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| Entered date | Event description | |
|---|---|---|
| ENS 46974 | 20 June 2011 17:10:00 | On June 20, 2011, at approximately 0945 hours, electrical power was lost to non-essential 120 volt busses V-1-F and V-2-F. The busses supply electrical power to the plant integrated computer system (ICS). As a result of the power loss, the Safety Parameter Display System (SPDS), the Emergency Response Data System (ERDS), and the automatic mode calculation of the Computer Aided Dose Assessment Program (CADAP) were unavailable. Preliminary investigation indicates the power loss was caused by receipt of a spurious high temperature alarm (greater than 95 degrees F) in the Technical Support Center (TSC) facility where the electrical busses are located. The alarm signal is believed to be invalid because the high temperature alarm came in for two minutes and reset, and the ambient temperature in the TSC remained steady at 65 degrees F. Electrical busses V-1-F and V-2-F were re-energized and restored to service at 1505 hours. The ICS, SPDS, ERDS, and CADAP systems were fully restored at 1652 hours on June 20, 2011. In the event of an emergency while these systems were unavailable, contingency plans were in place to transmit plant parameter data and perform the dose assessment function. This event is being reported in accordance with 10 CFR 50.72(b)(3)(xiii), as a condition that results in a major loss of emergency assessment and communications capability. The NRC Resident Inspector has been notified. |
| ENS 40404 | 22 December 2003 00:31:00 | On 12/21/03 at 2021, it was discovered that the temperature control valve for the Division 1 Emergency Closed Cooling system had two blown fuses. This results in the Division 1 Control Complex chiller becoming inoperable. Concurrent with this the Division 2 Control Complex chiller was inoperable for planned maintenance. With this configuration both trains of safety related ventilation have been declared inoperable. This results in a loss of safety function for AC and DC distribution systems. Additionally this results in all Emergency Core Cooling systems being inoperable. This is reportable under 10 CFR 50.72 (b) (3) (ii) (b) and (b) (3) (v) (a, b & d) for unanalyzed condition and loss of a single train safety system. The licensee notified the NRC Resident Inspector. |