David H. Leroy knows people snicker when they hear what his job is.

"People smile and assume it's impossible," he said in an interview yesterday. "But I like challenges, and this certainly is one. I think this mission is very doable."

Believing that David Leroy's job is doable is the definition of optimism. The 43-year-old lawyer and Republican activist from Idaho is the nation's first nuclear waste negotiator. He has two years to find a "volunteer host" to store the nation's growing mountain of highly radioactive waste from nuclear power plants.

If he can pull it off, he will have solved a problem that has plagued the nuclear industry, federal regulators and Congress since the 1950s and is one of the biggest obstacles to the growth of nuclear power today.

Spent fuel from nuclear reactors will be dangerously radioactive for thousands of years. By the end of the century, an estimated 40,000 metric tons of it will have accumulated at the nation's 111 nuclear power plants and a handful of federally owned reactors. Most of it is stored temporarily in racks submerged in pools of water at the power plants, but there has never been a consensus on where to put it permanently.

In the past, scientists considered dumping it at sea, or launching it into space. Current policy, adopted by Congress in 1987 amendments to the Nuclear Waste Policy Act, calls for the Energy Department to create a subterranean repository beneath Yucca Mountain, Nev. But scientific disputes and resolute opposition from the state have delayed that project until 2010 at least.

Leroy's assignment is to find a state or Indian tribe willing to accept such a facility or a temporary storage site that would house the waste until a permanent repository is ready. His position was created by the same 1987 law that designated Yucca Mountain, but was not filled until President Bush nominated him last summer.

A former attorney general and lieutenant governor of Idaho and unsuccessful Republican candidate for governor in 1986, he has set up his permanent office in Boise, but he also has a two-person staff in Washington. He said his proposed first-year budget is $2.5 million.

"I'm the guardian of a process, not the guarantor of a result," he said. "My challenge is to create a process by which states become willing to step forward to help solve a significant national problem."

Up to now, he said, "no proposal has ever been made that offers a governor an opportunity for neutrality. The challenge is to formulate a proposal that is not automatically an issue for a governor in the next election just for a willingness to listen."

He said he sent out about 250 letters to governors, environmental groups, anti-nuclear activists, Indian tribal leaders, state attorneys general and organizations such as the National League of Cities asking them to participate in "a truly new and different process based on openness and volunteerism to locate sites for these controversial facilities. There will be no compromise on safety or good science."

The next task, he said, is to figure out what he has to offer to any jurisdiction that might respond favorably. In the next four months, he said, he plans to devise "a sophisticated package of opportunities that will include but not emphasize money, the opportunity for participation and shared control, economic expansion and indirect benefits, maybe some health care."

Before his Senate confirmation, Sen. Richard H. Bryan (D-Nev.), a strong opponent of the Yucca Mountain project, asked Leroy in writing what he would do if an Indian reservation hungry for economic growth decided to volunteer but the state in which the tribe's reservation is located objected.

He replied that no agreement could be implemented without state cooperation, and therefore he would "negotiate and consult with both the governor and tribal leaders" about any such site.

If no central storage site can be found, he said, he might recommend other solutions, such as on-site storage in above-ground dry casks, as is done at Virginia Power's Surry plant, or reprocessing of the spent fuel. The United States, almost alone among nuclear nations, does not reprocess spent fuel because of fear that its byproduct -- plutonium -- might get into the wrong hands.

If a storage site is found, Leroy said, everyone concerned should be satisfied that the project's benefits are worthwhile. "You can't bribe a jurisdiction to forfeit the safety of unborn generations," he said.