Semantic search
| Entered date | Site | Region | Reactor type | Event description | |
|---|---|---|---|---|---|
| ENS 46426 | 17 November 2010 18:26:00 | Limerick | NRC Region 1 | GE-4 | 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 46474 | 12 December 2010 16:44:00 | Limerick | NRC Region 1 | GE-4 | During quarterly operability verification of the HPCI Turbine Overspeed Trip Assembly, the Trip/Reset knob was manually lifted and released to time the automatic reset function. Upon release of the knob, the Trip Assembly failed to automatically reset (the HPCI Turbine Stop and Control Valves remained closed). Adjustment of the Trip/Reset needle valve was unsuccessful. The HPCI Turbine Stop and Control Valves remain in the tripped condition, rendering HPCI unavailable. Engineering and Maintenance have been dispatched to troubleshoot and repair the Overspeed Trip Assembly and restore HPCI to operable status. All other required systems are available, operable, and protected. The licensee is in the 14 day LCO 3.5.1. The licensee has notified the NRC Resident Inspector. |
| ENS 46641 | 25 February 2011 11:48:00 | Limerick | NRC Region 1 | 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 46746 | 11 April 2011 06:30:00 | Limerick | NRC Region 1 | GE-4 | An ambulance responded to the site to assist a worker with a head injury. The worker was transported as potentially contaminated to an offsite medical facility. Follow-up to the above information, it was later determined that the worker was not contaminated. The contract worker was in secondary containment climbing a ladder when he hit his head on a scaffold pole. He was transported to Pottstown Memorial Hospital. The licensee notified the NRC Resident Inspector. |
| ENS 46883 | 25 May 2011 11:36:00 | Limerick | NRC Region 1 | GE-4 | On Saturday, April 2, 2011, Unit 2 refueling outage activities were in progress. The 2A RPS/UPS Static Inverter was out of service and bypassed with loads transferred to the primary alternate power supply. At 1218 hours, a post maintenance test was performed on the secondary alternate power supply. The inverter alternate power manual transfer switch was transferred from the 'primary alternate' to 'secondary alternate' position to support the post maintenance test. Since the transfer switch is 'break before make' the alternate power supply was interrupted momentarily. This deenergized the 2A RPS/UPS power distribution panel loads including the Division IA and IIA RPS relays and Division IA and IIA NSSSS (Nuclear Steam Supply Shutoff System) relays. Primary containment isolation valves (PCIVs) automatically closed on more than one system. The IB and IIB channels were unaffected. The portion of the primary containment isolation system that received an actuation signal functioned successfully. All of the affected open isolation valves automatically closed. The isolation was a partial actuation of the isolation actuation instrumentation. This 60-day ENS report is being made per 10CFR 50.73(a)(2)(iv)(A) and 10CFR50.73(a)(1) to report invalid automatic actuations of systems listed in paragraph (a)(2)(iv)(B). The listed system that actuated was general containment isolation signals affecting containment isolation valves in more than one system. Primary containment isolation valves (PCIVs) closed on drywell chilled water (DWCW), reactor enclosure cooling water (RECW), primary containment instrument gas (PCIG), and suppression pool cleanup. The licensee has notified the NRC Resident Inspector. |
| ENS 46903 | 29 May 2011 07:10:00 | Limerick | NRC Region 1 | 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 46906 | 30 May 2011 15:46:00 | Limerick | NRC Region 1 | 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 46919 | 3 June 2011 12:06:00 | Limerick | NRC Region 1 | 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 46973 | 20 June 2011 16:59:00 | Limerick | NRC Region 1 | GE-4 | 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 46979 | 23 June 2011 17:39:00 | Limerick | NRC Region 1 | GE-4 | During performance of scheduled surveillance testing, the Unit 1 High Pressure Coolant Injection (HPCI) turbine control valve did not fully close when the system was secured. The HPCI system was removed from service and the control valve was inspected. The inspection identified a broken steam supply valve internal to the control valve. This condition would have prevented HPCI from fulfilling its safety function and is being reported for the inability of a single train system to mitigate the consequences of an accident. |
