WASHINGTON — Turns out, it's going to cost taxpayers $32 billion more than first thought to open and operate the nation's first nuclear waste dump at Yucca Mountain in Nevada.

And Utah and Nevada members of Congress are using that news to try to kill that project and replace it with storing waste in dry casks at nuclear power plants that produce it.

The Bush administration's latest calculation — made public Tuesday — is that the Yucca Mountain facility will cost more than $90 billion. It's the first official estimate since 2001, when the figure was $58 billion.

Ward Sproat, the Energy Department official in charge of managing the controversial Yucca Mountain repository project in Nevada, disclosed the new number to reporters after a House hearing Tuesday.

The estimate includes $9 billion already spent and covers about 100 years of operation until the dump, 90 miles northwest of Las Vegas, is sealed up forever.

"That's a lot of money," said Rep. Jim Matheson, D-Utah, a member of the House Subcommittee on Energy and Air Quality, where the news was delivered. "We need to look at whether proceeding (with Yucca Mountain) is really the most cost-effective alternative. I don't believe it is."

Matheson and other Utah and Nevada members are pushing a bill calling for storing nuclear waste on-site at nuclear power plants in "dry cask" storage. Matheson notes that technology had not been developed when Congress first passed legislation calling for the Yucca Mountain repository.

Matheson said dry-cask storage could store all the radioactive waste produced in the last four decades on a space about the size of a football field. He says using that would be safer than transporting nuclear waste across the country, through Utah and into Nevada.

"Utahns have a hard time understanding why the transportation risks associated with shipping waste to Yucca Mountain have never been fully studied," despite all the money spent on Yucca Mountain so far, Matheson told the committee. "Given that 95 percent of the waste would go through Utah if rail were used, and 87 percent if we truck this waste, this is a huge concern to my constituents."

Matheson added, "The West — whether it is Utah's Skull Valley (proposed as an interim storage site), or Nevada's Yucca Mountain — is not the de facto dumping ground for this lethal material. Storing nuclear waste on site is the safest, most reasonable and most effective way of allowing nuclear power plants to continue operating while we search for an appropriate long-term storage solution."

Sproat said some of the estimated cost increase comes from inflation. Also, Energy Department officials now expect the dump will hold more radioactive waste than the 77,000 tons initially approved by Congress.

A report with precise cost breakdowns will be released to Congress in the next several weeks, Sproat said.

Already, some 64,000 tons of radioactive spent fuel rods are stored at commercial reactor sites in 33 states, according to the Nuclear Energy Institute. Most of it is stored in vault-like pools while some has been moved into dry-cask storage, where Nevada lawmakers, who oppose Yucca Mountain, would like it to stay — or be moved into dry-cask storage on-site.

Sproat opposes that plan as impractical. He also objected to other interim storage options raised Tuesday by frustrated lawmakers, who reported hearing from constituents about the need for new energy sources.

Commercial nuclear power plants now produce some 20 percent of U.S. electricity, but concern about waste disposal has hampered the industry's growth.

Yucca Mountain was originally supposed to open in 1998 but has been beset by lawsuits and political and scientific controversies. The best-possible opening date is now 2020, Sproat told lawmakers at an Energy and Commerce subcommittee hearing.

Even that is contingent on a steady money stream, something that Senate Majority Leader Harry Reid, D-Nev., has blocked.

The Energy Department did succeed in submitting a required construction license application to the Nuclear Regulatory Commission last month. The commission has up to four years to decide whether to approve it — but that timeline, too, is dependent on congressionally approved budgets.

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