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Uranium is a chemical element with symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium radioactively decays by emitting an alpha particle. The half-life of this decay varies between 159,200 and 4.5 billion years for different isotopes, making them useful for dating the age of the Earth. The most common isotopes in natural uranium are uranium-238 and uranium-235. Uranium has the highest atomic weight of the primordially occurring elements. Its density is about 70% higher than that of lead, and slightly lower than that of gold or tungsten. It occurs naturally in low concentrations of a few parts per million in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite.
Enriched uranium is a type of uranium in which the percent composition of uranium-235 has been increased through the process of isotope separation. Naturally occurring uranium is composed of three major isotopes: uranium-238, uranium-235, and uranium-234. 235U is the only nuclide existing in nature that is fissile with thermal neutrons.
Uraninite, also known as pitchblende, is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely UO2 but because of oxidation typically contains variable proportions of U3O8. Radioactive decay of the uranium causes the mineral to contain oxides of lead and trace amounts of helium. It may also contain thorium and rare-earth elements.
USS Core (CVE-13), a Bogue-class escort carrier named for the Core Sound in North Carolina, was originally classified AVG-13, but was reclassified ACV-13, 20 August 1942; CVE-13, 15 July 1943; CVHE-13, 12 June 1955; CVU-13, 1 July 1958; and T-AKV-41, 7 May 1959. She was launched 15 May 1942 by Seattle-Tacoma Shipbuilding of Tacoma, Washington, under a Maritime Commission contract; sponsored by Mrs. B. B. Smith, wife of Lieutenant Commander Smith; acquired by the Navy, 1 May 1942; and commissioned 10 December 1942, Captain M. R. Greer in command.
A natural nuclear fission reactor is a uranium deposit where self-sustaining nuclear chain reactions occur. The conditions under which a natural nuclear reactor could exist had been predicted in 1956 by Paul Kuroda. The remnants of an extinct or fossil nuclear fission reactor, where self-sustaining nuclear reactions have occurred in the past, can be verified by analysis of isotope ratios of uranium and of the fission products. An example of this phenomenon was discovered in 1972 in Oklo, Gabon by Francis Perrin under conditions very similar to Kuroda's predictions.
Uranium-238 is the most common isotope of uranium found in nature, with a relative abundance of 99%. Unlike uranium-235, it is non-fissile, which means it cannot sustain a chain reaction in a thermal-neutron reactor. However, it is fissionable by fast neutrons, and is fertile, meaning it can be transmuted to fissile plutonium-239. 238U cannot support a chain reaction because inelastic scattering reduces neutron energy below the range where fast fission of one or more next-generation nuclei is probable. Doppler broadening of 238U's neutron absorption resonances, increasing absorption as fuel temperature increases, is also an essential negative feedback mechanism for reactor control.
Plutonium-239 is an isotope of plutonium. Plutonium-239 is the primary fissile isotope used for the production of nuclear weapons, although uranium-235 is also used for that purpose. Plutonium-239 is also one of the three main isotopes demonstrated usable as fuel in thermal spectrum nuclear reactors, along with uranium-235 and uranium-233. Plutonium-239 has a half-life of 24,110 years.
Uranium (92U) is a naturally occurring radioactive element that has no stable isotope. It has two primordial isotopes, uranium-238 and uranium-235, that have long half-lives and are found in appreciable quantity in the Earth's crust. The decay product uranium-234 is also found. Other isotopes such as uranium-233 have been produced in breeder reactors. In addition to isotopes found in nature or nuclear reactors, many isotopes with far shorter half-lives have been produced, ranging from 214U to 242U. The standard atomic weight of natural uranium is 238.02891(3).
Natural uranium refers to uranium with the same isotopic ratio as found in nature. It contains 0.711% uranium-235, 99.284% uranium-238, and a trace of uranium-234 by weight (0.0055%). Approximately 2.2% of its radioactivity comes from uranium-235, 48.6% from uranium-238, and 49.2% from uranium-234.
