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 Entered dateSiteRegionReactor typeEvent description
ENS 5531116 June 2021 23:41:00PalisadesNRC Region 3CEOn June 16, 2021, at 1550 EDT, Palisades Nuclear Plant was operating in Mode 1 at 100% power. At that time, operations identified an acrid odor in the control room. Investigation revealed that the steam dump control relay had failed, rendering all four atmospheric steam dump valves inoperable. The loss of function of all four atmospheric steam dump valves is reportable in accordance with 10 CFR 50.72(b)(3)(v)(D) as an 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 mitigate the consequences of an accident. Troubleshooting and replacement of the relay are in progress. The plant remains stable in Mode 1 at 100% power. The NRC Resident Inspector has been notified. Unit 1 is in a 24 hour LCO for Tech Spec 3.7.4.b, atmospheric steam dump valve inoperability. The Unit is in a normal offsite power line-up.
ENS 5528531 May 2021 10:50:00Arkansas NuclearNRC Region 4CEA licensed operator 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 5528128 May 2021 09:04:00WaterfordNRC Region 4CEThis 60-day telephone notification is being made in accordance with 10 CFR 50.73(a)(1) and 10 CFR 50.73(a)(2)(iv)(A) to provide information pertaining to an invalid Engineered Safety Feature actuation signal. On April 1, 2021, at Waterford 3, while performing a replacement of power supplies on the Plant Protection System, a spurious signal caused a partial actuation of the Emergency Feedwater Actuation Signal. A partial Emergency Feedwater (EFW) logic trip path was met causing the opening of valves EFW-228A (EFW to SG 1 Primary Isolation), EFW-229A (EFW to SG 1 backup isolation), EFW-228B (EFW to SG 2 Primary Isolation), and EFW-229B (EFW to SG2 Backup Isolation). This inadvertent actuation was spurious and was not a valid signal resulting from parameter inputs. The 1992 Statements of Consideration (57 FR 41378) define an invalid signal to include spurious signals. Therefore, this actuation is considered invalid. This event was entered into the Waterford 3 corrective action program for resolution. This event did not result in any adverse impact to the health and safety of the public. The plant responded as expected. In accordance with 10 CFR 50.73(a)(1) a telephone notification is being made in lieu of submitting a written Licensee Event Report. The NRC Senior Resident Inspector has been notified.
ENS 5520221 April 2021 09:45:00PilgrimNRC Region 1GE-3On April 21, 2021, at 0752 hours (EDT), an offsite notification was made to the Commonwealth of Massachusetts Department of Environmental Protection (MADEP) in accordance with Regulation 310 CMR 40.0000: Massachusetts Contingency Plan (MCP). The notification documents non-radiological contaminants found above reportable concentrations in select samples collected during site characterization efforts. The reported reportable concentrations were slightly above reporting limits in a soil sample for Per and Polyfluoroalkyl Substances (PFAS), two groundwater sampling locations for PFAS, and isolated instances of metals in groundwater including Arsenic, Vanadium, Lead, Antimony, Beryllium, Cadmium, Chromium, Nickel, and Thallium. This report is being submitted in accordance with 10CFR50.72(b)(2)(xi) based on notification being made to another government agency. Concentrations above reporting limits have been entered into the site's corrective action program. As per MCP, the site will proceed with requirements to implement the phased MCP process. This condition does not represent a threat to station personnel or to members of the general public.
ENS 551692 April 2021 14:29:00River BendNRC Region 4GE-6At 1017 CDT on April 2, 2021, while operating at 85 percent power, River Bend Station experienced an automatic reactor scram caused by a turbine trip signal. The cause of the turbine trip signal is not known at this time and is being investigated. Reactor water level is being maintained by feedwater pumps and reactor pressure is being maintained by turbine bypass valves. The scram was uncomplicated and all plant systems responded as designed. This event is being reported under 10 CFR 50.72(b)(2)(iv)(B), as any event or condition that results in actuation of the Reactor Protection System (RPS) when the reactor is critical and 10 CFR 50.72(b)(3)(iv)(A) Specified System Actuation as result of expected post scram level 3 isolations. No radiological releases have occurred due to this event from the unit. The NRC Resident Inspector has been notified of this event.
ENS 5515425 March 2021 13:37:00River BendNRC Region 4GE-6On March 25, 2021 at 0901 CDT, River Bend Station Unit 1 (RBS) was operating at 93 (percent) reactor power (limited by 100 (percent) recirculation flow) when condenser vacuum began to lower due to ARC-AOV1A, Steam Jet Air Ejector Suction Valve, going closed. At 0918 CDT, a manual reactor SCRAM was inserted at approximately 80 (percent) reactor power due to condenser vacuum continuing to lower. After the SCRAM, all systems responded as designed and condenser vacuum was restored by starting a mechanical vacuum pump. The cause of the Steam Jet Air Ejector Suction Valve closure is unknown at this time and being investigated. Currently RBS is stable, and pressure is being maintained using Turbine Bypass Valves. The Main Steam Isolation Valves remained opened throughout the event. This event is being reported under 10 CFR 50.72(b)(2)(iv)(B), as any event or condition that results in actuation of the Reactor Protection System (RPS) when the reactor is critical and 10 CFR 50.72 (b)(3)(iv)(A) Specified System Actuation as result of expected post SCRAM level 3 isolations. No radiological releases have occurred due to this event from the unit. NRC Resident Inspector has been notified of this event.
ENS 5513814 March 2021 18:05:00Arkansas NuclearNRC Region 4B&W-L-LPOn March 14, 2021, at 1315 CDT, Arkansas Nuclear One, Unit 1(ANO-1) was manually tripped due to degraded voltage and momentary loss of the A-2, non-vital 4160 V Bus in accordance with Abnormal Operating Procedure. All control rods fully inserted. Degraded voltage of the A-2 non-vital 4160 V Bus resulted in de-energizing the A-4 vital 4160 V Bus. Emergency Diesel Generator No. 2, K-4B, started automatically and is currently powering the A-4 vital 4160 V Bus. All other Vital and Non-Vital Buses transferred power automatically to the Startup Transformer No. 1. Offsite power remains energized and available for ANO-1. All other systems responded as designed. The loss of the A-2 Non-Vital Bus is still under investigation. ANO-1 is currently stable in MODE 3 (Hot Standby), maintaining pressure and temperature with Main Feedwater pumps and steaming to the Condenser. There are no indications of a radiological release on either unit as a result of this event. This report satisfies the reporting criteria of both 10 CFR 50.72(b)(2)(iv)(B) for the Reactor Protection System actuation and 10 CFR 50.72(b)(3)(iv)(A) for the actuation of the Emergency Diesel Generator. The Licensee has notified the NRC Senior Resident Inspector.
ENS 550989 February 2021 10:35:00CooperNRC Region 4GE-4On February 9, 2021, at 0153 CST, Cooper Nuclear Station experienced a spike in Secondary Containment differential pressure which exceeded the Technical Specifications Surveillance Requirements 3.6.4.1.1 limit of -0.25 inches of water gauge. Secondary Containment differential pressure oscillated coincident with barometric pressure oscillations. Three additional spikes occurred which exceed the Technical Specification limit. The duration of each spike was less than one minute. The last spike occurred at 0232 CST. Secondary Containment differential pressure has restored to Technical Specification limits and further investigation is ongoing. This unplanned Secondary Containment inoperability constitutes a condition reportable under 10CFR50.72(b)(3)(v)(C) and (D), "An event or condition that at the time of discovery could have prevented the fulfillment of the safety function of (Structures, Systems, and Components) SSCs that are needed to control the release of radioactive material and mitigate the consequences of an accident. The NRC Senior Resident Inspector has been informed.
ENS 5507118 January 2021 17:31:00PilgrimNRC Region 1GE-3On January 18, 2021 at 1600 hours (EDT), Holtec Decommissioning International (HDI) made an off-site notification to the Environmental Protection Agency's Enforcement and Compliance Assurance Division in accordance with Section B of the station's National Pollutant Discharge Elimination System (NPDES) Permit No. 0003557. The event was associated with an underground sewage water system holding tank. The specific details of the occurrence are as follows: On January 13, 2021 at 1000 hours (EDT) site personnel identified what appeared to be water bubbling up from an unidentified cover within the security protected area of the site. The water emanating from the cap had no visible color or solid material and no odor. The water estimated at 25 gallons per hour or less was flowing to a site storm drain connected to permitted outfall number 007. Initial indication was that the water was potable water as part of the station's fire protection system. Further investigation determined that a back-up in an underground sewage holding tank inlet was the source of the leakage. By 1400 hours (EDT) when bathrooms including toilets on site were shutdown and removed from service, efforts were underway to pump the tank and remove the blockage, and the bubbling from the cover had stopped. The licensee has notified the Massachusetts Environmental Protection Agency, the Massachusetts Emergency Management Agency and the NRC Resident Inspector.
ENS 550567 January 2021 03:18:00Grand GulfNRC Region 4GE-6

