Nebraska's Fort Calhoun nuclear plant was forced to power down this week for a third time since exiting an extended outage late last year.
The reactor was operating normally Tuesday afternoon when an alarm indicated a control room air conditioner was inoperable, according to a report filed with the Nuclear Regulatory Commission. Another air conditioner was down for maintenance, and safety regulations require a reactor to power down if control room HVAC systems are offline beyond a certain amount of time. Operators began powering down the reactor a few hours later, with the unit reaching 33 percent power before one of the air conditioners was repaired.
An Omaha Public Power District spokesman told the Omaha World-Herald the plant was back up to 87 percent power Wednesday morning. The event followed a two-day unplanned shutdown in March to fix a turbine cooling system and a four-day unplanned shutdown in January caused by ice buildup on a water intake. Fort Calhoun reentered service in December after three years of repairs and NRC inspections following flooding at the site and a fire that affected safety equipment. Exelon has been contracted to handle day-to-day management of the plant.