Omaha Public Power District (OPPD) said Dec. 18 that its Fort Calhoun nuclear plant was automatically taken offline during the morning hours “after a lockout of the station’s main generator.”
“There was no risk to the public and no injuries associated with the shutdown as this was a non-emergency event. The public and the plant remain safe,” OPPD said in a news release.
The station is designed to shut down automatically as a safety precaution in the event of conditions such as the lockout experienced about 10:14 a.m.
Operations crews reacted accordingly, placing the plant into Mode 3 Hot Shutdown. This means it is offline, but remains at normal operating pressure and temperature.
The cause of the generator lockout is under review by the site’s Outage Control Center, which is staffed during events such as this. There is no apparent damage to any of the generator or transformer components. Every effort will be made to safely bring the station back online as soon as possible.
The Nuclear Regulatory Commission (NRC) has been notified of the non-emergency event.
The roughly 500-MW pressurized water reactor (PWR) is located in Blair, Neb. After a prolonged outage dating to early 2011, Fort Calhoun returned to active service in late December 2013.
Fort Calhoun had been shut for a routine refueling outage in April 2011. But the plant encountered rising water levels from flooding along the Missouri River the following month.
Then in June 2011 there was a feeder breaker fire that prompted OPPD to declare an alert. In September 2011 NRC issued a confirmatory action letter (CAL) for problems at Fort Calhoun. In early 2012, OPPD hired Exelon (NYSE:EXC), the nation’s largest nuclear operator, to help it with the plant.
Since restarting about a year ago, Fort Calhoun has been under a special NRC oversight program distinct from the normal performance levels because of an extended shutdown associated with significant performance issues. OPPD said in mid-September that it has addressed most of the issues cited by NRC.