An Unusual Event was declared at Grand Gulf Nuclear Station at 0124 (CST) on 01/07/2021 due to Unidentified Drywell Leakage exceeding 10 GPM for 15 minutes. Unidentified leakage has reduced to less than 0.44 GPM as of 0213 CST on 01/07/2021. The cause of the increase leakage rate is under investigation. The licensee notified the NRC Resident Inspector. Notified DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email).

  • * * UPDATE ON 01/07/21 AT 0619 EST FROM LEROY PURDY TO BRIAN LIN * * *

At 0356 CST, Grand Gulf Nuclear Station terminated the Unusual Event following plant parameters returning to normal. The current leakage rate is 0.3 gallons per minute and stable. The NRC Resident Inspector has been notified. Notified R4DO (Kozal), IRD MOC (Gott), NRR EO (Felts), DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email).

ENS 5503011 December 2020 15:15:00Grand GulfNRC Region 4GE-6On December 11, 2020 at 1204 CST, Grand Gulf Nuclear Station (GGNS) experienced an Automatic Reactor Scram from 100 percent Reactor Power after a Main Turbine and Generator Trip. All Control Rods fully inserted and there were no complications. All systems responded as designed. Reactor pressure is being maintained with Main Turbine Bypass Valves. Reactor water level is being maintained in normal band with the condensate system. No radiological releases have occurred due to this event from the unit. The NRC Branch Chief has been notified.
ENS 5502810 December 2020 20:43:00Arkansas NuclearNRC Region 4CE

On December 10, 2020 at 1608 CST, Arkansas Nuclear One, Unit 2 (ANO-2) experienced an automatic reactor scram from 100 percent power due to Low Steam Generator Water Level in 2E-24A Steam Generator. Emergency Feedwater actuated automatically due to low water level in the A Steam Generator. Due to inadequate control of the B Main Feedwater Control System, water level in the B Steam generator rose to a level requiring manual trip of the B Main Feedwater pump. Emergency Feedwater responded as designed to feed both steam generators automatically. All other systems responded as designed. All electrical power is being supplied from offsite power and maintaining unit electrical loads as designed. Unit 2 is currently stable in Mode 3 (Hot Standby) maintaining pressure and temperature via Emergency Feedwater and secondary system steaming. There are no indications of a radiological release on either unit as a result of this event. This report satisfies the reporting criteria of both 10 CFR 50.72(b)(2)(iv)(6) for the Reactor Protection System actuation and 10 CFR 50.72(b)(3)(iv)(A) for the actuation of the Emergency Feedwater System. The Arkansas Nuclear One NRC Senior Resident Inspector has been notified.

