Yes, the Hanford Site in southeastern Washington state is still significantly radioactive. It remains the most contaminated nuclear site in the Western Hemisphere, with an estimated one million gallons of radioactive waste that have already leaked into the soil and massive quantities of waste still stored in aging underground tanks. Cleanup has been underway for decades and is expected to continue for decades more.
What’s Still There
Hanford produced plutonium for nuclear weapons from 1943 through 1987. That work generated enormous volumes of radioactive and chemical waste, much of which remains on site today. The two biggest categories are liquid waste stored in 177 underground tanks and 1,936 capsules of cesium and strontium, a byproduct of plutonium production. Those capsules alone account for roughly one-third of the total radioactivity at the site. As of early 2026, crews began transferring the capsules into large concrete casks for safer outdoor storage, a process that will take several years.
The underground tanks hold a complex mix of radioactive sludge, liquids, and salt cake. Many of the older single-shell tanks, some more than 75 years old, have developed leaks. Tank B-109, for example, was found to be leaking about 3.5 gallons per day (roughly 1,300 gallons per year) into surrounding soil. That single tank had released an estimated 1,700 gallons before the leak was publicly tracked. It sits in a tank farm where other tanks had already leaked about 200,000 gallons into the ground. Across the entire site, approximately one million gallons of tank waste have seeped into the soil over the decades.
Groundwater and the Columbia River
The leaked waste hasn’t stayed in place. Contaminant plumes have spread through the groundwater beneath Hanford, and some extend toward the Columbia River, which borders the site. A U.S. Geological Survey study mapped plumes in areas along the river corridor and found five contaminants at concentrations above regulatory limits: hexavalent chromium (a toxic metal), tritium, nitrate, strontium-90, and carbon-14. Monitoring and pump-and-treat systems are in place to try to intercept contaminated groundwater before it reaches the river, but the plumes are large and move slowly through the subsurface.
Radiation Levels at the Boundary
For people living near but not on the Hanford reservation, the radiation picture is more reassuring than the contamination numbers might suggest. In 2021, monitoring stations along the site perimeter measured an average annual dose of about 91 millirem. For comparison, the average American receives roughly 555 millirem per year from all sources combined, including natural background radiation and medical procedures like CT scans. The perimeter reading is well below that national average, meaning Hanford’s operations are not currently adding a dangerous dose to nearby residents. The contamination risk is primarily to the environment and to workers on site, not to people in surrounding communities at present levels.
The Cleanup Effort
The centerpiece of Hanford’s cleanup is the Waste Treatment and Immobilization Plant, described as the world’s largest radioactive waste treatment facility. The plant uses a process called vitrification: liquid tank waste is mixed with glass-forming materials and heated to 2,100 degrees Fahrenheit inside large melters, then poured into stainless steel canisters where it cools into a solid glass form. Glass is far more stable and durable than liquid, making it suitable for long-term storage in a deep geological repository. The low-activity waste portion of the plant has begun initial operations after years of construction delays and cost overruns.
Other cleanup work has focused on stabilizing crumbling infrastructure. A storage tunnel next to the former Plutonium Uranium Extraction Facility (PUREX), which held radioactively contaminated equipment, partially collapsed. Workers filled the collapsed section with soil, placed a temporary cover over the tunnel, and then pumped in engineered grout to restore structural integrity and prevent further cave-ins. That kind of emergency stabilization work illustrates how Hanford’s aging Cold War infrastructure continues to pose risks even apart from the waste itself.
How Long Radioactivity Will Persist
Different radioactive isotopes decay at vastly different rates, and Hanford’s waste contains a wide mix. Strontium-90 and cesium-137, two of the most abundant isotopes in the tank waste, have half-lives of about 29 and 30 years respectively. That means the capsules and tank waste containing these isotopes will lose roughly half their radioactivity every three decades, but will remain hazardous for several hundred years. Other isotopes present in smaller quantities, like technetium-99 (half-life of 211,000 years) and plutonium-239 (half-life of 24,100 years), will remain radioactive on geological timescales. The site will require monitoring and institutional controls long after active cleanup ends.
Can You Visit Hanford?
Parts of Hanford are open to the public. The B Reactor, the world’s first full-scale plutonium production reactor, is a National Historic Landmark and part of the Manhattan Project National Historical Park. The Department of Energy began hosting public tours in 2009 and was drawing about 10,000 visitors per year by 2012. Safety improvements made since 2008 allow guests as young as 12 to tour the reactor building. Visitors do not need to be U.S. citizens. The tour areas have been assessed and prepared so that radiation exposure during a visit is minimal, but the vast majority of the 580-square-mile site remains closed to the public and will for the foreseeable future.