South Carolina and the Energy Department do agree on one thing: The current slowdown comes on top of past technical problems that pushed back the start of work by more than seven years and that more than doubled the cost.

Ms. Templeton said the tanks, which are near the Savannah River, already have leaks and are buried in soil below the water table, meaning that underground water flows around them.

“We have to get that waste out of the tanks so it’s not Fukushima, so you don’t have the groundwater interacting with the waste and running off,” she said, referring to the damaged Fukushima Daiichi plant in Japan, where natural flows of subterranean water pick up contamination from the reactors and flow into the sea.

At the Washington State Department of Ecology, Suzanne Dahl, the tank waste treatment manager, said: “I feel their pain. We think the same things out here.” All the deadlines there, in an agreement approved by a Federal District Court, will be missed. Ms. Dahl said that in the 1990s, her state approved a request by the Energy Department to delay work on solidifying wastes at Hanford while the technology was tried out first at Savannah River; Savannah River, therefore, has a 17-year head start, she said.

At Savannah, the Energy Department did succeed in building the world’s largest factory for stabilizing the liquid bomb waste, done by mixing it with molten glass and pouring it into stainless steel canisters, 10 feet high by two feet across. The stabilized waste should then last for millenniums.

The department has also perfected a technique for separating nearly all of the troublesome radioactive materials from salts in the underground tanks to reduce the volume that must be mixed with the molten glass. The rest of the radioactive material is mixed with cement that will bind it up for centuries. Last year the factory began the business of making the canisters and produced 325 of them — a respectable fraction of the 7,824 department officials say will be needed.

Over the years, production at the factory has become smoother as machines run more hours of the year and parts that were expected to last for only four or five years have been used successfully for 10. Such longevity is an important factor at a place where the radiation fields are so intense that all the work has to be done by remote control.