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 Entered dateSiteRegionReactor typeEvent description
ENS 5545813 September 2021 05:53:00McGuireNRC Region 2Westinghouse PWR 4-LoopAt 0011 EDT, with Unit 2 in Mode 5 (Cold Shutdown), actuations of the 2B Diesel Generator (DG) and the 2B Motor Driven Auxiliary Feedwater (AFW) Pump occurred during Engineered Safety Features Actuation Periodic Testing while resetting the 2B DG Load Sequencer. The 2B DG was running unloaded following test actuation, and during realignment from the test, a blackout condition was experienced when the breaker opened supplying the 4160 Volt Essential Power System 2ETB from the Standby Auxiliary Power Transformer SATB. Sequencer actuation closed the emergency breaker to 2ETB and loaded the 2B Motor Driven AFW Pump onto the bus. Steam supply valves to the Turbine Driven AFW Pump were open from the previous test configuration. This event is being reported in accordance with 10CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the 2B DG and the 2B Motor Driven AFW Pump. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 5544031 August 2021 16:00:00South TexasNRC Region 4Westinghouse PWR 4-LoopOn August 4, 2021 a Licensed Reactor Operator violated the station's FFD policy. The employee's unescorted access to South Texas has been terminated. The event was determined to be reportable under 10 CFR 26.719(b)(2)(ii). The NRC Resident Inspector will be been notified.
ENS 5542120 August 2021 16:00:00SequoyahNRC Region 2Westinghouse PWR 4-LoopAt 0905 EDT, it was discovered both trains of Auxiliary Building Gas Treatment System (ABGTS) were simultaneously INOPERABLE due to the auxiliary building secondary containment enclosure (ABSCE) being inoperable; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. ABSCE and ABGTS were returned to operable.
ENS 5541618 August 2021 13:51:00Wolf CreekNRC Region 4Westinghouse PWR 4-LoopAt 1036 CDT on 8/18/2021, Wolf Creek experienced a reactor trip due to low level in B Steam Generator. Auxiliary feedwater system actuated as designed. All systems actuated as expected. Decay heat is currently being removed by the auxiliary feedwater system. The NRC Senior Resident Inspector has been informed. All control rods fully inserted, and offsite power remained available.
ENS 553985 August 2021 17:30:00South TexasNRC Region 4Westinghouse PWR 4-LoopA non-licensed supervisor had a confirmed positive for alcohol during a random fitness-for-duty test. The employee's access to the plant has been terminated. The NRC Resident Inspector has been notified.
ENS 553953 August 2021 19:35:00BraidwoodNRC Region 3Westinghouse PWR 4-LoopAt approximately 1539 CDT on 8/3/2021, the Braidwood Station Main Control Room was notified of the inadvertent actuation of 17 Full Sounding sirens affecting Braidwood Station in Will County Illinois while testing other sirens. Will County EMA inadvertently actuated the sirens on 08/03/2021 at 1440 CDT. This event is reportable per 10CFR50.72(b)(2)(xi), News release or Notification of Other Government Agencies. This is a 4 Hour Reporting requirement. The Braidwood NRC Resident has been notified. See related Event Notification #55396.
ENS 5538428 July 2021 16:30:00SeabrookNRC Region 1Westinghouse PWR 4-LoopA licensed employee had a confirmed positive for alcohol during a random fitness-for-duty test. The employee's access to the plant has been suspended. The NRC Resident Inspector has been notified.
ENS 5537925 July 2021 16:00:00SequoyahNRC Region 2Westinghouse PWR 4-LoopAt 1238 EDT on July 25, 2021, the Unit 2 Ice Bed became INOPERABLE due to SR (Surveillance Requirement) 3.6.12.1 exceeding its surveillance interval. LCO (Limiting Condition for Operation) 3.6.12 was declared not met as required by SR 3.0.1. SR 3.6.12.1 to verify maximum ice bed temperature is less than or equal to 27 degrees F could not be completed due to a failed temperature recorder. The results of the backup method of temperature verification were verified satisfactory at 1258 EDT and the LCO condition was then exited. The ice bed is a single train system which functions to control radiation release and mitigate the consequences of an accident by scrubbing radioactive iodine and providing a heat sink to limit containment pressure within design limits, therefore the requirements of 10 CFR 50.72 (b) (3) (v) (C) and (D) were met. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 553394 July 2021 15:59:00CatawbaNRC Region 2Westinghouse PWR 4-LoopAt 0911 EDT on July 4, 2021, a failure occurred on 2 out of 3 of the required seismic monitoring instruments that feed the Operational Basis Earthquake (OBE) annunciator. The failure would prevent an OBE EXCEEDED alarm on the Seismic Monitoring Panel in the Control Room. This results in a major loss of emergency assessment capability. Corrective actions are being pursued to restore the seismic monitoring instruments. Compensatory measures are in place to assure adequate monitoring capability. 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 unplanned failure of the required seismic instruments affects the ability to assess a seismic event greater than the OBE. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 553383 July 2021 17:44:00South TexasNRC Region 4Westinghouse PWR 4-LoopOn July 03, 2021, at approximately 1011 CDT, a Security Force Supervisor at South Texas Project Electric Generating Station (STPEGS) was informed by a security officer that they had located what appeared to be drug paraphernalia inside the Protected Area. At 1033 CDT Local Law Enforcement was contacted and responded to STPEGS. At 1130 CDT the Matagorda County Sheriff's office took the item into evidence for testing to determine if there was any presence of a controlled substance. At 1311 CDT, the Matagorda County Sheriff's office notified STP Nuclear Operating Company (STPNOC) that the item tested positive for the presence of a controlled substance. At 1330 CDT the Unit 1 Shift Manager was notified. This event is being reported in accordance with 10 CFR 26.719(b)(1) for discovery or presence of illegal drugs within the protected area. STPNOC is continuing to investigate this incident. The Resident Inspector has been notified.
