Semantic search
| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 56360 | 6 February 2023 11:30:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Communications and Assessment Capabilities | The following information was provided by Constellation via email: On 02/06/2023 at 0416 EST, the Constellation Emergency Response Organization (ERO) Notification Database System uploaded data files into the Mass Notification System (Everbridge) which is used to notify ERO personnel when activated. At 0630, the individual reviewing the uploaded files discovered that the data files did not upload properly and that Everbridge may not notify all ERO individuals within the required 10 minutes of system initiation. Constellation resolved the issue by 0752. During the time period of 0416 to 0752, control room operators would have been unaware that the ERO notification was not successful. Therefore, this issue constitutes a loss of offsite communications capability and is reportable under 10 CFR 50.72(b)(3)(xiii), 'The licensee shall notify the NRC as soon as practical and in all cases within eight hours of the occurrence of any event that results in a major loss of emergency assessment capability, offsite response capability, or offsite communications capability (e.g., significant portion of control room indication, Emergency Notification System, or offsite notification system).' This loss of offsite communications capability affected all Constellation nuclear stations. There was no impact on the health and safety of the public or plant personnel. Each affected station NRC Resident Inspectors have been or will be notified. | ||
| ENS 54996 | 13 November 2020 07:45:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Automatic Reactor Scram Due to High Reactor Pressure Signal | 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. | Feedwater Reactor Protection System Main Steam Isolation Valve Primary containment Main Condenser Main Steam | |
| ENS 54098 | 4 June 2019 05:45:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Manual Scram During Rapid Plant Shutdown | 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. | Feedwater Main Condenser | |
| ENS 52270 | 29 September 2016 21:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Tsc Ventilation Indication Issue Identified Following Surveillance Testing | On 9/29/2016 at 1700 (EDT) the MCR (Main Control Room) was notified of a potential Technical Support Center (TSC) emergency ventilation indication issue following surveillance testing. At 2350 troubleshooting revealed a blown control power fuse which affected functionality of TSC HVAC emergency mode. The system was restored to operable as of 0043 on 9/30/16. If an emergency had been declared and TSC activation was required, the TSC would have been staffed and activated unless the TSC became uninhabitable due to ambient temperatures, radiological or other conditions. The Station Emergency Director would assess habitability in accordance with station procedures. If TSC relocation becomes necessary, then personnel would be directed as required until such time that the TSC emergency ventilation system was returned to service. The licensee informed the NRC Resident Inspector. | HVAC | |
| ENS 52101 | 18 July 2016 20:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Offsite Communications Capability | Testing of the Everbridge ERO (Emergency Response Organization) notification system identified the system was not able to notify all ERO individuals. This constitutes a loss of offsite communications capability. The issue was subsequently reported resolved by the vendor and site testing has verified resolution at 2037. The Everbridge system capability loss for Limerick was identified at approximately 1600 EDT on July 18, 2016, due to a loss of system communications. Emergency Response Data System (ERDS) capability was not lost. This event is reportable under 10 CFR 50.72(b)(3)(xiii) as a loss of communications capability. The NRC Resident inspector has been notified. | Emergency Response Data System | |
| ENS 51968 | 1 June 2016 13:00:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Manual Reactor Scram Due to Unexpected Core Flow Change | 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. | Feedwater Main Condenser Main Steam | 05000353/LER-2016-001 |
| ENS 51614 | 19 December 2015 12:02:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Automatic Reactor Scram Due to Low Reactor Water Level | 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. | Feedwater Main Condenser Main Steam | |
| ENS 50951 | 3 April 2015 14:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Inoperable Seismic Instrumentation Identified During Historical Review | Limerick Generating Station (LGS) has completed a review of recent seismic monitor performance. The seismic monitor is currently capable of fulfilling its emergency assessment support function. The review of the system performance over the last three years identified two occasions when the system was degraded and incapable of performing its emergency assessment support function such that emergency classification at the UNUSUAL EVENT and ALERT levels could not be declared within fifteen minutes as required with site instrumentation. The seismic monitor was determined to be degraded and incapable of performing its emergency assessment support function on the following dates: 1) January 17, 2014 - Unit 1 100% power, Unit 2 97% power 2) March 22, 2014 - Unit 1 Refueling, Unit 2 100% power These unplanned inoperable conditions of the seismic monitor were entered into the LGS Corrective Action Program (CAP) when they occurred. While Exelon procedural direction allowed the use of offsite sources to obtain seismic data when the seismic monitor is incapable of assessing emergency plan Emergency Action Levels (EALs), this was not explicitly referenced in the approved EALs. The loss of assessment capability is reportable to the NRC within 8 hours of discovery in accordance with 10 CFR 50.72(b)(3)(xiii). This report is required per 10 CFR 50.72(a)(1)(ii) as an event that occurred within 3 years of the date of discovery. For the two dates above, the 1/17/14 failure was related to function of the system CPU (central processing unit) and the 3/22/14 failure was due to a failed instrument backup battery. There was no seismic event on either of these two dates. The licensee informed the NRC Resident Inspector. | ||
