YUCCA MOUNTAIN, NEV. -- In the middle of a dusty desert about 75 miles from the glittering Las Vegas Strip stands a mountain that Nevadans fervently wish was somewhere else.

The mountain is unpretentious, actually more of a narrow ridge, and as rocky and barren as any of the neighboring ranges that tower in the misty distance all the way to California.

But it is what's inside Yucca Mountain that matters, both to the federal geologists who are preparing to spend $2 billion over the next six years exploring its nooks and crannies and to state officials who have vowed to fight them every inch of the way.

Yucca Mountain is the prospective site of the nation's first high-level nuclear-waste dump, a distinction conferred by Congress in the waning days of last year's session. Sometime early in the next century, if all goes according to schedule, it will become a $30 billion mausoleum for at least 70,000 metric tons -- the equivalent of 38,560,000 five-pound bags of sugar or more than 3,500 standard, 22-ton tractor-trailer loads -- of waste that will remain dangerously radioactive for tens of thousands of years.

Between now and then, a battalion of government scientists and engineers will attempt to do what has never been done: Predict the future, with enough certainty to know whether the mountain can safely contain more radioactivity than has ever been in one place at one time and still remain intact longer than recorded history.

The dump will contain, in its early years, about 21 billion curies of long-lived radionuclides -- 300,000 times the amount released into the atmosphere by all above-ground nuclear tests.

The Chernobyl nuclear accident, by contrast, released about 50 million curies of radioactivity, mostly in the form of short-lived radionuclides with half-lives measured in days or weeks.

The waste will be packaged in cylindrical canisters of metal, which are expected to last from 300 to 1,000 years. Beyond that, it is up to nature. When it is filled, the nuclear dump will be sealed, festooned with warning signs and left alone to guard its waste, essentially forever.

To the Department of Energy, which is managing the project, Yucca Mountain represents the potential end of a 30-year search for a place to put the mounting byproducts of the nuclear age, including thousands of spent fuel rods from nuclear power reactors and thousands of tons of waste from bomb-production facilities.

To Nevada, despite its high-rolling image, it is a gamble with odds too high to risk a wager.

"The general sentiment is that we're being had," said former governor Grant Sawyer, head of the Nevada Nuclear Commission. "Nevada seems to be the dumping ground for everything, and we resent it deeply. We're getting awfully sick and tired of it."

State officials are angry over last year's congressional action, which short-circuited an elaborate selection process and left Yucca Mountain the sole candidate for the dump. They say they have little reason to believe that the scientific inquiry will not be subject to the same political pressures.

"One doesn't have to be a rocket scientist to see what's happening here," said Gov. Richard H. Bryan (D). "You don't ordinarily have the judge telling the jury that he's convinced the defendant is guilty before the trial has been held."

DOE officials say they are "comfortable" with Congress' choice, but they insist they are prepared to start again if Yucca Mountain proves unsuitable.

"We don't want to build it if it's not the right place to build it," said Carl Gertz, head of DOE's waste-management office in Nevada.

Local opponents are skeptical, noting that the government has agreed to take responsibility for spent nuclear fuel by 1998, a deadline that leaves little time for identifying a substitute site if Yucca Mountain doesn't pass muster.

"DOE is in a bind," said Judy Treichel of Las Vegas, who is coordinating community opposition. "They agreed to take this waste by 1998 and they certainly aren't going to take it home with them."

Opposition to the dump is not universal in Nevada, which has long lived in the shadow of the atom. Yucca Mountain is at the edge of the Nevada nuclear test site, a reliable employment center here for more than three decades. "There are mixed emotions," Treichel said. "You have second-generation workers up there."

But Las Vegas isn't the small gambling mecca it once was, either. The city has grown 1,200 percent since the mid-1950s and is the center of the state's $6 billion-a-year gambling and tourism industry, which state officials believe would be threatened by the dump's proximity.

"Who wants to share a highway to Las Vegas with nuclear trucks?" asked Robert C. Loux, head of the state's Nuclear Waste Project Office, who noted that transporting nuclear waste by either train or truck would take it past most of the large resort hotels.

"DOE says the more folks hear about the nuclear dump, the more they'll like it," Treichel said. "I think it's the opposite, and we're both in the education business."

A decade ago, Yucca Mountain might not have been on anybody's short list. At the time, geologists believed that the most promising sites for permanent nuclear storage were salt, shale or crystalline formations. Yucca Mountain is a volcanic tuff formation, essentially a solidified ash flow laid down more than 11 million years ago by massive volcanoes that stretched through southern Nevada.

Salt was particularly favored because of its plasticity. When excavated, salt formations tend to flow back together, sealing themselves. Salt also is known to be an efficient conductor of heat, a considerable advantage in storing waste that is literally hot.

But salt formations have proved troublesome in practice. A pilot project for storing transuranic waste in New Mexico has developed water leakage problems that were not foreseen. In West Germany, a support ring on a waste-disposal tunnel collapsed under the pressure of the swelling salt.

