Hanford Tank Farms

Hanford Tank Farms. The Hanford Tank Farms are a collection of large underground storage facilities located within the Hanford Site in southeastern Washington. Operated by the United States Department of Energy, these farms store approximately 56 million gallons of radioactive and chemical waste generated from decades of plutonium production for the Manhattan Project and later Cold War nuclear weapons programs. The complex represents one of the most challenging environmental cleanup projects in the United States.

History and background

The tank farms were constructed beginning in 1943 as part of the secret Manhattan Project to support the B Reactor and subsequent plutonium production reactors at the Hanford Site. Their primary purpose was to store and manage the vast quantities of liquid waste byproducts from the PUREX and REDOX chemical separation processes used to extract plutonium from irradiated nuclear fuel. As the Cold War intensified, production expanded, leading to the construction of additional tank farms through the 1950s and 1960s. The last tanks were built in the 1980s, with major production activities ceasing by the late 1980s, shifting the site's mission to environmental remediation under frameworks like the Tri-Party Agreement.

Tank design and waste types

The farms consist of 177 underground storage tanks of two primary designs: older single-shell tanks and newer double-shell tanks. The original 149 single-shell tanks, built between 1943 and 1964, are primarily carbon steel vessels with a concrete shell, situated in groups known as "tank farms" like the B Tank Farm and S Tank Farm. Beginning in 1968, 28 more robust double-shell tanks were constructed, featuring an inner steel tank and an outer steel liner with reinforced concrete. The waste is a complex mixture of radioactive byproducts such as cesium-137, strontium-90, and plutonium, along with hazardous chemicals including nitric acid, organic solvents, and heavy metals.

Leaks and environmental concerns

Environmental contamination from the tank farms is a significant concern, with an estimated 67 single-shell tanks having leaked over one million gallons of waste into the surrounding vadose zone. Notable incidents include a 2013 leak from the Tank AY-102 double-shell tank. These leaks pose a long-term threat to the groundwater and the nearby Columbia River, a major regional waterway. The Washington State Department of Ecology and the Environmental Protection Agency regulate cleanup efforts under the Comprehensive Environmental Response, Compensation, and Liability Act and the Tri-Party Agreement. Monitoring and characterization of the plume of contamination is an ongoing priority.

Waste retrieval and treatment

The cornerstone of the cleanup mission is the retrieval of waste from the aging single-shell tanks and its transfer to the double-shell tanks for interim storage. This is followed by treatment at the Waste Treatment and Immobilization Plant, a first-of-its-kind facility designed to vitrify, or glassify, the waste into stable logs for permanent disposal. The treatment process separates the waste into high-level and low-activity fractions. Immobilized high-level waste is destined for a federal deep geological repository, while treated low-activity waste may be disposed of on-site. The project faces immense technical challenges, including managing hydrogen buildup and dealing with precipitate formations.

Management and oversight

Management of the tank farms is the responsibility of the United States Department of Energy's Office of Environmental Management. Primary operations and cleanup contracts have been held by companies such as CH2M Hill and Bechtel. Regulatory oversight is shared by the Washington State Department of Ecology and the Environmental Protection Agency under the legally binding Tri-Party Agreement. Independent review is provided by the Defense Nuclear Facilities Safety Board and the Hanford Advisory Board. The immense scale and cost of the cleanup, projected to last decades and cost hundreds of billions of dollars, make it a subject of continuous scrutiny by the United States Congress and public interest groups.

Category:Hanford Site Category:Nuclear waste repositories in the United States Category:Radioactive contamination in the United States