When Presidents Bill Clinton and Boris Yeltsin agreed in 1998 to cut the risk of war by destroying surplus plutonium from nuclear bombs, the American approach, for many people, had a pleasing ring to it: convert the material to fuel for civilian power reactors.

But that has proved slow, expensive and a challenge to market.

At first, the Energy Department wanted to sell the fuel to power companies, but no one seemed to want it. Eventually, Duke Energy, the large utility serving the Carolinas and parts of the Midwest, negotiated with D.O.E. to purchase about 40% of the promised fuel for a few of its reactors in North and South Carolina.

Deliveries were scheduled to begin in 2007.

But the $4.8 billion factory that the energy department is having built to make reactor fuel from the bomb material is only about 30% complete.

At this point, the earliest possible date for the first delivery is 2016.

As a result, Duke says that it allowed its contract with D.O.E. to lapse on Dec. 1, and the Energy Department is again having trouble finding anyone to agree to take the fuel when the project is completed - even though it is offering it at a discount compared to uranium.

Critics say the Mixed Oxide, or MOX Fuel Fabrication Facility, as the conversion plant is known, could prove a colossal waste of investment, not least because reliably converting weapons-grade plutonium for use in a reactor has not proven a complete success.

The U.S. sent a small quantity of weapons plutonium to France, which has a good deal of experience in making reactor fuel from plutonium - albeit plutonium produced as a by-product in power reactors, not surplus weapons plutonium. The fuel was supposed to run for three 18-month cycles, but at the end of two, the fuel was not performing to specifications and was withdrawn for analysis.

Taxpayers are pouring hundreds of millions of dollars a year into a facility that may never be used, said Edwin Lyman, a nuclear expert at the Union of Concerned Scientists, said of the MOX plant, which is located at the Department of Energy's Savannah River Site.

Russia, meanwhile, has not had similar difficulties with its weapons-grade plutonium. Its Atomic Energy Ministry is building special reactors to use the fuel.