Semantic search
Jump to navigation
Jump to search
| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 54103 | 18 April 2019 05:10:00 | 10 CFR 50.73(a)(1), Submit an LER | 60-Day Optional Telephonic Notification Due to Invalid Specified System Actuation | This 60-day telephone notification is being made in accordance with the reporting requirements specified by 10 CFR 50.73(a)(1) and 10 CFR 50.73(a)(2)(iv)(A) to describe an invalid actuation of a general containment isolation signal affecting multiple Main Steam Isolation Valves (MSIVs). On April 18, 2019 at approximately 0110 EDT, during performance of an ASME reactor vessel leak check, all four inboard MSIVs closed as a result of actuation of the Main Steam Line (MSL) high flow instrumentation. The high flow signal was spurious on the 'D' channel with no flow in the MSLs. Since an actual high flow condition did not exist at the time of the actuation, the actuation was considered invalid. The MSIVs functioned as designed on actuation of the MSL high flow instrumentation. All outboard MSIVs were closed at the time of the actuation in accordance with the vessel leak check procedure. The NRC Resident Inspector has been notified. | Main Steam Isolation Valve Main Steam Line | |
| ENS 52772 | 3 April 2017 01:27:00 | 10 CFR 50.73(a)(1), Submit an LER | 60-Day Optional Telephonic Notification of Invalid Specified System Actuation | This 60-day telephone notification is being made in accordance with the reporting requirements specified by 10 CFR 50.73(a)(2)(iv)(A) and 10 CFR 50.73(a)(1) to describe an invalid actuation of a general containment isolation signal affecting multiple Main Steam Isolation Valves (MSIVs). On April 2, 2017 at approximately 2127 Eastern Daylight Time, during performance of a reactor vessel leak check, all four inboard MSIVs closed as a result of actuation of the Main Steam Line (MSL) high flow instrumentation. The high flow signal was spurious on two channels with no flow in the MSLs. Since an actual high flow condition did not exist at the time of the actuation, the actuation was considered invalid. The MSIVs functioned as designed on actuation of the MSL high flow instrumentation. All outboard MSIVs were closed at the time of the actuation. The NRC Resident Inspector has been notified. | Main Steam Isolation Valve Main Steam Line | |
| ENS 48092 | 14 May 2012 13:28:00 | 10 CFR 50.73(a)(1), Submit an LER | 60-Day Optional Telephonic Notification for an Invalid Emergency Service Water Actuation | At 0928 EDT on May 14, 2012, the 'B' Emergency Service Water (ESW) pump started during testing from the Unit 1 remote shutdown panel (RSP). The likely cause of the start was either human error in performing continuity checks or inadvertent contact with the manual start circuit in the RSP. Based on the likely cause, this was an invalid actuation of a system listed in 10 CFR 50.73(a)(2)(iv). As indicated in 10 CFR 50.73(a)(1), in the case of an invalid actuation reported under 10 CFR 50.73(a)(2)(iv) other than actuation of the reactor protection system (RPS) when the reactor is critical, the licensee may, at its option, provide a telephone notification to the NRC Operations Center within 60 days after discovery of the event instead of submitting a written LER. This 60-day telephone notification is being made to meet the reporting requirements instead of submitting an LER since the actuation was invalid and was not an RPS actuation with the reactor critical. The following additional information is being provided as specified in NUREG-1022: The specific train(s) and system(s) that were actuated: The 'B' ESW pump inadvertently started during testing from the Unit 1 remote shutdown panel. Whether each train actuation was complete or partial: This was a partial actuation (one of four ESW pumps). Whether or not the system started and functioned successfully: The 'B' ESW pump started successfully, operated properly, and continued running until manually secured via normal controls. At the time of the event, the licensee was performing a surveillance where control was shifted from the control room to the remote shutdown panel. The licensee notified the NRC Resident Inspector. | Service water Reactor Protection System Remote shutdown | |
| ENS 45726 | 25 February 2010 19:18:00 | 10 CFR 50.73(a)(1), Submit an LER | Invalid Actuation of Containment Isolation Valves | This 60-day notification is being made in accordance with 10 CFR 50.73(a)(1), which states that in case of an invalid actuation reported under 10 CFR 50.73(a)(2)(iv)(A), other than the actuation of the Reactor Protection System (RPS) when the reactor is critical, the licensee may provide a telephone notification to the NRC within 60 days after discovery of the event instead of submitting a written LER. Because plant conditions necessary to prompt a containment isolation were not present, this event constitutes an invalid system actuation under 10 CFR 50.73(a)(2)(iv)(A). The condition meets the criteria of 10 CFR 50.73(a)(2)(iv)(B)(2) because the loss of the Unit 1 'B' RPS bus affected containment isolation valves in more than one system. On 1/4/2010 at 1418 hours, the Unit 1 'B' RPS bus was lost. This event resulted in a half scram and primary containment isolations. By design, when the RPS MG set output breaker trips, all EPA