WASHINGTON—The Department of Energy has been given the green light to move full speed ahead with its shutdown plans for the Yucca Mountain nuclear waste program.

A federal appeals court late Monday dismissed a request to freeze termination activities until later this year, after judges have weighed lawsuits challenging the shutdown.

The order clears the way for the DOE to resume dismantling the Nevada waste repository program that the Obama administration wants to shelve. Remaining federal employees were given pre-layoff notices earlier this year, and the DOE was scheduled to issue a termination letter to the project's management contractor.

"We welcome the court's decision," DOE spokeswoman Stephanie Mueller said. "It means the court agreed that the department can proceed with winding down the Yucca project responsibly while the litigation proceeds so as not to needlessly waste taxpayer money."

Sen. Harry Reid, D-Nev., the repository's leading opponent, said the DOE "will resume shutting down the Yucca Mountain Project almost immediately." "Billions of taxpayer dollars have already been wasted on this project, and ... (the) decision will allow DOE to cut its losses now rather than later," he said.

A half-dozen petitioners, including the states of Washington and South Carolina, have charged in federal lawsuits that the DOE does not have the authority to end the Yucca program without legislation from Congress.

Arguments on those lawsuits are scheduled to be held in September in the U.S. Court of Appeals for the District of Columbia Circuit. Separately, an arm of the Nuclear Regulatory Commission has scheduled two days of hearings on the issue in June.

In the meantime, Washington Attorney General Rob McKenna petitioned the court of appeals to issue an injunction freezing the Yucca shutdown until the cases are heard.

McKenna argued that the Department of Energy was gutting a skilled work force and dismantling the repository site, 100 miles northwest of Las Vegas. With each of these moves, the attorney general said, it would be that much more difficult to restore the Yucca program if the court decides ultimately that the repository should remain an option for handling the nation's high-level nuclear waste.

In a brief order, the court rejected the motion, saying Washington state did not show it would suffer "irreparable injury" if the DOE was not stopped in its tracks at this time.

Andy Fitz, a senior counsel in the Washington attorney general's office, said the state remains hopeful it will prevail when the judges hear the full case. The Department of Energy and Reid are moving to complete the termination this year, with Reid, the Senate majority leader, looking to zero out all Yucca funding.