Reuters
October 3, 2009 - 12:00 a.m. EST

(Reuters) - DTE Energy Co (DTE.N) shut the 1,122-megawatt Unit 2 at the Fermi power station in Michigan from full power on Sept. 30 due to hydrogen leakage into stator water cooling system, the company told the U.S. Nuclear Regulatory Commission in a report.

In the report, the company said the shutdown was uncomplicated and it was investigating the cause of the hydrogen leakage.

The stator is the stationary part of a rotor system.

The company did not say when the unit would likely return to service but electricity traders guessed it could be back within a week.

The 1,173-MW Fermi station is located in Newport in Monroe County about 30 miles southwest of Detroit. There are several units at the station including Unit 2, which entered service in 1988, and four 12- and 13-MW oil-fired turbines (1966).

In 2008, DTE filed with the NRC to build one of General Electric Co (GE.N)/Hitachi Ltd's (6501.T) 1,550-MW Economic Simplified Boiling Water Reactors (ESBWR) at Fermi.

Using an industry estimate of $3,300 per kilowatt, the new reactor could cost about $5.1 billion.

One MW powers about 800 homes in Michigan.

DTE, of Detroit, owns and operates about 11,000 MW of generation, markets energy commodities and distributes power to 2.2 million customers and gas to 1.2 million in Michigan. (Reporting by Scott DiSavino; Editing by John Picinich)