Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 51368 | 3 September 2015 22:04:00 | At 1901 EDT on 9/3/2015, the Unit 2 HPCI system inboard steam supply valve isolated due to a high steam flow instrument failure. The inboard steam supply valve closed and isolated as expected. There were no indications of a steam leak. Drywell parameters and affected Reactor Enclosure rooms and piping areas were inspected with no indications of a steam leak. In addition, the steam leak detection system did not indicate any rising temperatures for any of the affected areas. The issue has caused Unit 2 HPCI to be declared inoperable and unavailable. Unit 2 has entered into a 14 day (Technical Specification) Limited Condition of Operation per T.S. 3.5.1. The licensee notified the NRC Resident Inspector. |
| ENS 48963 | 24 April 2013 16:50:00 | 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 48824 | 15 March 2013 17:23:00 | 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 48653 | 6 January 2013 13:32:00 | 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 48372 | 3 October 2012 20:22:00 | 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 48001 | 7 June 2012 09:47:00 | 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 47941 | 22 May 2012 07:24:00 | 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 47389 | 29 October 2011 15:39:00 | 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 46903 | 29 May 2011 07:10:00 | 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 45307 | 28 August 2009 01:13:00 | Non-conservative Tech Spec setpoints were discovered that affected Steam Leak Detection for Unit 1 and Unit 2 (High Pressure Coolant Injection) HPCI room high differential temperatures. During a steam leak detection system design basis leak, the present temperature setpoint would not isolate the HPCI steam supply piping. A calculation has been performed by engineering which demonstrates that, with both room coolers secured, a design basis steam leak will result in the room ventilation differential temperature exceeding the present Tech Spec setpoints. At this time, the room unit coolers have been secured and HPCI and the associated steam leak detection system remain operable. Calculations are in-progress by engineering for changes to the high differential temperature steam leak detection setpoint. The licensee notified the NRC Resident Inspector. * * * RETRACTION FROM J. BROILET TO P. SNYDER ON 10/20/09 AT 1154 EDT * * * This is a retraction of the event notification made on 8/28/09 at 0113 EDT. This event (#45307) was initially reported as a condition that could have prevented fulfillment of a safety function under the requirement of 10 CFR 50.72 (b)(3)(v)(c). A follow-up review of the HPCI equipment room steam leak detection system calculations determined that other HPCI equipment room ambient high temperature instruments would have automatically actuated a HPCI steam line isolation during a 25 gpm design basis HPCI steam line leak event. Therefore, a condition did not exist at the time of discovery that could have prevented the fulfillment of the HPCI steam line isolation safety function. The licensee notified the NRC Resident Inspector. Notified R1DO (Doerflein). |
| ENS 45133 | 16 June 2009 05:51:00 | (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). |
| ENS 44623 | 2 November 2008 20:33:00 | The Unit 1 MCR (Main Control Room) HPCI (High Pressure Coolant Injection) flow indicator was observed oscillating just above zero gpm with periodic spikes to approximately 50% of scale (3000 gpm) with a concurrent drop in flow controller output signal while in standby. There were no activities in progress on or near the HPCI system when the oscillation and instrument spikes occurred. Walkdown of the instrument rack and HPCI room equipment found no abnormalities. The HPCI system was declared inoperable at 1550 hours 11/2/2008 (14 day Shutdown LCO). Troubleshooting is in progress to determine the cause of the flow oscillations. The HPCI system is considered available as there are no indications of controller failure that would impact operation in manual flow control mode. Unit 1 RCIC, and all other ECCS systems remain OPERABLE. The licensee will inform the NRC Resident Inspector. |
