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| Entered date | Event description | |
|---|---|---|
| ENS 44982 | 10 April 2009 12:43:00 | At 0538 on Friday, April 10, 2009, Nine Mile Point Unit One manually tripped the turbine at approximately 28% rated power in response to rising turbine bearing vibrations. Following the manual turbine trip, the High Pressure Coolant Injection (HPCI) system automatically initiated on the turbine trip signal. The HPCI system initiation signal was reset immediately following the turbine trip. Reactor water level was maintained in the normal operating range throughout the transient. At Nine Mile Point Unit One the HPCI system is a mode of operation of the feedwater and condensate system. It is not an Emergency Core Cooling System (ECCS). A HPCI system actuation signal on a turbine trip is an expected response of the HPCI system. Nine Mile Point Unit 1 remains at power since the turbine was tripped at a power level that is within the capacity of the turbine bypass valves. 10 CFR 50.72(b)(3)(iv)(A) requires reporting within 8 hours when a valid actuation of the feedwaler coolant injection system occurs. The event has been entered into the corrective action program. There are no other adverse impacts to the station based on this event. The NRC Resident Inspector was notified. |