The Nuclear Regulatory Commission, which oversees the nation's commercial nuclear reactors, says there's no guarantee the Savannah River Site's mixed oxide fuel program will ever get off the ground.

Duke Energy Corp., the company that wants to use the fuel in its nuclear power plants, also expressed concerns about the program.

The doubts come as Gov. Jim Hodges wrangles with the federal Department of Energy over sending plutonium to SRS. The DOE promises to convert the deadly toxic material into mixed oxide fuel, or MOX, for use in commercial power plants.

Hodges wants a deal filed in court specifying what happens to the plutonium if the MOX program is shelved.

Duke Energy's concerns were filed as part of the company's proposal to relicense its nuclear power plants in the Rock Hill and Charlotte areas, company spokesman Tom Shiel said. The plants would use MOX rather than the traditional type of nuclear fuel.

MOX would be made by blending weapons grade plutonium at the Savannah River Site with uranium.

In a memorandum and order filed last week, the Nuclear Regulatory Commission agreed with Duke's concerns about the MOX program.

"We see no reason to doubt Duke's statement that its submittal of a MOX license amendment application is uncertain," the NRC said last week.

The NRC, which oversees commercial nuclear facilities, says plants to make MOX won't be built for the next six years.

DOE spokesman Joe Davis said Wednesday the government remains committed to the MOX program because it has pledged to construct the fuel fabrication facilities. The government says it will spend nearly $4 billion over 20 years on the program.

"This is the policy of the United States," Davis said.

The DOE said Monday it will ship plutonium from the Rocky Flats, Colo., nuclear site to South Carolina as early as next month.

Hodges' office said Duke and the NRC's statements validate the governor's hard line against allowing plutonium into South Carolina without federal guarantees it will be removed. Hodges has threatened to use state troopers to block the shipments or file a lawsuit to stop them.

"This is a process and a plan with a lot of questions that need to be answered," Hodges' spokesman Jay Reiff said.

A key concern about MOX is whether a Russian program to neutralize plutonium ever takes off, Shiel said.

That program is part of a delicately balanced international arms agreement with the U.S., in which each country has pledged to make weapons grade plutonium unusable for nuclear bombs.

If one side doesn't do its part, the other may balk at making the plutonium unusable, Shiel said. Questions have surrounded the future of the Russian program for months.

"If this doesn't occur in Russia, then it very well could not occur here," Shiel said. "In that case, the program goes away, or the Department of Energy goes in another direction."