Oct. 31 (Bloomberg) -- American Electric Power Co., the biggest U.S. producer of electricity from coal, said its Cook 1 nuclear reactor in Michigan may be shut more than 10 months after damage from sudden vibration and a fire on Sept. 20.

``The potential for being back online late in the first quarter or early in the second is high, but the potential for being offline through the second half of 2009 is also a possibility,'' Chief Executive Officer Michael Morris said today on a conference call with investors to discuss third-quarter financial results. A repair schedule will be set in November.

American Electric will delay scheduled work on other plants to make up for the loss of the unit's output, Morris said. The shutdown will affect profit, Morris said, without giving a figure. It ``should'' raise wholesale prices in PJM Interconnection LLC, the market that stretches from New Jersey to Chicago and includes Washington, Morris said.

Cook 1 is one of two reactors at the plant, on Lake Michigan about 34 miles (55 kilometers) from South Bend, Indiana. Unit 1's capacity is 1,033 megawatts, according to the company, enough to power 826,400 average U.S. homes. Cook 2 is running at capacity, according to the U.S. Nuclear Regulatory Commission.

To contact the reporter on this story: Jim Polson in New York at jpolson@bloomberg.net.

Last Updated: October 31, 2008 10:59 EDT