Energy Secretary Spencer Abraham said Thursday that killing the Yucca Mountain project would leave the federal government without a plan for solving the nation's radioactive waste problem.

"There is no alternative at that point," Abraham told a congressional panel. "We go back to square one to see what comes next."

Urging Congress to move ahead with the Nevada burial site for nuclear waste, Abraham warned that energy companies would develop their own plans for transporting and disposing of waste from nuclear power plants.

"Do we want to do it in a coordinated national plan or on more of an ad hoc basis?" he said at a hearing of the House Energy and Commerce subcommittee on energy and air quality.

Abraham's first public defense of the Bush administration's recommendation that the Nevada desert site become the long-term home for nuclear waste also included a plea to skeptical members of Congress to move the project ahead in spite of their reservations.

Approving the Yucca Mountain depository would allow the Energy Department to apply to the Nuclear Regulatory Commission for a license to operate the facility beginning in 2010. Up to 77,000 tons of highly radioactive material generated by commercial nuclear power plants and the government's weapons program would be stored 900 feet beneath the desert.

Nevada Gov. Kenny Guinn, under special rules devised by Congress, rejected Bush's designation of Yucca Mountain 10 days ago.

Congress must ratify Bush's decision within 90 days or find a new burial site for high-level nuclear waste, now stored at 131 sites around the country.

Consolidating the waste was a major factor cited by committee members who support the project.

"You're well-served to put all your eggs in one basket and then watch that basket," Rep. Tom Sawyer, D-Ohio, said, quoting Mark Twain.

Nevada's congressional delegation, united in its opposition to Yucca Mountain, urged defeat of the project because of questions about the site's safety and the risks of transporting radioactive material across the country.

Sen. John Ensign, R-Nev., said the shipments of spent nuclear fuel through population centers would be ripe targets for terrorists. "We've heard that terrorists are looking for dirty bombs," Ensign said. "Well, these are dirty bombs."

But Abraham, who faced mostly friendly questioning, countered, "The presumption is that al-Qaida or some other terrorist group would wait 10 years ... when they already know where it is today at 131 sites."