The U.S. Nuclear Regulatory Commission says a lightning strike knocked out power to a northern Illinois nuclear plant for several hours Wednesday night, but emergency generators kicked in to keep the site running.
Exelon Generation says it believes lightning hit a substation that carries electricity to and from its LaSalle Generating Station. Both reactors shut down as a safety precaution, and diesel generators continued to power plant equipment.
Spokeswoman Krista Lopykinski says off-site power was restored late Wednesday night, and the plant officially exited the so-called "unusual event" on Thursday morning. An unusual event is the lowest of the four emergency classifications.
Exelon says reactors will remain offline until appropriate safety checks and procedures are completed.
The plant is in rural LaSalle County, about 75 miles southwest of Chicago.