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| Entered date | Event description | |
|---|---|---|
| ENS 45029 | 28 April 2009 23:50:00 | At 2159 Sequoyah Unit 1 was manually tripped from 18% reactor power. The manual trip was in response to automatic isolation of all intermediate pressure feedwater heater strings resulting in a loss of all condensate flow. The feedwater heater strings isolated following a manual trip of the main turbine. The main turbine was manually tripped in response to a failed open moisture separator reheater relief valve. At the time of the event Sequoyah Unit 1 was raising power following a refueling outage. Following the reactor trip, all safety-related equipment operated as designed. Auxiliary feedwater automatically actuated as expected on loss of the operating main feedwater pump. The plant is currently being maintained in Mode 3 at NOT/NOP, approximately 547 F and 2235 psig, with auxiliary feedwater supplying the steam generators and steam dumps to main condenser removing decay heat. Maintenance activities have been initiated to repair the MSR relief valve. Electrical lineup is normal with all safety related equipment operable. Licensee is investigation the cause for the relief valve failure. The NRC Resident Inspector has been notified. |