WASHINGTON -- Forgotten but not gone, the waste from more than 100 nuclear reactors that the federal government was supposed to start accepting for burial 10 years ago is still at the reactor sites, at least 20 years behind schedule. But it is making itself felt in the federal budget.

With court orders and settlements, the federal government has already paid the utilities $342 million. But it is virtually certain to pay a total of at least $7 billion in the next few years and probably more than $11 billion, government officials said. The industry said the total could reach $35 billion.

The payments come from an obscure government account that requires no new congressional appropriations and will balloon in size, experts said.

The payments are due because the reactor owners were all required to sign contracts with the Energy Department in the early 1980s, with the government promising to dispose of the waste for a fee of a tenth of a cent per kilowatt-hour. It was supposed to begin taking the fuel in the then far-off year of 1998.

Since then, the utilities have filed 60 lawsuits. The main argument -- employing legions of lawyers on both sides -- is when the government would have picked up the fuel if it had adhered to the original commitment, and thus how much of the storage expense would have fallen on the utilities anyway.

But the number is rising. If the repository that the government is trying to develop at Yucca Mountain, near Las Vegas, could start accepting waste at the date now officially projected, in 2017, the damages would run about $7 billion, according to Edward F. Sproat III, director of the Office of Civilian Radioactive Waste Management.

But that date is actually "clearly out the window," Sproat said in a conference call with reporters, because Congress underfinanced the effort to build the repository, among other problems. Sproat said the goal of applying by June for a license to build Yucca could no longer be met.

If the repository opens in 2020, the damages would come to about $11 billion, he said, and for each year beyond that about $500 million more.

"The rate-payer has paid for it," said Michael Bauser, the associate general counsel of the Nuclear Energy Institute, the industry's trade group. "The Department of Energy hasn't done it, and now the taxpayer is paying for it a second time."

The money comes out of a federal account called the Judgment Fund, which is used to pay settlements and court-ordered payments. For the past five years, the fund has made payments in the range of $700 million to $1 billion, with the average being $80,000 to $150,000. In contrast, payments to utilities have been in the tens of millions.

The government is also running up extra expenses on its own wastes. Some of the waste that is supposed to go to Yucca, left over from nuclear weapons production, is sitting in storage that is expensive to maintain.

Some extra expense was assured because Yucca has been beset with legal and managerial problems, and it is not clear whether the geology is suitable for storing the waste for a million years with only very small radiation doses for people outside the site.