WASHINGTON -- Although Yucca Mountain is nowhere close to being completed, the Energy Department is starting to consider developing a second nuclear waste repository, DOE officials told Congress on Wednesday.

No matter what the status of the Nevada project, the energy secretary is required to report to Congress between 2007 and 2010 on the need for further disposal of nuclear spent fuel.

All of the legally allowed space within Yucca Mountain is expected to be reserved almost as soon as it is built.

More than 55,000 tons of nuclear waste is being temporarily stored at commercial reactor sites, plus another 11,000 tons of Defense Department material, said Paul Golan, the acting chief of the DOE Office of Civilian Radioactive Waste Management.

The nuclear industry generates an additional 2,000 metric tons each year, which would increase if more nuclear power plants were licensed, industry officials said.

Meanwhile, Yucca Mountain has been capped by Congress at 77,000 tons.

The possible need for a second disposal site becomes clear "if you just look at the numbers in terms of what has been generated and what is the statutory cap," Golan said.

The study would cover issues that might alleviate the need for a second repository, such as the possibility of raising the legal capacity of Yucca Mountain or assessing whether spent fuel reprocessing might reduce waste volumes and allow more to fit inside the Nevada mountain, DOE officials said.

For a second repository, Golan told members of a House energy and water subcommittee that the agency would reconsider sites that were passed over when Nevada was singled out in the 1980s.

"We would start with the candidate sites that we looked at the first time and provide a map of the areas around the country that have the geological strata that would make those appropriate for second repositories," Golan said.

In 1983, DOE picked eight candidates besides the volcanic rock of Yucca Mountain as potential sites, including salt domes in Louisiana and Mississippi; bedded salt formations in Texas and Utah, and basalt in Washington state.

DOE also examined granite formations in 17 states in the East and Midwest.

"There are more than two dozen states where we would look to site a second repository," Clay Sell, Energy Department deputy secretary, said in a separate appearance on Capitol Hill on Wednesday.

Congress might become motivated to complete Yucca Mountain after DOE starts floating the idea of opening new nuclear repositories, said Rep. John Shimkus, R-Ill.

"It might provide more support for Yucca Mountain if we identify other sites around the country; that's just a wild guess on my part," he said.

Yucca Mountain is eight years behind schedule and faces technical and legal challenges and opposition from environmentalists and Nevada leaders.

Would Congress have the appetite to undertake a second repository?

"If we have to," said Rep. Joe Barton, R-Texas, the chairman of the House Energy and Commerce Committee.