ENS 5532524 June 2021 14:56:00BraidwoodNRC Region 3Westinghouse PWR 4-LoopThis 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 Technical Support Center (TSC) supply fan belt had failed, which affects the functionality of an emergency response facility. Corrective maintenance activities will be performed to restore functionality. The work includes replacing the failed belt and restarting the TSC supply fan. The work duration is approximately 8 hours. If an emergency is declared requiring TSC activation during this period, the TSC will be staffed and activated using existing emergency planning procedures unless the TSC becomes uninhabitable due to ambient temperature, radiological, or other conditions. If relocation of the TSC becomes necessary, the Emergency Director will relocate the TSC staff to an alternate location in accordance with applicable site procedures. (The Emergency Response Organization team has been notified of the maintenance and the possible need to relocate during an emergency.) There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector and Illinois Emergency Management Agency have been notified.
ENS 5532223 June 2021 01:55:00CookNRC Region 3Westinghouse PWR 4-LoopOn June 22, 2021, at 2331 EDT, DC Cook Unit 2 Reactor was manually tripped due to a large steam leak in a crossover pipe of the Moisture Separator Re-heater (MSR) to the low pressure turbine. This notification is being made in accordance with 10 CFR 50.72(b)(2)(iv)(B), Reactor Protection System (RPS) actuation as a four (4) hour report, and under 10 CFR 50.72(b)(3)(iv)(A), specified system actuation of the Auxiliary Feedwater System, as an eight (8) hour report. The DC Cook Resident NRC Inspector has been notified. Unit 2 is being supplied by offsite power. All control rods fully inserted. All Auxiliary Feedwater Pumps started properly. Decay heat is being removed via the Steam Dump System. Preliminary evaluation indicates all plant systems functioned normally following the Reactor Trip. DC Cook Unit 2 remains stable in Mode 3 while conducting the Post Trip Review. No radioactive release is in progress as a result of this event. Unit 1 was not affected.
ENS 5532021 June 2021 03:06:00BraidwoodNRC Region 3Westinghouse PWR 4-LoopAt 0051 CDT Braidwood Unit 1 experienced an automatic reactor trip due to a generator lockout relay trip and subsequent turbine trip and reactor trip. The cause of the generator lockout relay trip is unknown at this time and is under investigation. Numerous lightning strikes were present in the area during the time of the generator lockout relay trip. Both trains of auxiliary feedwater started automatically following the reactor trip to maintain steam generator water levels. All systems responded as expected with the exception of failure of source range nuclear instruments to automatically re-energize following the reactor trip. Both source range nuclear instruments were manually energized in accordance with station procedures. The main steam dump valves are in service to the main condenser to provide heat sink cooling. The plant is being maintained at normal operating pressure and temperature. AC power is being provided by Offsite Power with the 1B Diesel Generator in standby. 1A Diesel Generator is out of service for planned maintenance. All other safety systems are available. There is no impact to Unit 2. This report is being made per 10 CFR 50.72(b)(2)(iv)(B) for a RPS actuation, 4 hr. notification, and per 10 CFR 50.72(b)(3)(iv)(A) for an automatic actuation of the Auxiliary Feedwater system, 8 hr. notification. The NRC Resident Inspector and Illinois Emergency Management Agency have been informed.
ENS 5530512 June 2021 23:57:00Comanche PeakNRC Region 4Westinghouse PWR 4-LoopAt time 2227 CDT on 06/12/21, Main Steam Line 2-01 Radiation Monitor 2-RE-2325 was declared to be non-functional. With this radiation monitor non-functional, all of the emergency action levels for a steam generator tube rupture in Steam Generator 2-01 could neither be evaluated nor monitored. This unplanned condition is reportable as a loss of assessment capability per 10 CFR 50.72(b)(3)(xiii). Comanche Peak Nuclear Power Plant (CPNPP) has assurance of steam generator integrity and fuel cladding integrity. Compensatory measures are in place to assure adequate monitoring capability. Radiation Protection technicians have been briefed on taking local readings with a Geiger-Mueller tube on MSL 2-01. Corrective actions are being pursued to restore 2-RE-2325 to functional status. The NRC Resident Inspector has been notified.