| ENS 50847 | 24 February 2015 02:40:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Automatic Reactor Scram on Reactor High Pressure Signal | 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. | Feedwater Reactor Protection System Main Steam Isolation Valve Primary containment Main Condenser Main Steam | 05000352/LER-2015-001 |
| ENS 50376 | 17 August 2014 08:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Technical Support Center Emergency Ventilation System Inoperable | On 8/17/2014 at 0400 EDT, the Technical Support Center (TSC) emergency ventilation system was identified as inoperable. Troubleshooting of this equipment found a blown control power fuse. The system has been restored to operational status as of 0555 EDT on 8/17/2014. If an emergency had been declared and TSC activation was required, the TSC would have been staffed and activated unless the TSC became uninhabitable due to ambient temperatures, radiological or other conditions. 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 emergency ventilation system was returned to service. The licensee notified the NRC Resident Inspector. | ||
| ENS 49871 | 5 March 2014 04:34:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Unit 1 Manually Scrammed During a Rapid Shutdown in Response to a Turbine Ehc Failure | 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. | Feedwater Main Condenser Main Steam | 05000352/LER-2014-004 |
| ENS 49842 | 19 February 2014 15:19:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Technical Support Center Emergency Ventilation Failure | On 2/19/2014 at 1019 EST, the Technical Support Center emergency ventilation system failed to operate during TSC Ventilation Operability Check per EP-MA-124-1001-F-02 performed by Limerick Emergency Preparedness staff. Troubleshooting of this equipment deficiency found a blown control power fuse. The fuse failure is attributed to its age. The system has been restored to operational status as of 1430 EST on 2/19/2014. If an emergency had been declared and TSC activation was required, the TSC would have been staffed and activated unless the TSC became uninhabitable due to ambient temperatures, radiological or other conditions. 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 emergency ventilation system was returned to service. The licensee notified the NRC Resident Inspector. | ||
| ENS 49275 | 13 August 2013 20:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Planned Maintenance on Technical Support Center Ventilation System Power Supply | This ENS (event notification) is being issued in advance of planned corrective maintenance on a TSC (Technical Support Center) HVAC (Heating Ventilation Air Conditioning) power supply. On 8/13/2013 at 1600 (EDT), the Technical Support Center ventilation system will be removed from service to perform corrective maintenance on an electrical panel that supplies power to the system. The emergency ventilation system will not be available and cannot be restored within the time period required to staff and activate the Emergency Response Organization (ERO). The work is scheduled to complete on 8/13/2013 at 1800 (EDT). If an emergency is declared and the TSC activation is required, the TSC will be staffed and activated unless the TSC becomes uninhabitable due to ambient temperatures, radiological or other conditions. 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. An update will be sent upon TSC HVAC restoration. The licensee has notified the NRC Resident Inspector.
At 2030 EDT on 8/13/13, the TSC emergency ventilation system has been restored to normal. The licensee notified the NRC Resident Inspector. Notified R1DO (Powell). | HVAC | |
| ENS 48653 | 7 January 2013 01:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Planned Corrective Maintenance on the Technical Support Center (Tsc) Hvac Power Supply | This ENS (report) is being issued in advance of planned corrective maintenance on a TSC HVAC power supply. On 1/6/13 at 2000 (EST), the Technical Support Center Emergency Ventilation system will be removed from service to perform corrective maintenance on the load center that supplies power to the TSC HVAC system. The emergency ventilation system will not be available and cannot be restored within the time period required to staff and activate the Emergency Response Organization (ERO). The work is scheduled to complete on Friday 1/11/13 at 1500 (EST). If an emergency is declared and the TSC activation is required, the TSC will be staffed and activated unless the TSC becomes uninhabitable due to ambient temperatures, radiological or other conditions. 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. An update will be sent upon TSC HVAC restoration. The licensee has notified the NRC Resident Inspector.