| ENS 47170 | 19 August 2011 12:32:00 | Limerick | NRC Region 1 | GE-4 | Limerick Generating Station Site EP (Emergency Preparedness) Manager was informed by Chester County 911 Dispatch Center that Limerick Emergency Preparedness Zone (EPZ) Siren #132, located at Pothouse Road West of Ridgeview Road in Chester County, was sounding. Notification occurred at 1030 hrs. (EDT) 8/19/11. The siren maintenance contractor was contacted, and the sounding was terminated at 1120 hrs. 8/19/11. No actual plant emergency exists. The siren activation was caused by equipment malfunction. (The) remaining 164 of 165 Limerick EPZ Sirens remain functional, no other reportability threshold(s) have been met or exceeded. An 'Event of Potential Public Interest' will be issued to the state and local agencies. The maintenance contractor is currently troubleshooting the cause. The licensee will be notifying the NRC Resident Inspector. |
| ENS 47185 | 23 August 2011 14:56:00 | Limerick | NRC Region 1 | GE-4 | Seismic event occurred resulting in a Notification of an Unusual Event. No plant impact to either unit. Both units are stable with safety systems functional. There were no personnel injuries and no reports of structural damage. The licensee has notified the NRC Resident Inspector.
Limerick is terminating from the Unusual Event (HU5) based on the conditions that originally presented entry to the Unusual Event (HU5) no longer exist and it is unlikely that plant conditions will deteriorate. No emergency conditions exist at this time for either unit. Both Unit 1 and Unit 2 are operating at 100% power and are stable. A walk down of the facility has been completed with no deficiencies identified. No indication of system degradation has been detected. The licensee has notified the NRC Resident Inspector and has notified state and local authorities. Notified R1 IRC (Dentil), IRD (Gott), DHS (Bean), FEMA (Via), USDA (Kraus), and DOE (Turner). |
| ENS 47303 | 29 September 2011 12:19:00 | Limerick | NRC Region 1 | GE-4 | EAL HU7 was declared at 1135 hrs. (EDT) for a toxic of flammable gas which has been released onsite which could affect plant operations. Current plant conditions do not threaten public safety. Less than 1 gallon of 15% sodium hypochlorite sprayed onto the floor during securing of a completed delivery to the water treatment plant, located within the Protected Area boundary. There have been no injuries to personnel. The licensee has notified the local and state authorities and will be notifying the NRC Resident Inspector.
Limerick is terminating from the Unusual Event (HU7) due to the threat of toxic gas having been terminated. The sodium hypochlorite leak in the water treatment plant has been stopped and clean up activities are in progress. U1 and U2 remain at 100% power. There were no injuries. The licensee has notified state and local authorities and will be notifying the NRC Resident Inspector. Notified R1DO (Doerflein), IRD (Gott), NRR (Thomas), FEMA (O'Connell) and DHS (Flinter). |
| ENS 47389 | 29 October 2011 15:39:00 | Limerick | NRC Region 1 | GE-4 | 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 47726 | 8 March 2012 23:26:00 | Limerick | NRC Region 1 | GE-4 | Limerick Generating Station was informed by Montgomery County 911 dispatch center that Limerick Emergency Preparedness Zone (EPZ) siren # 128, at the corner of Vaughn and Springer town roads in Montgomery County was sounding. Notification time was 2218 EST. The siren was silenced at 2227 EST. The siren maintenance contractor was contacted for repairs. No actual plant emergency exists. The siren activation was caused by an equipment malfunction. The remaining 164 of 165 Limerick EPZ sirens remain functional. No other reportability thresholds have been met or exceeded. An 'Event of Potential Public Interest' will be issued to the state and local agencies. The licensee has notified the NRC Resident Inspector. The licensee will also notify state and local authorities. |
| ENS 47754 | 19 March 2012 12:41:00 | Limerick | NRC Region 1 | GE-4 | 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 47823 | 11 April 2012 16:32:00 | Limerick | NRC Region 1 | GE-4 | The following ENS is being submitted late. On Monday, March 19, 2012 at 3 a.m. a manhole overflowed during a scheduled and permitted radiological release through the cooling tower blow down outfall. As a result, several thousand gallons of water overflowed briefly, formed puddles in the area, and was discharged through a different National Pollutant Discharge Elimination System (NPDES) permitted outfall. The overflow was terminated, water samples were collected from the impacted areas, and the area was remediated in keeping with the Station's environmental monitoring program. Several samples showed increased levels of tritium that were well below permitted Commonwealth and Federal effluent limits. There were no public health risks associated with this event. The NRC Resident Inspector was notified, and courtesy notifications were made to all appropriate government agencies and local stakeholders in accordance with NEI 07-07, Industry Groundwater Protection Initiative, on March 20, 2012. Due to notification of government agencies, this event is being reported under 10CFR50.72 (b)(2)(xi). The licensee informed the Commonwealth of Pennsylvania, and Berks, Montgomery and Chester counties. |
