In southeastern Washington, a stretch of the river passes through the Hanford Site, established in 1943 as part of the Manhattan Project. The site served as a plutonium production complex, with nine nuclear reactors and related facilities along the banks of the river. From 1944 to 1971, pump systems drew cooling water from the river and, after treating this water for use by the reactors, returned it to the river. Before being released back into the river, the used water was held in large tanks known as retention basins for up to six hours. Longer-lived isotopes were not affected by this retention, and several terabecquerels entered the river every day. By 1957, the eight plutonium production reactors at Hanford dumped a daily average of 50,000 curies of radioactive material into the Columbia. These releases were kept secret by the federal government until the release of declassified documents in the late 1980s. Radiation was measured downstream as far west as the Washington and Oregon coasts.
in southeastern washington a stretch of the river passes through the hanford site established in 1943 as part of the manhattan project the site served as a plutonium production complex with nine nuclear reactors and related facilities along the banks of the river from 1944 to 1971 pump systems drew cooling water from the river and after treating this water for use by the reactors returned it to the river before being released back into the river the used water was held in large tanks known as retention basins for up to six hours longer-lived isotopes were not affected by this retention and several terabecquerels entered the river every day by 1957 the eight plutonium production reactors at hanford dumped a daily average of 50000 curies of radioactive material into the columbia these releases were kept secret by the federal government until the release of declassified documents in the late 1980s radiation was measured downstream as far west as the washington and oregon coasts