Uranium

The first thing we must do when discussing uranium is to explain exactly what it is, as much of the fear people have regarding the mineral is based on a lack of accurate knowledge. It is therefore important to get the facts concerning uranium laid out first and take it from there. These facts are:

• The uranium chemical symbol is U.


• Uranium has a melting point of 1132 degrees Celsius.



As one of heaviest of metals, uranium can be used as a ready source of concentrated energy.



• This high density makes it useful in yacht keels as well as counterweights for surfaces related to aircraft control. It is also useful as a shield against radiation.


• Uranium is not common in the solar system and it appears to have been formed in a supernova around 6.6 billion years ago.


• Because of uranium’s slow radioactive decay it is important in retaining heat inside of Earth by creating convection and continental drift.


• Uranuim is found in most rocks at a concentration of no more than two to four parts per million. It is most commonly found in the earth\'s crust in the form of molybdenum, tungsten and tin. It is also available in sea water and can be recovered from all the world\'s oceans.


• Uranium was discovered by German chemist Martin Klaproth in 1789 within the mineral pitchblende. As the planet Uranus had only been discovered eight years beforehand he called his discovery uranium.



Uranium is one of the Heaviest Naturally Occurring Element Known to Mankind




Where hydrogen is one of the lightest naturally occurring elements, uranium is one of the heaviest, as it is 18.7 times as dense as water and, as is the case with other elements, the different forms of uranium are known as isotopes. The differences in the isotopes being the number of uncharged particles, or neutrons, in its nucleus. Naturally occurring uranium within the surface of the earth is a mixture of two isotopes, one known as uranium-238 (U-238) which accounts for 99.3 percent of available uranium and the other, uranium-235 (U-235), which account for the other 0.7 percent.




Uranium is Unique in That it can be Split




Uranium U-235 is regarded as being important because, if the conditions are right, it can be split. When this occurs it yields a substantial amount of energy, This release of energy is called fissile and this is where we get the expression \'nuclear fission\' from. Just like all other radioactive isotopes U- 238 decays, in this case very slowly as it has a half life of 4,500 million years ( roughly the age of the Earth itself). Because of this it is hardly radioactive at all far less than many other isotopes occurring in sand and rocks generally. However it is still capable of generating 0.1 watt/tonne in the form of decay heat and this is quite sufficient to warm the core of the Earth. U-235 decays faster.




The Splitting of the Atom Creates Great Heat




The nucleus of the atom within the U-235 comprises 143 neutrons and 92 protons. This is where the number 235 comes from as 143 plus 92 equals 235. When this U-235 nucleus\'s atom captures a moving neutron it splits in two and releases energy in the form of heat, at the same time two or three neutrons are thrown off. If enough of these neutrons are expelled they cause other U-235 atoms to also split releasing more heat and a further release of more neutrons. This creates a chain reaction whereby a great amount of heat can be created from a relative small amount of uranium. This is what takes place inside a nuclear reactor to create heat to, in turn, create steam, to turn the turbines, to produce electricity. Other than the method used to create heat, fossil fuelled power stations are much the same as nuclear power stations.




A Uranium Fuel Malfunction can-not Explode




If a major malfunction occurs the worst that can happen is that the fuel can overheat and melt but it can-not explode like a bomb as many believe. A 1,000 megawatt reactor can produce sufficient electricity to cater for a city of one million people.




Plutonium Burns as Does Uranium




Because U-235 nucleus is fissile it can capture a neutron in the core of the reactor and turn into plutonium-239 (Pu-239) this is also fissile, much like U-235 and also yields a lot of energy in the form of heat. This occurs frequently, in fact about one third of the energy produced is from burning Pu-239. When the used fuel is removed from the reactor after about three years the plutonium recovered is not suitable for use in nuclear weapons but it is able to be recycled once again as fuel or buried underground.




Mining of Uranium




Uranium can be mined either by open cut or underground methods. The ore is crushed and ground before being treated with an acid to dissolve the uranium. The uranium is recovered from the resulting solution. It is also possible to mine uranium in a porous ore body by means of in-situ- leaching (ISL). In this case the uranium is dissolved from the porous rock while underground and pumped to the surface.
Australia has three uranium mines. These are:



• Ranger in the Northern Territory.


• Olympic Dam in South Australia.


• Beverley in South Australia.



Two other projects, FourMile and Honeymoon, both in South Australia are able to begin production within 12 to 18 months. Significant deposits also exist in Western Australia at Kintyre and Yeelirre.