Yesterday afternoon, an explosion and fire took place in the Unit 1 transformer at the Oconee Nuclear Station near Seneca, South Carolina. The reactor shut itself down as a result of the incident. According to a report filed today with the Nuclear Regulatory Commission, Oconee asked for additional assistance for its on-site fire brigade, with three nearby units responding.
Initially, the incident caused plant operators to declare an Unusual Event, the lowest level of emergency under NRC guidelines. However, following the discovery of damage to overhead cables that provide power to all three reactors at the facility, the emergency level was raised to an Alert.
Almost two hours after the initial explosion, the fire was declared out. Three hours after that, the emergency declaration was lifted. The cause of the transformer explosion is still under investigation.