  • * * UPDATE FROM JOHN LINDSEY TO DONALD NORWOOD AT 1605 EST ON 12/11/2020 * * *

The purpose of this (report) is to provide an update to NRC Event Number 55028. The cause of the inadequate control of the B Main Feedwater Control System to control B Steam Generator Level was verified to be associated with the failure that led to the A Steam Generator low level condition. After taking action to trip the B Main Feedwater Pump, Emergency Feedwater was manually actuated for the B Steam Generator and the Emergency Feedwater System was verified to maintain proper automatic control of both Steam Generator levels. At the time of the initial event notification, plant temperature and pressure control had been transferred from Emergency Feedwater to Auxiliary Feedwater along with secondary system steaming. The licensee notified the NRC Resident Inspector. Notified R4DO (Kellar).

ENS 5501230 November 2020 14:16:00River BendNRC Region 4GE-6A non-licensed employee supervisor had a confirmed positive for a controlled substance. The employee's access to the plant has been terminated. The licensee informed the NRC Resident Inspector.
ENS 5499110 November 2020 22:06:00River BendNRC Region 4GE-6On November 10, 2020, at 1827 CST, River Bend Station (RBS) received a report of a single inadvertent and malfunctioning siren which is part of the Emergency Notification System. The siren was heard by residences in the area and they contacted local agencies, who in turn contacted RBS. This siren activation was not related to any condition or event and no emergency has occurred at RBS. RBS has notified the appropriate authorities and the Governor's Office of Homeland Security and Emergency Preparedness of the inadvertent siren activation. RBS has sent a team to locally disable the siren to prevent any further inadvertent sounding and it is now disabled. A press release from Entergy is not planned at this time. The NRC resident has been notified of the event. The licensee also notified the East and West Feliciana Parish Authorities. If an emergency notification were required, there is overlap of working sirens to cover the area of the siren that is out of service.
ENS 549866 November 2020 05:00:00Grand GulfNRC Region 4GE-6On November 6, 2020, at 0239 CST, Grand Gulf Nuclear Station (GGNS) experienced an Automatic Reactor Scram from 84 percent Reactor Power after a Main Turbine and Generator Trip. All control rods fully inserted and there were no complications. All systems responded as designed. Reactor pressure is being maintained with Main Turbine Bypass Valves. Reactor water level is being maintained in normal band with the condensate system. No radiological releases have occurred due to this event from the unit. The NRC Resident has been notified.
ENS 549782 November 2020 08:10:00WaterfordNRC Region 4CEOn November 2, 2020, at 0419 CST, Waterford 3 experienced an automatic reactor trip due to a Control Element Drive Mechanism Control System timer failure while attempting to synchronize a second motor generator set. All control rods fully inserted. The plant is currently in Mode 3 and stable with normal feedwater feeding and maintaining both Steam Generators. The NRC Senior Resident Inspector has been notified. The cause of the failure is still under investigation.
ENS 549761 November 2020 09:34:00CooperNRC Region 4GE-4On November 1, 2020, at 0534 CST the reactor was manually scrammed due to an un-isolable leak on the Turbine High Pressure Fluid System. Initial power level when the leak was identified was 100 percent. Power was lowered commencing at 0525 in accordance with shutdown procedures. The Reactor Operator scrammed the reactor at 0534 from approximately 75 percent power. Following the scram, Reactor vessel water level lowered to approximately -20 inches on the Wide Range Instruments, and was subsequently recovered to normal post scram range (approximately 36 inches) using the Reactor Feedwater system. Group 2 Isolation occurred due to Reactor vessel level reaching the isolation setpoint (3 inches). The plant is stable in MODE 3 and proceeding to cold shutdown. The Main Condenser remained available throughout the evolution and condenser vacuum is currently being maintained by the Mechanical Vacuum Pumps. Pressure is being controlled using the steam line drains to the main condenser. All control rods fully inserted and there were no complications. All systems responded as designed. The Turbine High Pressure Fluid System has been secured. This event is reportable under 10 CFR 50.72(b)(2)(iv)(B) due to RPS Actuation-Critical and 50.72(b)(3)(iv)(A) Valid Specified System Actuation. The licensee has notified the NRC Resident Inspector.
ENS 5495419 October 2020 07:20:00Arkansas NuclearNRC Region 4CE
B&W-L-LP

On October 18, 2020 at 2313 CDT, Arkansas Nuclear One (ANO) discovered that 2VRA-1B (2VSF-9 outside air damper reserve bottle) was below 600 psig. This condition caused the control room envelope to be inoperable in accordance with OP-2104.007 Attachment L. ANO Unit 1 entered TS 3.7.9 Condition B for inoperable control room boundary. ANO Unit 2 entered TS 3.7.6.1 Action D for inoperable control room boundary. A procedurally controlled temporary modification was implemented to install a blank flange on the 2VSF-9 outside air damper. Both Units declared the control room boundary operable at 2358 CDT. The associated control room emergency recirculation fan remains inoperable with the blank flange installed. This is a 7-day shutdown-LCO for both units. The licensee informed the NRC Resident Inspector.

  • * * RETRACTION FROM AARON TOSCH TO HOWIE CROUCH ON 10/24/2020 AT 1657 EDT * * *..

Previously, Entergy notified the NRC that ANO control room envelope was inoperable due to 2VRA-1B (2VSF-9 outside air damper reserve bottle) was below required pressure of 600 psig. After additional engineering evaluation, it was determined the control room boundary remained intact for this condition. As documented in version 2 operability determination for condition report ANO-C-2020-2818, the control room ventilation boundary remained intact for the condition identified and was able to fulfill its function for the required 30-day mission time. In accordance with NUREG-1022, 'Event Report Guidelines 10 CFR 50.72 and 50.73,' a report may be retracted based on a revised operability determination. The CRE remained operable; therefore, this report may be retracted. The NRC Resident Inspector has been informed. Notified R4DO (Pick).

