|
Uranium mining in the United States produced 4.8 million pounds of uranium concentrate in 2013, the largest amount since 1997. Production came from one conventional uranium mill in Utah, and six in-situ leach operations: three in Wyoming, two in Texas, and one in Nebraska. The plants in Wyoming provided 81% of the nation’s uranium production.〔US Energy Information Administration, (Domestic Uranium Production Report – Quarterly, - 4th Quarter 2013 ), 31 Jan 2014.〕 While uranium is used primarily for nuclear power, uranium mining had its roots in the production of uranium-bearing ore in 1898 with the mining of carnotite-bearing sandstones of the Colorado Plateau in Colorado and Utah, for their vanadium content. The late 1940s and early 1950s saw a boom in uranium mining in the western U.S., spurred by the fortunes made by prospectors such as Charlie Steen. The United States was the world's leading producer of uranium from 1953 until 1980, when annual U.S. production peaked at 16,810 metric tons U3O8.〔''Uranium 2003: Resources, Production and Demand'', Paris: OECD Nuclear Energy Agency, 2004, p.238〕 Until the early 1980s, there were active uranium mines in Arizona, Colorado, New Mexico, South Dakota, Texas, Utah, Washington, and Wyoming.〔Warren I. Finch and others (1973) ''Nuclear fuels'', in ''United States Mineral Resources'', US Geological Survey, Professional Paper 820, p.458.〕 Price declines in the late 1970s and early 1980s forced the closure of numerous mines. Most uranium ore in the United States comes from deposits in sandstone, which tend to be of lower grade than those of Australia and Canada. Because of the lower grade, many uranium deposits in the United States became uneconomic when the price of uranium declined sharply in the late 1970s. By 2001, there were only three operating uranium mines (all in-situ leaching operations) in the United States. Annual production reached a low of 779 metric tons of uranium oxide in 2003, but then more than doubled in three years to 1672 metric tons in 2006, from 10 mines.〔(【引用サイトリンク】title=World Uranium Mining 2011 )〕 The U.S. DOE's Energy Information Administration reported that 90% of U.S. uranium production in 2006 came from in-situ leaching.〔(U.S. Energy Information Administration: ''U.S. uranium mine production and number of mines and sources'' ), accessed 6 March 2009.〕 The average spot price of uranium oxide (U3O8) increased from $7.92 per pound in 2001 to $39.48 per pound ($/kg) in 2006.〔Department of Energy's (Energy Information Administration data ), official energy statistics from the U.S. Government〕 In 2011 the United States mined 9% of the uranium consumed by its nuclear power plants.〔US Energy Information Administration, (Where our uranium comes from ), 2 July 2012.〕 The remainder was imported, principally from Russia (50%), Canada, and Australia.〔Warren I Finch (2003) ''Uranium-fuel for nuclear energy 2002'', US Geological Survey, Bulletin 2179-A.〕〔See (''S&TR'': September 2005, How One Equation Changed the World ), which discusses the progress of the HEU Purchase Agreement made between the Russian Federation and the United States in 1993. "Currently, Russian plants are processing about 30 metric tons of HEU per year into about 875 metric tons of LEU. This amount meets half the annual fuel requirement for U.S. nuclear power plants and provides the fuel to generate 10 percent of the electricity used in the U.S."〕 Although uranium production has declined to low levels, the United States has the fourth-largest uranium resource in the world, behind Australia, Canada, and Kazakhstan.〔 United States uranium reserves are strongly dependent on price. At $50 per pound U3O8, reserves are estimated to be 539 million pounds; however, at a price of $100 per pound, reserves are an estimated 1227 million pounds.〔US Energy Information Administration, (''U.S. uranium reserves estimates'' ), July 2010.〕 Rising uranium prices since 2001 have increased interest in uranium mining in Arizona, Colorado, Texas and Utah.〔WISE Uranium Project: (''New uranium mining projects - USA'' ), accessed 25 March 2009.〕 The states with the largest known uranium ore reserves (not counting byproduct uranium from phosphate) are (in order) Wyoming, New Mexico, and Colorado.〔J. Keller and others, ''Colorado'', Mining Engineering, May 2006, p.76.〕 The radiation hazards of uranium mining and milling were not appreciated in the early years, resulting in workers being exposed to high levels of radiation. Inhalation of radon gas caused sharp increases in lung cancers among underground uranium miners employed in the 1940s and 1950s. In 1950, the US Public Health service began a comprehensive study of uranium miners, leading to the first publication of a statistical correlation between cancer and uranium mining, released in 1962.〔Dawson, Susan E, and Gary E Madsen. "Uranium Mine Workers, Atomic Downwinders, and the Radiation Exposure Compensation Act." In Half Lives & Half-Truths: Confronting the Radioactive Legacies of the Cold War, 117-143. Santa Fe: School For Advanced Research, 2007)〕 In 1969, the federal government regulated the standard amount of radon in mines.〔Brugge, Doug, Timothy Benally, and Esther Yazzie-Lewis. The Navajo People and Uranium Mining. Albuquerque : University of New Mexico Press, 2006.〕 In 1990, Congress passed the Radiation Exposure Compensation Act (RECA), granting reparations for those affected by mining.〔 Out of 50 present and former uranium milling sites in 12 states, 24 have been abandoned, and are the responsibility of the US Department of Energy.〔(Nuclear Decommissioning Title 1 Uranium Mills Summary Table )〕 == By state == 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「Uranium mining in the United States」の詳細全文を読む スポンサード リンク
|