| ENS 47850 | 19 April 2012 11:10:00 | Limerick | NRC Region 1 | 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 47888 | 2 May 2012 13:15:00 | Limerick | NRC Region 1 | GE-4 | In response to a trip of Unit 1 reactor enclosure (secondary containment) HVAC and subsequent loss of reactor enclosure delta-p, a Unit 1 manual secondary containment isolation was initiated per station procedures. This manual initiation also resulted in an isolation signal to containment atmosphere control (CAC) system valves and primary containment instrument gas (PCIG) system valves. System responses were as expected. Unit 1 secondary containment delta-p was restored via standby gas treatment system (SGTS), and Unit 1 secondary containment integrity remains intact and operable. Investigation of the trip of Unit 1 reactor enclosure HVAC is ongoing. This is being reported under 50.72(b)(3)(iv) for containment isolation signal affecting containment isolation valves in more than one system. The licensee notified the NRC Resident Inspector. |
| ENS 47941 | 22 May 2012 07:24:00 | Limerick | NRC Region 1 | GE-4 | The MCR (Main Control Room) at Limerick Generating Station was informed by PEMA (Pennsylvania Emergency Management Agency) that EPZ (Emergency Planning Zone) siren #129 located at Maryland and Western avenues in Chester County was sounding. The siren maintenance contractor was contacted to silence and repair the siren. No plant emergency exists. The siren activation was caused by an equipment malfunction. The remaining sirens in the EPZ remain functional. An 'Event of Potential Public Interest' will be issued for this problem. The NRC Resident Inspector, the State, and local officials will be notified of the siren malfunction. The state is expected to issue a press release.
The siren was not an EPZ siren but rather a local fire house siren. Therefore, the licensee is retracting this event. Notified the R1DO (Trapp). |
| ENS 48001 | 7 June 2012 09:47:00 | Limerick | NRC Region 1 | GE-4 | 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 48041 | 21 June 2012 08:03:00 | Limerick | NRC Region 1 | GE-4 | 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 48107 | 14 July 2012 16:52:00 | Limerick | NRC Region 1 | GE-4 | A licensed operator employee had a confirmed positive during a random fitness-for-duty test. The employee's unescorted access has been suspended. Contact the Headquarters Operations Officer for additional details. The licensee notified the NRC Resident Inspector. |
| ENS 48117 | 18 July 2012 09:33:00 | Limerick | NRC Region 1 | 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 48121 | 19 July 2012 21:56:00 | Limerick | NRC Region 1 | GE-4 | During surveillance testing, the reactor mode switch was moved from the locked shutdown position and placed in the refuel position without the minimum required operable source range monitors per Limerick Generating Station Technical Specifications. Upon discovery of the issue, the reactor mode switch was returned to the locked shutdown position causing an expected but valid RPS actuation. No control rod motion occurred because all control rods were already inserted at the time of the event. The licensee has notified the NRC Resident Inspector. |
| ENS 48334 | 21 September 2012 21:29:00 | Limerick | NRC Region 1 | GE-4 | A review of load sequencing during a design basis loss of coolant accident (LOCA) with offsite power available has identified an issue with 24 motor operated valves (MOVs - 12 per unit). These valves all use limit switch 8 (LS-8) as an isolation permissive and may indicate closed if they are in a dead band zone when stroking closed from a containment isolation signal at the time of the load shed. The valves will then not resume movement to full isolation when power is restored potentially impacting containment leakage. This condition could occur during specific LOCA conditions, dependent on several variables. The systems affected by this issue are: - RWCU - DWCW - PCIG - CAC - Suppression Pool Cleanup Actions are in progress to resolve the LS-8 issue with a modification to remove this vulnerability. Appropriate testing will be done to prove that all valves perform their required safety function after the modifications are complete for each valve. All affected valves are either closed and de-energized, or have been modified at this time. The licensee has notified the NRC Resident Inspector. |