ENS 549357 October 2020 10:25:00Grand GulfNRC Region 4A non-licensed employee 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 licensee informed the NRC Resident Inspector.
ENS 5490824 September 2020 06:31:00Grand GulfNRC Region 4On September 24, 2020, at 0258 CDT, Grand Gulf Nuclear Station (GGNS) was notified that one Emergency Notification Siren located on US Hwy 61 had actuated. Claiborne County was informed that no emergency exists at GGNS. The alarming siren has since been secured. Notification is being provided to the NRC in regards to the potential for media inquiry. The licensee informed the NRC Resident Inspector.
ENS 5489711 September 2020 22:54:00PalisadesNRC Region 3At 1930 EDT, on September 11, 2020, Palisades Nuclear Plant was conducting ultrasonic data analysis from reactor vessel closure head in-service inspections. During this analysis, signals that display characteristics consistent with primary water stress corrosion cracking were identified in head penetration 34. No leak path signal was identified during ultrasonic testing. The plant was in cold shutdown at 0% power and in Mode 6 for a refueling outage at the time of discovery. Repair actions will be completed prior to plant startup from the outage. This condition has no impact to the health and safety of the public. This report is being made in accordance with 10 CFR 50.72(b)(3)(ii)(A) for degradation of a principal safety barrier. This is the only indication that is currently present, however, if additional indications are found, they will also be repaired prior to the plant startup. The licensee notified the NRC Senior Resident Inspector.
ENS 5489510 September 2020 16:09:00PilgrimNRC Region 1A contract employee supervisor had a confirmed positive for alcohol during a random fitness-for-duty test. The employee's rights to access the plant have been suspended. The licensee notified the NRC Region I Decommissioning Lead Inspector.
ENS 548804 September 2020 01:40:00River BendNRC Region 4River Bend Station experienced an inadvertent initiation and injection of High Pressure Core Spray (HPCS) at 2048 (CDT) on 9/3/2020 while operating at 92% power. Initial investigation indicates a power supply failure in the Division III trip units which feeds HPCS and Division III Diesel Initiation signals. The Control Room Operator responded to the event by taking manual control of Feedwater Level Control to maintain Reactor Water Level nominal values. The HPCS injection valve was open for approximately 25 seconds before operators manually closed the valve. The manual closure of the injection isolation valve caused the system to be incapable of responding to an automatic actuation signal. The manual override of the injection isolation valve was reset approximately 52 minutes after the event. The HPCS system has remained inoperable. The event is being reported in accordance with 10 CFR 50.72(b)(3)(v)(D) as a condition that caused loss of function of the HPCS System. No radiological releases have occurred due to this event. The Senior NRC Resident Inspector has been notified. These conditions put the unit in a 14-day LCO (3.5.1) for HPCS Inoperability and a 30-day LCO (3.7.1) for one Standby Service Water Pump Inoperable (2C).
ENS 5486731 August 2020 08:28:00PalisadesNRC Region 3A contract employee supervisor had a confirmed positive for alcohol during a fitness-for-duty test. The employee's access to the plant has been terminated. The licensee notified the NRC Resident Inspector.
ENS 5485525 August 2020 02:26:00Grand GulfNRC Region 4On August 24, 2020 at 2305 CT at Grand Gulf Nuclear Station (GGNS) an Automatic Reactor Scram occurred after a trip of the Reactor Feed Pump B and subsequent lowering of reactor water level to 11.4 inches Narrow Range. The scram occurred with Reactor Power at 14% and the main generator offline. All control rods fully inserted and there were no complications. All systems responded as designed. Main Steam Isolation Valves were manually closed to control reactor cooldown, Currently GGNS reactor pressure is being maintained at 450-600psig. Reactor water level is being maintained with condensate through startup level control. No radiological releases have occurred due to this event from the unit. The NRC Resident has been notified. Decay heat is being removed via the main condenser. Notified R4DO.
ENS 5484921 August 2020 12:53:00River BendNRC Region 4On August 21, 2020 at 0908 CDT, River Bend Station was operating at 100% reactor power when reactor recirculation pump 'B' tripped. At 0918 CDT, a manual reactor scram was inserted at 67% reactor power after receiving indications of thermal hydraulic instability as indicated by flux oscillations on the period based detection system (PBDS) and average power range monitors (APRMs). All control rods fully inserted and there were no complications. All systems responded as designed. Currently River Bend Station Unit 1 is stable and pressure is being maintained using turbine bypass valves. This event is being reported under 10 CFR 50.72(b)(2)(iv)(B), as any event or condition that results in actuation of the reactor protection system (RPS) when the reactor is critical and 10 CFR 50.72 (b)(3)(iv)(A) Specified System Actuation as result of Group 3 isolations. NRC Resident Inspector has been briefed on this event. No radiological releases have occurred due to this event from the unit.
