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| Entered date | Site | Region | Scram | Reactor type | Event description | |
|---|---|---|---|---|---|---|
| ENS 54996 | 13 November 2020 05:32:00 | Limerick | NRC Region 1 | Automatic Scram | GE-4 | At 0245 EST on November 13, 2020, the Limerick Unit 1 reactor automatically scrammed on a valid Reactor High Pressure signal (1096psig). The Reactor High Pressure signal was caused by the closure of the 1B Inboard Main Steam Isolation Valve (MSIV), causing reactor pressure to rise, exceeding the Reactor Protection System (RPS) setpoint of 1096psig. The shutdown was normal and the plant is stable in Hot Shutdown with normal pressure control via the Main Steam Bypass Valves to the Main Condenser and normal level control using the Feedwater System. The closure of the 1B Inboard MSIV appears to have been caused by a loss of Primary Containment Instrument Gas (PCIG) pneumatic supply to the valve. The licensee notified the NRC Resident Inspector, and will be notifying Berks, Chester, and Montgomery Counties, as well as the Pennsylvania Emergency Management Agency. |
| ENS 54098 | 4 June 2019 04:10:00 | Limerick | NRC Region 1 | Manual Scram | At 0145 EDT, on 6/4/19, Unit 2 was manually scrammed during a Rapid Plant Shutdown. At 64 percent reactor power, a Rapid Plant Shutdown was initiated due to lowering Main Condenser vacuum as a result of the loss of a plant electrical panel that powers Offgas System controls. The shutdown was normal and the plant is stable in Hot Shutdown with normal pressure control via the Main Turbine Bypass Valves to the Main Condenser and normal level control using Feedwater and Condensate. Main Condenser Vacuum has been restored. The licensee notified the NRC Resident Inspector. Additionally, State and local government agencies were notified. Prior to restarting Unit 2, an evaluation needs to be done due to the Unit 1 Diesel currently out of service for maintenance. The Unit 1 Diesel is a power supply for some of the common systems under the Unit 2 Technical Specifications and therefore required. | |
| ENS 51968 | 1 June 2016 10:40:00 | Limerick | NRC Region 1 | Manual Scram | GE-4 | Limerick Unit 2 was manually scrammed from 100 (percent) power at 0900 (EDT) on 6/1/2016 in accordance with plant procedure OT-112 'Unexpected/Unexplained change in core flow' when both 2A and 2B Recirculation Pump Adjustable Speed Drives (ASDs) tripped due to an electrical fault. The shutdown was normal and the plant is stable in Hot Shutdown with normal pressure control via the Main Steam Bypass valves to the Main Condenser and normal level control using Feedwater. The Manual RPS actuation is reportable under 10 CFR 50.72 (b)(2). All rods inserted fully on manual scram and the plant is in a normal shutdown electrical line up. Unit 1 was not affected by this event. The licensee plans to issue a press release. The licensee notified local counties and Pennsylvania Emergency Management Agency (PEMA). The NRC Resident Inspector has been notified. |
| ENS 51614 | 19 December 2015 10:38:00 | Limerick | NRC Region 1 | Automatic Scram | GE-4 | At 0702 EST on 12/19/2015, the Unit 2 reactor automatically scrammed on a valid reactor low level signal (12.5 inches). The reactor low level signal was caused by the trip of the in-service 2A Reactor Feedwater Pump, causing reactor level to lower, exceeding the low reactor level setpoint of 12.5 inches. The shutdown was normal. The plant is stable in Hot Shutdown with normal reactor level, pressure control via the Main Steam Bypass Valves to the Main Condenser and normal level control using the Condensate System. High level trip of the 2A Reactor Feedwater Pump was caused by high reactor level of +54 inches following opening of bypass valves during reactor start-up and pressurization. The cause is still being investigated. All systems functioned as expected following the reactor scram. The licensee notified the NRC Resident Inspector. |
| ENS 50981 | 13 April 2015 09:56:00 | Limerick | NRC Region 1 | Manual Scram | GE-4 | Following a pre-planned scram for entry into the U2 Refueling Outage, the 'B' Reactor Protection system (RPS) was unable to be reset due to a deficiency with the '2H' Intermediate Range Power Monitor. Due to this failure to reset RPS, a manual full scram was initiated as required by plant procedures. The licensee notified the NRC Resident Inspector. |