The TSC emergency ventilation system was restored to normal at 2200 EST on 1/10/13. The licensee notified the NRC Resident Inspector. Notified the R1DO (Newport). | HVAC | |
| ENS 48629 | 28 December 2012 08:30:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Communications with All Emergency Planning Zone Sirens | Limerick and associated local counties have lost communications with all Emergency Planning Zones (EPZ) sirens for greater than 1 hour. This exceeds the 25% notification threshold. The contract vendor is responding to the loss to determine repair actions and timeline. The EPZ plan contains alternate methods of notifying the public in the event of an evacuation. Notifications have been made to the State and local agencies regarding this loss of Emergency Preparedness capability at 0913 EST on 12/28/12, which constitutes the 'Offsite Notification' per 10CFR50.72(b)(2)(xi). The licensee has notified Montgomery, Chester, Burkes counties, and the NRC Resident Inspector.
Communications with all EPZ sirens have been restored. The licensee will notify the affected counties and the NRC Resident Inspector. R1DO (Conte) notified. | ||
| ENS 48117 | 18 July 2012 12:15:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Flashover in the Load Center Transformer Cabinet | 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) | 05000352/LER-2012-005 | |
| ENS 48041 | 21 June 2012 12:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Planned Maintenance on the Technical Support Center Ventilation | This ENS is being issued in advance of a planned maintenance activity. Today 6/21/12, the Technical Support Center (TSC) ventilation system will be removed from service to perform corrective maintenance on a ventilation damper. The emergency ventilation system will not be available and cannot be restored within the time period required to staff and activate the Emergency Response Organization (ERO). The work will complete today 6/21/12. If an emergency is declared and the TSC activation is required, the TSC will be staffed and activated unless the TSC becomes uninhabitable due to ambient temperatures, radiological or other conditions. 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 work planned for the TSC ventilation system was not performed and will be rescheduled to a later date TBD. The NRC Resident Inspector has been notified." Notified the R1DO (Holody). | ||
| ENS 48001 | 7 June 2012 13:47:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Technical Support Center Ventilation System Maintenance | This ENS is being issued in advance of a planned activity. Today, 6/7/12, the (TSC) Technical Support Center Emergency Ventilation system will be removed from service to support preventive maintenance activities. The emergency ventilation system will not be available and cannot be restored within the time period required to staff and activate the Emergency Response Organization (ERO). The work will complete today, 6/7/12. If an emergency is declared and TSC ERO activation is required, the TSC will be staffed and activated unless the TSC becomes uninhabitable due to ambient temperatures, radiological or other conditions. If relocation of the TSC staff becomes necessary, the Station Emergency Director will relocate the staff to an alternate TSC location. The licensee has notified the NRC Resident Inspector. | ||
| ENS 47850 | 19 April 2012 11:53:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Manual Reactor Scram Following Loss of Recirculation Pumps | 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). | Feedwater Main Condenser Main Steam | |
| ENS 47754 | 19 March 2012 17:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Technical Support Center Ventilation Out of Service | On March 19th 2012 at 1300, Limerick Generating Station will be performing routine preventative maintenance on the Charcoal Adsorber and HEPA Filter associated with the on-site Technical Support Center (TSC) Emergency Ventilation system. While performing this maintenance, the TSC Emergency Ventilation system will not be available to be restored within the time period required to staff and activate the TSC Emergency Response Organization (ERO). This work is expected to be completed by 3/19/12. If an emergency is declared requiring TSC ERO activation, the TSC will be staffed and activated using emergency planning procedures unless the TSC becomes uninhabitable due to ambient temperature, radiological, or other conditions. If relocation of TSC staff becomes necessary, the Station Emergency Director will relocate the staff to an alternate TSC location in accordance with applicable procedures. This notification is being made in accordance with 10CFR50.72(b)(3)(xiii) due to the loss of an Emergency Facility because of the planned unavailability of the TSC Emergency Ventilation system. The NRC Resident Inspector has been informed. The TSC ventilation is expected to be out of service for approximately four hours. The licensee notified the NRC Resident Inspector.