Uranium mining is the process of extraction of uranium ore from the ground. Over 50 thousand tons of uranium were produced in 2019. Kazakhstan, Canada, and Australia were the top three uranium producers, respectively, and together account for 68% of world production. Other countries producing more than 1,000 tons per year included Namibia, Niger, Russia, Uzbekistan, the United States, and China. Nearly all of the world's mined uranium is used to power nuclear power plants. Historically uranium was also used in applications such as uranium glass or ferrouranium but those applications have declined due to the radioactivity of uranium and are nowadays mostly supplied with a plentiful cheap supply of depleted uranium which is also used in uranium ammunition. In addition to being cheaper, depleted uranium is also less radioactive due to a lower content of short-lived 234
U and 235
U than natural uranium.
Uranium mining in the United States produced 173,875 pounds (78.9 tonnes) of U3O8 in 2019, 88% lower than the 2018 production of 1,447,945 pounds (656.8 tonnes) of U3O8 and the lowest US annual production since 1948. The 2019 production represents 0.3% of the anticipated uranium fuel requirements of the US's nuclear power reactors for the year.
The Artillery Mountains are a mountain range in Mohave County in western Arizona. High point of the range is Artillery Peak, 2,917 feet above sea level. Artillery Peak is at coordinates N 34.36946 W 113.58160.
The mineral mining industry is a crucial piece of the Economy of Niger. Exports of minerals consistently account for 40% of exports.
Canada is the world's second largest producer of uranium, behind Kazakhstan. In 2009, 20% of the world's primary uranium production came from mines in Canada. 14.5% of the world production came from one mine, McArthur River. Currently the only producing area in Canada is northern Saskatchewan, although other areas have had active mines in the past.
Mauritania's mineral sector was dominated by iron ore mining and beneficiation. Other mineral commodities produced in the country included cement, copper, gold, gypsum, petroleum, salt, and steel. The Ministère des Mines et de l’Industrie was the Government agency responsible for enacting the Mining Code and for the coordination of all activities in the mining sector. The Direction des Mines et de la Géologie was the entity responsible for promoting the mineral sector and for providing geologic and mining information to potential investors; the Direction des Hydrocarbures was in charge of the development of the petroleum sector; and the Office Mauritanien des Recherches Géologiques was the Government entity responsible for evaluating areas of mineral potential for exploration. Société Nationale Industrielle et Minière (SNIM) was responsible for iron ore production and benefciation.
The Tummalapalle Mine is a uranium mine in Tumalapalli village located in Kadapa of the Indian state of Andhra Pradesh. Results from research conducted by the Atomic Energy Commission of India, in 2011, led the analysts to conclude that this mine might have one of the largest reserves of uranium in the world.
The Firawa mine is a large open pit mine located in the western part of Mauritania. Firawa represents one of the largest uranium reserves in Mauritania having estimated reserves of 30 million tonnes of ore grading 0.025% uranium.
The Reguibat mine is a large open pit mine located in the western part of Mauritania. Reguibat represents one of the largest uranium reserves in Mauritania having estimated reserves of 69 million tonnes of ore grading 0.028% uranium.
The Driefontein mine is a large mine located in the northern part of South Africa in Gauteng. Driefontein is an important gold producer and represents one of the largest uranium reserves in South Africa having estimated reserves of 238 million tonnes of ore grading 0.0053% uranium.
The Pine Nut mine is a large uranium mine located in the southern part of the United States in Mohave County, Arizona. It is located just north of the Colorado River outside the Grand Canyon National Park. Pine Nut represents one of the largest uranium reserves in the United States having estimated reserves of 24.8 million tonnes of ore grading 0.68% uranium.
References
- ↑ "Uranium in Mauritania". wise-uranium.org. 2012. Retrieved 2013-07-16.
24°53′N11°17′W / 24.883°N 11.283°W
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