breakers downstream of the MG set also trip resulting in a half scram and primary containment isolation signals. An event investigation found the Unit 1 'B' RPS MG set running with its output breaker tripped. The output voltage was indicating 120VAC, which indicates that the voltage regulator was operating properly. Upon removal of the MG set cover, the underfrequency relay (UFR) contacts were found to be chattering, with frequency steady at approximately 60 Hz. A review of plant drawings indicated that a chattering UFR could cause the MG set output breaker to trip. Voltage readings were taken and no additional electrical problems (other than the UFR) were identified. The affected RPS loads were subsequently powered from their alternate source and all actuations and isolations were reset. Inspection and test of the failed UFR found that one leg of a capacitor on the UFR electronic board had broken adjacent to its solder joint connection on the board. It is suspected that the capacitor lead may have been flawed during manufacture of the board. The failure was accelerated by the constant vibration that the connection is subjected to, as the UFR is mounted on the MG set. The failed UFR electronic board was subsequently replaced and successfully passed all functional tests. There were no actual safety consequences associated with this event. Valves affected by the invalid signal fulfilled their isolation function by successfully closing. The RPS loads were transferred to their alternate power supply and the trips and isolations were reset. In addition, the Unit 1 'B' RPS bus did not experience an underfrequency condition. The licensee has notified the NRC Resident Inspector. | Reactor Protection System Primary containment | |
| ENS 43555 | 9 June 2007 09:11:00 | 10 CFR 50.73(a)(1), Submit an LER | Invalid Actuation of the 'C' Emergency Diesel Generator | This 60-day notification is being made in accordance with 10 CFR 50.73(a)(1), which states that in case of an invalid actuation reported under 10 CFR 50.73(a)(2)(iv), other than the actuation of the Reactor Protection System when the reactor is critical, the licensee may provide a telephone notification to the NRC within 60 days after discovery of the event instead of submitting a written LER. On 6/9/07 at approximately 0511 hours, the 'C' Emergency Diesel Generator (EDG) and associated 'C' Emergency Service Water pump unexpectedly started while performing procedure TP-024-147, Diesel Generator 'C' Restoration after being out of service for scheduled overhaul and corrective maintenance activities. The EDG inadvertently started in response to an invalid emergency start signal that occurred when the incorrect states ink (SL-8) was opened in panel 0C521C. The cause of this event was due to a human performance error. The EDG was subsequently shutdown following the inadvertent start. Post- maintenance testing of the 'C' EDG was successfully completed. The consequences of this event are limited to the unplanned start of the 'C' EDG. The EDG started and functioned in accordance with its design. Since no actual plant condition existed which required the EDG to start, and since the start occurred inadvertently as a result of human error, this event has been classified as an invalid actuation. The NRC Resident Inspector has been notified. | Service water Reactor Protection System Emergency Diesel Generator | |
| ENS 42489 | 11 March 2006 09:32:00 | 10 CFR 50.73(a)(1), Submit an LER | Invalid Actuation of Containment Isolation Valves | On 03/11/06 at approximately 0432 hours, with Susquehanna Unit 1 in the Refueling Mode (0% power), the Unit experienced a partial isolation of Primary Containment isolation valves. The actuation occurred when a blown fuse disrupted power to a containment isolation logic relay. The inboard isolation valve to the 'B' Drywell Floor Drain Sump and the Containment Instrument Gas purge supply valve to the TIP indexer both closed. The 'A' Standby Gas Treatment system fan and the 'A' Reactor Building Recirculation fan successfully auto started during the event. This event constitutes an invalid system actuation and is reportable under 10CFR 50.73(a)(2)(iv)(A). The condition meets the criteria of 10CFR 50.73(a)(2)(iv)(B)(2) because a general containment isolation signal affected containment isolation valves in more than one system. This notification is being provided via a 60-day optional phone call as permitted under 10CFR 50.73(a)(1) in lieu of a written LER. As stated above, both valves affected by the invalid signal fulfilled their isolation function by successfully closing. At the time of the event, no other Primary Containment isolation valve was being maintained in a manner that required re-positioning. There were no challenges to the Reactor as a result of this event. The plant responded as expected. Following replacement of the subject fuse, the isolation logic was successfully reset and affected equipment was restored to the desired status. The licensee notified the NRC Resident Inspector. | Primary containment Standby Gas Treatment System | |
