ENS 46127: Difference between revisions
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| event date = 05/25/2010 13:14 EDT | | event date = 05/25/2010 13:14 EDT | ||
| last update date = 07/26/2010 | | last update date = 07/26/2010 | ||
| title = 60-Day Optional Report | | title = 60-Day Optional Report for Inadvertent Safety Injection System Actuation | ||
| event text = At 1314 hours [EDT] on May 25, 2010, with the unit defueled during Refueling Outage 26, an inadvertent Safety Injection (SI) Signal occurred. The signal was received when Safeguards Train 'A' breaker DP-A-20 was closed during the performance of procedure PIC-020, 'Time Delay Relay Calibration Safeguards Train 'A'.' The SI Signal resulted in a containment phase 'A' isolation, containment ventilation isolation, control room ventilation transfer to emergency pressurization mode, and Radiation Monitors R-11 and R-12 (Containment Vessel Airborne Particulate and Gas Monitors) isolation. Emergency Bus 1 and Emergency Diesel Generator 'A' were under clearance, including the Train 'A' sequencer. Therefore, automatic loading of the 'A' Train Sequencer did not occur and no actual injection into the reactor vessel occurred. The affected systems actuated as expected. | | event text = At 1314 hours [EDT] on May 25, 2010, with the unit defueled during Refueling Outage 26, an inadvertent Safety Injection (SI) Signal occurred. The signal was received when Safeguards Train 'A' breaker DP-A-20 was closed during the performance of procedure PIC-020, 'Time Delay Relay Calibration Safeguards Train 'A'.' The SI Signal resulted in a containment phase 'A' isolation, containment ventilation isolation, control room ventilation transfer to emergency pressurization mode, and Radiation Monitors R-11 and R-12 (Containment Vessel Airborne Particulate and Gas Monitors) isolation. Emergency Bus 1 and Emergency Diesel Generator 'A' were under clearance, including the Train 'A' sequencer. Therefore, automatic loading of the 'A' Train Sequencer did not occur and no actual injection into the reactor vessel occurred. The affected systems actuated as expected. | ||
The cause of the inadvertent SI Signal resulted from SI Initiation Latching Relay SIA1 when power was restored to Safeguards Rack 51. Subsequent investigation determined the SIA1 relay was in an unexpected position (i.e., latched). The SIA1 relay likely became inadvertently latched while performing cable pulls in Safeguards Rack 51 for work associated with Water Cooled Condensing Unit 1A. | The cause of the inadvertent SI Signal resulted from SI Initiation Latching Relay SIA1 when power was restored to Safeguards Rack 51. Subsequent investigation determined the SIA1 relay was in an unexpected position (i.e., latched). The SIA1 relay likely became inadvertently latched while performing cable pulls in Safeguards Rack 51 for work associated with Water Cooled Condensing Unit 1A. | ||
Latest revision as of 22:09, 1 March 2018
| Where | |
|---|---|
Robinson  South Carolina (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1485.07 h61.878 days <br />8.84 weeks <br />2.034 months <br />) | |
| Opened: | Ashley Valone 14:18 Jul 26, 2010 |
| NRC Officer: | Howie Crouch |
| Last Updated: | Jul 26, 2010 |
| 46127 - NRC Website
| |