The TSC emergency ventilation system has been returned to a normal status. The licensee will notify the NRC Resident Inspector. R1DO (Schmidt) notified. | ||
| ENS 47389 | 29 October 2011 19:15:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Greater than 25% of Epz Sirens Due to Weather | Limerick Generating Station reports a loss of >25% of the EPZ sirens for greater than 1 hour. Forty eight of the 165 offsite sirens are not functioning due to loss of power related to the recent storm. The licensee has notified the NRC Resident Inspector, and state and local government. A press release may be issued. | ||
| ENS 46973 | 20 June 2011 15:56:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Technical Support Center Charcoal Failed Testing for Methyl Iodine | During 24 month Technical Support Center (TSC) Ventilation System Charcoal Analysis testing, the charcoal failed due to Methyl Iodine penetration of 3.1%, which is above the procedural limit of 1%. The TSC non-emergency ventilation system remains functional. Charcoal replacement is planned. If an emergency is declared requiring TSC activation during this period, the TSC will be staffed and activated using existing Emergency Planning procedures and checklists. If radiological conditions require TSC facility evacuation prior to completion of charcoal replacement; the Station Emergency Director will evacuate and relocate the TSC staff in accordance with applicable site procedures. The licensee informed the NRC Resident Inspector. | ||
| ENS 46919 | 3 June 2011 14:21:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Automatic Scram Following a Turbine Trip | 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. | Feedwater Secondary containment Main Turbine Control Rod | |
| ENS 46903 | 29 May 2011 09:02:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Automatic Reactor Trip Due to Low Pressure in Ehc System | 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. | Feedwater Secondary containment Control Rod | 05000353/LER-2011-004 |
| ENS 46641 | 25 February 2011 14:10:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Manual Scram Due to Recirculation Pump Trip | 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. | Feedwater Secondary containment Stator Water Control Rod | 05000353/LER-2011-002 |
| ENS 46426 | 18 November 2010 08:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Planned Technical Support Center Ventilation Corrective Maintenance | This ENS is being issued in advance of a planned activity. On November 18th 2010 at 0300, Limerick Generating Station (will apply) a clearance to perform corrective maintenance associated with MD-1 (Outside Air Damper). During the time that the block is applied, the TSC ventilation system will not be available to be restored in a time period required to staff and activate the TSC ERO (Emergency Response Organization). This work is expected to be complete on 11/18/10 at 1800. If an emergency is declared requiring TSC activation, the TSC will be staffed and activated using emergency planning procedures unless the TSC becomes uninhabitable due to ambient temperature, radiological, or other conditions. If relocation becomes necessary the Station Emergency Director will relocate the TSC staff to an alternate TSC location in accordance with applicable site procedures. This notification is being made in accordance with 10CFR50.72(b)(3) due to the loss of an emergency response facility (ERF) because of unavailability of the emergency ventilation system. An update will be provided when the TSC ventilation has been restored to normal operation. The NRC resident has been notified. * * * UPDATE FROM PAUL MARVEL TO DONG PARK AT 1729 EST ON 11/18/10 * * * Planned work on the TSC ventilation system has been completed at 1700 on November 18, 2010. The TSC has been restored to normal status. The licensee will notify the NRC Resident Inspector. Notified R1DO (Gray). | ||
| ENS 46330 | 14 October 2010 05:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Technical Support Center Emergency Ventilation System Scheduled Maintenance | This ENS is being issued in advance of a planned activity. On 10/14/10 at 0100 hours Limerick Generating Station will apply a clearance to inspect and repair fire suppression equipment associated with the onsite Technical Support Center (TSC) Emergency Ventilation System and perform corrective maintenance associated with the MD-1 (outside air) damper. While the clearance is applied, the TSC Emergency Ventilation system will not be available to be restored within the time period required to staff and activate the TSC Emergency Response Organization (ERO). This work is expected to be completed 10/14/10. If an emergency is declared requiring TSC ERO activation, the TSC will be staffed and activated using emergency planning procedures unless the TSC becomes uninhabitable due to ambient temperature, radiological, or other conditions. If relocation of TSC staff becomes necessary, the Station Emergency Director will relocate the staff to an alternate TSC location in accordance with applicable procedures. This notification is being made in accordance with 10CFR50.72(b)(3)(xiii) due to the loss of an Emergency Response Facility because of the planned unavailability of the TSC Emergency Ventilation system. The NRC Resident Inspector has been informed.