ENS 548248 August 2020 05:34:00Grand GulfNRC Region 4On August 8, 2020, at 0127 CDT, Grand Gulf Nuclear Station was manually shut down due to a turbine high pressure control valve malfunction. Reactor pressure is being controlled with bypass control valves to the main condenser. Reactor level is being maintained with condensate and feedwater through startup level control. The plant is stable in MODE 3 and proceeding to cold shutdown. The cause of the 'D' high pressure control valve malfunction is under investigation at this time. All rods fully inserted and there were no complications. All systems responded as designed. This event is being reported under 10 CFR 50.72(b)(2)(iv)(B), as any event or condition that results in actuation of the Reactor Protection System (RPS) when the reactor is critical. Additionally, at 0159 CDT, with all rods fully inserted and after the 0127 CDT manual reactor Scram, an automatic valid RPS actuation signal was received. This event is also being reported under 10 CFR 50.72(b)(3)(iv)(A), as an event or condition that results in a valid actuation of any of the systems listed in 10 CFR 50.72(b)(3)(iv)(B).
ENS 547418 June 2020 01:08:00Grand GulfNRC Region 4On June 7, 2020, at 2238 CDT Grand Gulf Nuclear Station (GGNS) was notified by Claiborne County that one Emergency Notification Siren located on US Hwy 61 South had actuated. Claiborne County was informed that no emergency exists at GGNS. The alarming siren has since been secured. Notification is being provided to the NRC in regards to the potential for media inquiry. The licensee informed the NRC Resident Inspector.
ENS 5472525 May 2020 08:44:00Grand GulfNRC Region 4An (automatic) reactor SCRAM occurred at 0433 CDT, on 05/25/2020, from 66 percent core thermal power. The cause of the SCRAM was due to a Main Turbine Trip. The cause of the Turbine Trip is under investigation. All systems responded as designed. No loss of offsite power or (Emergency Safety Feature) (ESF) power occurred. No (Emergency Core Cooling System) (ECCS) or Emergency Diesel Generator initiations occurred. Main Steam Isolation valves remained open and no radioactive release occurred due to this event. The plant is stable in mode 3. This event is being reported under 10 CFR 50.72(b)(2)(iv)(B), as any event or condition that results in actuation of the Reactor Protection System (RPS), when the reactor is critical. The NRC Resident Inspector has been notified. Decay heat removal is through the Feedwater and Condensate System.
ENS 5472421 May 2020 17:38:00WaterfordNRC Region 4A licensed operator had a confirmed positive for alcohol during a pre-access fitness-for-duty test. The individual's unescorted access has been terminated.
ENS 546901 May 2020 15:34:00CooperNRC Region 4At 0831 CDT, the Main Control Room received a 'Reactor Building 903 ft. Access Both Doors Open' alarm. Investigation found the interlock between the inner and outer doors did not prevent the opening of both doors while personnel were accessing the Reactor Building. The doors were immediately closed. Based on alarm times, both doors were open for less than one second. With both doors open, SR 3.6.4.1.3 was not met and Secondary Containment was declared inoperable. This unplanned Secondary Containment inoperability constitutes a condition reportable under 10 CFR 50.72(b)(3)(v)(c) and (d), 'An event or condition that at the time of discovery could have prevented the fulfillment of the safety function of SSCs that are needed to control the release of radioactive material and mitigate the consequences of an accident.' Secondary Containment was declared operable at 0836 CDT after independently verifying at least one Secondary Containment access door was closed. The NRC Senior Resident Inspector has been informed.
ENS 546321 April 2020 21:05:00WaterfordNRC Region 4On April 1, 2020, a licensed senior reactor operator, returning from a leave of absence, disclosed a Fitness-For-Duty policy violation, which occurred on July 29, 2019. The individual's site access has been removed. The NRC Resident Inspector has been notified.
ENS 544709 January 2020 19:25:00River BendNRC Region 4The Division I Control Building Chiller 'A' failed to start during post maintenance testing. By design, the Division II Control Building Chiller 'B' should have started automatically but did not. Operators then manually placed the Division I Control Building Chiller 'C' in service. This condition rendered both Divisions of the Control Building Air Conditioning System Inoperable. The applicable LCO was entered and exited 10 minutes later with all required actions and completion times met. The cause of the failure is not known at this time. The plant was at 100% power at the time of the event and is currently stable at 100% power. The NRC Resident Inspector has been notified.
ENS 544255 December 2019 16:03:00CooperNRC Region 4The following was received via email from Cooper Nuclear Station: At 0810 (CST), on 12/5/19, Operations personnel discovered BLDG-DOOR-R209, FIRE DOOR BETWEEN CRITICAL SWITCHGEAR ROOMS F & G, was unlatched. The door was immediately latched upon discovery. Based on door logs, the door separating the two critical switchgear rooms was inadvertently left unlatched for approximately 5 minutes. This door is a Steam Exclusion Boundary (SEB) door. It is required to be closed and latched when the Auxiliary Steam Boiler is in service due to Auxiliary Steam piping passing through Critical Switchgear Room 'G'. If a steam line break was to occur with the door unlatched, steam could render both Critical Switchgear busses inoperable. This is being reported under 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, and 10 CFR 50.72(b)(3)(v), 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 (B) remove residual heat and to (D) mitigate consequences of an accident. There was no impact on the health and safety of the public or plant personnel. The door closes automatically and appeared to have been left unlatched by the last person passing through. The door was tested and latches as required. The licensee notified the NRC Resident Inspector.
ENS 543716 November 2019 01:17:00Grand GulfNRC Region 4

