WASHINGTON -- Nevada could launch between 250-500 license challenges to Yucca Mountain, state officials said, making the proposed radioactive waste repository by far the most contentious issue ever weighed by nuclear safety regulators.

Attorneys for the state presented the Nuclear Regulatory Commission with the ballpark estimate this week as the federal agency prepares to launch its review of a construction application the Department of Energy says it will file in June.

Other participants in the licensing hearings, such as Clark County and Nye County, reported they each may introduce between 11 and 25 "contentions" to be debated before administrative judges during the licensing process.

All told, "We could be looking at about 650-plus proposed contentions from 11 parties," NRC spokesman David McIntyre said in an email, adding that would be the most ever filed in a licensing case since the agency revised its rules in 1989.

It is likely that some will be combined or weeded out.

Among other high-profile cases, McIntyre said 138 contentions were submitted when the NRC considered the private fuel storage application to temporarily store nuclear waste on the Goshute Indian Reservation in Utah, although only 25 were admitted into the hearing.

About 100 contentions were filed in an ongoing license renewal case for the Indian Point nuclear power station in New York, he said.

Nevada officials said they are preparing technical challenges to DOE's science research and engineering designs for the Yucca site.

Bob Loux, executive director of the Nevada Agency for Nuclear Projects, said the state also plans to object to DOE's fitness as an operator.

He said the state will point out DOE has struggled with quality assurance over the years and for a time did not adequately control harmful dusts that were ingested by tunnel workers.

The planned challenges reflect the scope of the first-ever attempt to license underground high-level nuclear waste storage.

DOE will try to persuade safety regulators that specially designed waste canisters and the warren of tunnels it wants to build a thousand feet below the surface and a thousand feet above the water table will prevent decaying nuclear particles from leaking into groundwater and seeping into the neighboring valley.

It also shows the intent of Nevada leaders to pull out the stops to kill an unpopular project that was forced on the state.

"Nevada has suggested for some time that it would be filing a lot of contentions," said Michael Bauser, deputy general counsel of the Nuclear Energy Institute. "This is a first-of-its-kind proceeding and we expected it to be hotly contested.I would imagine it would be as much of a challenge as any proceeding the NRC has undertaken so far."

If the NRC agrees to docket the application after an initial three-month examination, the agency would perform internal safety studies and convene public hearings where controversies surrounding the decades-long project are expected to be aired in a courtroom-style atmosphere.

The NRC by federal law must render a decision within three years, with an option to add a fourth year. Many experts believe the undertaking will test the agency, which has assigned 120 engineers and scientists to review an application that DOE officials say will be 8,000 pages long and backed by 200 supporting references totalling another 50,000 pages.

Loux earlier had been reported as saying Nevada could present as many as 2,000 contentions, a number so high it caused industry and government officials to bolt up and take notice.

Loux said he put the number out there "to keep the DOE and the NRC a little off-balance."