| ENS 48372 | 3 October 2012 20:22:00 | Limerick | NRC Region 1 | GE-4 | During logic and cable routing reviews for Multiple Spurious Operations (MSO), an existing unprotected cable issue was identified that impacts the D22 emergency Diesel Generator (EDG) output breaker. This unprotected cable could fail due to fire damage in fire area 067W when the associated 4kV safeguard bus is credited for Post-Fire Safe Shutdown. The single spurious fire induced cable failure identified can cause the D22 EDG output breaker to spuriously close when the 4kV safeguard bus is credited using the offsite power source. The existing fire safe shutdown analysis failed to identify this cable required protection in order to credit the 4kV safeguard bus in area 067W postulated fire. The licensee has notified the NRC Resident Inspector. |
| ENS 48575 | 10 December 2012 21:40:00 | Limerick | NRC Region 1 | GE-4 | On Saturday, October 13, 2012, Unit 1 was operating at 100% power. At 1841 (EDT), the 1A RPS/UPS inverter tripped and the automatic transfer of the RPS and UPS 120 VAC distribution panel (1A-Y160) loads to the primary alternate AC power source was delayed. The delay in automatic load transfer caused the RPS series breakers to trip on undervoltage. The failure caused a loss of power to Division IA and IIA RPS relays and Division IA and IIA NS4 relays. This caused primary containment isolation valves (PClVs) to automatically close on more than one system. The IB and IIB channels were unaffected. The most probable cause for the delayed load transfer was a failed logic power supply with a momentary loss of synchronization. Troubleshooting continues (in order) to confirm the specific cause of the component failure. The distribution panel loads are currently supplied by an installed alternate AC power source. The portion of the primary containment isolation system that received an actuation signal functioned successfully. All of the affected open isolation valves automatically closed. The isolation was a partial actuation. This 60-day ENS report is being made per 10CFR50.73(a)(2)(iv)(A) and 10CFR50.73(a)(1) to report invalid automatic actuations of systems listed in paragraph (a)(2)(iv)(B). The listed system that actuated was general containment isolation signals affecting containment isolation valves in more than one system. Primary containment isolation valves (PCIVs) closed on drywell chilled water (DWCW), reactor enclosure cooling water (RECW), primary containment instrument gas (PCIG), Unit 1 containment leak detector, and Unit 2 containment leak detector. The licensee notified the NRC Resident Inspector. |
| ENS 48629 | 28 December 2012 09:55:00 | Limerick | NRC Region 1 | GE-4 | 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 48653 | 6 January 2013 13:32:00 | Limerick | NRC Region 1 | GE-4 | 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). |
| ENS 48824 | 15 March 2013 17:23:00 | Limerick | NRC Region 1 | GE-4 | This Part 21 initial notification addresses a pump impeller defect that resulted in a post maintenance test (PMT) failure. The 0C RHR Service Water Pump was being replaced due to degraded performance which caused an In-Service Test (IST) failure. The replacement pump impeller received from the supplier had not been machined to the purchase order specifications. The IST of the new pump could not be completed since the required test conditions could not be established. The pump was later replaced and the IST was completed successfully. The pump was declared operable on March 2, 2013. This Part 21 Initial Notification is being submitted pursuant to the requirements of 10CFR21.21 (d)(3)(i). The licensee has notified the NRC Resident Inspector. |
| ENS 48837 | 20 March 2013 20:52:00 | Limerick | NRC Region 1 | GE-4 | After securing the Unit 1 HPCI turbine from service following a planned pump, valve, and flow surveillance test an oil leak of approximately 1 pint per minute developed. The oil leak was stopped by securing the auxiliary oil pump for the HPCI system. There was no loss of oil pressure while the HPCI turbine was operating. This issue has caused the Unit 1 HPCI system to be declared inoperable and unavailable. Per LGS (Limerick Generating Station) Unit 1 Technical Specifications section 3.5.1, the HPCI system must be restored to operable status within 14 days. The cause of the oil leak is being investigated." The licensee notified the NRC Resident Inspector.
