A federal oversight agency and a citizens advisory board are challenging the long-term disposal plans for tons of surplus plutonium stored at South Carolina's aging Savannah River Site.

Six tons of the highly radioactive material are stored at SRS in 1950s-era structures not built for that purpose. The Energy Department is considering whether to move all the nation's surplus plutonium, now scattered among four installations, to Savannah River.

The prospect of South Carolina becoming the nation's plutonium dump prompted former Gov. Jim Hodges to threaten to lie down in front of incoming tractor-trailer shipments two years ago. Plutonium retains half its radioactivity after 24,000 years.

"It seems like he was on target with his concerns," said Tom Clements of Greenpeace International this week. "It has implications for bringing more material into the site. If they want to store on-site, do they have the safety and security for that option?"

The Energy Department acknowledged in a June 16 report that it hasn't decided what to do with some of the nation's surplus plutonium, including the material stored at SRS.

But the department insists South Carolina won't be stuck with it.

"We're not going to bring anything into South Carolina for which we don't have a disposition pathway out of South Carolina," said spokesman Joe Davis.

The department plans to recycle 34 metric tons of weapons-grade plutonium by blending it into fuel for nuclear power plants, including Duke Power's two Charlotte-area plants.

That plan has some uncertainties, however.

It's based on a U.S. agreement with Russia that each nation turn surplus plutonium into mixed-oxide, or MOX, nuclear fuel. But the Russians have struggled to keep pace with the United States. Licensing of the United States' MOX fabrication plant at Savannah River has also been delayed.

Even if the plans to make MOX become reality, some leftover plutonium isn't pure enough for that purpose. It will have to be disposed of or stored for years -- and signals point to Savannah River.

An independent agency that oversees the Energy Department's nuclear weapons complex criticized the department's decision, in 2001, to scrap plans for a special plutonium storage facility.

"DOE now proposes to rely on a combination of 50-year-old facilities that currently do not meet modern safety standards," the Defense Nuclear Facilities Safety Board said in a December report. "The lack of careful, consistent planning has forced (SRS) ... to focus on what can be done with existing facilities, foreclosing options that may have been both cost-effective and safety-conscious."

One of the storage structures, a retired reactor, doesn't have fire-protection equipment that could prevent the accidental release of plutonium, the report said. A second major structure also lacks modern safety systems.

The report said plutonium could be safely stored at those facilities for only four to five years. But it said the Energy Department is developing plans to store plutonium there for 20 years or longer.

Since September, Savannah River's Citizen's Advisory Board has also pressed the Energy Department to explain what it will do with its non-MOX plutonium.

"Basically the response we received is very general," said board chair Jean Sulc. "You know as much as we do at this point."

SRS officials have promised an update to the board by July 26.

In a June 16 response to the defense agency's report, Energy Secretary Spencer Abraham said the DOE is re-evaluating its storage plan "to determine if there are better options." A safety study of SRS storage is due in April.

The response said the Energy Department is also revisiting a disposal plan that the Bush administration ditched two years ago. Under that plan, plutonium not pure enough to make MOX fuel would be encased in glass and buried at a government repository in Yucca Mountain, Nev.

U.S. Sen. Lindsey Graham, R-S.C., says the concern about plutonium at SRS is overblown. As a House member in 2002, Graham helped enact legislation intended to guarantee that plutonium didn't stay forever at SRS.

"If plutonium is coming into the state, the law says they can't just leave it there," said Graham spokesman Kevin Bishop.

The measure was intended to ensure that weapons-grade plutonium entering South Carolina be blended into MOX. It calls for fines of up to $100 million a year if the Energy Department doesn't begin making MOX by 2011. If production doesn't begin by 2017, unprocessed plutonium has to be removed from the state.

"If the idea is to move this material to South Carolina outside the mixed-oxide use, then the governor would obviously expect for a disposition plan to be in place," said Will Folks, spokesman for Gov. Mark Sanford.