TRAVEL INSIDER : Trip to the Outer Limits, Compliments of the Feds : Tours: This government-sponsored open house at the proposed Yucca Mountain nuclear waste dump may be Las Vegas’ most unusual junket. And lunch is free.

As a rule, people don’t come here to contemplate nuclear crises. But they could, and I recently did, on one of the strangest and most intriguing junkets a traveler is likely to encounter.

The destination was Yucca Mountain, a dusty pile of hardened volcanic ash 100 miles northwest of the neon and gaming tables. Here the federal Department of Energy hopes to build the world’s first high-level nuclear waste dump. Since March, 1991, federal officials have been trying to soften local opposition by offering monthly guided tours of the area.

The daylong visit, however, is open to all citizens, local or not. It costs nothing--the government will even buy your lunch--and introduces you to a remote desert landscape ordinarily off limits to common civilians. It also throws open a window on the strange world of nuclear power and politics--a world in which an orange Fiestaware plate sets a Geiger counter chirping, in which federal officials have allowed 30-some years of high-level nuclear waste to accumulate without establishing a single permanent dumpsite, in which hopes for a permanent site now ride on a 117-mile network of storage areas and passageways beneath Yucca Mountain.

“It would be about 1,000 feet under where we’re standing right now,” said geologist Dick Crawley, addressing two dozen visitors atop the wind-raked, hardscrabble mountaintop during the tour I took in May.

That was near the end of the day. The tour began at 7:15 a.m. in the DOE’s Las Vegas information office. (There are two other such offices, also devoted to Yucca Mountain, elsewhere in the state.) The citizen-guests, more than 100 of us, each pre-approved by the government, sipped coffee and circulated among exhibits. How a nuclear reactor works. Environmental awareness. The Climax Mine Spent Fuel Test. What uranium fuel pellets look like. Outside, six hulking tour buses idled.

“I thought they’d have a couple of mini-vans,” marveled one visitor, a young man with longish hair.

The demographics were tough to calculate. Most of the guests were Nevada residents, though one professor from northern Michigan had brought his spike-haired, earringed son out for a day away from the casinos. A few elderly guests moved through the process with familiarity, apparently having taken the tour--and the free meal--several times before. A former military pilot regaled friends with the tale of a flyer who took a projectile through the thigh, “dead-sticked and stalled,” yet lived to tell the tale. Another guest, inspecting a technical display, began his appraisal with the words, “When I worked at Rockwell . . . “ No one was obvious about his or her politics.

On the 90-minute bus ride to the project area, suburbs gave way to desert floor, and while DOE geologist Jeanne Cooper rose to outline the big nuclear picture, Joshua trees and creosote bushes zipped past and receded into a flat, gray distance. Soon we were approaching the Nevada Test Site and the Nellis Air Force bombing range, where various nuclear experiments have been conducted over the years. We carried no cameras (except for one photographer with special clearance) and no tape recorders.

Since the first U.S. nuclear power facility began operating more than 30 years ago, we learned, nuclear power plants in the United States have generated about 20,000 metric tons of high-level radioactive waste, mostly spent fuel in pellet form. That waste is now stored “temporarily” at power plants in 30 or more states. But since 1982 the federal government has been pushing forward plans to establish a single repository to isolate the nation’s most radioactive waste. In 1987, sites in Hanford, Wash., and Deaf Smith County, Texas, were eliminated, leaving Yucca Mountain the leading candidate.

So it remains, despite opposition from Nevada state officials. Another seven to 10 years or so of “site characterization” tests must pass before the DOE can ask the Nuclear Regulatory Commission, a fellow federal agency, for approval, Cooper noted. Even if all went according to schedule, the first waste probably wouldn’t arrive before the year 2010.

“This has never been done before anywhere in the world,” Cooper said, describing the scores of tests in progress to assess the area’s volcanic history, seismic stability, underground water and air, and threatened desert-tortoise population. (Out there amid the creosote and Joshua trees, more than 100 tortoises wander with electronic tracking devices affixed to their shells.)

Outside the air-conditioned bus, Mummy Mountain lay baking, and the Indian Spring state prison stood silent behind silvery fences. The hills and mesas were formed by volcanic eruptions 11 million years ago, we learned, or perhaps a few million years before that.

At Lathrop Wells, we passed the Cherry Patch, a legal brothel. A few moments later, after passing the military checkpoint and entering restricted territory, we approached a knot of empty buildings that once housed MX missile research.

Finally we arrived at Jackass Flat, where the Yucca Mountain water and mineral research is based, and where thousands of black beetles have surrounded and infiltrated lab facilities. The scientists, some of whom have been on this project for three years, hardly notice them anymore.

“This is a pretty interesting place,” said Cooper, meaning the scientists and the mountains, but probably not the beetles.

Inside, the scene was like parents’ day at Caltech. On every hand, earnest civilians listened as bright young scientists explained their projects: logging rock core samples; estimating the age of the gases trapped inside the mountain rock; charting the desert water table, which seems to run 2,000-2,500 feet underground at Yucca Mountain, 1,000 feet or more beneath the envisioned location of the waste storage area. One cheerful scientist offered a down-to-earth summary of how potentially dangerous the dump’s contents would be.

“This,” he said, “is the really nasty stuff.”

Then it was lunchtime: pastrami, turkey, ham, chicken, corn on the cob, cheese, carrots and celery, fruit, soda, juices, Sara Lee Snack Pack Pound Cake--and more displays.

One of them demonstrated the radioactivity of various common household objects, including a Fiestaware plate. Bleep bleep bleep beep, said the Geiger counter when drawn across the plate’s face. The plate is perfectly safe, said the man holding the Geiger counter, but it’s uranium in the glaze that gives it such a brilliant orange sheen.

An archeologist explained that there don’t seem to be any Indian American burial grounds on the proposed repository site, though there are artifacts and other clues suggesting that ancient peoples passed through the area. Someone asked how an industry could spend 30 years generating radioactive waste without settling on a place to put it.

“Each generation,” he said, “believes the next one is going to be smarter.”

To reach the mountaintop, we left the buses behind, piled into a fleet of more agile vans, and scrambled up a series of steep and winding dirt roads. Soon thousands of bare acres stretched out beneath us: Crater Flat, parts of the Amargosa Valley, and a pair of million-year-old volcanic cones ringed by lava flows. The valley floor was 500 feet or more below.

We sat on wooden benches and heard again about the unique circumstances that might make this the ideal place to isolate a nation’s radioactive waste. The low water table, the stable earth, the remote landscape.

The guests squinted into the distance, leaned into the wind, stamped on the rocky ridge like customers kicking the tires of a new car that would have to take them across 10,000 miles of unknown road. Then the vans rolled down the mountain, the buses rolled across the desert, and we stepped back into the neon, cheap drinks and relatively low stakes of Las Vegas.

Yucca Mountain project tours, staged monthly, are open to any U.S. citizen over the age of 14. Reservations must be made two weeks in advance, and anyone interested should be ready to provide a name, address, Social Security number, birth date and birthplace for each guest. Upcoming tour dates are June 27, July 17, August 22, Sept. 26 and Oct. 27. Tours usually begin at 7:15 a.m. at the Yucca Mountain Information Center, 4101 Meadows Lane, Las Vegas, and end about 4:30 p.m. For more information call (702) 794-7104.