ENS 5530412 June 2021 22:00:00Comanche PeakNRC Region 4Westinghouse PWR 4-LoopAt time 1725 CDT on 06/12/21, Main Steam Line 2-03 Radiation Monitor 2-RE-2327 was declared to be non-functional. With this radiation monitor non-functional, all of the emergency action levels for a steam generator tube rupture in Steam Generator 2-03 could neither be evaluated nor monitored. This unplanned condition is reportable as a loss of assessment capability per 10 CFR 50.72(b)(3)(xiii). Comanche Peak Nuclear Power Plant (CPNPP) has assurance of steam generator integrity and fuel cladding integrity. Compensatory measures are in place to assure adequate monitoring capability. Radiation Protection technicians have been briefed on taking local readings with a Geiger-Mueller tube on MSL 2-03. Corrective actions are being pursued to restore 2-RE-2327 to functional status. The NRC Resident Inspector has been notified.
ENS 552957 June 2021 18:31:00Comanche PeakNRC Region 4Westinghouse PWR 4-LoopAt 1527 (Central Standard Time) Unit 2 Reactor tripped caused by a turbine trip due to a fault and fire on Unit 2 Main Transformer #1. All Aux Feedwater Pumps started due to steam generator Lo-Lo levels. Unit 2 is being maintained in Hot Standby (Mode 3) in accordance with Integrated Plant Operating Procedure IPO-007B. The Emergency Response Guideline Network has been exited. Decay heat is being rejected to the Main Condenser via the steam dump valves. Fire was extinguished at 1546 without offsite assistance. No major injuries reported and no personnel transported offsite for medical attention. Cause of the fault and fire are under investigation. NRC Resident Inspector has been notified. All rods inserted into the core during the trip. There were no relief valves or safety valves lifted during the transient. The plant is stable in its normal shutdown electrical lineup via the auxiliary transformer with all safety equipment available. Unit 1 was not affected by the transient.
ENS 5527525 May 2021 21:38:00CatawbaNRC Region 2Westinghouse PWR 4-LoopAt 1751 EDT on May 25, 2021, it was determined the local leak rate test (LLRT) for the 2EMF-IN containment penetration did not meet 10 CFR 50 Appendix J requirements for both the inboard and outboard containment isolation valves (2MISV5230 and 2MISV5231). The LLRT was performed during the previous refueling outage at which time primary containment was not required to be operable. The leakage assigned to the penetration also resulted in total leakage exceeding the allowed overall leakage. The valves were repaired and retested satisfactory prior to entering the mode of applicability, 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 5527224 May 2021 12:01:00SequoyahNRC Region 2Westinghouse PWR 4-LoopUnit 2 is not impacted and remains stable in Mode 1 at 100 percent power. 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) and in accordance with 10 CFR 50.72 (b)(3)(iv)(A) as an event that results in a valid actuation of the AFW system. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. No relief valves opened. All Rods fully inserted. Decay heat is being removed by Auxiliary Feedwater via the steam dumps. The plant is in a normal post-trip electrical line-up.
ENS 5525915 May 2021 00:55:00CallawayNRC Region 4Westinghouse PWR 4-LoopAt approximately 1300 CDT on 05/14/2021, a contract worker, who was using a scaffold ladder to access their work area on the iso-phase bus duct system for the main transformers at the Callaway plant, fell approximately 27 feet to the ground. An ambulance was dispatched to transport the individual to a local hospital. Union Electric (Ameren Missouri) subsequently learned that the event caused the individual to have a serious injury that required an overnight hospital stay. This event is reportable to OSHA per 29 CFR 1904.39(a)(2) by the contract worker's employer and is reportable to the Missouri Public Service Commission in accordance with Missouri regulation 20 CSR 4240-3.190(3)(A). This notification is being made to the NRC pursuant to 10 CFR 50.72(b)(2)(xi) due to other government notifications that will occur as a result of a situation related to the health and safety of onsite personnel. The NRC Senior Resident Inspector has been notified of this event. The individual was not working in a contamination area.
ENS 5525613 May 2021 20:35:00South TexasNRC Region 4Westinghouse PWR 4-LoopA non-licensed temporary supervisor had a confirmed positive during a random fitness-for-duty test. The employee's access to the plant has been terminated. The NRC Resident Inspector has been notified.
ENS 5525212 May 2021 15:41:00Wolf CreekNRC Region 4Westinghouse PWR 4-LoopWith Reactor power at approximately 8 percent following a refueling outage, Steam Generator levels began to oscillate while in automatic control. Manual control of Main Feedwater Regulating Valves was unable to stabilize steam generator levels prior to reaching the "C" Steam Generator Low Level Reactor Trip setpoint. Reactor Trip, Main Feedwater Isolation and Auxiliary Feedwater Actuation automatically actuated. The plant is stable in Mode 3 at Hot Standby. All equipment has responded as expected. The Resident has been contacted.
ENS 5524710 May 2021 21:59:00CallawayNRC Region 4Westinghouse PWR 4-LoopOn May 10, 2021, Callaway determined that a violation of 10 CFR 26.4(c) occurred. A licensee employee was assigned to perform Emergency Response Organization (ERO) duties that required that employee to be subject to the Fitness for Duty (FFD) program. However, the individual had been removed from the FFD program. The individual's unescorted access to the plant had been temporarily removed, but the individual was still required to report to the Emergency Operations Facility in accordance with the emergency plan procedures. The individual's ERO qualification has been deactivated. A review determined that this condition did not apply to any other ERO responders. This discovery is reported pursuant to 10 CFR 26.719(b)(4). The NRC Senior Resident Inspector has been notified of the event.