When DOE, acting under a 1982 law, narrowed the candidate list to three western sites in 1986, it included a salt formation in Deaf Smith County, Tex. The other two involved geological forms that had been little considered for nuclear disposal. Besides Yucca Mountain, there was the Hanford Nuclear Reservation in eastern Washington state, a volcanic basalt formation.

Federal officials acknowledge that Hanford and Yucca Mountain made the list in part because of a major nongeological advantage. Both sites are in federal hands, which promised to cut years off the nuclear dump project.

By law, all three sites were to have been evaluated and a finalist chosen by 1989. Instead, the process collapsed in a welter of politics and lawsuits. Last December, unable to reconstruct the fragile compromises that led to the 1982 law, Congress simply narrowed the list to one: Yucca Mountain.

"It was a simple, almost primordial strategy," a lobbyist said at the time. "Nobody wants the dump, but Nevada only has four votes."

Nonetheless, the choice appeared to be a natural, at least on the surface. For example, a key concern of siting the nuclear dump is keeping the waste canisters away from water, which can corrode their metal casings and free radionuclides to enter the environment.

Yucca Mountain is one of the driest places in the United States. The caverns envisioned for waste storage there would be more than 600 feet above the water table in an area that receives an average of six inches of rain a year.

The area also practically defines the term "remote." The surrounding land is so sparsely populated that Nevada was able to create a new 144-square-mile county around the proposed dump site without including a single resident.

But the site also has drawbacks, not the least of which is that it lies between two significant earthquake faults. A third, smaller fault would run directly through the repository vault, as it is currently envisioned.

DOE officials say the vault and nearby waste-handling facilities can be constructed to withstand earthquakes, although that would raise the cost of the repository.

But a report from a DOE researcher recently suggested that the department is overlooking another troubling possibility. The report, by physical scientist Jerry S. Szymanski, warned that DOE has inadequately accounted for the fact that Yucca Mountain also sits in a thermally active zone.

The volcanoes that created the mountain are long dormant, although at least one nearby cinder cone shows evidence of having erupted as little as 20,000 years ago. But Szymanski argued that the combination of thermal and seismic pressures can cause the water table to rise, perhaps dramatically.

"In extreme cases," Szymanski wrote, "these displacements can result in the flooding of the repository and in expulsion of ground water at the ground surface."

The concept is not entirely new to the DOE. More than a decade of testing related to underground nuclear detonations has shown instability of water tables from the seismic activity produced by the bombs.

But Szymanski's report was not publicly released until last year, two days after Congress tapped Yucca Mountain as the dump site.

Bryan angrily accused the department of intentionally suppressing the report. "This is outright deception," he said. "We don't know if this theory is capable of being validated or not, but what appears to be happening is that they ignore any dissenting voice, any voice of caution or concern."

DOE officials insist they have not disregarded Szymanski's report, and intend to explore his theory during research at Yucca Mountain.

However, Don Vieth, then head of DOE's Nevada operations, told a Senate hearing last summer that the department was "confident" that Yucca Mountain would be able to handle the dump. "It is not conceivable to me that we would discover something of a major nature that would cause us to change our mind about it," Vieth testified.

Over the next six years, DOE will try to justify that confidence with a multibillion-dollar investigation that will put more than 800 scientists on the cutting edge of guesswork.

Much of that time will be spent excavating two 14-foot-wide shafts into the heart of Yucca Mountain, boring nearly two miles of tunnels and installing several subterranean laboratories. There, geologists will test for faults, record cracks and determine how the dense but brittle tuff responds to intense heat.

According to DOE, the investigation will answer any remaining questions about Yucca Mountain and support an eventual licensing application to the Nuclear Regulatory Commission.

"If our assumptions are correct, there's a good chance that the waste package itself would last 10,000 years," said William Dudley, a U.S. Geological Survey scientist.

State officials have challenged DOE's plans, contending that the project is little more than an engineering exercise designed to put the department in the best position to build the repository quickly.

"DOE's whole effort is more focused on how we engineer the site than it is on site suitability," said Loux. "No one's ever done this before, and we're treating it like we're building an apartment building."

In an effort to sweeten a bitter pill, Congress made Nevada eligible for up to $20 million a year in direct payments if the decision is made to locate the dump here. State officials say they are not interested in the money, which would require them to drop opposition to the project.

Instead, the state went to court to win federal money to conduct its own investigation of the dump. Nevada won, but Loux said officials have been stymied in their efforts to gain access to the site. "We appear to have all the cards stacked against us," he said.

Opponents concede they are facing an uphill battle. Nevada still has only four congressional votes, and 49 states weren't tapped for the nuclear dump.

"But I always felt it's not over till it's over," said Sawyer. "If the people are unified enough, if Nevada is militant enough, we will find a way to get rid of this."