Hanford’s tank farms contain waste created during plutonium production that was generated when irradiated fuel rods were exposed to a series of chemical processes designed to dissolve away the fuel rod itself, allowing workers to retrieve the plutonium. After the chemicals needed for plutonium processing had been used, they were put into underground storage tanks that were constructed throughout Hanford’s 200 Area in a series of groups.
As part of the agreement regulating Hanford cleanup (called the Tri-Party Agreement), crews must remove at least 99% of the material in every tank on the Site, or at least as much waste that can be removed based on available technology. The final process associated with the tank farm waste is at the Waste Treatment Plant, also known as the Vitrification Plant.
For more information, please see the Tank Farms Fact Sheet.