ENS 552355 May 2021 13:22:00Diablo CanyonNRC Region 4Westinghouse PWR 4-LoopA non-licensed employee supervisor had a confirmed positive during a random fitness-for-duty test. The employee's access to the plant has been terminated. The NRC Resident Inspector has been notified.
ENS 552291 May 2021 15:39:00CatawbaNRC Region 2Westinghouse PWR 4-LoopAt 0755 EDT, on May 1, 2021, with Unit 2 in Mode 3 at 0 percent (not critical) power, the reactor trip breakers opened during heat-up activities. The trip was not complex, with all systems responding normally post-trip. At 1013 EDT, on May 1, 2021, with Unit 2 in Mode 3 at 0 percent power, an actuation of the Auxiliary Feedwater (AFW) System occurred. The loss of both main feedwater pump turbines caused an AFW auto-start. The 2A and 2B motor driven auxiliary feedwater (MDAFW) pumps automatically started as designed when the loss of both main feedwater pumps signal was received. The cause of the actuation is still being evaluated. Operations responded and stabilized the plant. Decay heat is being removed by the steam generators and discharging steam to the condenser. Unit 1 is not affected. Due to the Reactor Protection System (RPS) actuation while not critical and the actuation of the AFW system, this event is being reported as an eight-hour, non-emergency notification per 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 5520121 April 2021 02:37:00CatawbaNRC Region 2Westinghouse PWR 4-LoopDuring the performance of reactor vessel closure head (RVCH) examinations, at 2230 EDT on April 20, 2021, it was determined that the Unit 2 RVCH penetration nozzle number 74 did not meet the requirements of 10CFR50.55a(g)(6)(ii)(D) and ASME code case N-729-6 . All other RVCH penetration examinations have been completed per 10CFR50.55a(g)(6)(ii)(D) and ASME code case N-729-6 with no other relevant indications identified. The condition of the Unit 2 reactor vessel head penetration nozzle number 74 will be resolved prior to re-installation of the Unit 2 RVCH. This event is being reported as an eight-hour, non-emergency notification per 10CFR50.72(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 5514317 March 2021 12:59:00Watts BarNRC Region 2Westinghouse PWR 4-LoopAt 1004 EDT on March 17, 2021, with Unit 2 in Mode 1 at 90 percent power, the reactor automatically tripped due to a main turbine trip. The trip was not complex, with all systems responding normally post-trip. Operations responded and stabilized the plant. Decay heat is being removed by the Auxiliary Feedwater and Steam Dump Systems. Unit 1 is 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). The expected actuation of the Auxiliary Feedwater System (an engineered safety feature) is being reported as an eight hour report under 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. All controls rods fully inserted and the electrical system is in normal shutdown alignment. The cause of the turbine trip is being investigated.
ENS 551309 March 2021 11:58:00SequoyahNRC Region 2Westinghouse PWR 4-LoopThis 60-day telephone notification is being submitted in accordance with 10 CFR 50.73(a)(1) and 50.73(a)(2)(iv)(A). The event was an invalid actuation of the Unit 1 Containment Ventilation Isolation (CVI) system. On January 11, 2021 at 1152 Eastern Standard Time (EST) with Unit 1 at 100% power, Train 'A' of the CVI System actuated due to an invalid high radiation signal from 1-RM-90-130, Containment Purge Air Exhaust Monitor. The cause of the signal was determined to be a failed sample pump associated with the radiation monitor. 1-RM-90-130 was in service at the time of the invalid signal. The Train 'A' Containment Ventilation Isolation signal was a full actuation of that train and the system functioned as designed. Prior to and following the invalid high radiation alarms, all radiation monitors except 1-RM-90-130 were stable at their normal values; therefore, the CVI was invalid. Control room operators performed appropriate checks and confirmed that all required automatic actuations occurred as designed. The failed pump was replaced and returned to service. This event was entered into the corrective action program as CR 1663398. The NRC Resident Inspector was notified.
ENS 5510415 February 2021 10:06:00South TexasNRC Region 4Westinghouse PWR 4-LoopAt 0526 (CST) on 02/15/2021, Unit 1 automatically tripped due to low steam generator levels. The low steam generator levels were due to loss of Feedwater pumps 11 and 13 (cause unknown). Auxiliary Feedwater and Feedwater Isolation actuated as designed. All Control and Shutdown Rods fully inserted. No primary or secondary relief valves opened. There were no electrical problems. Normal operating temperature and pressure (NOT/NOP) is 567 degrees F and 2235 psig. There were no significant TS LCOs entered. This event was not significant to the health and safety of the public based on all safety systems performed as designed. Unit 2 was not affected. Decay heat removal is being controlled via Steam Dumps. (Auxiliary Feedwater is supplying water to the Steam Generators.) Offsite power is in the normal electrical lineup. The NRC Resident inspector has been notified. Unit 2 was not affected and remains at 100% power.
