Reuters
September 17, 2009 - 12:00 a.m. EST

(Reuters) - DTE Energy Co (DTE.N) reduced the output of the 1,122-megawatt Unit 2 at the Fermi power station in Michigan following a test of the cooling water system, a spokesman for the plant said Wednesday.

During routine testing, one of the plant's two recirculation pumps shut, reducing the plant output.

It was operating at about 45 percent power early Wednesday down from full power early Tuesday.

Workers were investigating the cause. The spokesman could not say when the unit would return to full power.

Electricity traders guessed it would return to full power within a few days.

The 1,173-MW Fermi station is located in Newport in Monroe County about 30 miles (48 km) 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 Lisa Shumaker)