Nuclear weapons production

• DEFINITION: Manufacture of explosive devices that are powered by uncontrolled nuclear reactions

The manufacture of nuclear weapons produces radioactive waste, which creates disposal problems. Environmental cleanup of the many sites that participated in the production of nuclear weapons in the past continues to require massive amounts of government funding and effort.

In 1942, a research group headed by Enrico Fermi built an atomic pile—literally, a pile of graphite blocks interspersed with uranium, uranium oxide, and cadmium control rods. On December 2, they achieved a self-sustaining chain reaction in which neutrons from fissioning uranium nuclei caused a constant number of other uranium nuclei to fission as well. The atomic pile was the direct ancestor of the nuclear reactor. Its successful operation opened the door to the production of plutonium and the plutonium route to nuclear weapons. Since the pile’s constituent parts became radioactive, it also marked the beginning of long-term nuclear waste disposal challenges.

The development of the atomic bomb in the United States was a feverish race driven by the fear that Nazi dictator Adolf Hitler would reach the goal first. For the most part, reasonable precautions were taken to protect the scientists and others who worked on the project from dangerous exposure to radiation, but insufficient attention was given to potential environmental problems. The urgency of war dictated that environmental concerns be postponed until more time and resources were available. With the Cold War following on the heels of World War II, this attitude continued for a generation.

The Office of Environmental Management has the assignment of dealing with the legacy of nuclear weapons production in the United States. The office’s responsibilities include restoring the environment where possible, dealing with nuclear waste, shutting down old production facilities, and safeguarding special nuclear materials. Among the tasks to be accomplished is the cleanup of thousands of contaminated areas and buildings, along with 500,000 cubic meters (17.6 million cubic feet) of various levels of radioactive waste. Despite years of planning, permanent disposal sites for high-level nuclear waste remain unavailable, so the worst former production sites can only be stabilized, not fully cleaned up. The estimated cost for this work is over $539 billion spent over more than a century. For comparison, the estimated cost of repairs after the 1995 earthquake in Kobe, Japan, was $100 billion.

Uranium

The pollution problems associated with the production of nuclear weapons begin with uranium ore. It is mined, then pulverized and leached to enable extraction of the uranium. After drying, the depleted ore, called tailings, consists of particles the size of sand grains or smaller. More than 250 million tons of uranium tailings are known to exist in the United States, and more than one billion tons worldwide. The two main hazards from these tailings are radon, a gas produced by the decay of radium, and the contamination of groundwater with heavy metals through runoff. Proper control requires that tailing piles be located away from population centers and covered with earth to trap the radon; the earth cover must then be held in place by grasses and other plants. Care must also be taken to prevent runoff from tailings piles from entering the water supply.

Uranium leaves the mill as a compound called yellowcake. For the American atomic weapons program, yellowcake was converted to the gas uranium hexafluoride, and then the isotope uranium-235 was separated from the more common uranium-238 at factories in Oak Ridge, Tennessee. Metal highly enriched in uranium-235 was fabricated into weapons parts at Oak Ridge. Natural  uranium was shipped to the Hanford Nuclear Reservation in the state of Washington, where large nuclear reactors converted some of it into plutonium.

At Hanford, spent reactor fuel, now highly radioactive, was dissolved, and its plutonium extracted. The plutonium was shipped to the Rocky Flats plant in Colorado, where it was fabricated into weapons parts. These parts were shipped to the Pantex plant in Amarillo, Texas, where the weapons were assembled. Each plant produced radioactive waste, and the US government continues to deal with these contaminated areas and equipment.