ENS 5508326 January 2021 15:46:00Watts BarNRC Region 2Westinghouse PWR 4-LoopA licensed operator had a confirmed positive alcohol test during a random fitness-for-duty test. The employee's access to the plant has been terminated. The NRC Resident Inspectors have been notified.
ENS 5506612 January 2021 20:26:00BraidwoodNRC Region 3Westinghouse PWR 4-LoopA corporate supervisor had a confirmed positive during a random fitness-for-duty test. The employee's access to the plants has been terminated. The NRC Resident Inspectors will be notified.
ENS 550587 January 2021 18:51:00Diablo CanyonNRC Region 4Westinghouse PWR 4-LoopA non-licensed employee supervisor had a confirmed positive for alcohol during a follow-up test. The employee's access to the plant has been terminated. The licensee informed the NRC Resident Inspector.
ENS 550553 January 2021 08:33:00VogtleNRC Region 2Westinghouse PWR 4-LoopAt 1414 EST on 12/31/2020, a planned maintenance outage commenced on the Vogtle 1and 2 Seismic Monitoring System. The work was to address abnormal indications on the uninterruptable power supply, and was scheduled for an eight (8) hour duration. During the restoration activities, the system did not respond properly and has remained Non-Functional. Compensatory measures for seismic event classification were implemented in accordance with Vogtle procedures prior to removing the system from service. Based upon the troubleshooting conducted, the system is not expected to be restored within 72 hours from the start of the planned outage. 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 Seismic Monitoring System is the method for evaluating that an Operational Basis Earthquake (OBE) threshold has been exceeded following a seismic event in accordance with Initiating Condition 'Seismic event greater than OBE levels' and Emergency Action Level HU2. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. Compensatory measures implemented include having a phone number to call to verify if an earthquake has occurred.
ENS 5505330 December 2020 20:30:00South TexasNRC Region 4Westinghouse PWR 4-LoopOn December 30, 2020 at 1550 CST, South Texas Project (STP) received a report that two Emergency Notification System sirens inadvertently actuated. The sirens were heard by residents in the area who contacted the Matagorda County Sheriff's office, which notified the Emergency Response Division at STP of the siren actuation at 1557 CST. Both sirens were initially restored, however siren #24 subsequently actuated again at 1735 CST. Siren #24 has been disconnected. Siren #27 remains available. Thirty-one of thirty-two sirens are available. This notification is being made under 10CFR50.72(b)(2)(xi) as an event where other government agencies were notified. The sirens are no longer alarming. A social media release is planned. The NRC Resident Inspector has been notified of the event. The licensee believes the sirens actuated due to significant rain in the area but will be investigating the cause of the inadvertent actuation.
ENS 5504924 December 2020 16:14:00CallawayNRC Region 4Westinghouse PWR 4-LoopAt 1235 CST on December 24, 2020, Callaway Plant was in Mode 1 at approximately 90 percent power when a turbine trip/reactor trip, from a vital main generator trip signal, occurred. All safety systems responded as expected with exception of an indication issue with the 'B' Feedwater Isolation Valve, which was confirmed closed, and one intermediate range nuclear instrumentation channel which failed off-scale low following the trip. A valid Feedwater Isolation Signal and Auxiliary Feedwater Actuation Signal were also received as a result of the plant trip. The plant is being maintained stable in Mode 3. All control rods fully inserted from the reactor trip signal, and decay heat is being removed via the Auxiliary Feedwater and Steam Dump Systems. The NRC Senior Resident Inspector was notified.
ENS 5502610 December 2020 10:58:00MillstoneNRC Region 1Westinghouse PWR 4-LoopThis 60-day telephone notification is being submitted in accordance with paragraphs 10 CFR 50.73(a)(1) and 50.73(a)(2)(iv)(A) to report an invalid actuation of the 'B' train High Head Safety Injection Pump (3SIH*P1B), the 'B' train Low Pressure Safety Injection Pump (3RHS*P1B) and four Steam Generator Blowdown Containment isolation valves at Millstone Nuclear Power Station Unit 3. At 1908 EST on November 6, 2020, with Unit 3 in Mode 3, a partial invalid actuation of 'B' train Emergency Core Cooling System (ECCS) components occurred. The 'B' train SIH pump and the 'B' train RHS pump had started, and ran successfully on recirculation. Four Steam Generator Blowdown Containment isolation valves also closed. Due to this condition the 'B' Emergency Diesel Generator and the 'B' Emergency Generator Load Sequencer (EGLS) were declared inoperable and the required Technical Specification action statements were entered. Troubleshooting determined that this actuation was caused by a failure of one of the circuit boards in the 'B' train EGLS that caused a partial 'B' train 'SIS only' signal. Other 'B' Train components received the 'SIS only' signal but did not start because they were already running or were a backup to an already running component. Troubleshooting discovered a failed NAND gate on the 'B' Train EGLS XA93 circuit card. The card was replaced, retested, and the Technical Specification action statements were exited. The pumps and valves responded in accordance with plant design. No other equipment was affected during this event. There were no safety consequences or impacts on the health and safety of the public. The event was entered into the station's corrective action program. The actuation was not due to actual plant conditions or parameters meeting design criteria for an ECCS actuation. Therefore, this is considered an invalid actuation. The NRC Resident Inspector was notified.
