{"id":12136,"date":"2016-06-10T19:09:03","date_gmt":"2016-06-10T19:09:03","guid":{"rendered":"http:\/\/sitepourvtc.com\/?page_id=12136"},"modified":"2022-10-15T10:48:36","modified_gmt":"2022-10-15T10:48:36","slug":"uranium","status":"publish","type":"page","link":"https:\/\/sitepourvtc.com\/nuclear-power-plant\/nuclear-fuel\/uranium\/","title":{"rendered":"Uranium"},"content":{"rendered":"
Uranium<\/strong> is a naturally occurring chemical element with atomic number 92, which means there are 92 protons and 92 electrons in the atomic structure<\/a>. The chemical symbol for uranium is U<\/strong>. Uranium was discovered in 1789 by Martin Klaproth in the mineral called pitchblende (uraninite). He named the newly discovered element after the planet Uranus, which had been discovered eight years earlier. It was first isolated as a metal in 1841 by Eugene-Melchior Peligot. Henri Becquerel discovered uranium to be radioactive<\/a> in 1896. He discovered that uranium minerals could expose a photographic plate through another material. He was the first to discover the process of radioactivity.<\/p>\n Uranium is commonly found at low levels (a few ppm – parts per million) in all rocks, soil, water, plants, and animals (including humans). Uranium also occurs in seawater and can be recovered from ocean water. Significant concentrations of uranium occur in some substances such as uraninite<\/strong> (the most common uranium ore), phosphate rock deposits, and other minerals.<\/p>\n Natural uranium<\/strong> consists primarily of isotope 238<\/sup>U<\/a> (99.28%). Therefore the atomic mass of the uranium element is close to the atomic mass of the 238<\/sup>U\u00a0isotope (238.03u). \u00a0Natural uranium also consists of two other isotopes: 235<\/sup>U<\/a> (0.71%) and 234<\/sup>U<\/a> (0.0054%). Differences in the half-lives cause the abundance of isotopes in nature. All three naturally occurring isotopes of uranium (238<\/sup>U, 235<\/sup>U, and 234<\/sup>U) \u00a0are unstable<\/a>. On the other hand, these isotopes (except 234<\/sup>U) belong to primordial nuclides<\/a>\u00a0because their half-life is comparable to the age of the Earth (~4.5×109<\/sup> years for\u00a0238<\/sup>U).<\/p>\n In nuclear reactors we have to consider three artificial isotopes<\/strong>, 236<\/sup>U<\/a>, 233<\/sup>U<\/a> and 232<\/sup>U<\/a>. These are produced by transmutation in nuclear reactors<\/a> from 235<\/sup>U\u00a0and 232<\/sup>Th.<\/strong><\/p><\/div><\/div> Source:\u00a0JANIS (Java-based Nuclear Data Information Software);\u00a0ENDF\/B-VII.1<\/p><\/div><\/div> The main isotopes, which have to be considered in the fuel cycle of all commercial light water reactors, are:<\/p>\n Naturally-occurring isotopes<\/strong><\/p>\n Artificial isotopes<\/strong><\/p>\n All three naturally occurring uranium isotopes<\/strong>\u00a0(238<\/sup>U, 235<\/sup>U, and 234<\/sup>U) have a very long half-life<\/strong> (e.g.,, 4.47×109<\/sup> years for 238<\/sup>U). Because of this very long half-life, uranium is weakly radioactive<\/strong> and contributes to low natural background radiation levels in the environment. These isotopes are alpha radioactive (emitting alpha particle<\/a>), but they can also rarely spontaneously fission. Consumption of a 3000MWth (~1000MWe) reactor (12-months fuel cycle)<\/strong><\/p>\n It is an illustrative example, and the following data do not<\/strong> correspond to any reactor design.<\/span><\/em><\/p>\nIsotopes of Uranium<\/h2>\n
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Uranium in the Environment<\/h2>\n
\nAll naturally occurring isotopes belong to primordial nuclides<\/a>\u00a0because their half-life is comparable to the age of the Earth (~4.54×109<\/sup> years). Uranium has the second-highest atomic mass of these primordial nuclides, lighter only than plutonium<\/a>. Moreover, the decay heat of uranium and its decay products (e.g.,, radon, radium, etc.) contributes to heating the Earth’s core. Together with thorium and potassium-40 in the Earth’s mantle, these elements are the main source of heat that keeps the Earth’s core liquid.<\/p><\/div><\/div>Uranium consumption in a nuclear reactor<\/h2>\n
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