UNIT 1 HPCI has been restored to operable status following repairs and post-maintenance testing at 1300 EDT on March 21, 2013. The licensee changed the reporting requirement from 10CFR50.72(b)(3)(ii)(A) to 10CFR50.72(b)(3)(v((D). The licensee will notify the NRC Resident Inspector. Notified R1DO (Trapp). |
| ENS 48936 | 17 April 2013 02:11:00 | Limerick | NRC Region 1 | 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 48963 | 24 April 2013 16:50:00 | Limerick | NRC Region 1 | GE-4 | A non-licensed, supervisory employee had a confirmed positive for alcohol during a random fitness-for-duty test. The employee's access to the plant has been restricted. The licensee has notified the NRC Resident Inspector. |
| ENS 49024 | 10 May 2013 18:08:00 | Limerick | NRC Region 1 | GE-4 | A Non-licensed, Supervisory employee had a confirmed positive alcohol test during a random fitness-for-duty test. The employee's access to the Plant has been removed. The licensee informed the NRC Resident Inspector. |
| ENS 49239 | 5 August 2013 21:38:00 | Limerick | NRC Region 1 | GE-4 | Both Limerick 4 KV offsite sources were inoperable and Technical Specification 3.0.3 was entered for Unit 2 from 1456 to 1512 (EDT) during D23 4KV Undervoltage testing. During the undervoltage test, the affected diesel and one offsite source (101 Bus) are inoperable. During the test, the alternate offsite source (201 Bus) UV relay was tested and found to be inoperable, resulting in the need to declare the second offsite source (201 Bus) inoperable. When notified of the failure, action was taken to restore the 101 Bus offsite source to operable and exit the 3.0.3 condition (at) (1512 EDT). The 201 Bus Relay was successfully calibrated and tested to subsequently restore the 201 Bus to operability (at) (1543 EDT). Testing of the 201 bus UV relay is directed per procedure while the 101 bus is powered from the diesel generator. The licensee notified the NRC Resident Inspector. |
| ENS 49275 | 13 August 2013 14:46:00 | Limerick | NRC Region 1 | GE-4 | 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). |
| ENS 49318 | 3 September 2013 14:10:00 | Limerick | NRC Region 1 | GE-4 | During planned maintenance activities, station personnel simultaneously opened the inner and outer airlock doors from unit 2 reactor enclosure to the U2 reactor enclosure HVAC room, resulting in a lowering of reactor enclosure delta pressure to below the tech spec minimum required value. The airlock doors were closed within approximately 5 seconds and reactor enclosure delta pressure recovered to greater than the tech spec minimum required value within approximately 20 seconds. Unit 2 secondary containment was declared inoperable for the time that reactor enclosure delta pressure was below the tech spec minimum required value, and was declared operable when reactor enclosure delta pressure recovered to greater than the tech spec minimum required value. Total Limiting Condition of Operation time was approximately 20 seconds. The licensee has notified the NRC Resident Inspector. |
| ENS 49526 | 10 November 2013 16:16:00 | Limerick | NRC Region 1 | GE-4 | Station personnel simultaneously opened the inner and outer air lock doors from the unit 1 reactor enclosure to the radwaste enclosure. Reactor enclosure secondary containment integrity was declared INOPERABLE per TS 4.6.5.1.1.b.2 due to report of both containment airlock doors on the 217 foot elevation being momentarily open at the same time. Reactor enclosure D/P (differential pressure) remained steady at .35 inches water column. Reactor enclosure secondary containment integrity was declared OPERABLE following verification that at least one airlock door to each access of secondary containment was closed per U1 TS 4.6.5.1.1.b.2. Total LCO time was approximately 10 seconds. The licensee has notified the NRC Resident Inspector. |
