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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 48662 | 30 November 2012 03:00:00 | 10 CFR 50.73(a)(1), Submit an LER | 60-Day Optional Telephonic Notification of Invalid System Actuation | This telephone notification is being made for an invalid actuation in accordance with 10 CFR 50.73(a)(2)(iv)(A) following the reporting guidance of 10 CFR 50.73(a)(1) and is not considered a Licensee Event Report. With Unit 2 at Cold Shutdown (about 105?F and depressurized), an invalid actuation of the Main Feedwater (FW) isolation occurred at 2200 (EST) during removal of the 'A' Train Hi Consequence Limiting Safeguards (CLS) fuses. This action caused the 'A' train FW isolation relay to actuate and, as designed, tripped the operating 'B' Main Feed Pump (MFP) and the Main Turbine, which was latched for testing. The 'A' MFP was not in operation at the time of the event. This was a partial actuation of the SI system. SI signals were inhibited prior to removal of the Hi CLS fuses by the tagging of the lead connecting the Hi CLS relay to the SI master relay. Although FW isolation occurs with SI actuation, the relay associated with the FW isolation circuitry is separately actuated and had not been tagged out. When the Hi CLS fuses were removed, the FW isolation relay was energized. Plant systems and components responding to the signal started and functioned as designed with the exception of those inhibited by tag out. The affected components were restored to their pre-event configuration, The action to determine and initiate corrective actions is complete, and the necessary procedures are under revision. The licensee notified the NRC Resident Inspector. | Feedwater Main Turbine | |
| ENS 48661 | 29 November 2012 04:05:00 | 10 CFR 50.73(a)(1), Submit an LER | 60-Day Optional Telephonic Notification of Invalid System Actuation | This telephone notification is being made for an invalid actuation under 10 CFR 50.73(a)(2)(iv)(A) following the reporting guidance of 10 CFR 50.73(a)(1) and is not considered a Licensee Event Report. With Unit 2 at Cold Shutdown (about 105?F and depressurized), an invalid actuation of the Unit 2 'A' train of the High High Consequence Limiting Safeguards (Hi-Hi CLS) system occurred at 2305 (EST) during reinstallation of fuses in preparation for return to service testing. The fuses were pulled to implement a design modification to replace existing relays with a new design. The 'A' train of the High High CLS actuated as soon as the fuses were installed. Plant systems and components responding to the Hi-Hi CLS 'A' train signals started and functioned successfully as designed with the exception of those systems and components procedurally rendered inoperable due to the RCS being below 350?F and 450 psig. Shutdown cooling was not lost due to safety injection leads being tagged out. The signal could not be reset from the Main Control Room due to system design in this configuration requiring manual local manipulations to address affected components. The relays on both trains were replaced with the original design and the fuses reinstalled. The affected systems were restored to their pre-event configuration. Specific trains and systems that actuated as a result of the "A" train of Hi-Hi CLS signal are described below: -- Component Cooling from the A Reactor Coolant Pump isolated. -- Containment Spray realigned and gravity flowed the Refueling Water Storage Tank and Caustic Addition Tank to the Containment Sump. The level did not reach the point where any components in the containment basement were affected. -- Service Water flowed to the A and C Recirculation Spray Heat Exchangers. -- Containment Instrument Air isolated. -- Emergency Diesel Generator (EDG) No.2 started but did not load since its associated Emergency Bus remained energized by offsite power. The EDG was stopped and returned to automatic. A root cause evaluation is in progress. The licensee notified the NRC Resident Inspector | Service water Emergency Diesel Generator Shutdown Cooling Containment Spray | |
