Operators shut down Exelon's Clinton nuclear plant in Illinois Sunday night when a transformer fault caused a partial power loss.
"This resulted in the operators inserting a manual scram due to loss of instrument air to containment and the scram air header," read a report filed with the Nuclear Regulatory Commission. The plant was required to report the event because it resulted in the loss of normal ventilation in the reactor's secondary containment and a change in its air pressure for about 15 minutes. The partial power loss also left part of the low-pressure core-spray system inoperable, according to the NRC.
The reactor near Champaign, Ill., had been operating at full power and last underwent a refueling outage in October. The single-unit Clinton plant uses a 1,065 megawatt General Electric Type 6 boiling water reactor first licensed in 1987. According to Exelon, it had a 100 percent capacity factor in 2012.