On November 5, 2019 at 1811 CST, station service water A and the Division 1 diesel generator (DG) were declared inoperable based on the results of an engineering evaluation of a Class 3 piping leak. This was determined to be a potential inability to fulfill a safety function due to concurrent inoperability of two emergency diesel generators. Division 3 DG was inoperable due to planned maintenance on November 4, 2019 at 0000 CST. This event is being reported an 8-hour non-emergency notification per 10 CFR 50.72 (b)(3)(v)(D) as an event or condition that could have prevented the fulfillment of a safety function (Accident Mitigation). Division 3 DG and high pressure core spray have been restored, and the fulfillment of the accident mitigation safety function has been restored. The NRC Senior Resident Inspector has been notified.

  • * * RETRACTION ON 11/11/19 AT 1739 EST FROM GABRIEL HARGROVE TO BETHANY CECERE * * *

This was initially reported under 10 CFR 50.72(b)(3)(v)(D). However, subsequent engineering evaluation determined that the condition did not affect safety system operability. The evaluation determined that the leakage was within allowable limits and piping structural integrity was not challenged at this time nor in the past three years. The Division 1 DG and SSW A were at the time of discovery OPERABLE and EN54371 is being retracted. The licensee will notify the NRC Resident Inspector. Notified R4DO (Drake).

ENS 5434824 October 2019 16:25:00River BendNRC Region 4At 1035 CDT the Automatic Depressurization System (ADS) was rendered inoperable due to the failure of the 'A' Safety Vent Valve (SVV) Compressor (SVV-C4A) to manually start with SVV-C4B tagged out. System pressure slowly dropped below 131 psig (normal pressure is 165 psig). This caused the ADS safety relief valves to be declared inoperable. The station entered Technical Specification 3.5.1 Condition G. The Required Action was to be in Mode 3 in 12 hours. As a result, the station was in a condition that could have prevented the fulfillment of a safety function. The breaker for SVV-C4B was reset and the clearance for SVV-V4B was released. System pressure was restored to greater than 131 psig at 1116 CDT which allowed exit of the action statement to be in Mode 3 in 12 hours. System parameters are currently stable in the normal pressure range. Investigation for the cause of the system failure is ongoing. No radiological releases have occurred due to this event from the unit. The licensee notified the NRC Resident Inspector.
ENS 5433920 October 2019 19:21:00Arkansas NuclearNRC Region 4

At 1030 CDT, it was discovered that the loop seal on the condensate drain was empty for VUC-9 Control Room AC Unit. This creates a breach in the Control Room envelope. Unit 2 entered (Technical Specification) T.S. 3.7.6.1 Action D. Unit 1 is in Mode 6; therefore, not in a mode of applicability. Compensatory action were being performed and the licensee was in the process of sealing the loop. The licensee will notify the NRC Resident Inspector.

  • * * RETRACTION FROM DONNA BOYD TO DONALD NORWOOD AT 1336 EDT ON 10/24/2019 * * *

This report is being retracted. The Control Room Envelope (CRE) provides a safety function which limits radiological dose to occupants to no more than 5 rem for 30 days post-accident. The dose limitation assumes the occupants are stationed within the CRE 24 hours a day for the entire 30-day period. The CRE also functions to protect occupants from potential hazards such as smoke or toxic chemicals. The CRE is declared inoperable when a potential breach is identified, regardless of the ability to seal the breach. With respect to the event of October 20, 2019, the water level in a loop seal could not be maintained at the desired level. Subsequent evaluation determined that sufficient water was maintained in the loop seal to prevent a breach of the CRE. The subject reporting criterion is based on the assumption that safety-related systems, structures, and components (SSCs) may no longer be capable of mitigating the consequences of an accident. In accordance with NUREG 1022, 'Event Report Guidelines 10 CFR 50.72 and 50.73,' a report may be retracted based on a revised operability determination. The CRE remained operable; therefore, this report may be retracted. The licensee notified the NRC Resident Inspector. Notified R4DO (Young).

ENS 5433818 October 2019 10:45:00River BendNRC Region 4

EN Revision Text: INADVERTENT OPENING OF MAIN TURBINE BYPASS VALVES POTENTIONALLY AFFECTED SAFE SHUTDOWN CAPABILITY At 0207 (CDT), the Bypass Electro-Hydraulic Control (EHC) system was secured for planned maintenance. When the Bypass EHC pumps were secured, both of the Main Turbine Bypass Valves unexpectedly opened to approximately 4.5 percent. Plant parameters indicated no impact to Turbine Control Valve position, Reactor Pressure, Turbine First Stage Pressure, or Main Steam Line flows. There were no other abnormal indications noted. With the Turbine Bypass Valves partially open, there is a potential to affect instrumentation that trips on high Turbine First Stage Pressure. Therefore, this event is being reported as a potential loss of Safety Function. At 0256, the Bypass EHC system pumps were restored and the Turbine Bypass Valves Closed. No radiological releases have occurred due to this event from the unit. The licensee has notified the NRC Resident Inspector.

  • * * RETRACTION FROM THONG LE TO HOWIE CROUCH AT 1019 EST ON 11/19/19 * * *

This Event Notification was contingent on the Main Turbine Bypass Valves opening which resulted in the inoperability of Turbine First Stage Pressure monitoring instrumentation. A detailed review of system design and plant parameter trends has confirmed that the Main Turbine Bypass Valves remained closed for the duration of the event, permitting the instrumentation systems dependent on accurate Turbine First Stage Pressure to perform their respective design and licensing basis functions. Valve drift in the open direction was observed by position indication when hydraulic control pressure was removed. However, the valves were at an over-travel closed position prior to the event allowing the valves to settle at a position where an internal spring could provide closing force to the valve disc. Multiple plant parameter trends including Turbine First Stage Pressure, Reactor Pressure, Main Steam Line flows, and Main Turbine Bypass Valve discharge line temperatures indicate that the Main Turbine Bypass Valves remained closed for the duration of the event. The licensee has notified the NRC Resident Inspector. Notified R4DO (O'Keefe).

