The Cleanup Project at Hanford

Environmental History

Plutonium production and extraction at the Hanford Site have created a number of environmental concerns of varying severity and scale. Major releases of radioactive material were carried out, intentionally and unintentionally,  from 1944 to 1971. These releases included:

  • Water used to cool nuclear reactors being released back into the Columbia River.
  • Airborne radioactive isotopes released during plutonium separation process.
  • Leaking high-level radioactive waste from underground storage tanks.
  • Direct release of waste into the groundwater through injection wells and surface trenches.
  • Pits and burial grounds of solid waste contaminated with radioactive material. 


These releases reached populations downstream or downwind from the Hanford Site, especially those (like some American Indian tribes and farming families) who relied on Columbia River fish or local agriculture for a relatively large part of their diet. The shutdown of most of the nuclear reactors by the 1970s brought an end to some of the most severe releases. However, areas of the Hanford Site remain heavily contaminated due to the practices of the previous three decades.

Citizen pressure and an increased public awareness of the contamination released from the Hanford Site resulted in the Department of Energy publishing historical documents about Hanford operations. The culmination of this citizen pressure resulted in the Tri-Party Agreement, which shifted the focus of Hanford operations to environmental cleanup.

Current Environmental Challenges

The greatest concern at Hanford is the 56 million gallons of high-level radioactive waste stored in 177 underground tanks, 67 of which have leaked a total of at least one million gallons to soil and groundwater. As a result of these and other leaks, about 67 square miles of groundwater under Hanford are contaminated above drinking water standards. Major cleanup operations at Hanford center around two objectives:

  1. Removing high-level waste from underground tanks and processing it into a solid form that is more stable and safe to store while the radioactivity decays.
  2. Preventing the waste that has already leaked from reaching the Columbia River.

These are long-term problems with long-term solutions. Cleanup is expected to continue at least until 2050.