The Byron nuclear plant in Illinois ended an unusual event notification Wednesday night after restoring an off-site power source.
Unit 1 operators reported a loss of off-site power just after 7 p.m. Tuesday to the Nuclear Regulatory Commission. Two emergency diesel generators started automatically, as did an auxiliary feedwater pump, according to an NRC event report. The reactor remained online throughout, and neighboring unit 2 was unaffected.
In a press release, Exelon said an insulator had failed in a switchyard. The unusual event, the least severe of the NRC’s emergency declarations, ended 9 p.m. Wednesday.
“We are working on a plan to inspect all the switchyard insulators and replace them as necessary,” Byron Site Vice President Tim Tulon said in the release.
The plant generates 2,300 megawatts from two Westinghouse pressurized water reactors that began operating in the mid-1980s, according to the NRC.