Formation of Uranium
Where did uranium come from?
Supernovae are the probale cause
of the formation of Uranium.
Cosmochemists have been concerned not only with patterns and secular trends of abundance of the elements in galaxies but also with the origins of abundance anomalies in particular stars and with theories on the synthesis of different nuclei to account for these observations. According to the theories developed, the Earth's uranium was produced in one or more supernovae ("An explosive brightening of a star in which the energy radiated by it increases by a factor of ten billion ... A supernova explosion occurs when a star has burned up all its available nuclear fuel and the core collapses catastrophically." - Oxford Dictionary of Physics). The main process concerned was the rapid capture of neutrons on seed nuclei at rates greater than disintegration through radioactivity. The neutron fluxes required are believed to occur during the catastrophically explosive stellar events called suopernovae. Gravitational compression of iron (the island of nuclear stability, incapable of further exothermic fusion reactions) and sudden collapse in the centre of a massive star triggers the explosive ejection of much of the star into space, together with a flood of neutrons. Remnants of hundreds of supernovae have been found, and we "witnessed" one in the Magellanic Clouds in 1987. For more read: World Nucleur Association.
Uranium is one of the more commonly found elements in the Earth's crust. Uranium is 500 times more abundant than gold, 25 times more abundant than mercury and about twice as common as tin. Naturally occurring traces of uranium can be found everywhere - in all rocks and soils, rivers and oceans, as well as in food and in human tissue. Because uranium is naturally radioactive and exists virtually everywhere, it contributes to what is called "natural background radiation." The concentration of uranium varies greatly from substance to substance and place to place. Granite, for instance, which makes up 60% of the Earth's crust, averages four parts per million (ppm) of uranium. Uranium in phosphate rock, which is used to produce fertilizer, can range as high as 400 ppm, and some coal deposits contain uranium concentration levels as high as 1000 ppm.
Next page Different Types of Uranium and its Energy Contents
