WASHINGTON (AP) - Nevada and Utah lawmakers jointly introduced legislation Wednesday to store nuclear waste at reactor sites where it is produced.

The bills introduced in the Senate and House would block radioactive waste from being transported from sites around the country to the planned Yucca Mountain nuclear waste dump in Nevada or a temporary site proposed for Utah.

The legislation had been long-planned by Nevada Sens. Harry Reid, a Democrat, and John Ensign, a Republican, who are trying to stop the federal government from completing the troubled Yucca Mountain dump in the desert 90 miles northwest of Las Vegas.

The participation of Utah Republican Sens. Orrin Hatch and Robert Bennett was another sign of growing cooperation on nuclear waste issues between the neighboring states, which were once at odds over the issue.

Hatch and Bennett angered Nevada lawmakers by voting in favor of Yucca Mountain when Congress approved it in 2002, but now are trying to block a proposed temporary nuclear waste storage site in Utah's Skull Valley that's being pushed by a coalition of utilities.

Bennett announced recently that his support for Yucca Mountain was a mistake, while Hatch still says he favors it. But both senators have concluded that the onsite storage plan is the best way to keep nuclear waste out of their state.

"This country faces an imminent nuclear waste disposal problem. That's what led to the lame-brained Skull Valley plan in the first place," Hatch said in a statement. "This bill is a way to take the pressure off the need for Skull Valley."

The "Spent Nuclear Fuel On-Site Storage Security Act of 2005" mandates that nuclear power plants move waste into aboveground casks approved by the Nuclear Regulatory Commission. The commission says so-called dry cask storage is safe and environmentally sound, and already is in use at about half the nation's more than 60 active nuclear power plants.

Although the waste would remain at reactor sites, the Energy Department would take title to it. The government is facing mounting legal costs because it promised to accept utilities' nuclear waste beginning in 1998.

The on-site storage plan has been opposed by the nuclear industry and the Energy Department, though Reid and Ensign contend nuclear waste could safely remain in dry casks for at least 100 years.

"This bill is essentially kicking the can down the road. The bill in no way resolves the issue of permanent storage of spent nuclear fuel," Energy Department spokesman Craig Stevens said. "The department remains committed to the law, which states that we must develop Yucca Mountain as the site for a permanent repository."

Yucca Mountain, planned to store 77,000 tons of the nation's nuclear waste, has suffered a series of setbacks, funding shortages and delays. The government was forced to rewrite radiation safety rules for the site when a federal court threw out the first ones, and the final rules have yet to be issued.

"The Yucca Mountain project is never going to open," Reid said. "It is time we put the safety of this country first and approach the storage of nuclear waste in a way that is productive and realistic."

"What we are proposing today represents the safest and most responsible course of action available for storing nuclear waste," Ensign said. "The dry cask storage technology exists to provide a viable, on-site alternative to shipping waste across the country and it is time we make use of that technology."

Companion legislation was introduced in the House by Nevada's representatives, Republicans Jon Porter and Jim Gibbons and Democrat Shelley Berkley, and Utah Reps. Rob Bishop and Chris Cannon, both Republicans, and Jim Matheson, a Democrat.