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| Entered date | Event description | |
|---|---|---|
| ENS 50700 | 23 December 2014 00:57:00 | On December 22, 2014 at 2230 hours (EST) while performing a containment walkdown due to increased RCS (Reactor Coolant System) unidentified leakage, a leak was identified upstream of 1-RC-68, B Loop Cold Leg Drain Isolation Valve. The source of this leakage cannot be isolated and is considered RCS pressure boundary leakage. (Unit 1) Entered TS LCO 3.4.13 RCS Operational Leakage, Condition B for the existence of pressure boundary leakage. TS 3.4.4 RCS Loops - Modes 1 and 2 condition A, TR 3.4.6 ASME Code Class 1, 2, and 3 components, Condition B. Unit 1 will be taken to Mode 5 for repair. This event is reportable in accordance with 10 CFR 50.72(b)(2) for "initiation of plant shutdown required by Technical Specifications" and 10 CFR 50.72(b )(3)(ii)(A) for "any event or condition that results in the condition of the nuclear power plant, including its principal safety barriers, being seriously degraded. The RCS leakage has been quantified as 0.053 gallons per minute from a containment sump in-leakage calculation. The exact location of the leak has not been identified due to the installation of lagging on the RCS components. The licensee anticipates entering Mode 3 (Hot Standby) within the next 30 minutes. There is no safety-related equipment out-of-service at this time. The licensee will inform Louisa County and has informed the NRC Resident Inspector. |
| ENS 48269 | 3 September 2012 05:17:00 | At 22:04 CDT on 9/02/2012, the Emergency Reserve Auxiliary Transformer (ERAT) transferred unexpectedly to the Reserve Auxiliary Transformer (RAT). During this transfer, the Fuel Pool Cooling and Cleanup (FC) system pump 'A' tripped and the Fuel Building Ventilation (VF) system isolated. Upper containment pool level dropped below the minimum required level per Technical Specifications (TS) 3.6.2.4 and Secondary Containment differential pressure increased above 0.25 inches vacuum per TS 3.6.4.1. Upper Containment Pool level was restored above the minimum level at 01:27 CDT on 9/3/2012 within the 4 hour completion time. The Upper Containment Pool is a part of the suppression pool makeup system used to ensure the Primary Containment function. Secondary Containment differential pressure was restored at 22:19 on 9/2/2012 when the Standby Gas Treatment System was started. Maintaining secondary containment differential pressure helps to control the release of radioactive material. This event is being reported as a condition that could have prevented the fulfillment of a safety function per 10 CFR 50.72(b)(3)(v)(B) and 10 CFR 50.72(b)(3)(v)(C). The station is currently in a 72-hour action to restore the ERAT to an operable status per TS LCO 3.8.1 Required Action A.2. Plant conditions are stable and actions are underway to repair the ERAT. The NRC Resident (Inspector) has been notified.
Upper Containment Pool level dropped below the normal pool level of 827 feet-3 inches when the Fuel Pool Cooling and Cleanup system pump 'A' tripped, and was initially reported as dropping below the minimum level (825 feet-6 inches) required by Technical Specification (TS) 3.6.2.4. However, subsequent reports from the field confirmed that the lowest level reached was 827 feet 0 inches, which is greater than the minimum required TS level. Therefore, no loss of safety function occurred for the Upper Containment Pool level as a result of this event, and the event is not reportable under 50.72 (b)(3)(v)(B). The NRC Resident (Inspector) has been notified." Notified R3DO (Pelke). |