"The accident or terrorism risk for fuel in dry cask storage is orders of magnitude less than from fuel in reactors or storage pools at operating nuclear power plants," he said.

Von Hippel, who was assistant director for national security in the White House Office of Science and Technology Policy in 1993 and 1994, said he doesn't agree with the nuclear industry's stance that there's a pressing need for a repository at Yucca Mountain, 100 miles northwest of Las Vegas.

"I'm not anti-nuclear, but I'm anti-pro-nuclear," he told attendees of the International Symposium on Technology and Society.

Nevertheless, he said there eventually will be a need for geologic disposal of highly radioactive waste in some repository, but not necessarily one in Nevada.

"A geologic process is not a bad idea," he said after the symposium. "But the process was corrupt in imposing this on Nevada."

While other countries such as France and Russia have reprocessed waste, there's a security risk involved with how easily the plutonium that has been separated from radioactive remnants could be obtained and fashioned into a nuclear bomb by a rogue nation or militant group.

"That's my beef with reprocessing," said von Hippel, who played a major role in programs with Russia to increase its security of special nuclear weapons materials.

On the waste issue, he concluded that the not-in-my-backyard mind-set is "an extremely powerful force and can drive governments to crazy and dangerous policies."

The terrorism risk in transporting spent nuclear fuel assemblies to a repository have been "over-exaggerated," he said.

Even if a transportation cask has been breached by an armor-piercing explosive or weapon, a relatively small amount of radioactive powder would come out but wouldn't catch fire.

"It would be dwarfed by a chlorine tank accident," he said.