| ENS 50847 | 24 February 2015 01:02:00 | Limerick | NRC Region 1 | Automatic Scram | GE-4 | At 2140 EST on 02/23/2015, Unit 1 reactor automatically scrammed on a valid reactor high pressure signal (1096#). The reactor high pressure signal was caused by the closure of the 1C inboard main steam isolation valve (MSIV), causing reactor pressure to rise, exceeding the reactor protection system (RPS) setpoint of 1096# pressure. The shutdown was normal and the plant is stable in Hot Shutdown with normal pressure control via the main steam bypass valves to the main condenser and normal level control using the feedwater system. The closure of the 1C inboard MSIV appears to have been caused by a loss of primary containment instrument gas (PCIG) pneumatic supply to the valve. Instrument air was aligned to the remaining MSIV's. Limerick Unit 1 will remain in Hot Shutdown until repairs can be made. All rods inserted into the core during the scram. No relief or safety valves actuated during the transient. The electric grid is stable and supplying all plant loads. There was no affect on Unit 2. The licensee notified the NRC Resident Inspector, Pennsylvania Emergency Management Agency, and Berks, Chester and Montgomery counties. |
| ENS 49871 | 5 March 2014 02:26:00 | Limerick | NRC Region 1 | Manual Scram | GE-4 | At 2334 EST on 3/4/14 Unit 1 was manually scammed during a Rapid Plant Shutdown. The Rapid Plant Shutdown was initiated due to an Electro Hydraulic (Control) (EHC) System failure resulting in all Low Pressure Turbine lntercept Valves failing closed. The shutdown was normal and the plant is stable in Hot Shutdown with normal pressure control via the Main Steam Bypass Valves to the Main Condenser and normal level control using Feedwater. The licensee informed both State and local agencies and the NRC Resident Inspector. A press release will be issued by the licensee. |
| ENS 48936 | 17 April 2013 02:11:00 | Limerick | NRC Region 1 | Manual Scram | GE-4 | During outage main turbine stop valve RPS logic surveillance testing, an invalid RPS actuation occurred due to an error in executing main turbine surveillance testing procedures. A Turbine Stop Valve closure RPS signal occurred due to an error in the restoration sequence of restoring the RPS bypass signal and a subsequent manual trip of the main turbine. This resulted in a full scram and a trip of both reactor recirculation pumps. The site post-scram response procedure was entered, which required that the mode switch be placed in the locked SHUTDOWN position. This caused an expected but valid RPS actuation. No control rod motion occurred due to all control rods were inserted at the time of the invalid RPS actuation and subsequent valid RPS actuation. The license has notified the NRC Resident Inspector. |
| ENS 48117 | 18 July 2012 09:33:00 | Limerick | NRC Region 1 | Manual Scram | GE-4 | An electrical transformer fault occurred resulting in a loss of both Recirc Pumps. The reactor was manually scrammed from 100% power as required by Plant Procedure OT-112. The electrical transformer was walked down by Operations supervisor. Licensee's assessment was that a flashover occurred, and was confined to the load center transformer cabinet. Based on observed damage, EAL declaration of HU3 was made. HU3 is identified as an explosion within the Protected Area. The licensee has notified the NRC Resident Inspector. Licensee also notified state, local and other government agencies. Notified other agencies (DHS SWO, FEMA, DHS NICC)
Limerick, Unit 1 is terminating from their Unusual Event (HU3) due to the initiating event and conditions no longer being present. The 124A Fault was isolated by the trip of the designed protection features (feeder breaker trip). A walkdown of the area/equipment was completed with no adverse conditions noted. Normal plant shutdown activities are in progress. The area/equipment is quarantined for investigation. The licensee will be issuing a press release. Notified other agencies (DHS SWO, FEMA, DHS NICC) The licensee has notified the NRC Resident Inspector. Notified R1DO (Dimitriadis) and NRR EO (Davis) |
| ENS 47850 | 19 April 2012 11:10:00 | Limerick | NRC Region 1 | Manual Scram | GE-4 | Limerick Unit 1 was manually scrammed from 100% power at 0753 hours on 4/19/12 in accordance with plant procedure OT-112 'Recirculation Pump Trip' when both 1A and 1B Recirculation Pump Adjustable Speed Drives (ASDs) tripped due to an electrical fault affecting the 144D and 114A non-safety related 480V Load Centers. The shutdown was normal and the plant is stable in Hot Shutdown with normal pressure control via the Main Steam Bypass valves to the main condenser and normal level control using feedwater. The manual RPS actuation is reportable under 10 CFR 50.72(b)(2). The Technical Support Center (TSC) Normal Air conditioning systems shut down due to loss of power from the 144D Load Center. The loss of power also affects the flow indication for the Emergency Ventilation system. This is considered a Loss of Emergency Assessment Capability, and reportable under 10 CFR 50.72(b)(3)(xiii). The Emergency TSC Ventilation system is available but flow cannot be verified. During a required activation the TSC, responders would report to the TSC. If conditions required use of the Emergency Ventilation system, the Station Emergency Director would assess habitability in accordance with Station procedures. TSC relocation of personnel would be directed as required until such time that the TSC ventilation system is returned to service The licensee notified the NRC Resident Inspector.