| ENS 46434 | 27 October 2010 03:56:00 | 10 CFR 50.73(a)(1), Submit an LER | Invalid Actuation of High Consequence Limiting Safeguards and Safety Injection Systems | This telephone notification is being made for an invalid actuation under 10 CFR 50.73(a)(2)(iv)(A) following the reporting guidance of 10 CFR 50.73(a)(1). With Unit 1 at cold shutdown (about 105 degrees Fahrenheight and depressurized), an invalid actuation of the Unit 1 'A' train of the High Consequence Limiting Safeguards (HI CLS) system and Unit 1 'A' train of the Safety Injection (SI) system occurred at 23:56 during setup for 'H' Bus Logic Testing. Plant systems and components responding to the HI CLS and SI 'A' train signals started and functioned successfully as designed (with the exception of those systems and components procedurally rendered inoperable due to the RCS being below 350 degrees Fahrenheight and 450 psig). The HI CLS and SI 'A' trains were reset and the affected systems were restored to their pre-event configurations. Specific trains and systems that actuated for the 'A' train of HI CLS and SI are described below: - With the unit at cold shutdown, one high head pump was running (the two redundant pump controls were in the pull to lock position in compliance with Technical Specifications). The 'A' train High Head Safety Injection motor operated valves re-aligned such that the running high head pump provided flow to the RCS cold legs from the Refueling Water Storage Tank (RWST). During this time the pressurizer level increased from approximately 23 percent to about 42 percent. - Auxiliary Feedwater (AFW) Pump motor operated valves opened but no flow was delivered to the steam generators since the AFW pumps were in pull to lock. - The 'A' train containment isolation valves closed, isolating the 'A' Residual Heat Removal (RHR) heat exchanger. However, shutdown cooling was previously aligned to the 'B' train RHR and therefore shutdown cooling was uninterrupted. Containment isolation valves were later restored to a normal alignment. - One train of Auxiliary Ventilation actuated and was restored to normal after the Safety Injection signal was reset. - Emergency Diesel Generator (EDG) No. 1 started but did not load since its associated Emergency Bus remained energized by offsite power. The EDG was stopped and returned to automatic. An apparent cause evaluation is in progress. The licensee notified the NRC Resident Inspector. | Steam Generator Emergency Diesel Generator Auxiliary Feedwater Shutdown Cooling Residual Heat Removal | |
| ENS 44729 | 29 October 2008 23:04:00 | 10 CFR 50.73(a)(1), Submit an LER | 60 Day Report - Invalid System Actuation | This report is being made under 10 CFR 50.73(a)(2)(iv)(A) and is not considered a Licensee Event Report. With Unit 1 at Intermediate Shutdown (226?F and 300 psig), an invalid actuation of the Unit 1 'B' train of the Safety Injection (SI) system occurred at 1804 (EDT) during repair of a broken light socket located on the SI relay cabinet door. Plant systems and components responding to the 'B' train SI signal started and functioned successfully as designed (with the exception of those procedurally rendered inoperable due to the RCS being below 350?F and 450 psig). SI train 'B' was reset and the affected systems were restored to their pre-event configuration. Specific trains and systems that actuated for train 'B' of SI are described below: - With the unit at intermediate shutdown, one high head pump was currently running (the two redundant pump controls were in the Pull to Lock position in compliance with Technical Specifications). The 'B' train High Head Safety Injection motor operated valves re-aligned such that the running high head pump provided flow to the RCS Cold Legs from the RWST. During this time a bubble was present in the Pressurizer and the level remained on scale (increased 8%). - One train of the Control Room Bottled Air System actuated on the Control Room Isolation. The ventilation alignment was restored to normal thereby isolating the Bottled Air System. The system was re-pressurized and restored to an operable condition. - Auxiliary Feedwater (AFW) Pump motor operated valves opened but no flow was delivered to the Steam Generators since the AFW pumps were in Pull to Lock. - The 'B' train containment isolation valves closed, isolating the 'B' RHR heat exchanger. However, shutdown cooling was previously being provided by the 'A' RHR train and was therefore uninterrupted. Containment isolation valves were later restored to a normal alignment. - One train of Auxiliary Ventilation actuated and was restored to normal after the Safety Injection signal was reset. - Emergency Diesel Generator (EDG) No. 3 started but did not load since its associated Emergency Bus remained energized by offsite power. The EDG was stopped and returned to automatic. - Reactor Coolant Pumps (RCPs) were stopped due to the closure of the seal water return containment isolation valve. A root cause evaluation is determining the cause. The licensee notified the NRC Resident Inspector. | Steam Generator Emergency Diesel Generator Auxiliary Feedwater Shutdown Cooling |