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Entered date | Event description | |
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ENS 41984 | 12 September 2005 23:27:00 | On September 12, 2005 at 1709 hours, one feedwater train bypass valve (TV-1CN-100) unexpectedly opened at Beaver Valley Power Station Unit No. 1, causing the temperature of the feedwater going to the three steam generators to reduce. Reactor power then increased due to cooler feedwater temperature entering the steam generators. Reactor power increased to approximately 103 percent. The control room crew commenced reducing plant load and reactor power. Approximately 4 minutes later, TV-1CN-100 automatically closed as designed following an automatic opening signal. Reactor power decreased below 100% at approximately the same time. Currently, the plant is stable with reactor power at 93 percent. A calibration procedure of the Steam Dump Control System was ongoing at the time of the event. Preliminary investigation determined that this event occurred due to removal of an instrument card within the Steam Dump Control System which caused TV-1CN-100 to inappropriately open. Actuation of TV-1CN-100 was not initiated by a valid actuation signal. This event is being reported as a voluntary notification since the reactor power exceeded maximum licensed steady state power level of 102 percent. The licensee notified the NRC Resident Inspector. |