ENS 543125 October 2019 16:29:00Arkansas NuclearNRC Region 4At 0850 CDT, on 10/5/2019, the control room was notified of a personnel injury in the Unit 1 containment building. The individual was considered potentially contaminated since a complete frisk could not be performed prior to transport to a local hospital. At 1234 CDT, a radiological survey determined that the individual and their clothing had trace amounts of activity that was easily removed. The employee did not sustain any life threatening injuries. This is reportable under 10 CFR 50.72(b)(3)(xii). Additionally, at 1135 CDT contact was made with the Arkansas Department of Health about transport of the potentially contaminated individual. This is reportable under 10 CFR 50.72(b)(2)(xi) due to notification of an offsite agency. The NRC Resident Inspector has been notified.
ENS 5427112 September 2019 00:49:00Grand GulfNRC Region 4On September 11, 2019 at 1719 CDT, plant personnel identified a condition in which the 208 foot elevation inner primary containment airlock door was not in its fully seated and latched position while the 208 foot elevation outer primary containment airlock door was opened. The 208 foot elevation outer containment airlock door was subsequently closed by the individual exiting the area. The time that both 208 foot elevation containment airlock doors were not in their fully seated and latched positions was less than 1 minute. Following this occurrence, maintenance personnel inspected the 208 foot elevation inner containment airlock door and re-positioned this door to its fully seated and latched position. There was no radioactive release as a result of this event. This condition requires an 8-hour non-emergency notification in accordance with 10CFR50.72(b)(3)(v)(C) as an event or condition that could have prevented fulfillment of a safety function needed to control the release of radioactive material. The NRC Resident Inspector has been notified.
ENS 5424428 August 2019 19:10:00Grand GulfNRC Region 4On Wednesday, August 28, 2019, at 1316 CDT, Grand Gulf Nuclear Station experienced a power loss to the Control Room High Pressure Core Spray (HPCS) Instrumentation Panel due to an internal inverter failure. The power loss caused the loss of the HPCS System (a single train system). The minimum flow valve (a Primary Containment Isolation Valve) for HPCS opened due to this power loss as well. This valve was manually closed in response to this, and the outboard isolation requirement for the associated penetration (which) is closed (for the) system remained intact throughout this event. No other accident mitigation systems were affected by this event. The cause of this event is under investigation at this time. The NRC Resident Inspectors were notified. This Condition is an 8-hour reportable condition as an event or condition that could have prevented the fulfillment of a safety function, in accordance with 10 CFR 50.72(b)(3)(v)(D).
ENS 5423220 August 2019 18:28:00CooperNRC Region 4At 0939 CDT, on 8/19/19, the National Weather Service reported to Cooper Nuclear Station that the National Warning System (NAWAS) Radio would neither transmit nor receive. The system has been intermittently available since then, but never declared fully functional. The backup notification system has been verified to be available throughout this period. Additional information from the National Weather Service received 8/20/19 at 1414 determined that the Shubert Tower transmitter is non-functional and would not be repaired until 8/21/19. The transmission outage is conservatively assumed to have begun at the first notification on 8/19/19 at 0939. The Shubert Tower transmitter activates the (EMERGENCY ALERT SYSTEM) EAS/Tone Alert Radios used for public notification. This is considered to be a major loss of the Public Prompt Notification System capability and is reportable under 10 CFR 50.72(b)(3)(xiii) when the primary notification system is or will be unavailable for greater than 24 hours with the backup system available. The NRC Senior Resident has been informed.
ENS 542058 August 2019 13:26:00WaterfordNRC Region 4This 60-day telephone notification is being made in accordance with 10 CFR 50.73(a)(1) and 10 CFR 50.73(a)(2)(iv)(A) to provide information pertaining to an invalid Engineered Safety Feature actuation signal. On June 25, 2019, at Waterford 3, while performing an emergent replacement of relays on the Engineered Safety Features Actuation System Train A that affected Shield Building Ventilation Train A and HVAC Equipment Room Supply Fan AH-1 3A, unintentional contact was made between two contacts on the relay, resulting in an inadvertent initiation of other relays in the sequencer circuit. This caused the starting of Low Pressure Safety Injection Pump A, Switchgear Ventilation Fan A, and Boric Acid Makeup pumps. This was a partial actuation of Engineered Safety Features Actuation System Train A. Affected plant systems started and functioned successfully. This inadvertent actuation was caused by human error and was not a valid signal resulting from parameter inputs. The 1992 Statements of Consideration define an invalid signal to include human error. Therefore, this actuation is considered invalid. This event was entered into the Waterford 3 corrective action program for resolution. This event did not result in any adverse impact to the health and safety of the public. In accordance with 10 CFR 50.73(a)(1), a telephone notification is being made in lieu of submitting a written Licensee Event Report. The NRC Senior Resident Inspector has been notified.
ENS 542015 August 2019 17:06:00Grand GulfNRC Region 4On August 5, 2019, at 0936 CDT, Grand Gulf entered Technical Specification (TS) 3.6.4.1 due to a Secondary Containment personnel door, 1A401B, not being able to meet its design function. Door 1A401B was unable to be closed and latched. This condition is being reported as a loss of safety function. The station also entered 05-S-01-EP-4, Auxiliary Building Control (Secondary Containment) to address Auxiliary Building differential pressure due to the opened Secondary Containment penetration. Actions were taken to close and latch Door 1A401B. Secondary Containment has been declared operable. TS 3.6.4.1 and 05-S-01-EP-4 were exited. The NRC Resident Inspector was notified of the condition.
