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The Hanford Site is a mostly decommissioned nuclear production complex operated by the United States federal government on the Columbia River in the U.S. state of Washington. The site has been known by many names, including: Hanford Project, Hanford Works, Hanford Engineer Works or HEW and Hanford Nuclear Reservation or HNR. Established in 1943 as part of the Manhattan Project in the town of Hanford in south-central Washington, the site was home to the B Reactor, the first full-scale plutonium production reactor in the world. Plutonium manufactured at the site was used in the first nuclear bomb, tested at the Trinity site, and in Fat Man, the bomb detonated over Nagasaki, Japan. During the Cold War, the project expanded to include nine nuclear reactors and five large plutonium processing complexes, which produced plutonium for most of the more than 60,000 weapons in the U.S. nuclear arsenal. Nuclear technology developed rapidly during this period, and Hanford scientists produced notable technological achievements. Many early safety procedures and waste disposal practices were inadequate in hindsight, and government documents have confirmed that Hanford's operations released significant amounts of radioactive materials into the air and the Columbia River. The weapons production reactors were decommissioned at the end of the Cold War, and decades of manufacturing left behind of high-level radioactive waste stored within 177 storage tanks, an additional of solid radioactive waste, and of contaminated groundwater beneath the site.〔(【引用サイトリンク】title=Hanford Facts )〕 In 2011, DOE emptied 149 single-shell tanks by pumping nearly all of the liquid waste out into 28 newer double-shell tanks. DOE later found water intruding into at least 14 single-shell tanks and that one of them had been leaking about 640 gallons per year into the ground since about 2010. In 2012, DOE discovered a leak also from a double-shell tank caused by construction flaws and corrosion in the bottom, and that 12 double-shell tanks have similar construction flaws. Since then, DOE changed to monitoring single-shell tanks monthly and double-shell tanks every 3 years, and also changed monitoring methods. In March 2014, DOE announced further delays in the construction of the Waste Treatment Plant, which will affect the schedule for removing waste from the tanks. Intermittent discoveries of undocumented contamination have slowed the pace and raised the cost of cleanup. In 2007, the Hanford site represented two-thirds of the nation's high-level radioactive waste by volume. Hanford is currently the most contaminated nuclear site in the United States and is the focus of the nation's largest environmental cleanup.〔 Besides the cleanup project, Hanford also hosts a commercial nuclear power plant, the Columbia Generating Station, and various centers for scientific research and development, such as the Pacific Northwest National Laboratory and the LIGO Hanford Observatory. == Geography == The Hanford Site occupies in Benton County, Washington (centered on ), roughly equivalent to half of the total area of Rhode Island.〔 This land is closed to the general public. It is a desert environment receiving under 10 inches of annual precipitation, covered mostly by shrub-steppe vegetation. The Columbia River flows along the site for approximately , forming its northern and eastern boundary. The original site was and included buffer areas across the river in Grant and Franklin counties. Some of this land has been returned to private use and is now covered with orchards and irrigated fields. In 2000, large portions of the site were turned over to the Hanford Reach National Monument. The site is divided by function into three main areas. The nuclear reactors were located along the river in an area designated as the 100 Area; the chemical separations complexes were located inland in the Central Plateau, designated as the 200 Area; and various support facilities were located in the southeast corner of the site, designated as the 300 Area. The site is bordered on the southeast by the Tri-Cities, a metropolitan area composed of Richland, Kennewick, Pasco, and smaller communities, and home to over 230,000 residents. Hanford is a primary economic base for these cities. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hanford Site」の詳細全文を読む スポンサード リンク
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