October 28, 2021
Uranium is the chemical element with atomic number 92, symbol U. It is part of the actinide family. Uranium is the 48th most abundant natural element in the earth's crust, its abundance is greater than that of silver, comparable to that of molybdenum or arsenic, but four times less than that of thorium. It is found everywhere in traces, including in seawater. It is a radioactive heavy metal (alpha emitter) with a very long half-life (~ 4.468 8 billion years for uranium 238 and ~ 703.8 million for uranium 235). Its radioactivity, added to that of its descendants in its decay chain, develops a power of 0.082 watts per tonne of uranium, which in fact, with thorium 232 (four times more abundant, but three times less radioactive) and the potassium 40, the main source of heat which tends to maintain the high temperatures of the Earth's mantle, greatly slowing its cooling. The 235U isotope is the only naturally occurring fissile isotope. Its fission releases an energy of around 202.8 MeV per fissioned atom, including 9.6 MeV of unrecoverable energy, communicated to the neutrinos produced during fission. Recoverable energy is more than a million times greater than that of fossil fuels for an equivalent mass. As a result, uranium has become the main raw material used by the nuclear industry. World uranium production amounted to 54,742 tonnes in 2019, mainly split between Kazakhstan (41.7%), Canada (12.7%), Australia (12.1%) , Namibia (10%), Uzbekistan (6.4%), Niger (5.4%), Russia (5.3%) and China (3.4%). In 2020, production fell to 47,731 tonnes. For its use in nuclear reactors, the resources recoverable at a cost of less than 130 dollars / kg of uranium were estimated in 2019 by the IAEA at 6.15 million tonnes worldwide, distributed mainly between Australia (28 %), Kazakhstan (15%), Canada (9%), Russia (8%) and Namibia (7%).