| ENS 49644 | 17 December 2013 15:11:00 | Limerick | NRC Region 1 | GE-4 | A licensed operator had a confirmed positive for alcohol during a random fitness for duty test. The employee's access to the plant has been restricted. The licensee has notified the NRC Resident Inspector. |
| ENS 49651 | 18 December 2013 12:22:00 | Limerick | NRC Region 1 | GE-4 | Station Personnel simultaneously opened the inner and outer air lock doors from Unit 1 Reactor Enclosure to the Radwaste Enclosure. Reactor Enclosure Secondary Containment Integrity was declared inoperable per U1 TS 3.6.5.1.1, due to failure to meet surveillance requirement U1 TS 4.6.5.1.1.b.2, due to the report of both containment airlock doors on 217 (foot elevation, being) momentarily open at the same time. Reactor Enclosure D/P (delta pressure) remained steady at 0.35 inches vacuum water gauge. Reactor Enclosure Secondary Containment Integrity was declared Operable following verification that at least one air lock door to each access of secondary containment was closed per U1 TS 4.6.5.1.1.b.2. Total LCO time was approximately 5 seconds. The licensee has notified the NRC Resident Inspector. |
| ENS 49659 | 18 December 2013 18:50:00 | Limerick | NRC Region 1 | GE-4 | Station Personnel simultaneously opened the inner and outer air lock doors from Unit 2 Reactor Enclosure to the Refuel Floor. Reactor Enclosure Secondary Containment Integrity was declared inoperable per U2 TS 3.6.5.1.1, due to failure to meet surveillance requirement U2 TS 4.6.5.1.1.b.2, due to the report of both containment airlock doors on the 352 foot elevation being momentarily open at the same time. Reactor Enclosure D/P (differential pressure) remained steady at 0.35 inches vacuum water gauge. Reactor Enclosure Secondary Containment Integrity was declared Operable following verification that at least one air lock door to each access of secondary containment was closed per U2 TS 4.6.5.1.1.b.2. Total LCO time was approximately 5 seconds. The licensee notified the NRC Resident Inspector. |
| ENS 49691 | 4 January 2014 01:22:00 | Limerick | NRC Region 1 | GE-4 | Limerick Generating Station Main Control Room was informed that a Limerick Emergency Preparedness Zone (EPZ) Siren located in South Coventry, Chester County Pennsylvania area was sounding by an off-duty plant employee and confirmed by the Chester County 911 Dispatch Center. Notification occurred at 2300 hours on 1/13/14. This notification is being made in accordance with SAF 1.9 due to a spurious actuation of Limerick Emergency Preparedness Zone (EPZ) Siren. The siren maintenance contractor has been contacted to investigate and silence the sounding alarm. No actual Plant emergency exists. The siren activation was caused by equipment malfunction. (The) remaining 164 of 165 Limerick EPZ Sirens remain functional, no other reportability threshold(s) have been met or exceeded. The licensee has notified the NRC Resident Inspector and state and local authorities. |
| ENS 49706 | 9 January 2014 15:21:00 | Limerick | NRC Region 1 | GE-4 | Station Personnel simultaneously opened the inner and outer air lock doors from Unit 2 (U2) Reactor Enclosure to the Refuel Floor. Reactor Enclosure Secondary Containment Integrity was declared Inoperable per U2 TS 3.6.5.1.1, due to failure to meet surveillance requirement U2 TS 4.6.5.1.1.b.2, due to the report of both containment airlock doors on 352' momentarily open at the same time. Reactor Enclosure D/P(differential pressure) remained steady at 0.35 inches vacuum water gauge. Reactor Enclosure Secondary Containment Integrity was declared Operable following verification that at least one air lock door to each access of secondary containment was closed per U2 TS 4.6.5.1.1.b.2. Total (Limiting Condition for Operation) time was approximately 5 seconds. The NRC Resident Inspector has been informed. |
