SOUTH TEXAS EVENT REPORT: UNUSUAL EVENT DECLARED DUE TO MAIN TRANSFORMER FIRE

An Unusual Event was declared based on EAL HU-2 - Fire or explosion in protected area or switchyard which affects normal plant operations.

At 1655 CST, South Texas Unit 2 declared an Unusual Event due to a main transformer fire. Unit 2 tripped from 100% power and is currently at 0% power in Mode 3. The transformer fire is out. In addition to the loss of the main transformer, several safety related electrical busses and non-safety electrical busses lost offsite power. The appropriate emergency diesel generators started and powered the safety related busses. Unit 2 is currently stable and on natural circulation due to the loss of power to the reactor coolant pumps. Auxiliary feedwater is functioning as required and decay heat is being removed through the steam generator atmospheric relief valves. Unit 1 was unaffected by the event.
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