Yes, the Nevada Test Site (now called the Nevada National Security Site) is still radioactive, though the levels vary dramatically depending on where you are on the sprawling 1,360-square-mile property. Some areas carry only natural background radiation typical of the desert Southwest, while others, particularly the craters left by underground detonations and soil disturbed by atmospheric blasts, contain measurable contamination from man-made radioactive materials that will persist for centuries.
What Happened There
Between 1951 and 1992, the U.S. government detonated 928 nuclear devices at the site, roughly 65 miles northwest of Las Vegas. Eighty-four of those were atmospheric tests, meaning bombs set off above ground or on towers before the Limited Test Ban Treaty of 1963 pushed testing underground. The atmospheric shots scattered radioactive fallout across the desert surface and, in some cases, across neighboring states. After the treaty, testing moved underground, with 289 announced underground detonations in just the first 14 years alone. Underground tests contained most of the radioactive material below the surface, but not all of it. Venting events occasionally released radioactive gases and particles into the air, and the underground cavities themselves remain contaminated.
Radiation Levels at the Surface Today
Most of the site’s surface now registers radiation levels that overlap with natural background. Recent measurements of natural soil across the site found terrestrial gamma dose rates ranging from 26 to 144 nanosieverts per hour, with an average of 93 nanosieverts per hour. To put that in practical terms, standing in an area with the average reading for a full year would give you roughly 0.8 millisieverts of external exposure from the ground, which is well within the range of normal background radiation people receive everywhere on Earth (typically 1 to 3 millisieverts per year from natural sources, depending on local geology and altitude).
Those numbers, however, describe undisturbed natural soil. The picture changes at former test locations. Craters like Sedan Crater, a massive depression created by a 1962 underground shot that deliberately breached the surface, still contain elevated levels of cesium-137, strontium-90, and other fission products in the soil. Cesium-137 has a half-life of about 30 years, meaning roughly half of what was deposited in the 1950s and 1960s has decayed, but significant quantities remain. Plutonium contamination, with a half-life of 24,000 years, is essentially permanent on any human timescale. These hot spots are why public access to most of the site remains restricted.
What’s Happening Underground
The deeper contamination problem is groundwater. Hundreds of underground nuclear tests created cavities and fractured rock formations beneath the desert, trapping radioactive materials like tritium, plutonium, and various fission products in the subsurface. The primary concern is whether these contaminants will migrate into the regional groundwater system that feeds springs and wells in surrounding communities. Groundwater moves slowly through the desert rock, and monitoring wells have tracked contaminant movement for decades. So far, contaminated groundwater has not reached any off-site water supplies, but the Department of Energy maintains an extensive monitoring network because the contamination will outlast any human institution currently watching it.
The Site Is Still Actively Used
The Nevada National Security Site isn’t just a legacy cleanup project. It remains an active federal facility. One of its ongoing roles is radioactive waste disposal. The Area 5 Radioactive Waste Management Complex accepts low-level radioactive waste, mixed low-level waste, and classified non-radioactive waste from 25 approved generators across the Department of Energy complex nationwide. The facility receives at least 1.1 million cubic feet of waste annually and has enough capacity at its current rate to continue operations for more than 50 years.
The site also supports subcritical nuclear experiments (tests that study plutonium behavior without triggering a chain reaction), national security training exercises, and emergency response drills. It is a working facility with thousands of employees, not an abandoned wasteland.
Can You Visit?
The Department of Energy offers free public tours of the site several times a year, and visitors on those tours receive minimal radiation exposure, comparable to what you’d get on a short airplane flight. Tour routes stick to areas with low contamination, and dosimeters worn by visitors consistently show negligible readings. Sedan Crater is a popular tour stop, and while the area carries slightly elevated readings, the brief time spent there keeps any dose trivially small.
Outside the guided tours, the site is closed to the public. Fencing, security patrols, and federal law enforcement keep people out, partly for national security reasons and partly because wandering into the wrong area could mean walking through soil with concentrated plutonium or other long-lived contaminants.
How Long the Contamination Will Last
The timeline depends entirely on which radioactive materials you’re talking about. Tritium, a contaminant in groundwater, has a half-life of about 12 years, so tritium from the last underground tests in 1992 has already decayed to roughly 7% of its original activity. Strontium-90 and cesium-137, the main surface soil contaminants from atmospheric testing, have half-lives around 30 years. They’ve lost roughly 75% of their original radioactivity but won’t drop to negligible levels for another century or so.
Plutonium is the long game. With a 24,000-year half-life, the plutonium scattered across certain test areas will remain essentially unchanged for thousands of years. It’s not a major external radiation hazard just sitting in soil, but it becomes dangerous if inhaled as dust. This is one reason the contaminated areas will likely never be released for unrestricted public use. The land will remain under federal control for as far into the future as anyone can reasonably plan.