Nevada National Security Site

MERCURY, Nev. -- From the side that faced away from the blast, you might never even have bothered to look at this concrete dome. But walk around the other side, and there's no question something extraordinary happened here.

Welcome to the Nevada National Security Site, formerly known as the Nevada Test Site. As part of Road Trip 2012, I've come to visit this 1,375-square-mile expanse of harsh desert and even harsher mountains that begins about 75 miles north of Las Vegas. Here, from 1951 through 1992, a total of 928 nuclear weapons exploded, many of them sending instantly familiar giant mushroom clouds high into the skies above.

Of those, 828 were detonated underground. But that means 100 were tested above ground, and people in Las Vegas were said to be able to see the light from the blasts, and even some of the mushroom clouds rising skyward.

On June 24, 1957, a 37-kiloton atomic bomb called Priscilla was detonated on a wide piece of Nevada Test Site known as Frenchman Flat. About three times the size of the 1945 atom bomb dropped on Hiroshima, Japan, the weapon was meant to test, among other things, how a variety of structures could hold up to the initial fireball and the resulting pressure blast.

And that's why walking around the front side of this concrete dome -- which was built with a six-inch-thick reinforced concrete shell -- tells such a story. Essentially, it was ripped to shreds. Fifty-four years later, that wrecked concrete and twisted rebar, plus a nearby rail trestle whose thick, straight steel I-beams were bent into wide curves, and a reinforced concrete bank vault with one side torn to bits, are still a visible reminder of the power of nuclear weapons.

The Nevada Test Site

In the early years after World War II, the United States conducted most of its nuclear weapons tests in the Pacific Ocean. But according to a Nevada National Security Site fact sheet, "Security and logistical issues quickly illustrated the need for a continental test site."

The government considered a number of potential locations before settling in 1950 on what was then called the Las Vegas Bombing and Gunnery Range. And less than two months later, the first atmospheric test of a nuclear weapon was conducted there. Over the years, 100 above ground detonations took place at various locations around the giant site, until in 1963, when the newly signed Limited Test Ban Treaty required all future tests to be conducted underground.

Though the fireballs of the above ground tests were obviously quite spectacular -- leading to a "spectator sport" of VIPs coming to watch the detonations from the safety of a set of bleachers several miles away, according to Dante Pistone, the public affairs officer for the Nevada National Security Site -- the lasting effects of the underground tests may well be the more impressive visuals.

Throughout the giant facility, there are hundreds of what are known as subsidence craters -- caused when the dirt and earth, at first superheated by a blast as much as 1,000 feet or more below ground, cooled and subsided. These craters can be small and barely noticeable, or they can be gigantic and awe-inspiring.

Perhaps the most impressive of all is one called Sedan Crater. This was the result of a detonation that was part of what was called the Plowshare Program -- an initiative meant to explore the possible use of nuclear weapons for peaceful means. The idea was that the bombs could be extremely useful for large-scale excavation for projects such as dams, or canals, or quarries. Only after years of such experimentation was it decided that the resulting radioactivity made such a program impractical.

Still, the Sedan Crater is a testament to the power of these weapons. Created by a 104-kiloton bomb lowered 635 feet below the surface and detonated with the blast focused upward, the explosion displaced 12 million tons of dirt and earth, and left a hole in the ground 1,280 feet across and 320 feet deep.

Current missions

Though the Nevada National Security Site offers a stark lesson in our nation's nuclear history, it's also host to a roster of modern nuclear- and chemical-related missions being undertaken on behalf of a laundry list of government agencies and private companies.

There's also the matter of cleaning up the past -- literally. One giant quadrant of the site is devoted to storing the radioactive waste left over from those decades of tests. The waste that is buried there is cataloged and monitored, in order to be able to track any leakage, and the water table below is watched for contamination.

Another crucial mission is making sure that the country's remaining nuclear stockpile is still reliable all these years later. That involves conducting experiments where scientists from the country's leading laboratories -- Lawrence Livermore, Los Alamos, Sandia, and so on -- work on various methods of splitting small amounts of plutonium. In order to do that and guarantee that no new radioactivity is released into the environment, there's a network of deep underground tunnels, and a secondary system of side tunnels. The experiments are carried out there, and when finished, and all the relevant data is collected, the side tunnels are shut down and filled in with concrete.

At the same time, it's clear that first responders around the country need training on handling serious emergencies like the explosion of a dirty bomb or the threat of some sort of radiological weapon in public, and so the site is home to a training program where first responders come and learn how to tackle such situations.

In the end, though, unless you're privy to some of the secret work that goes on at the site -- in facilities like the ultrasecure Device Assembly Facility, where scientists put together the projects that are detonated in the underground tunnels, and others no one will talk about -- the thing that stays with you when you leave the NNSS is the image of the power of even a very small nuclear blast. After all, when you've seen a quarter-mile wide crater, you're not likely to ever forget it.