WASHINGTON (AP) - The Energy Department is revamping a Clinton-era plan to dispose of 50 metric tons of surplus plutonium amid cost overruns, prompting threats from South Carolina's governor to block shipments into the state. 

An Energy Department report, made public Thursday by a private group, concludes that the cost of disposing of the plutonium will be at least $6.6 billion over 22 years, about 50 percent more than estimated two years ago. 

At the same time, the Bush administration has put on hold part of the program that called for some of the plutonium to be put in glass logs for eventual burial at the Yucca Mountain nuclear repository in Nevada, once that facility is approved. 

That decision has brought complaints from South Carolina officials who are concerned that the department will ship tons of plutonium from its weapons facilities into the state for processing with no assurance the material will ever leave the state. 

“When South Carolina agreed to accept plutonium ... DOE agreed that there would a clear exit strategy,'' South Carolina Gov. Jim Hodges said recently. 

Hodges, a Democrat, said the “shifting nature'' of the government's plutonium disposition strategy suggests that the Energy Department “plans to renege on many of its prior commitments'' to the state. 

Energy Department spokesman Joe Davis said that Energy Secretary Spencer Abraham, who talked with Hodges earlier this week, is eager to resolve the dispute. 

In 1999, the Clinton administration announced a “dual strategy'' for getting rid of the excess plutonium from Cold War-era warheads and plutonium found at various weapons facilities. Under the plan, 33 metric tons would be converted into a mixed-oxide, or MOX, fuel for burning in civilian power reactors. Another 17 metric tons, thought too impure for conversion would be immobilized in glass containers and eventually buried in Nevada. 

But earlier this year, the administration stopped funding the immobilization program and announced the entire plutonium disposal plan was being reviewed. 

Abraham said that it was too expensive to pursue both programs and that the department would focus for now on building the MOX conversion facilities at the Savannah River complex. He suggested that the immobilization track would be resumed later. 

But South Carolina officials fear that might never happen. 

“The dual track was an essential component of our agreement,'' insists Hodges, pledging that if he is not assured of a “timely exit strategy'' he would block shipments into the state - raising the specter of a standoff with federal officials. 

Years ago, Idaho's governor dispatched the highway patrol and set up roadblocks to keep nuclear spent fuel shipments out of that state until a settlement was reached with the Energy Department. 

Meanwhile, an Energy Department report released Thursday by the Nuclear Control Institute, a Washington-based advocacy group involved in nuclear nonproliferation issues, showed the cost of the program has grown from about $4.4 billion in 1999 to $6.6 billion over its 22-year life. 

“This shows a massive cost escalation,'' said Tom Clements, the group's executive director, adding it calls into question the MOX option which represents most of the increase. The institute opposes using plutonium for civilian reactors and argues all of it should be put in glass to reduce the risks of nuclear proliferation. 

AP-NY-08-09-01 1844EDT