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Uranium is everywhere. You are breathing it with every breath. Depleted uranium is much less radioactive than natural uranium.
What is depleted uranium?
Depleted uranium (DU) is the material left behind after most of the highly radioactive form of uranium - known as U-235 - is removed from natural uranium ore.
U-235 provides the fuel used to produce nuclear power and the powerful explosions used in nuclear weapons.
DU is less radioactive, mainly emitting alpha particles, which don't have enough energy to go through skin, so exposure to the outside of the body is not considered a serious hazard.
It can be a serious health hazard, however, if it is swallowed or inhaled.
The Earth's uranium (chemical symbol U) was apparently formed in supernovae up to about 6.6 billion years ago (see information page on The Cosmic Origins of Uranium). Its radioactive decay provides the main source of heat inside the Earth, causing convection and continental drift. As decay proceeds, the final product, lead, increases in relative abundance.
Uranium was discovered by Martin Klaproth, a German chemist, in 1789 in the mineral pitchblende, and was named after the planet Uranus. It occurs in most rocks in concentrations of 2 to 4 parts per million and is as common in the Earth's crust as tin, tungsten and molybdenum and about 40 times as common as silver. Being relatively soluble (in contrast to thorium), it is also found in the oceans, at an average concentration of 3 parts per billion. There are a number of locations in different parts of the world where it occurs in economically-recoverable concentrations. When mined, it yields a mixed uranium oxide product, U3O8. Uraninite, or pitchblende, is the most common uranium mineral.
Natural uranium is a mixture of isotopes, including a small proportion of one that is fissile – readily able to fission (split) to yield vastly more energy than any combustion process.
In the past, uranium was also used to colour glass (from as early as 79 AD) and deposits were once mined in order to obtain its decay product, radium. This element was used in luminous paint, particularly on the dials of watches and aircraft instruments up to the 1950s, and in medicine for the treatment of disease.
For many years from the 1940s, virtually all of the uranium that was mined was used in the production of nuclear weapons, but this ceased to be the case in the 1970s. Today the only substantial use for uranium is as fuel in nuclear reactors, mostly for electricity generation. Uranium-235 is the only naturally-occurring material which can sustain a fission chain reaction, releasing large amounts of energy.
While nuclear power is the predominant use of uranium, heat from nuclear fission can be used for industrial processes. It is also used for marine propulsion (mostly naval). And small nuclear reactors are important for making radioisotopes. |
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