A blown fuse in a backup monitoring system at Commonwealth Edison’s twin-reactor nuclear power plant Monday afternoon caused a 25-minute alert to be initiated while workers replaced the fuse.
While the fuse was being replaced, backup warning lights were out of service for some instruments that monitor the Unit 2 reactor, said Gary Wald, an Edison spokesman.
The blown fuse did not affect the main controls, instruments or the reactor, he said.
“There was absolutely no risk to the public at any time,” he said.
The alert was called as part of standard procedure that is required whenever safety and backup systems could be affected, Wald said. During an alert, Edison officials notify the Illinois Department of Nuclear Safety and the Illinois Emergency Management Agency that safety systems could be affected. The fuse went out at 2:05 and was replaced by 2:30 p.m., he said, when the alert was called off.
Wald described the incident as similar to blowing a fuse that controls the dashboard indicator lights in a car.
“If you lost a fuse, you’d lose the warning lights,” he said, “so you’d put a new one in.”