The Technical Support Center (TSC) 144D load center has been re-energized, restoring the emergency ventilation flow indication and emergency assessment capability to its normal stand-by condition." The switchgear was inspected for any potential grounds and then reenergized at approximately 0800 EDT on 4/20/2023. The licensee notified the NRC Resident Inspector. Notified the R1DO (Joustra). |
| ENS 46919 | 3 June 2011 12:06:00 | Limerick | NRC Region 1 | Automatic Scram | GE-4 | Limerick Unit 1 automatically scrammed from 100% power at 1021 EDT hrs on 6/3/11. The RPS actuation occurred as designed upon an automatic trip of the Main Turbine. The cause of the Main Turbine trip is under investigation. Plant response to the Main Turbine trip was per design without complications. All control rods fully inserted. No ECCS or RCIC initiations occurred. No Primary or Secondary Containment isolations occurred. The plant is currently in Hot Shutdown with the normal Feedwater system maintaining reactor water level, and the Main Turbine Bypass valves maintaining reactor pressure. Limerick Unit 2 was unaffected. The post-scram electrical alignment is normal. The licensee has notified the NRC Resident Inspector and plans to notify appropriate state and local authorities. The licensee is also planning a press release. |
| ENS 46906 | 30 May 2011 15:46:00 | Limerick | NRC Region 1 | Manual Scram | GE-4 | Limerick Unit 2 was 'manually scrammed' from 0% power on 5/30/11 at 1150 hours in accordance with plant procedure OT-112 'Recirculation Pump Trip', when both the '2A' and '2B' Recirculation Pumps tripped. The cause of the pump trip is currently under investigation at this time. At the time of the 'manual' SCRAM: The Reactor Mode Switch was in 'Startup' Mode 2. All control rods were inserted to 'full-in' position (00). Reactor Shutdown was in-progress in accordance with Plant procedure GP-3 'Normal Plant Shutdown'. No primary or secondary containment isolations occurred. The plant is currently in HOT SHUTDOWN maintaining normal Reactor level with Control Rod Drive (CRD) hydraulic and Reactor Water Cleanup (RWCU) systems. Licensee is investigating a potential issue with the relay logic associated with the scram bypass feature. Offsite power circuits and emergency diesel generators are operable and available. There was no increase in plant risk associated with this event. The NRC Resident Inspector has been notified. |
| ENS 46903 | 29 May 2011 07:10:00 | Limerick | NRC Region 1 | Automatic Scram | GE-4 | Limerick Unit 2 automatically scrammed from 75% power while restoring EHC (Electro Hydraulic Control) fluid to number 3 Turbine Control Valve following maintenance work. Preliminary indications as to the cause of the scram indicate a low pressure condition in the EHC system resulting in an RPS actuation. All control rods inserted as required. No ECCS or RCIC initiations occurred. No primary or secondary containment isolations occurred. The plant is currently in Hot Shutdown maintaining normal reactor water level with feedwater. Decay heat is being removed via the bypass valves to the condenser. The plant is in a normal shutdown electrical lineup. There was no impact on Unit 1. The NRC Resident Inspector has been informed. The licensee will inform the Pennsylvania Emergency Management Agency, Montgomery, Burke, and Chester counties. |
| ENS 46641 | 25 February 2011 11:48:00 | Limerick | NRC Region 1 | Manual Scram | GE-4 | Limerick Unit 2 was manually scrammed from 100% power on 2/25/11 at 0910 EST in accordance with plant procedure OT-112 'Recirculation Pump Trip', when both the '2A' and '2B' recirculation pumps tripped. Preliminary indication of why the recirculation pumps tripped is due to main generator stator water coolant runback. The cause of the stator water coolant runback is currently under investigation at this time. All control rods inserted as required. No ECCS or RCIC initiations occurred. No primary or secondary containment isolations occurred. The plant is currently in HOT SHUTDOWN maintaining normal Reactor Water Level with Feedwater in service. Primary plant pressure and temperature is 600 psia and approximately 485 degrees F. All unit safety related equipment is operable and available, if needed. The decay heat path is via turbine bypass valves. There is no affect on Unit 1. The licensee informed Montgomery, Chester, Burks Counties and the Pennsylvania Emergency Management Agency (PEMA). The licensee intends to issue a press release. The NRC Resident Inspector has been notified. |
