Ameren Missouri's Callaway Energy Center is still offline after an unexpected electrical problem shut the plant down just after midnight Wednesday morning. Mark McLachlan, senior director of engineering at the Callaway plant, said the plant experienced an electrical problem which caused a turbine trip and a reactor trip that shut the plant down.
The nuclear plant's reactor went from producing 100 percent power to 0, according to a U.S. Nuclear Regulatory Commission (NRC) report. The report classified the shutdown as a non-emergency.
McLachlan said the nuclear facility, which generates about 20 percent of the electricity for Ameren Missouri's 1.2 million customers, doesn't yet know the cause of the electrical problem and does not have an estimated time the plant will be back online.
"We are investigating the cause of the problem and until we know what happened we don't have an estimate on how long it will take to repair it or when the plant can get back online," McLachlan said.
He added that the plant operated as it is designed to and shut down when the electrical trip occurred. The turbine and reactor trips and reactor automatic shutdown are safety mechanisms within the plant's operation, according to the NRC.
While the plant shut down its operations and stopped producing power, the facility did not lose power and remained connected to the grid.
"We are pulling power off the grid and not supplying power to the grid," McLachlan said.
McLachlan said the control room is staffed around the clock. Control room staff noticed the problem and plant shutting down immediately. The nuclear facility notified the NRC of the problem Wednesday and began investigating the problem.
"(We are) logically going through the plant systems to determine where the problem occurred and once we figure out where, then we can go in and determine what parts need to be repaired or replaced to fix the plant and get it back online," McLachlan said.
Ameren Missouri customers will not notice a difference, McLachlan said. Ameren Missouri has other generating stations that produce electricity.
The Associated Press reported that Ed Smith with Missouri Coalition for the Environment found the nuclear facility's shutdown to be concerning and reported a statement from Smith regarding the unexpected shutdown.
"Unexpected shutdowns like today show how nuclear electricity production can go from 100 percent to 0 percent without warning," Smith said in a statement. "Nuclear energy comes with its own set of risks and vulnerabilities that are often minimized by the industry and its supporters."