suspended, Washington State sued, joined by South Carolina. Their first suit was dismissed in July 2011. In a subsequent suit, federal authorities were ordered to either approve or reject plans for the Yucca Mountain storage site. During excavations from 2004 to 2007, a sample of purified plutonium was uncovered inside a safe in a waste trench, and has been dated to about the 1940s, making it the second-oldest sample of purified plutonium known to exist. Analyses published in 2009 concluded that the sample originated at Oak Ridge, and was one of several sent to Hanford for optimization tests of the TPlant until Hanford could produce its own plutonium. Documents refer to such a sample, belonging to "Watt's group", which was disposed of in its safe when a radiation leak was suspected. See also Lists of nuclear disasters and radioactive incidents Timeline of nuclear weapons development Notes References * Further reading Explores the history of the Hanford nuclear reservation and the tri-cities of Richland, Pasco, and Kennewick, Washington Recounts the role of the Hanford site in creation and continuation of nuclear weapons External links Federal agency that regulates Hanford cleanup State agency that regulates Hanford cleanup Historic American Engineering Record documentation: Geography of Benton County, Washington Columbia River Environmental disasters in the United States Geography of Washington (state) Historic American Engineering Record in Washington (state) History of Washington (state) History of the Manhattan Project Industrial buildings and structures in Washington (state) Nuclear history of the United States Nuclear weapons infrastructure of the United States Radioactive waste repositories in the United States Tri-Cities, Washington United States Department of Energy facilities Buildings and structures in Benton County, Washington Tourist attractions in Benton County, Washington Radioactively contaminated areas 1943 establishments in Washington (state) Military Superfund sites Superfund sites in Washington (state) Military research of the United States Gravitational-wave astronomy Atomic tourism