ENS 5499715 November 2020 06:11:00Watts BarNRC Region 2Westinghouse PWR 4-LoopAt 0144 EST on November 15, 2020, with Unit 1 in Mode 1 at 100 percent power and Unit 2 in Mode 5 at 0 percent power, an actuation of the Emergency Diesel Generator (EDG) system occurred while transferring the 2A-A 6.9 kV Shutdown Board (SDBD) from the maintenance feed to its normal power supply. The reason for the 2A-A 6.9 kV SDBD failing to transfer to the normal power supply is under investigation. The EDGs automatically started as designed when the valid actuation 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 EDGs. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 5499512 November 2020 21:14:00VogtleNRC Region 2Westinghouse PWR 4-LoopAt 1732 EST on November 12, 2020, with Unit 2 in Mode 1 and 100 percent power, the reactor automatically tripped due to a turbine trip. The trip was not complex with all systems responding normally post trip. Operations responded and stabilized the plant. Decay heat is being removed by the steam generators through the steam dumps into the condenser. Unit 1 is not affected. An automatic actuation of the Auxiliary Feedwater System (AFW) also occurred. The AFW auto-start is an expected response from the reactor trip. Due to the Reactor Protection System actuation while critical, this event is being reported in accordance with 10 CFR 50.72(b)(2)(iv)(B), as well as in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the Auxiliary Feedwater System. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 5499411 November 2020 16:11:00Watts BarNRC Region 2Westinghouse PWR 4-LoopAt 1311 EST on November 11, 2020, it was determined, after evaluation of the Watts Bar Nuclear Plant (WBN) Unit 2 Steam Generator (SG) tube eddy current test data collected during the on-going refueling outage, that the WBN Unit 2 Reactor Coolant System pressure boundary did not meet the performance criteria for SG tube structural integrity. Specifically, SG number 3 failed the condition monitoring assessment for conditional burst probability. WBN has completed tube plugging and additional corrective actions 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 549888 November 2020 10:10:00MillstoneNRC Region 1CE
Westinghouse PWR 4-Loop

Millstone Units 2 & 3 declared an Unusual Event at 0921 EST after an earthquake was felt onsite. The earthquake monitoring instrumentation did not actuate, and there were no station system actuations. No damage has been detected at this time. Millstone has initiated their Abnormal Operating Procedure for an earthquake and performing station walkdowns. The State of Massachusetts has been notified. The Waterford Police and U.S. Coast Guard have contacted the station. The NRC resident has been notified. Notified DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email).

  • * * UPDATE ON 11/09/2020 AT 0715 EST FROM JASON HARRIS TO THOMAS KENDZIA * * *

At 1510 EST on November 8, 2020, Millstone Units 2 & 3 exited the Unusual Event due to the earthquake following plant walkdowns that revealed no damage to plant structures, systems, or components. Station and System walkdowns identified no issues due to the earthquake. Millstone notified the State and local authorities, and the NRC Resident Inspector. Notified R1DO (DeFrancisco), IRD (Grant), NRR (Nieh), R1RA (Lew), NRR EO (Miller), DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email).

ENS 549771 November 2020 11:04:00SequoyahNRC Region 2Westinghouse PWR 4-LoopAt 0556 EST on 11/01/2020, Sequoyah received unexpected alarms for seismological recording initiated and (Units) 1/2 Safe Shutdown Earthquake response spectra exceeded. No seismic event was felt on site, the National Earthquake Information Center was contacted to confirm there was no seismic activity, and this was also confirmed on the U.S. Geological Survey website. The alarms were determined to be invalid, and they occurred due to a failure in the seismic monitoring system. This failure results in loss of ability to assess the Emergency Action Level for Initiating Condition HU2 'Seismic event greater than Operating Basis Earthquake (OBE) levels' per procedure EPIP-1. If an actual seismic event occurred, HU2 could not be assessed. However, compensatory measures have been implemented and include assessing OBE criteria based on alternative criteria contained in procedure AOP-N.05 'Earthquake' which provides conservative guidance when seismic instruments are unavailable. This is an eight hour, non-emergency notification for an event resulting in a major loss of Emergency Assessment Capability. This event is reportable in accordance with 10 CFR 50.72(b)(3)(xiii). There is no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 5496827 October 2020 21:43:00Wolf CreekNRC Region 4Westinghouse PWR 4-Loop

At 1608 CDT on 10/27/2020, Wolf Creek Unit 1, operating at 100 percent rated thermal power in Mode-1, experienced a loss of the on-site wired corporate network. During actions to restore, it was discovered the ability to access the dose assessment software was compromised due to a security program. Access to the program was established after some time using Wi-Fi connectivity, but was not able to be accessed without network access. Actions are being taken to rectify. The NRC Resident Inspector has been notified. The licensee believes this was not a cyber-event and that the Emergency Response Data System was available, but couldn't verify. Should the Wi-Fi network access be lost, there's no capability to perform a dose assessment. Standalone laptops are being provided but have not been placed onsite yet. That should restore the ability to have dose assessment capability at all times.

