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| Entered date | Event description | |
|---|---|---|
| ENS 52966 | 12 September 2017 19:11:00 | On September 12, 2017, at 1228 PDT, Reactor Building (Secondary Containment) pressure momentarily rose above the Technical Specification (TS) limit. Secondary Containment was declared inoperable and TS Action Statement 3.6.4.1.A was entered. The pressure rise was due to unexpected isolation of the supply and exhaust valves in the Reactor Building ventilation system due to an electrical transient on the power panel feeding the valve operators' solenoid pilot valves during maintenance. The cause of the electrical transient is under investigation. The Reactor Building differential pressure controller restored the building pressure to within limits. The Control Room operators reopened the Reactor Building ventilation supply and exhaust valves. Secondary Containment was declared operable at 1228 PDT and TS Action Statement 3.6.4.1.A was exited. This condition is being reported under 10 CFR 50.72(b)(3)(v)(C) and 10 CFR 50.72(b)(3)(v)(D) for an event or condition that could have prevented fulfillment of a safety function needed to control the release of radioactive material and accident mitigation. The licensee notified the NRC Resident Inspector. |
| ENS 52510 | 26 January 2017 03:11:00 | On January 25, 2017, at 1836 PST, smoke was detected in the High Pressure Core Spray System (HPCS) diesel room with no indication of a fire. Investigation found the motor starter coil for DMA-FN-32 (Diesel Mixed Air Fan 32), HPCS diesel generator room normal cooling fan, failed. This fan is required for operability of the switchgear that powers the HPCS pump. The HPCS pump is currently inoperable due to maintenance being performed on other support systems. This condition is being reported under 10 CFR 50.72(b)(3)(v)(D) for an event or condition that could have prevented fulfillment of a safety function needed to mitigate the consequences of an accident. The licensee has notified the NRC Resident Inspector. |
| ENS 52442 | 18 December 2016 18:13:00 | On December 18, 2016 at time 1124 PST the plant experienced a full reactor scram. Preliminary investigations indicate that the scram was caused by a load reject from the Bonneville Power Administration (BPA) Ashe substation. Further investigations continue. The following conditions have occurred: Turbine Governor valve closure Reactor high pressure trip +13 inches reactor water level activations E-TR-B (backup transformer) supplying E-SM-7/SM-8 (vital power electrical busses) Complete loss of Reactor Closed Cooling (RCC) E-TR-S (Startup transformer) supplying SM-1/2/3 (non-vital power electrical busses) E-DG-1/2/3 (emergency diesel generators) auto start Low Pressure Core Spray (LPCS) and Residual Heat Removal (RHR) A/B/C initiation signals Main Steam Isolation Valves (MSIV) are closed Reactor Core Isolation Cooling (RCIC) RCIC and High Pressure Core Spray (HPCS) were manually activated and utilized to inject and maintain reactor water level. Pressure control is with Safety Relief Valves (SRV) in, manual. Level control is with RCIC and Control Rod Drive (CRD). RCIC has experienced an over speed trip that was reset so that level control could be maintained by RCIC. This event is being reported under the following: 10 CFR 50.72(b)(2)(iv)(A) which requires a 4 hour notification for Emergency Core Cooling System (ECCS) discharge into the reactor coolant system. 10 CFR 50.72(b)(2)(iv)(B) which requires a 4 hour notification for any event or condition that results in actuation of the Reactor Protection System (RPS) when the reactor is critical. 10 CFR 50.72(b)(3)(iv)(A) which requires an 8 hours notification for actuation of ECCS systems. All control rods fully inserted. The NRC Resident Inspector has been informed. The licensee indicated that no increase in radiation levels were detected. |