The Hanford Site Tank Farms contain waste created during Hanford’s plutonium production era. The waste was generated when irradiated uranium fuel rods were chemically treated to dissolve away the rod itself, allowing workers to retrieve plutonium from them. After the chemicals needed for plutonium processing had been used, they were put into underground storage tanks in Hanford’s 200 Area.
Hanford is home to 177 underground waste storage tanks: 149 single-shell tanks (SST) and 28 double-shell tanks (DST), ranging from 0.055 to 1.265 million gallons in capacity. Those tanks are organized into 18 different groups, called farms.
More information is available on Hanford.gov.