| ENS 44260 | 3 June 2008 12:50:00 | On Wednesday April 9, 2008 at 0416 hours, an invalid actuation of the 1B Refueling Floor Ventilation Exhaust Radiation Monitor occurred. The actuation caused a Division 2 Group 6C isolation signal, which caused primary containment isolation valves (PCIVs) to automatically close on the Containment Leak Detector Radiation Monitor (10-S182) and the Drywell Hydrogen/Oxygen Analyzer (10-S205). The 1A, 1C, and 1D channels were unaffected and indicated normal ventilation exhaust radiation levels during the event. The cause of the event was a failure of the K2 relay in the 1B Refueling Floor Ventilation Exhaust Radiation Monitor. The failed relay has been replaced and the radiation monitor was declared operable on Wednesday April 9, 2008 at 2024 hours. 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 only equipment malfunction during the event was the failed K2 relay. The Division 2 Group 6C isolation was a partial actuation. This event is reportable per 10CFR50.73(a)(2)(iv)(A) since isolation valves for the Containment Leak Detector Radiation Monitor and Drywell Hydrogen/Oxygen Analyzer automatically closed due to an invalid signal. The licensee has notified the NRC Resident Inspector. |
| ENS 44088 | 22 March 2008 20:50:00 | 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. |
| ENS 43366 | 16 May 2007 14:30:00 | This 60-day ENS report is being made per 10CFR 50.73(a)(2)(iv)(A) and 10CFR 50.73(a)(1) to report invalid automatic actuations of systems listed in paragraph (a)(2)(iv)(B), namely core spray (CS) and residual heat removal (RHR). Unit 2 commenced refueling outage activities on Saturday March 10, 2007. Relay replacements for the 4 kv safeguard bus LOCA auxiliary control time delay relays were planned for all four buses due to a relay failure on Unit 1 that was identified during the prior refueling outage testing. On Monday March 19, 2007, at 02:20 hours, during emergency diesel generator (EDG) surveillance testing a Unit 2 Division 3 LOCA signal was inadvertently initiated during the planned replacement of the D23 bus LOCA auxiliary control relay (162-117). The relay was being replaced at a pre-determined step in the test. The relay was in an energized state when removed. When the new relay was installed an unplanned actuation of LOCA load shedding and sequential loading occurred. The relay was subsequently replaced and tested successfully. D23 EDG had been secured just prior to the event. The following loads were tripped and automatically restored: 2C CS pump and D234 load center breaker. The C emergency service water (ESW) pump tripped and did not restart since the EDG was not running. The 2C RHR pump continued to run. The 2A CS loop received a partial actuation in that the Division 3 signal was initiated but the Division 1 signal was not initiated. The 2C CS pump was operating in full flow test mode; therefore, it tripped and re-started as designed and 2A CS pump did not start which was expected. The 2A CS loop automatic valve alignment is initiated by the Division 1 signal; therefore, no automatic 2A CS loop valve alignment occurred. On Wednesday March 21, 2007 at 14:08 hours during EDG surveillance testing a Unit 2 Division 2 LOCA signal was initiated during the test which started the D22 EDG and tripped the D224 load center breaker as expected. However, the load center breaker did not re-close which was not expected and other expected actions did not occur. At 14:41 hours, 33 minutes later, the remaining LOCA actions occurred when 2B RHR pump, 2B CS pump, and 2B reactor enclosure recirculation system (RERS) fan automatically started, and D224 load center breaker automatically closed due to a late actuation of the D22 bus LOCA auxiliary control relay (162-116). At 15:48 an additional unexpected relay actuation caused the 2B CS pump and D224 load center breaker to trip. The relay had been replaced earlier in the day and the ongoing testing was intended to satisfy the post maintenance test (PMT). However, the relay did not actuate at the point in the test designated as the PMT; the relay actuated unexpectedly 33 minutes later. The cause of the first event was a less than adequate technical review of a test revision that added a step to replace the bus LOCA auxiliary control relay. The affected tests have been revised to replace the relay at a point in the test when it is de-energized. The cause of the second event was an equipment failure due to an intermittent connection between the relay pin connector and the relay base. The affected relay and base have been replaced and tested successfully. All of the systems that received start signals functioned successfully. The only equipment malfunction was associated with the degraded relay. The RHR and CS starts were partial actuations. The D22 EDG train start was an expected actuation. The C ESW train was tripped but was not automatically started. This event is reportable per 10CFR50.73(a)(2)(iv)(A) since 2B RHR pump, 2B CS pump, and 2C CS pump automatically actuated on an invalid signal. Component data: Equipment name: D22 Bus LOCA Aux Control Time Delay Relay Equipment number: 162-116 Manufacturer: A348 Amerace Corp Model number: ETR14D3A002 Serial number: 83330224 The licensee notified the NRC Resident Inspector. |