| ENS 49842 | 19 February 2014 15:32:00 | Limerick | NRC Region 1 | GE-4 | 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 49871 | 5 March 2014 02:26:00 | Limerick | NRC Region 1 | 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 50007 | 8 April 2014 09:45:00 | Limerick | NRC Region 1 | GE-4 | U1 entered Technical Specification 3.0.3, and initiated actions to reduce power via control rod insertion in preparations to enter startup within the following 6 hours. Entry into Tech Spec 3.0.3 was a result of both HPCI and RCIC injection systems being inoperable at the same time. During startup from the U1 refueling outage, RCIC and HPCI full flow testing was unable to be completed at rated reactor pressure prior to the expiration of the 12 hour allowance per Tech Spec Surveillances 4.7.3.b* and 4.5.1.b.3** respectively. This occurred due to testing issues encountered while attempting to perform the rated pressure pump valve and flow tests. U1 HPCI testing was completed satisfactorily at 0830, and HPCI was restored to operable. Plant shutdown was terminated at 0830 (EDT) as conditions for 3.0.3 no longer existed. The licensee will notify the NRC Resident Inspector. |
| ENS 50376 | 17 August 2014 11:21:00 | Limerick | NRC Region 1 | GE-4 | 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 50518 | 8 October 2014 07:24:00 | Limerick | NRC Region 1 | GE-4 | This notification is being made as a result of notifications to other government agencies. A sodium hypochlorite leak occurred on site at Limerick Generating station on 10/7/14, that had the potential to enter the environment. The leak has been isolated. A flow control valve in the U1 cooling tower chemical treatment system caused the leak. The sodium hypochlorite that leaked was deposited into the onsite Holding Pond. The Holding Pond was being discharged at the time of the leak in accordance with procedures to support normal plant operations. The leak was discovered at 2110 hours (EDT on 10/7/14) and isolated at 2115 hours. The Holding Pond discharge was secured at 2125 hours. Sampling of the Holding Pond confirmed the presence of sodium hypochlorite. Since the Holding Pond was being released at the time of the leak, there is a potential that greater than 67 gallons of sodium hypochlorite could have been released to the Schuylkill River. This report is being made due to the potential that a reportable quantity of sodium hypochlorite could have discharged to the Schuylkill River while the Holding Pond was releasing during the sodium hypochlorite leak. Evaluations are being performed to quantify this actual volume of sodium hypochlorite that was discharged as a result of the leak. The licensee has notified the NRC Resident Inspector and state and local authorities. |
| ENS 50670 | 11 December 2014 14:52:00 | Limerick | NRC Region 1 | GE-4 | Station personnel simultaneously opened the inner and outer air lock doors from Unit 2 Reactor Enclosure to the Refuel Floor. Reactor Enclosure Secondary Containment Integrity was declared inoperable per Unit 2 TS 3.6.5.1.1, due to failure to meet surveillance requirement U2 TS 4.6.5.1.1.b.2, due to the report of both containment airlock doors on 352' momentarily open at the same time. Reactor Enclosure D/P (differential pressure) remained steady at 0.35 inches vacuum water gauge. Reactor Enclosure Secondary Containment Integrity was declared operable following verification that at least one air lock door to each access of secondary containment was closed per U2 TS 4.6.5.1.1.b.2. Total time was approximately 5 seconds. The secondary containment doors do not have a mechanical interlock and this event has been classified as a human performance error. The licensee notified the NRC Resident Inspector |