Nevada has asked the Nuclear Regulatory Commission for an emergency order blocking shipment of radioactive waste from Ohio to the federal Nevada Test Site.
Earlier this week, Nevada also threatened to file a lawsuit to bar shipments.
The NRC received the state's request, but had no immediate response, commission spokesman David McIntyre said in a telephone interview Friday from Rockville, Md.
The state cited a 2003 law that requires radioactive waste from the Cold War-era uranium processing facility in southern Ohio to be stored at a NRC-regulated facility, said Bob Loux, director of the state Nuclear Projects Office.
The test site, where the government tested nuclear weapons for decades, is administered by the National Nuclear Security Administration, a branch of the Energy Department.
"They cannot send it to the test site at all, under any circumstances," Loux said. "It can only be disposed of at an NRC facility. We don't have an NRC-regulated facility in Nevada of any kind."
The Energy Department said it plans to go ahead with shipments from the Fernald, Ohio, nuclear plant.
"We are aware of Nevada's activities to block our legal right to ship this low-level defense waste, including their petition before the NRC," Energy Department spokesman Joe Davis said by telephone from Washington.
The threatened lawsuit is based on federal environmental law. The NRC effort cites a 2003 congressional appropriations measure that passed before plans to dispose of the Fernald waste at a private facility near Clive, Utah, were shelved because of opposition there.
Nevada officials say waste from Fernald is more radioactive than low-level waste and is mixed with more hazardous waste - and will need a more secure disposal site with lined pits.
A lawsuit could delay the Fernald cleanup, which has been under way more than a decade and has cost about $4 billion.
Nevada already is battling the government in federal court over Washington's plan to open a national nuclear waste repository at Yucca Mountain, on the western edge of the test site, 90 miles northwest of Las Vegas.
The Energy Department plans to entomb 77,000 tons of the nation's most radioactive spent reactor fuel from 39 states at the repository beginning in 2010.
On the Net:
Nevada Attorney General: http://www.ag.state.nv.us
Nevada Test Site: http://www.nv.doe.gov/nts