A federal appeals court on Friday rejected Nevada's arguments against building a nuclear waste site in the state, but ordered the government to develop a new plan to protect the public against radiation releases beyond the proposed 10,000 years.

The three-judge panel dismissed claims by Nevada that the Bush administration's plan to build the Yucca Mountain (search) waste site was unconstitutional and said that actions by the Energy Department and President Bush leading up to approval of the waste site were not subject to review by the court.

In a victory for Nevada, however, the court rejected the government standard that the public would have to be protected from radiation leaks only for 10,000 years. The court said the compliance period for the radiation standards would have to be developed well beyond that period.

It was not immediately clear how severe an impact the court's rejection of the radiation standard would have on the project. The Environmental Protection Agency (search) will have to develop a standard that is protective beyond 10,000 years, and some opponents of Yucca Mountain have argued the current design for waste containment does not do that.

While the court dismissed Nevada's key arguments, state officials focused on the court's rejection of the radiation standard and suggested that might be enough to scuttle the program.

"The Yucca Mountain site cannot meet the (radiation) standard" beyond 10,000 years, said Bob Loux, Nevada's state nuclear project director. He called the Yucca project "effectively dead — over."

Allen Benson, a spokesman for the Energy Department's Yucca Mountain project in Las Vegas, declined immediate comment.

But the 100-page ruling by the U.S. Court of Appeals for the District of Columbia was also a setback to Nevada's attempt to block construction of the repository planned for 90 miles northwest of Las Vegas on constitutional and procedural grounds.

The court rejected the state's argument that selection of the site was unconstitutional and that some procedures violated the nuclear waste law — the key arguments made by the state before the court last January.

The state has vowed to continue fighting the case before the Nuclear Regulatory Commission (search), which must issued a permit for the facility. The site is planned to store underground 77,000 tons of highly radioactive waste, mostly spent reactor fuel from commercial power plants.

Congress approved the Yucca Mountain site in 2002, overriding an attempt by Nevada to block the project.

While rejecting the heart of Nevada's arguments, the appeals court upheld arguments by environmentalists that the Environmental Protection Agency requirements for safeguarding the environment from radiation were inadequate and would have to be strengthened.

The court said that the EPA's standard calling for protection from radiation up to 10,000 years "is not based or consistent with the recommendations of the National Academy of Sciences," which had concluded that the danger to the public goes years beyond that.

In arguments in January, lawyers for the Natural Resources Defense Council (search), which had challenged the EPA standard, argued that many of the isotopes in the waste would reach their peak radiation levels and be most dangerous up to 300,000 years into the future.

The National Academy of Sciences (search) had reached a similar conclusion in an examination of the standard. The court noted that the EPA's own policy required that the radiation standard must be consistent with the National Academy of Sciences conclusions.

"We're absolutely thrilled," said Geoffrey Fettus, an attorney for the Natural Resources Defense Council.

Nevada had argued that the process by which Yucca Mountain was selected as the only site to be studied for a possible waste site was unconstitutional. It also challenged a Nuclear Regulatory Commission rule on procedures for considering Yucca Mountain as in violation of the federal nuclear waste law.

The panel — composed of Judges Harry Edwards, Karen Henderson, David Tatel — disagreed.

"We vacate the EPA's 10,000-year compliance period," the judges wrote. "In all other respects we deny Nevada's petition for review challenging the NRC rule. We also reject the state's challenge to the constitutionality of the resolution (passed by Congress) approving the Yucca Mountain site."

"And we dismiss the state's petition attacking the Department of Energy and the president's actions leading to passage of that resolution, as those actions are unreviewable," the panel continued.

The Energy Department plans to submit an application for an NRC license later this year, a process that could take three years or more. A recent controversy over Yucca Mountain funding in Congress also has put the 2010 target date for opening the facility into jeopardy.