Waste Storage and Cleanup

Some 220 million liters (56 million gallons) of nuclear waste liquids and sludges were stored in concrete-encased steel tanks at Hanford. The highly radioactive waste includes chemicals such as nitrates, mercury, and cyanide. An estimated 4 million liters (1 million gallons) have leaked into the ground from the oldest storage tanks. Because it was believed that the pollution would not migrate beyond the large Hanford site, low-level waste, including 1,700 billion liters (449 billion gallons) of processing water, was poured directly onto the ground or into injection wells. The Hanford site represents the largest cleanup of its kind ever undertaken; after government initiation of the project in 1989, the cleanup has continued into the twenty-first century. A new problem for workers at Hanford is liquid waste creating underground “plumes” of contaminants that have joined with existing water beneath the Earth’s surface. The “plumes” are slowly making their way toward the Columbia River, and employees at Hanford are actively involved in coming up with solutions to prevent further contamination of the river.

At the Weldon Spring, Missouri site, where uranium and thorium were processed, forty-four buildings and several waste disposal pits were contaminated. The buildings have been demolished, and 170,000 cubic meters (6 million cubic feet) of radioactive sludge have been stabilized, enclosed under a thick layer of sand, clay, and rock. In 2002, the cleaned-up site, which features this seven-story-high special disposal cell and an interpretive center for visitors, was opened for public inspection. A similar site, the Fernald Preserve near Fernald, Ohio, had 200 structures and 2.4 million cubic meters (85 million cubic feet) of waste. The cleanup of Fernald included shipping some waste elsewhere and storing slightly contaminated soil onsite in a special facility. The project was begun in 1990 and completed in 2006; the total cost was $4.4 billion. The Fernald Preserve was turned into a museum and park and remains under long-term environmental monitoring and stewardship.

Bibliography

“About Hanford Cleanup.” Hanford Site, 13 Jan. 2025, www.hanford.gov/page.cfm/AboutHanfordCleanup. Accessed 13 Apr. 2026.

Alvarez, Robert. “Uranium Mining and the U.S. Nuclear Weapons Program.” Federation of American Scientists, 14 Nov. 2013, fas.org/pir-pubs/uranium-mining-u-s-nuclear-weapons-program-3/. Accessed 13 Apr. 2026.

Gerber, Michele Stenehjem. On the Home Front: The Cold War Legacy of the Hanford Nuclear Site. 2nd ed., University of Nebraska Press, 2002.

Hacker, Barton C. Elements of Controversy: The Atomic Energy Commission and Radiation Safety in Nuclear Weapons Testing, 1947-1974. University of California Press, 1994.

“Hanford Cleanup: DOE Should Consider Including Expedited Nuclear Waste Treatment Alternatives in Upcoming Analysis.” U.S. Government Accountability Office, 26 July 2023, www.gao.gov/products/gao-23-106151. Accessed 13 Apr. 2026.

“The Hanford Site Begins Solidifying Tank Waste in Glass.” U.S. Department of Energy, 15 Oct. 2025, www.energy.gov/em/articles/hanford-site-begins-solidifying-tank-waste-glass. Accessed 12 Apr. 2026.

Hansen, Keith A. “Early Efforts to Limit Nuclear Testing.” The Comprehensive Nuclear Test Ban Treaty: An Insider’s Perspective. Stanford University Press, 2006.

Huegel, Casey A. Cleaning Up the Bomb Factory: Grassroots Activism and Nuclear Waste in the Midwest. University of Washington Press, 2024.

Makhijani, Arjun, et al., editors. Nuclear Wastelands: A Global Guide to Nuclear Weapons Production and Its Health and Environmental Effects. 1995. Reprint. MIT Press, 2000.

Marcial, José, et al. “Hanford Low-Activity Waste Vitrification: A Review.” Journal of Hazardous Materials, vol. 461, Jan. 2024, p. 132437, doi:10.1016/j.jhazmat.2023.132437. Accessed 13 Apr. 2026.

“Nuclear Waste Disposal.” US Government Accountability Office, www.gao.gov/nuclear-waste-disposal. Accessed 13 Apr. 2026.

Waggitt, Peter. “A Review of Worldwide Practices for Disposal of Uranium Mill Tailings.” Department of Climate Change, Energy, the Environment and Water, 1994, www.agriculture.gov.au/sites/default/files/documents/tm48.pdf. Accessed 13 Apr. 2026.