| ENS 40766 | 4 April 2004 18:57:00 | 10 CFR 50.73(a)(1), Submit an LER | 60 -Day Report: Invalid Actuation of the "E" Emergency Diesel Generator | On 04/04/04 at 14:57 hours, the "E" Emergency Diesel Generator unexpectedly started in the emergency mode of operation during performance of Unit 1 LOCA/LOOP surveillance testing. The diesel generator started in response to a false loss of offsite power signal that occurred after an electrical test jumper was incorrectly installed in panel 1A201. While the procedure directed installation of the jumper across the field side of states links T5-10 and T5-12, the jumper was instead installed across the panel side of the links. When link T5-10 was opened per procedural direction, a false LOOP signal was sent to the "E" diesel generator start circuit. The "E" emergency diesel generator successfully started and properly responded to the complete train actuation signal. The diesel was shutdown following the incident. No other plant equipment was affected by this jumper use error. At the time of this event, Unit 1 was in Mode 5 and Unit 2 was in Mode 1. Both Units continued in Modes 5 and 1, respectively. Surveillance testing was successfully completed on 04/05/04. The consequences of this event were limited to the unplanned start of the "E" emergency diesel generator. The diesel generator started and functioned in accordance with its design. This event comprises an invalid actuation of an emergency AC electrical power system and is therefore being reported in accordance with 10 CFR 50.73(a)(2)(iv)(A) as a 60- day telephone notification per the provision of 10 CFR 50.73 (a)(1). The NRC Resident Inspector was notified of the 60- day report notification by the licensee. | Emergency Diesel Generator | |
| ENS 40733 | 21 March 2004 16:32:00 | 10 CFR 50.73(a)(1), Submit an LER | Invalid Actuation of Containment Isolation Signals in More than One System | The following information was obtained from the licensee via facsimile: On 03/21/04 at 12:32 hours (EST), a JLG Manlift working on the Unit 1 Cooling Tower came into contact with a 230 KV transmission line, causing the loss of one of two off-site power supplies to the plant (Startup Transformer T-10 and its associated loads). The other Startup Transformer (T-20) assumed the extra electrical load, as designed, and restored power to the station. At the time of this event, Unit 1 was in Mode 5 and Unit 2 was in Mode 1. Both Units continued in Modes 5 and 1, respectively. As a result of the loss of the T-10 transformer, the following Unit 2 Primary Containment Isolation (Valves)(PCIVs) closed on loss of logic power: Containment Atmosphere Control PCIVs HV-25740A, HV-25750A, HV-25776A, HV25780A, HV-25736A, and HV-25742A, HV-25752A, HV-25774A, HV-25782A, HV-25734A. Drywell Sump PCIVs HV-261108 A1 and A2 closed. Reactor Building Chilled Water PCIVs HV-28791 A1 and A2 and HV-28792 A1 and A2 closed. Recirculation Sample PCIV HV-243F019 closed. All isolation signals were successfully reset and the T-10 line was subsequently restored. The Unit 2 electrical transient event resulted in general containment isolation signals affecting containment isolation valves in more than one system and is therefore being reported per 10 CFR 50.73(a)(1) and 10 CFR 50.73(a)(2)(iv)(A). A voluntary ENS Phone Notification to the NRC, related to this event, was previously made on 03/21/04, due to notification of the Pennsylvania Emergency Management Agency (PEMA), because an emergency vehicle entered plant property. The above listed systems' Division 1 containment isolation valve actuations were completed and functioned successfully on loss of logic power. The licensee has informed the NRC Resident Inspector of this notification. | Primary containment | |
| ENS 40173 | 29 August 2003 14:25:00 | 10 CFR 50.73(a)(1), Submit an LER | Invalid Actuation of Containment Isolation Valves | On August 29th, 2003 at approximately 1025 EDT, an electrical perturbation affecting both Unit 1 & 2 at PPL Susquehanna LLC resulted in a partial isolation of Primary Containment Isolation valves on Division 1, specifically A & B Containment Radiation Monitors and the Containment Instrument Gas Purge supply valve. This event is being reported as an invalid system actuation and is reportable under 10CFR 50.73(a)(2)(iv)(A). The condition meets the criteria of 10CFR 50.73(a)(2)(iv)(B)(2) due to a general containment isolation signal that affected containment isolation valves in more than one system. This notification is being provided via 60 day optional phone call as permitted under 10CFR 50.73(a)(1) in lieu of a written LER. The event was initiated when Operators were returning a Unit 1 13.8 KV Non-ESS breaker back in service following routine maintenance. When the breaker was restored to its closed position, a fault downstream of the breaker caused it to immediately re-open. The 13.8 Kv system supplies power to both unit's Division 14kV ESS busses. The perturbation was sufficient to cause several 'fail closed' containment isolation valves to actuate and close. The transient caused other non-safety related plant equipment to trip/auto-start, no other safety-related equipment or functions were lost. There also were no challenges to the reactor systems or containments. All plant equipment and/or systems were capable of being restored to their original alignment. The fault that caused the electrical perturbation originated at a non-ESS transformer and is currently being replaced. The licensee will inform the NRC Resident Inspector. | Primary containment |