The TVA says that it has studied similar power increases at other reactors and believes it can be done safely at Browns Ferry, The Nashville Tennessean reported. The facility is 100 miles south of Nashville.

"This is the best way that TVA saw to increase power, to help with our delivery costs and to keep a good strong generation mix that helps meet our commitment to the environment," said Craig Beasley, spokesman for Browns Ferry. "Our work is done in a very deliberate and conservative manner."

No new nuclear plants have been built in the United States for decades. With demand for electricity soaring, existing plants have been applying for license extensions and for "uprates" -- increases in the amount of power generated, the report said.

Some plants have had problems. At the Vermont Yankee plant, owned by Entergy, a cooling tower collapsed last year after a 20-percent increase in generating capacity in 2006.