| ENS 46042 | 23 June 2010 23:57:00 | Limerick | NRC Region 1 | Manual Scram | GE-4 | Limerick Unit 1 was manually scrammed from 100% power on 6/23/10 at 2051 hours in accordance with plant procedure OT-112 'Recirculation Pump Trip' when both 1A and 1B recirc pump MG set drive motor breakers were observed to have tripped, resulting in a loss of both reactor recirculation pumps. Preliminary indication is a loss of power to 114A Load Center, caused by 'A' phase overcurrent trip of 13.2 KV feeder breaker (11-BUS-07) to the 114A Transformer and Load Center. The cause of the MG set drive motor breaker trips is under investigation at this time. All Control Rods inserted as required. No ECCS or RCIC initiations occurred. No Primary or Secondary Containment Isolations were received. The plant is currently in Hot Shutdown maintaining normal reactor level with feedwater in service. All systems functioned as required during the transient. The manual scram was characterized as uncomplicated. No PORVs or Safety Relief valves lifted during the transient. Decay heat is being discharged to the condenser via turbine bypass valves. The unit is in a normal shutdown electrical lineup and there was no impact on Unit 2. The electrical supplies for the recirc pump MG sets has been walked down by the licensee and no indication of any damage or electrical faults has been found at this time. The NRC Resident Inspector has been notified and the licensee indicated a media or press release will be made. |
| ENS 43949 | 1 February 2008 05:45:00 | Limerick | NRC Region 1 | Automatic Scram | GE-4 | Unit 2 automatically scrammed (at) 0445 as a result of an RPS actuation due to a turbine trip. All rods inserted. The plant is stable. No ECCS or SRV actuation occurred. This report is made pursuant to 50.72(B)(iv)(B). An investigation into the cause is currently in progress. Primary plant pressure is 900 psig. with the decay heat path to the condenser via turbine bypass valves. All safety related systems are operable, and the licensee is investigating a potential issue with the EHC system. The NRC Resident Inspector has been informed. The Commonwealth of Pennsylvania and local government agency will be informed. The licensee will issue a press release. |
| ENS 43315 | 24 April 2007 04:04:00 | Limerick | NRC Region 1 | Automatic Scram | GE-4 | Limerick Unit 2 automatically shutdown on low reactor water level (+12.5 inches) at 0210 on 4/24/07. The cause is under investigation at this time. All control rods inserted as required. HPCI and RCIC initiated, injected and restored reactor water level. Lowest reactor water level noted was -73 inches. Primary containment isolation signals on +12.5 inches and -38 inches occurred. All isolations completed as required. The plant is currently in hot shutdown maintaining normal reactor level with feedwater in service. Approximately 16000 gallons was injected in 4 minutes. There was no indication of RCS leakage. The licensee is investigating whether a feedwater runback had occurred. No SRVs lifted with the highest pressure observed at 1050 psi. The main condenser remains in service for decay heat removal. All EDGs are available, if needed. The licensee informed the NRC Resident Inspector and will inform both the State and Local authorities. |
| ENS 42054 | 12 October 2005 23:55:00 | Limerick | NRC Region 1 | Automatic Scram | GE-4 | Unit 2 Reactor automatically scrammed at 2224 (EDT) as a result of an RPS actuation due to Reactor High Pressure. All control rods inserted. The plant is stable. No ECCS or SRV actuation occurred. This report is made pursuant to 50.72(B)(2)(iv)(B). An investigation into the cause is currently in progress. Electric plant lineup is in a normal stable lineup. Reactor water level is being maintained via main feedwater system and removing decay heat via the steam bypass valves to the main condenser. This event had no effect on Unit 1. The licensee notified the NRC Resident Inspector, Pennsylvania Emergency Management Agency (PEMA), and the Berks, Chester, and Montgomery County emergency agencies. |
| ENS 40832 | 22 June 2004 15:10:00 | Limerick | NRC Region 1 | Automatic Scram | GE-4 | Unit 2 reactor scrammed at 13:13 (EDT) following an electrical yard manipulation. The reactor scram occurred as a result of an RPS (Reactor Protections System) actuation following an automatic trip of the main turbine from a generator lockout. All control rods inserted (fully). The plant is stable (in mode 3). No ECCS (Emergency Core Cooling System) or safety relief valve actuations have occurred. This report is being made pursuant to 50.72(b)(2)(iv)(b). At this time the plant is stable, as expected. An investigation is in progress to determine the reason for the electrical fault. All plant systems functioned as required and decay heat removal is being performed via bypass to the main condenser. The licensee notified local and State authorities and the NRC Resident Inspector. |