ENS 5419131 July 2019 16:20:00WaterfordNRC Region 4On July 31, 2019, at 1206 CDT, Waterford 3 commenced initiation of a plant shutdown as required by Technical Specification (TS) Limiting Condition for Operation (LCO) 3.0.3. Prior to this, on July 31, 2019, at 1108 CDT, the boron injection flow paths were declared inoperable in accordance with LCO 3.1.2.2, 'Flow Paths - Operating,' and the charging pumps were declared inoperable in accordance with LCO 3.1.2.4, 'Charging Pumps-Operating.' This was due to visual examination identifying that propagation had progressed on a previously identified flaw on piping upstream of the header supplying the charging pumps. TS LCO 3.0.3 was entered due to the action statements of LCOs 3.1.2.2 and 3.1.2.4 not being met. LCO 3.0.3 requires that action shall be initiated within one hour to place the unit in a mode in which the specification does not apply by placing it in hot standby within the next 6 hours and cold shutdown within the next 30 hours. At 1206 CDT, Waterford 3 commenced direct boration to the reactor coolant system. This condition meets the reporting criteria of 10 CFR 50.72(b)(2)(i) due to the initiation of plant shutdown required by Technical Specifications and 10 CFR 50.72(b)(3)(v)(A) and (D) due to an event or condition that could have prevented fulfillment of a safety function of structures or systems that are needed to (A) shutdown the reactor and maintain it in a safe shutdown condition and (D) mitigate the consequences of an accident.
ENS 541528 July 2019 18:40:00Arkansas NuclearNRC Region 4A non-licensed contract supervisor had a confirmed positive for a controlled substance 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 541473 July 2019 18:32:00Arkansas NuclearNRC Region 4This 60-day telephone notification is being made in accordance with 10 CFR 50.73(a)(1) and 10 CFR 50.73(a)(2)(iv)(A) to provide information pertaining to an invalid Engineered Safety Feature actuation signal. On May 9, 2019, at Arkansas Nuclear One (ANO) Unit 1, while performing an Emergency Feedwater Initiation and Control (EFIC) Channel B monthly test, a test pushbutton was mispositioned, resulting in an inadvertent initiation of the Emergency Feedwater (EFW) System. In accordance with the Engineered Safeguards Actuation System (ESAS) Trip Test portion of the surveillance, the first technician placed EFIC Train B in the tripped condition. The second technician then went to the front of the control room to verify Remote Switch Matrix (RSM) indications. The first technician recalls thinking he was given the order to reset Train B EFW Bus 1 Trip. Therefore, the first technician performed the step using three-part communication, but there is uncertainty about what was said. Due to the amount of time the second technician spent in front of the control room, the first technician assumed Operations reset the RSM to complete the Train B reset. The second technician returned to the ESAS cabinet and directed the first technician to perform the reset of Train B EFW Bus 1 Trip. The first technician, expecting his next action to be the trip of Train B EFW Bus 2, placed Bus 2 in the tripped condition. This put both buses of Train B EFW in trip and caused the actuation of P-7A EFW Pump. This inadvertent actuation was caused by human error and was not a valid signal resulting from parameter inputs. The 1992 Statements of Consideration define an invalid signal to include human error. Therefore, this actuation is considered invalid. This event was entered into ANO's corrective action program for resolution. This event did not result in any adverse impact to the health and safety of the public. The plant responded as expected. In accordance with 10 CFR 50.73(a)(i) a telephone notification is being made in lieu of submitting a written Licensee Event Report. The licensee has notified the NRC Resident Inspector.
ENS 5413125 June 2019 11:09:00WaterfordNRC Region 4On June 25, 2019, at 0428 CDT, the Waterford 3 shift operating crew declared the control room envelope inoperable in accordance with Technical Specification (TS) 3.7.6.1 due to both Broad Range Gas Monitors being inoperable. Operations entered TS 3.7.6.1 action b, which requires that with one or more control room emergency air filtration trains inoperable due to inoperable control room envelope boundary in Modes 1, 2, 3, or 4, then: 1. Immediately initiate action to implement mitigating actions; 2. Within 24 hours, verify mitigating actions ensure control room envelope occupant exposures to radiological, chemical, and smoke hazards will not exceed limits; and 3. Within 90 days, restore the control room envelope boundary to operable status. Action b.1 was completed by placing the control room in isolate mode at time 0441 CDT. This event is reportable pursuant to 10 CFR 50.72(b)(3)(v)(A) and 10 CFR 50.72(b)(3)(v)(D), event or condition that could have prevented fulfillment of a safety function of structures or systems that are needed to (A) shutdown the reactor and maintain it in shutdown condition and (D) mitigate the consequences of an accident, due to the control room envelope being inoperable. The NRC Senior Resident Inspector has been notified.
ENS 5412117 June 2019 12:56:00River BendNRC Region 4This 60-day telephone notification is being made in accordance with the reporting requirements specified by 10 CFR 50.73(a)(1) and 10 CFR 50.73(a)(2)(iv)(A) to describe an invalid actuation of a general containment isolation signal affecting multiple systems. On April 30, 2019, at approximately 0650 CDT, a level 2 containment isolation signal was introduced when a fuse for the Nuclear Steam Supply Shutoff System was removed for a maintenance clearance. The level 2 containment isolation signal caused a trip of the Division I DC bus back-up charger, leaving only the Division I battery to carry the DC bus. At 0707 CDT the bus was de-energized when another unrelated clearance opened the battery supply breaker to the DC bus causing another containment isolation signal. This event did not affect Shutdown Cooling or any other protected Safety Related Equipment. The containment isolation signals caused an isolation of the systems listed below. All components that were not removed from service, gagged in position, already in the expected position due to plant conditions, or de-energized due to plant condition performed as designed. Containment Isolation valves for the following systems isolated as expected: Drywell and Containment Floor Drains, Drywell and Containment Equipment Drains, Condensate Makeup, Fire Protection Water, Service Air, Instrument Air, Reactor Water Cleanup, Spent Fuel Cooling and Cleanup, Reactor Plant Component Cooling Water, Chilled Water, Reactor Recirculation, Main Steam Drains, Reactor Building Ventilation, and Fuel Building Ventilation. The licensee notified the NRC Resident Inspector.
ENS 5410811 June 2019 16:57:00Arkansas NuclearNRC Region 4A non-licensed contract employee supervisor had a confirmed positive for a controlled substance during a pre-access fitness for duty test. The individual's unescorted access to the plant has been terminated and the badge removed.