Cook Nuclear Plant unit 2 refueling outage to begin Wednesday

Indiana Michigan Power’s Cook Nuclear Plant Unit 2 began power reduction Monday morning in preparation for its 19th refueling outage. Testing at 70 percent power will conclude at midnight Tuesday when the unit is taken out of service.

The unit ran for 471 consecutive days since the previous refueling. This is known in the industry as a breaker-to-breaker run, as the unit’s output circuit breakers remained connected to the transmission grid for the entire 18-month fuel cycle.

The projected capacity factor for the fuel cycle is 101.7 percent with a net generation of 12,393 gigawatthours. It was possible to average greater than 100 percent capacity factor for the period due to favorable lake water temperatures that increased efficiency during the period.

Aside from refueling the reactor and performing regular maintenance and testing work, the current outage also includes installation of new main output transformers. There is a separate 223-ton transformer for each of the three electric phases of the output of the Unit 2 Main Generator. The transformers increase the 26,000 volt generator output to 765,000 volts. Transmission of electricity is more efficient at higher voltage. The new transformers replace the original transformers that have been in service since the unit began operation in 1978.

Over the course of the outage, about 1,000 contracted workers will supplement the regular 1,100-person plant staff. More than 12,000 maintenance, inspection and equipment modification job activities totaling more than 250,000 work-hours are scheduled for two daily 12-hour work shifts. The expected outage duration is not released for commercial reasons.

At full capacity, the 1,030-net MW Unit 1 and 1,077-net MW Unit 2 combined produce enough electricity for more than one and one half million average homes.

Indiana Michigan Power is a wholly owned subsidiary of American Electric Power (NYSE:AEP).