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| Entered date | Event description | |
|---|---|---|
| ENS 54466 | 8 January 2020 02:49:00 | On January 7, 2020, Columbia Generating Station (CGS) experienced an equipment failure that resulted in a loss of the seismic assessment instrumentation. This is being reported as a major loss of emergency assessment capability in accordance with regulation 10 CFR 50.72(b)(3)(xiii). No other plant systems were affected. Compensatory measures have been implemented and will remain in place until the seismic system has been restored. The NRC resident has been notified. Licensee received a design basis earthquake alarm, but no other local indication of seismic activity, nor on the U.S. Geological Survey website. Licensee compensatory measures include local readings on seismic instrumentation. |
| ENS 53410 | 18 May 2018 13:27:00 | At 0651 (PDT) on May 18th, 2018, Columbia Generating station experienced a Main Transformer trip, that caused a Reactor Scram. Reactor Power, Pressure and Level were maintained as expected for this condition. MS-RV-1A (Safety Relief Valve) and MS-RV-1B (Safety Relief Valve) opened on reactor high pressure during the initial transient. MS-RV-1B appeared to remain open after pressure lowered below the reset point. The operating crew removed power supply fuses for MS-RV-1B and it currently indicates intermediate position. SRV (Safety Relief Valve) tail pipe temperatures indicate all valves are closed. Suppression pool level and temperature have remained steady within normal operating levels. All control rods inserted and reactor power is being maintained subcritical. RPV (Reactor Pressure Vessel) water level is being maintained with condensate and feed system with startup flow control valves in automatic. Reactor Pressure is being maintained with the Turbine Bypass valves controlling in automatic. The main condenser is the heat sink. No ECCS (Emergency Core Cooling Systems) systems actuated or injected; the EOC-RPT (End of Cycle-Recirculation Pump Trip) and RPS (Reactor Protection System) systems actuated causing a trip of the RRC pumps and a reactor scram. Core recirculation is being maintained with RRC-P-1A (Reactor Recirculation Pump) running. No release has occurred. At this time there will be no notifications to state, local or other public agencies. The NRC Senior Resident has been notified. The cause of the event is currently under investigation. Plant conditions are stable. The plant is in its normal electrical alignment and offsite power is available to the site. |