The Technical Support Center Emergency Ventilation System maintenance is complete and the system has been returned to service. The licensee has notified the NRC Resident Inspector. Notified R1DO (Jackson). | ||
| ENS 46290 | 29 September 2010 19:25:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Technical Support Center Hvac Emergency Damper Failed Quarterly Test | During quarterly testing of the Technical Support Center (TSC) HVAC System, Emergency Damper MD-1 failed to fully close when the system was placed into the Emergency mode of operation. This damper being not fully closed allows outside air to bypass the filter train and renders the Emergency mode of operation unavailable. At 1725 the Emergency Damper MD-1 was failed to the closed position which makes the Emergency mode of the TSC HVAC system available. Troubleshooting and restoration of Emergency Damper MD-1 will continue on dayshift 9/30/2010. The licensee has notified the NRC Resident Inspector. | HVAC | |
| ENS 46042 | 24 June 2010 00:51:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Manual Reactor Scram Following Loss of Both Recirculation Pumps | 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. | Feedwater Secondary containment Reactor Recirculation Pump Safety Relief Valve Control Rod | 05000352/LER-2010-001 |
| ENS 46005 | 14 June 2010 07:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Planned Maintenance on Tsc Emergency Ventilation System | On June 14, 2010 at 0300 hours, Limerick Generating Station will apply a clearance to inspect and repair Fire Suppression Equipment associated with the Onsite Technical Support Center (TSC) Emergency Ventilation System and perform corrective maintenance associated with MD-1 (Outside Air Damper). During the time that the clearance is applied, the TSC Ventilation System will not be available to be restored in a time period required to staff and activate the TSC Emergency Response Organization. This work is expected to be completed on June 16, 2010. If an emergency is declared requiring TSC activation, the TSC will be staffed and activated using emergency planning procedures unless the TSC becomes uninhabitable due to ambient temperature. Radiological or other conditions. If relocation becomes necessary, the Station Emergency Director will relocate the TSC staff to an alternate TSC location in accordance with applicable Site procedures. This notification is being made in accordance with 10CFR50.72(b)(3)(xiii) due to the Loss of an Emergency Response Facility (ERF) because of the Unavailability of the Emergency Ventilation System. The NRC Resident Inspector has been informed.
The TSC Emergency Ventilation System was returned to service at 2150 EDT on 6/14/10. The licensee has informed the NRC Resident Inspector. R1DO (Holody) notified. | ||
| ENS 45693 | 11 February 2010 13:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Technical Support Center Emergency Ventilation System Maintenance | On Thursday, February 11, 2010, the Limerick Technical Support Center (TSC) emergency ventilation system will be removed from service for planned preventative maintenance activities on the damper flow controller and air filtration charcoal system. During the maintenance, the non-emergency ventilation system will be functional. The TSC air filtration fan and dampers will be non-functional, rendering the TSC HVAC accident mode non-functional. This maintenance is scheduled to minimize out of service time. The planned TSC ventilation outage is scheduled to be completed within 12 hours. If an emergency is declared requiring TSC activation during this period, the TSC will be staffed and activated using existing EP (Emergency Planning) procedures and checklists. If radiological conditions require TSC facility evacuation during ventilation system restoration, the Station Emergency Director will evacuate and relocate the TSC staff in accordance with applicable site procedures. The licensee has notified the NRC Resident Inspector.
The maintenance on the Limerick Technical Support Center (TSC) emergency ventilation system has been completed and the TSC is available. The licensee has notified the NRC Resident Inspector. Notified R1DO (Powell) | HVAC | |
| ENS 45153 | 24 June 2009 00:30:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Partial Loss of the Emergency Response Data System (Erds) | A partial loss of the ability to send ERDS data to the NRC for greater than 60 minutes occurred. The loss affects transmission of Standby Liquid Control Tank levels, Main Condenser Vacuum levels, and data for North and South Ventilation Stacks and Drywall Post LOCA radiation monitors. The (Safety Parameter Display System) SPDS, (Health Physics Network) HPN and (Emergency Notification System) ENS systems are not affected. Troubleshooting to identify and correct the data loss to ERDS is in progress. The licensee notified the NRC Resident Inspector.
