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At 7:30 a.m. (CDT) on October 1, 2004, an … At 7:30 a.m. (CDT) on October 1, 2004, an automatic reactor scram occurred as a result of an electrical fault on the main generator output lines that caused a main generator trip and turbine trip. All control rods inserted. Approximately 13 minutes prior to the fault, a loss of one station service transformer had occurred. This resulted in an automatic start of the Division 1 diesel generator and a loss of power to some plant auxiliaries, including the feedwater level regulation isolation valves.</br>The loss of reserve station service no. 1, combined with the trip of the main generator, caused a loss of power to two condensate pumps and one main feedwater pump. The remaining two feedwater pumps tripped on low suction pressure. The reactor containment isolation cooling pump (RCIC) steam supply isolated during the scram transient, so the control room operators manually started the high-pressure core spray system (HPCS) pump for level control. The injection valve was closed as level had already reached the high water level isolation setpoint for that valve. It was later reopened manually as level approached the low level setpoint (level 2), which would have automatically opened the valve. The level 2 setpoint was reached briefly after the valve was already open.</br>Reactor pressure is being controlled manually with safety relief valves (SRV's). The main steam isolation valves (MSIV's) were manually closed due to lowering pressure from steam loads in the plant that could not be immediately isolated because of loss of power to their valves. RCIC is also running in CST (condensate storage tank) to CST mode, to augment pressure control. </br>The electrical load center which supplies power to the instrumentation and valves needed for feedwater operation was cross-tied to an alternate power source, and feedwater was restored to operation and is presently controlling reactor water level. During the event, standby service water also initiated.</br>This is the presently known information. Further information will be provided as the investigation continues.</br>The licensee has notified the NRC Resident Inspector.e has notified the NRC Resident Inspector.
12:30:00, 1 October 2004 +
41,082 +
12:00:00, 1 October 2004 +
12:30:00, 1 October 2004 +
At 7:30 a.m. (CDT) on October 1, 2004, an … At 7:30 a.m. (CDT) on October 1, 2004, an automatic reactor scram occurred as a result of an electrical fault on the main generator output lines that caused a main generator trip and turbine trip. All control rods inserted. Approximately 13 minutes prior to the fault, a loss of one station service transformer had occurred. This resulted in an automatic start of the Division 1 diesel generator and a loss of power to some plant auxiliaries, including the feedwater level regulation isolation valves.</br>The loss of reserve station service no. 1, combined with the trip of the main generator, caused a loss of power to two condensate pumps and one main feedwater pump. The remaining two feedwater pumps tripped on low suction pressure. The reactor containment isolation cooling pump (RCIC) steam supply isolated during the scram transient, so the control room operators manually started the high-pressure core spray system (HPCS) pump for level control. The injection valve was closed as level had already reached the high water level isolation setpoint for that valve. It was later reopened manually as level approached the low level setpoint (level 2), which would have automatically opened the valve. The level 2 setpoint was reached briefly after the valve was already open.</br>Reactor pressure is being controlled manually with safety relief valves (SRV's). The main steam isolation valves (MSIV's) were manually closed due to lowering pressure from steam loads in the plant that could not be immediately isolated because of loss of power to their valves. RCIC is also running in CST (condensate storage tank) to CST mode, to augment pressure control. </br>The electrical load center which supplies power to the instrumentation and valves needed for feedwater operation was cross-tied to an alternate power source, and feedwater was restored to operation and is presently controlling reactor water level. During the event, standby service water also initiated.</br>This is the presently known information. Further information will be provided as the investigation continues.</br>The licensee has notified the NRC Resident Inspector.e has notified the NRC Resident Inspector.
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