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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 49739 | 17 January 2014 23:36:00 | 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | Technical Specification Required Shutdown Due to Reactor Pressure Boundary Leakage | Leakage into the Reactor Building Closed Cooling Water (RBCCW) system has been determined to be Reactor Pressure Boundary leakage as identified by the plant's Technical Specification (LCO 3.4.4). Based on this, the LCO is not met and a plant shutdown is required. The shutdown commenced at 2029 CST. All of the leakage has been retained within the RBCCW system. There has been no radioactive release from the Monticello plant and all other systems remain operable and available. The unit continues to be operated in a safe and predictable fashion as it is being removed from service. The NRC Resident Inspector has been notified. The leakage rate was 0.12 gallons per minute at power. | ||
| ENS 43581 | 20 August 2007 15:53:00 | 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | Electrical Breaker B4305 Unable to Function | During panel walk downs in the Main Control Room, an Operator discovered no light indication for V-AC-4, B RHR ROOM AIR COOLING UNIT. Operator was dispatched to Breaker B4305 and 'B' RHR room to determine cause of loss of indicating light. The Operator determined that breaker B4305 (V-AC-4, 'B' RHR ROOM AIR COOLING UNIT 480V SUPPLY) was unable to function. Division II RHR pumps, Division II CS pump, and associated low pressure injection systems were declared inoperable. Tech Spec Actions 3.5.1.A, 3.5.1.B, and 3.5.1.M were entered resulting in entry into LCO 3.0.3 at 1053 on August 20, 2007. At 1151 on August 20, 2007 power reduction was commenced using normal shutdown procedures. Site Electricians determined that a line fuse had blown. The fan motor was meggared and all three line fuses were replaced. At 1230 on August 20, 2007, V-AC-4 was tested and returned to service. Division II RHR pumps, Division II CS pump and associated low pressure injection systems were declared operable. LCO 3.0.3 and T.S. Actions 3.5.1.A, 3.5.1.B, and 3.5.1.M were exited. Power reduction was terminated at 98%. At the completion of the call the power level had returned to 100%. The licensee notified the NRC Resident Inspector. |