Nov. 29--Where others see only radioactive waste, engineers at TVA and the Department of Energy envision another source of needed energy.

Most of the potential energy in the nuclear fuel used to generate nearly 30 percent of the electricity in the Tennessee Valley remains untapped in spent fuel pools or dry casks at the Sequoyah, Watts Bar and Browns Ferry nuclear plants, said Sherrell R. Greene, director of Oak Ridge National Laboratory's nuclear technology programs.

"We basically discard over 90 percent of the energy value that is still left in the fuel bundles after they are used," Mr. Greene said. "This spent nuclear fuel is potentially a very valuable resource for our country."

But figuring out how to recycle nuclear fuel safely at an economical cost remains a challenge, Mr. Greene concedes. Although other countries reprocess nuclear fuel, the United States abandoned the technology in 1977 to help curb the proliferation of nuclear weapons that use the plutonium generated in reprocessing fuel.

Critics of nuclear reprocessing complain such technologies are too expensive and create and disperse more dangerous materials than they recycle.

Diane D'Arrigo, radioactive waste project director for the Nuclear Information and Resource Service, grew up near the Nuclear Fuel Services' reprocessing plant in western New York that operated from 1966 to 1972. She said cleaning up the plant's radioactive wastes that could leak into the Great Lakes is projected to cost at least another $10 billion.

"Reprocessing creates more waste, and the fact that the Department of Energy is even considering repeating this mistake is very depressing," she said.

CLOSING THE FUEL CYCLE

President George W. Bush pushed his Advanced Fuel Cycle Initiative and joined the Global Nuclear Energy Partnership as a way for the United States to develop new and better technologies to reprocess nuclear fuel to reduce the volume of radioactive wastes and generate more energy. The Department of Energy announced in October it favored some type of nuclear fuel reprocessing, but agency officials did not choose among competing technologies.

Oak Ridge is among 13 sites being considered for a reprocessing facility where spent nuclear fuel from America's 104 nuclear plants could be shipped. The Oak Ridge National Laboratory spent $92 million in fiscal 2008 on nuclear power research.

President-elect Barack Obama has not specified his plans for the global nuclear partnership.