At the same time, production costs sank to a record 1.66 cents per kilowatt hour in 2006, despite three years of price increases for uranium, the fuel used in nuclear generation.

These are preliminary figures, the institute said, and final numbers are expected in two months.

Utilities are increasingly eyeing nuclear energy, which does not create air pollution, as an alternative to electricity generated from burning coal, which emits greenhouse gases linked to global warming.

But the public has been wary about relying on nuclear energy since a partial meltdown of a reactor at the Three Mile Island plant in Pennsylvania in 1979.

"It's going to take a collaborative effort of all forms of electricity generation, as well as much-improved efficiency, to meet the sizable energy needs that our nation faces," Frank Bowman, the group's president and chief executive, said in a statement.

"Still, the exceptional performance achieved at US nuclear power plants in 2006 shows that the nation's future energy security hinges in part upon increased reliance on clean, safe and affordable nuclear energy."