Data for North and South Ventilation Stacks and Drywell Post LOCA radiation monitors was restored to ERDS at 2345 hours on 6/23/09" The licensee will notify the NRC Resident Inspector.
Data gathered from Standby Liquid Control and Main Condenser Vacuum is not plant data that is transmitted to ERDS. ERDS was fully restored with the required input data at 2345 hours on 6/23/2009. The licensee informed the NRC Resident Inspector. Notified R1DO (Henderson). | Emergency Response Data System Standby Liquid Control Main Condenser | |
| ENS 45133 | 16 June 2009 04:31:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Emergency Response Data System (Erds) Out of Service Due to Computer Problems | (The licensee experienced) a loss of the ability to send ERDS data to the NRC for greater than 60 minutes due to a computer problem. The HPN and ENS communications systems were not affected and remained available through a commercial communication line. SPDS also remained in service and remained available during this period. The ERDS system was restored to service after 109 minutes. The licensee notified the NRC Resident Inspector.
06-22-2009 Update to clarify the above statement: The HPN and ENS communications systems were affected by the computer problem, however, they remained available for use through an alternate and unaffected commercial communication line. Notified R1DO (Burritt). | Emergency Response Data System | |
| ENS 44283 | 11 June 2008 02:55:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | 54 of 165 Emergency Sirens Inoperable Due to Power Outage | On June 10, 2008, at 2255 hours it was determined that 54 of the 165 Limerick Generating Station's Emergency Offsite Sirens were inoperable due to a loss of power. The loss was a result of heavy storms which passed through the area resulting in power outages throughout the region. Efforts are underway to restore power to the affected sirens. The licensee notified the NRC Resident Inspector
On June 11, 2008 at 1645 restoration efforts have recovered 44 of the 54 sirens rendered inoperable by the storm. The remaining 10 inoperable sirens no longer represents a major loss of emergency preparedness capabilities. Restoration of power to the remaining inoperable sirens continues under normal prioritization and using routine siren operating and maintenance procedures. No completion time was provided concerning repair of the remaining sirens. The licensee will be notifying the NRC Resident Inspector. Notified R1DO (Summers). | ||
| ENS 44169 | 25 April 2008 21:30:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Emergency Response Data System Outage | Limerick Generating Station experienced a loss of the Emergency Response Data System (ERDS), which provides real time plant data to the NRC Operations Center, from approximately 17:30 until 21:30 on 4/25/08. The plant monitoring system (PMS) and Safety Parameter Display System (SPDS) in the main control room were functional for the duration that ERDS was out of service, providing the Limerick Operators with all required data for monitoring the plant had an actual event occurred. In addition, all external phone lines were functioning to allow contact with the NRC Operations Center had an actual event occurred. The licensee notified the NRC Resident Inspector. | Emergency Response Data System Safety Parameter Display System | |
| ENS 44088 | 22 March 2008 23:39:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Turbine Trip Resulting in a Reactor Scram | Limerick Unit 1 automatically shutdown from a turbine trip at 1939 hrs on 03/22/08. The cause of the turbine trip is under investigation at this time. All control rods inserted as required. No ECCS (Emergency Core Cooling System) and no RCIC (Reactor Core Isolation Cooling) initiation occurred. No primary or secondary containment isolations were received. The plant is currently in Hot Shutdown maintaining normal reactor level with feedwater in service. Minimum water level after the scram was 5 inches. Level 3 had been reached however all level 3 isolation valves were already shut. No SRVs lifted after the scram. Decay heat is being removed by steam loads with the turbine bypass valves available if needed. The plant is in its normal shutdown electrical lineup. The licensee will issue a press release and has informed the NRC Resident Inspector. | Feedwater Secondary containment Control Rod | |
| ENS 43991 | 17 February 2008 14:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Planned Phone Outage | The Emergency Notification System (ENS), Health Physics Network (HPN), site commercial telephone lines and Emergency Response Data System (ERDS) have been taken out of service for a planned maintenance outage. The outage is scheduled for a duration of six hours. The plant radio system, plant page system, and Prelude phone system are unaffected by the maintenance. The licensee notified the NRC Resident Inspector. * * * UPDATE AT 1534 ON 2/17/08 FROM NED DENNIN TO JEFF ROTTON * * * All phones are back in service and operable. The licensee will notify the NRC Resident Inspector. Notified R1DO (Dentel). | Emergency Response Data System | |
