trip caused by a generator phase differential lockout. At the time of the RPS actuation, Unit 3 was exiting a planned refueling outage and power was at 42%. Immediately after the trip, Operators entered the appropriate emergency operating procedure and post-trip response was determined to be normal. Operators transitioned to the normal shutdown procedure at 2056 hours. Unit 3 is currently in Mode 3 and stable. This event is being reported as a 4-Hour Non-Emergency per 10 CFR 50.72(b)(2)(iv)(B). Initial Safety Significance: No Emergency Action Limits (EALs) were met and there was no safety significance as a result of the Unit 3 trip. Units 1 and 2 remain at 100% power (Mode 1) and were unaffected by the Unit 3 trip. Corrective Actions(s): Planned corrective actions are to maintain Unit 3 in Mode 3 (Hot Standby) until completion of the post-trip evaluation. The NRC Resident Inspector has been notified. All control rods fully inserted. The reactor is currently subcritical and shutdown margin within Technical Specification limits. RCS Inventory Control is via normal makeup. PORV and Pressurizer Code Safeties are closed. SG inventory control is being maintained via Main Feedwater. Heat is being removed from the Steam Generators to the Main Condenser via Turbine Bypass Valves.|
|ENS 44656||13 November 2008 11:17:00||Oconee||NRC Region 2||B&W-L-LP|
A controlled substance was found within the protected area. Contact the Headquarters' Operations Officer for additional details. The licensee notified the NRC Resident Inspector.
A non-licensed, contract employee was found in possession of a controlled substance. The contract employee's access to the plant has been terminated. Contact the Headquarters' Operations Officer for additional details. The R2DO (Bonser) was notified.
The material was turned over to and tested by the Oconee County Sheriff's Office (OCS). On 11/24/08 at 1500 hours OCS informed site security that the test result was positive. The investigation into this matter is continuing. Notified R2DO (Guthrie).
|ENS 44638||7 November 2008 12:05:00||Oconee||NRC Region 2||B&W-L-LP||At 0834 on 11-7-08, Oconee Nuclear Station (ONS) Unit 3 experienced an automatic reactor trip due to a reactor protective systems (RPS) actuation. ONS Unit 3 post trip parameters are normal. Main Feedwater remained in service following the event and Emergency Feedwater was not required and remained available. Electrical power automatically transferred to the Startup power source from the switchyard and emergency AC power sources were not required and remained available. The cause of the RPS actuation and automatic reactor trip are under investigation. ONS Unit 1 remained at 100% power with no issues following the ONS Unit 3 reactor trip. ONS Unit 2 remained in No-Mode. No other safety systems have actuated or exhibited abnormal behavior. Therefore, the safety significance of this condition is low. All control rods fully inserted during this event. The unit is removing decay heat to the main condenser. No primary relief valves lifted and Main Steam relief valves cycled following the trip. There are no Steam Generator tube leaks. The licensee notified the NRC Resident Inspector.|