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| Entered date | Event description | |
|---|---|---|
| ENS 51637 | 6 January 2016 09:38:00 | At (2258) CST, on January 5, 2016, with the plant operating at 100 percent power, the main control room alarm indicating high pressure in the auxiliary building actuated. Operators confirmed that the building pressure, corrected for temperature, indicated slightly positive, whereas the building pressure limit in Technical Specifications is 0.0 - 3.0 inches of water negative pressure. Secondary containment was declared inoperable, and the Division 2 standby gas system was started. This action restored building pressure to the acceptable range, and the building was declared operable at (0027 CST) on January 6. This condition is being reported in accordance with 10 CFR 50.72(b)(3)(v)(C) as an event that caused the secondary containment to be potentially incapable of performing its safety function. The NRC Senior Resident Inspector was notified. |
| ENS 50774 | 28 January 2015 13:50:00 | On December 6, 2014, at approximately 1012 CST, while the plant was operating at 100 percent power, the Division 2 reactor protection system (RPS) bus de-energized unexpectedly. This resulted in a half-scram and a Division 2 primary containment isolation signal. Operators executed the appropriate abnormal operating procedures to begin an orderly restoration of the affected systems. Atmospheric pressure in the primary containment momentarily reached the high-pressure alarm setpoint, necessitating entry into the emergency operating procedure for that condition. Automatic isolation valves in the following systems closed as designed: - reactor plant component cooling water - drywell unit cooler water supply - reactor building floor and equipment drains - reactor building HVAC chilled water supply - containment airlock seal air supply - reactor recirculation system flow control valve hydraulics - main steam line drains - reactor water cleanup - auxiliary building and annulus HVAC systems These engineered safety systems actuated as designed: - standby gas control filter trains - fuel building filter trains - control building filter trains The event occurred approximately 25 hours after the Division 2 RPS motor-generator (MG) was aligned to the bus following replacement of the voltage regulator. Following the event, the MG set was found running with its output breaker tripped. A failure analysis determined that the spike suppressor and the field flash card were potential sources of the MG breaker trip. The spike suppressor was replaced. Inspection of the field flash card found a strand of wire from one of the attached leads nearly touching a trace on the circuit board. Testing determined that the wire strand was the most likely cause for the breaker trip. With no spare card readily available, the wire strand was removed and the field flash card was re-installed. Other cards were inspected, and no similar conditions were found. The MG set was load tested for 30 hours, and was placed in service on December 17(, 2014). Additionally, it is suspected that there is an intermittent failure occurring in the field flash card. A design change will be developed to correct that condition. The licensee has notified the NRC Resident Inspector. |
| ENS 45380 | 24 September 2009 03:45:00 | At time 0130 CDT the Louisiana Governor's Office of Homeland Security and Emergency Preparedness was notified of an inadvertent sounding of one siren (WF39) at River Bend Station. The Louisiana Governor's Office of Homeland Security and Emergency Preparedness initiated their procedure for inadvertent siren sounding which includes a broadcast of an EAS (Emergency Alert System) message of the inadvertent sounding. West Feliciana Parish Sheriff Office 911 center was also contacted. The cause of the siren actuation is under investigation and the siren has been disabled until the problem is identified and repaired. The licensee has notified State and local authorities and the NRC Resident Inspector. |