  • * * UPDATE ON 10/27/2020 AT 2220 FROM JOHN WEBER TO OSSY FONT * * *

The licensee notified the NRC that the network has been restored to the Technical Support Center building and the emergency plan dose assessment group was capable of performing dose assessment. The licensee also noted that the group is able to perform dose assessment without the network, if needed. The network is still unavailable in the control room. The licensee confirmed that ERDS is available. The licensee will notify the NRC Resident Inspector. Notified R4DO (Pick).

ENS 5342827 May 2018 00:40:00MillstoneNRC Region 1CE
Westinghouse PWR 4-Loop
County and state governments were notified due to the spurious actuation of a single emergency notification siren located in New London County in the Town of Lyme. The siren was silenced. If required, alternate notification of the public in the area will be through local Emergency Operations Center route alerting. The NRC Resident Inspector has been notified.
ENS 5342623 May 2018 18:32:00CallawayNRC Region 4Westinghouse PWR 4-LoopOn May 23, 2018 Callaway determined that a violation of one provision of the site's Fitness for Duty (FFD) policy occurred. FFD pre-access testing confirmed a test failure for alcohol. The violation was committed by a non-licensed supervisory employee. The individual did not hold unescorted access to the plant but did perform behavioral observation program (BOP) duties. The BOP qualification has been removed. The NRC Resident Inspector has been notified by the licensee.
ENS 5342323 May 2018 16:10:00Comanche PeakNRC Region 4Westinghouse PWR 4-Loop

At time 0848 (CDT), Main Steamline Radiation Monitor 2-RE-2328 (Main Steamline 2-04) lost communications and was declared non-functional.

With this radiation monitor non-functional, all of the emergency action levels for a steam generator tube rupture in steam generator 2-04 could neither be evaluated nor monitored. This unplanned condition is reportable as a loss of assessment capability per 10CFR50.72(b)(3)(xiii). Comanche Peak Nuclear Power Plant (CPNPP) has assurance of steam generator integrity and fuel cladding integrity and there is a negligible safety significance to the current condition from a public health and safety perspective. Additionally, compensatory measures are in place to assure adequate monitoring capability is available to implement the CPNPP emergency plan in the unlikely event of challenges to the steam generator or fuel cladding. The N16 radiation monitor serves as a backup with alarm function and Radiation Protection technicians have been briefed on taking local readings with a Geiger-Mueller tube on MSL 2-04. Corrective actions are being pursued to restore 2-RE-2328 to a functional status. The NRC Resident Inspector has been notified.

ENS 5339811 May 2018 15:19:00Watts BarNRC Region 2Westinghouse PWR 4-LoopAt 1011 EDT on May 11, 2018, Containment Shield Building Annulus differential pressure exceeded the required limit. The Shield Building was declared inoperable requiring entry into Technical Specification (TS) 3.6.15 Conditions A and B. The event was initiated by failure of the operating annulus vacuum fan. Main Control Room Operators manually started the stand-by annulus vacuum fan to recover pressure. Shield Building Annulus differential pressure was restored to the required value at 1016 EDT and TS 3.6.15 Condition A and B were exited on May 11, 2018 at 1016 EDT. The failure mechanism for the annulus vacuum fan is being investigated. The Containment Shield Building ensures the release of radioactive material from the containment atmosphere is restricted to those leakage paths and associated leakage rates assumed in the accident analysis during a Loss of Coolant Accident (LOCA). The Emergency Gas Treatment System (EGTS) would have automatically started and performed its design function to maintain the Shield Building Annulus differential pressure within required limits. The event is being reported pursuant to 10 CFR 50.72(b)(3)(v)(C) and 10 CFR 50.72(b)(3)(v)(D). The NRC Resident has been notified.
ENS 533887 May 2018 16:31:00CallawayNRC Region 4Westinghouse PWR 4-LoopOn May 7, 2018, during an engineering review of mission time requirements for Technical Specification related equipment, a deficiency was discovered regarding the Emergency Operating Procedure (EOP) guidance for natural circulation cooldown with a stagnant loop. This condition could be the result of a postulated Main Steam Line Break with a loss of offsite power. During a natural circulation cooldown with a faulted steam generator, flow in the stagnant reactor coolant system (RCS) loop associated with the isolated faulted steam generator (SG) could stagnate and result in elevated temperatures in that loop. This becomes an issue when RCS depressurization to residual heat removal system (RHR) entry conditions is attempted. The liquid in the stagnant loop will flash to steam and prevent RCS depressurization. In this condition, the time required to complete the cooldown would be sufficiently long that the nitrogen accumulators associated with Callaway's atmospheric steam dumps and turbine driven auxiliary feedwater pump flow control valves would be exhausted. The atmospheric steam dumps and turbine driven auxiliary feedwater pump would not be capable of performing their specified safety functions of cooling the plant to entry conditions for RHR operation. This issue has been analyzed by Westinghouse in WCAP-16632-P. This WCAP determined that to prevent loop stagnation, the RCS cooldown rate in these conditions should be limited to a rate dependent on the temperature differential present in the active loops. The WCAP analysis was used to support a revision to the generic Emergency Response Guideline (ERG) for ES-0.2 "Natural Circulation Cooldown." Figure 1 in ES-0.2 provides a curve of the maximum allowable cooldown rate as a function of active loop temperature differential which is directly proportional to the level of core decay heat. At the time of discovery of this condition, Callaway's EOP structure did not ensure that the ES-0.2 guidance would be implemented for a natural circulation cooldown with a stagnant loop. Callaway has issued interim guidance to the on-shift personnel regarding this concern and is in the process of revising the applicable EOPs. This condition is reportable per 10 CFR 50.72(b)(3)(v) for any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to (A) Shutdown the reactor and maintain it in a safe shutdown condition, (B) Remove residual heat, or (D) mitigate the consequences of an accident." The licensee notified the NRC Resident Inspector of this condition.
