AEP Mich. Cook 1 reactor exits 15-month outage

NEW YORK Dec 21 (Reuters) - American Electric Power Co Inc's (AEP.N) 1,009-megawatt Unit 1 at the Cook nuclear power station in Michigan exited a 15-month outage and ramped up to 48 percent power by early Monday from 3 percent early Friday, the U.S. Nuclear Regulatory Commission said in a report.

The unit shut on Sept. 20, 2008 when turbine vibrations, caused by broken low pressure turbine blades on two of the three low pressure turbines, damaged the turbine generator, support structures and associated systems.

The company said in a release the unit will be connected to the grid with repaired low pressure turbine rotors that do not include the last row of blades.

When the unit returns to full power, its output will be reduced by an annual average of about 70 MW.

The company said it planned to install new low pressure turbine rotors that would allow the unit to reach its full power output in the autumn of 2011.

In the past, AEP has said the estimated $330 million cost to repair and replace the turbines would be covered by warranty and insurance.

Cook station is located in Bridgman in Berrien County about 80 miles (128 km) east of Chicago. (Reporting by Scott DiSavino; Editing by John Picinich)