WASHINGTON (AP) _ Nearly six months after Congress tabbed Yucca Mountain, Nev., as the permanent burial site for high-level nuclear wastes, a House panel began deliberations Thursday on how to get the stuff there without risking a catastrophe.

House Interior Chairman Morris K. Udall, D-Ariz., noted that the years-long struggle to pick a repository site for spent reactor fuel and other highly radioative junk may have been only half the battle.

''No one wants a repository in his backyard, but no one wants nuclear waste trucks driving down his street either,'' he said.

Major shipments of nuclear wastes, principally from storage pools near the 110 nuclear power plants around the nation, will not begin until the repository is completed early next century. But nearly every state is on proposed transit routes.

Industry officials told Udall's energy subcommittee that past, albiet limited, experience in shipping high-level wastes demonstrates no cause for alarm.

''There has never been an accident in over 20 years of spent fuel shipment that has resulted in a release of radiation,'' said D.A. Brodnick, a nuclear specialist at the Florida Power & Light Co.

But Melinda Kassen of the Environmental Defense Fund said that ''although the people of the United States have been spared the consequences of an accident involving a release of radioactivity, it is not because the government runs a technically unimpeachable program, but rather because, so far, we have been lucky.''

She pointed to a Nuclear Regulatory Commission study which said an ''extreme'' accident involving a truck carrying one type of container used in the past, called an LLD-1, could result in the release of a kilogram, or 2.2 pounds, of plutonium. If that happened in a major urban area, she said, it could result in thousands of latent cancer deaths and billions of dollars in contamination damage.

Udall's panel is considering a variety of bills designed to upgrade shipping standards, including new requirements for the crash-worthiness of shipping casks, selection of routes and pre-notification to communities along the way.

Ron Lurie, the nuclear waste project manager for Las Vegas, Nev., complained that his city was ''at the end of the transportation funnel'' to Yucca Mountain, and that ''without a beltway bypass and alternative railroad spurs, we will become exposed to the hazards and risks of thousands of road and rail shipments.''

Robert M. Jefferson, an industry consultant, said a study by the Lawrence Livermore Laboratories indicated that, using trucks, there was a probability of one accident involving a measurable release of radiation for every 15 billion miles traveled.

Jefferson said that assuming all shipments of spent fuel were made by truck, ''there might be an accident which results in a minor release about every 1,300 years, with minimal public health consequences.''

But Rep. James Bilbray, D-Nev., said the Energy Department had told him its own calculations indicated an accident would be likely every 40 million truck miles. And that, he noted, would be the mileage required to transport the waste already stored at reactor sites - to say nothing of the amount that will be generated in the years ahead.