ENS 533877 May 2018 06:42:00CookNRC Region 3Westinghouse PWR 4-LoopOn May 7, 2018 at 0336 (EDT), DC Cook Unit 2 Reactor was manually tripped due to a high-high level experienced in the East Moisture Separator Drain Tank (MSDT) of the Moisture Separator Reheater (MSR). This notification is being made in accordance with 10 CFR 50.72(b)(2)(iv)(B), Reactor Protection System (RPS) actuation as a four (4) hour report, and under 10 CFR 50.72(b)(3)(iv)(A), specified system actuation of the Auxiliary Feedwater System, as an eight (8) hour report. The NRC Resident Inspector has been notified. Unit 2 is being supplied by offsite power. All control rods fully inserted. All Aux Feedwater Pumps started properly. Decay heat is being removed via the Steam Generator Power Operated Relief Valves following Main Steam Stop Valve closure at 0431 due to a slow RCS (Reactor Coolant System) cooldown. Preliminary evaluation indicates all plant systems functioned normally following the Reactor Trip. DC Cook Unit 2 remains stable in Mode 3 while conducting the Post Trip Review. No radioactive release is in progress as a result of this event.
ENS 533867 May 2018 05:23:00SalemNRC Region 1Westinghouse PWR 4-LoopThis 4 and 8 hour notification is being made to report that Salem Unit 2 initiated a manual reactor trip and subsequent automatic Auxiliary Feedwater system actuation. The trip was initiated due to a 21 Reactor Coolant Pump reaching its procedural limit for motor winding temperature of 302F. Salem Unit 2 is currently stable in Mode 3. Reactor Coolant system pressure is 2235 PSIG and Reactor Coolant System temperature is 547 F with decay heat removal via the Main Steam Dump and Auxiliary Feedwater Systems. Unit 2 has no active shutdown technical specification action statements in effect. All control rods inserted on the reactor trip. All ECCS (emergency core cooling systems) and ESF (emergency safety function) systems functioned as expected. No safety related equipment or major secondary equipment was tagged for maintenance prior to this event. No personnel were injured during this event. The NRC Resident Inspector was notified. The Lower Alloways Creek Township will be notified.
ENS 533803 May 2018 18:40:00Comanche PeakNRC Region 4Westinghouse PWR 4-LoopDuring planned maintenance on Unit 2 Radiation Monitor 2-RE-4270 (Service Water Train B to Discharge Canal Rad Monitor), at 1220 CDT, several other Unit 2 Radiation Monitors that are used for Emergency Action Level evaluation became nonfunctional for about 1 hour. With these radiation monitors non-functional, all of the Emergency Action Levels associated with these monitors could neither be evaluated nor monitored. This unplanned condition is reportable as a loss of assessment capability per 10 CFR 50.72(b)(3)(xiii). A PC11 computer reboot restored the affected radiation monitors to a functional status. The NRC Resident Inspector has been notified.
ENS 5337130 April 2018 14:53:00BraidwoodNRC Region 3Westinghouse PWR 4-LoopAt 1124 CDT, Braidwood Unit 1 experienced an automatic Reactor Trip. The cause of the Reactor Trip was a Turbine Trip with reactor power greater than P-8. The turbine trip was actuated as a result of a Turbine Motoring Generator Trip. The cause of the generator trip is unknown at this time and is under investigation. After the Reactor Trip occurred, the 1A Auxiliary Feedwater pump was manually started to provide feedwater flow to all four steam generators. The 1A Auxiliary Feedwater pump was subsequently secured and placed in standby when the Startup Feedwater pump was placed in service. Train A Main Control Room Ventilation Filtration system shifted to Makeup Mode due to a spurious actuation signal. No secondary relief valves lifted and no secondary steam was released as a result of the Reactor Trip. The Main Steam dump valves are in service to the Main Condenser to provide heat sink cooling. The plant is being maintained at normal operating pressure and temperature. AC power is being provided by Offsite Power with the Diesel Generators in standby and all safety systems available. There is no impact to Unit 2. This report is being made per 10 CFR 50.72(b)(2)(iv)(B) for a RPS actuation, 4-hr notification, and per 10 CFR 50.72(b)(3)(iv)(A) for a manual actuation of the Auxiliary Feedwater system, 8-hr notification. The licensee notified the NRC Resident Inspector and Illinois Emergency Management Agency.