Whatever her opinion of Yucca Mountain, Macfarlane believes a geologic repository has got to be built, and soon. Even if the U.S. starts reprocessing waste, it will leave behind glass bricks of deadly radionuclides that will need to be squirreled away for good. For the sake of the climate, Macfarlane says, "we don't really want to back away from the 20 percent nuclear power that we have in this country. We need all the help we can get."

All the evidence suggests that Obama agrees with Macfarlane: We need nuclear energy, even if Yucca Mountain isn't the best place to store waste. Obama's pick for Energy secretary, Lawrence Berkeley Lab Director Steven Chu, agrees with him, at least about the first part. Asked in 2005 whether nuclear should be part of the nation's energy mix, Chu answered without hesitation: "Absolutely."

But to maintain that energy mix will require replacing and retrofitting the country's aging fleet of reactors, and to support those efforts without the prospect of Yucca Mountain, the new administration will have to act quickly to locate a waste storage project. That won't be easy. Congress will need to throw out all previous laws regarding nuclear waste disposal and start the site selection process from scratch. The Energy Department will need to tear up decades of contracts with nuclear energy providers and negotiate new terms for temporary storage. Legislators would then set to work investigating sites: Morris, Ill., where the government once experimented with a nuclear waste reprocessing operation? Oak Ridge, Tenn., the once-secret hub of the Manhattan Project? Those states would undoubtedly mount opposition of their own, just as they did in the 1980s, when Congress picked Yucca Mountain out of nine possibilities, not least because the federal government already owns almost 90 percent of Nevada's land.

And not everyone in Nevada would be happy if Yucca Mountain failed. Under the Nuclear Waste Policy Act, Nye County, Nev., expects to gain more than $10 million a year from the site, which is within its boundaries, along with a few new jobs. Kevin Phillips, the nuclear-besotted mayor of Caliente in neighboring Lincoln County, has pinned his small town's economic recovery on the construction of the railroad line that would form the final leg in the long transportation chain of waste to Yucca Mountain. "Caliente has always been a railroad town," he told government officials at a meeting in December. "To us it looks like renewal."

Official government agencies say little about whether the president-elect has the authority to stop Yucca Mountain. Energy Department spokesman Allen Benson refused to even speculate. Nick Shapiro wrote in an e-mail that, "We are confident that Dr. Chu shares (Obama's) goals (on Yucca Mountain) and that he will work with the President-elect and Congress to realize them." Sen. Reid, too, has claimed Chu as an ally. In August of 2008, however, Chu was among 10 scientists to sign a document recommending that the licensing review proceed, if only to give short-term confidence to the nuclear industry while scientists come up with better ideas.