| ENS 43949 | 1 February 2008 09:45:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Automatic Scram as a Result of Turbine Trip | 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 43455 | 28 June 2007 13:55:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Greater than 25% of the Epz Sirens for Greater than 1 Hour | This eight hour notification is being made per 10 CFR 50.72(b)(3)(xiii) to report a loss of >25% of the EPZ sirens for greater than one hour. 44 of 165 offsite sirens are not functioning due to loss of power/equipment problems because of a recent storm. Efforts are in progress to restore the affected sirens. At 1000 6/28/07 less than 25% of sirens are unavailable. The licensee notified the NRC Resident Inspector, the State of Pennsylvania, and local governments. | ||
| ENS 43315 | 24 April 2007 06:10:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge | Automatic Reactor Scram with Eccs Injection on Lowering Reactor Vessel Water Level | 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. | Feedwater Primary containment Decay Heat Removal Main Condenser Control Rod | |
| ENS 42715 | 19 July 2006 02:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Emergency Siren Capability Due to Adverse Weather | 48 of 165 offsite sirens are not functioning due to loss of power/equipment problems because of recent storm. Efforts are in progress to restore power to the affected sirens. The affected sirens are located in Chester County. Compensatory measures are in effect to alert the public should the need arise. The licensee informed the NRC Resident Inspector.
The licensee reported that only 22 of 165 sirens are now inoperable. This is less than the reportable (25%) amount of 41 sirens. The licensee notified the NRC Resident Inspector. Notified R1DO (Kinneman). | ||
| ENS 42054 | 13 October 2005 02:24:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Automatic Scram Due to Reactor High Pressure Signal | 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. | Feedwater Main Condenser Control Rod | 05000353/LER-2005-004 |
| ENS 41848 | 18 July 2005 13:52:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Automatic Reactor Scram | Unit 1 reactor automatically scrammed at 09:52 as a result of an RPS Actuation following a main turbine trip caused by unit protection relaying. All control rods inserted. The plant is stable. No ECCS or SRV actuations occurred. This report is made pursuant to 50.72(b)(2)(iv)(B). An investigation into the cause is currently in progress. The plant is currently stable in mode 3. No safety relief valves actuated. The current decay heat removal path is normal feedwater to the reactor steaming through the turbine bypass valves to the condenser. No other safety systems actuated. Electric power to the safety busses was supplied via normal offsite power. No bad weather conditions are present. Current reactor pressure is 900 psi with temperature at about 540 degrees. Currently troubleshooting is ongoing to investigate the cause of the trip. The licensee currently plans to stay in mode 3 until the investigation is complete. No safety related systems are currently out of service. There was no estimated restart date. The licensee notified the NRC Resident Inspector. | Feedwater Decay Heat Removal Safety Relief Valve Control Rod | |
| ENS 40832 | 22 June 2004 17:13:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation | Automatic Reactor Scram Following an Electrical Yard Manipulation | 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. | Main Turbine Decay Heat Removal Safety Relief Valve Main Condenser Control Rod | |
| ENS 40329 | 18 November 2003 09:35:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Communications Capability | On 11/18/03 at 0435 EST, it way discovered that the ENS phone system was inoperable when the NRC was unable to contact the Limerick Generating Station Control Room for a routine plant status update. The NRC was able to contact the Limerick Control Room via a normal station telephone. The cause of the communication loss was investigated and determined to be an ENS phone in TSC that was "off the hook". The TSC ENS phone had a headset connected that was inadvertently turned on and resulted in the busy signal when the NRC attempted to call. The TSC ENS phone headset was turned off restoring the communication line. Communications were verified with the NRC at 0459 via the ENS phone. This condition is being reported as an 8 hour notification per the requirements of 10 CFR 50.72(b)(3)(xiii) for loss of offsite communications capability. The licensee notified the NRC Resident Inspector. | ||
| ENS 40176 | 19 September 2003 08:00:00 | 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Emergency Siren Capability Due to Adverse Weather Conditions | 32 of 165 offsite sirens not functioning due to loss of power/equipment failure because of ongoing storm. The licensee will inform the affected counties/PEMA and the NRC Resident Inspector. |