In 1934, a group of scientists at the University of Rome reported the discovery of element 94 and named it hesperium. The sample was subsequently found to be a mixture of barium, krypton, and other elements. It wasn’t until 1940 that a group of US scientists at Berkeley University identified plutonium in an experiment involving the bombardment of uranium. It was then identified as element 94 and named plutonium, after the planet Pluto, with the chemical symbol of Pu.
Plutonium is now manufactured synthetically and is responsible for producing over one third of the energy required to run the world’s nuclear power plants.
What is plutonium made from?
Plutonium is a rare earth element
, so called because it is only found in trace amounts in the Earth’s crust. It is radioactive and has a silvery colour, but degrades to a dull grey, olive or yellow when it oxidises. All of the plutonium in use today is manufactured synthetically.
There are two different types of plutonium produced for different purposes:
- Reactor-grade plutonium is recovered as a by-product from nuclear reactors after the fuel has been irradiated (‘burned’) for about three years.
- Weapons-grade plutonium is produced in a plutonium production reactor by irradiating uranium fuel for around two to three months. This creates a higher grade of plutonium used for military purposes.
How is plutonium used?
Nuclear reactors use uranium as a fuel source, producing plutonium as a by-product. In MOX reactors, plutonium oxide is extracted from the used fuel, then mixed with the depleted uranium oxide, forming a mixed oxide (MOX) fuel that is fed back into the reactor. In a conventional nuclear reactor, one kilogram of plutonium can produce sufficient heat to generate nearly 10 million kilowatt-hours of electricity.
Weapons-grade plutonium has a slightly different chemical structure and is used as an explosive in nuclear weapons.
Where is plutonium found?
Plutonium has a relatively short half-life (the amount of time it takes to degrade) compared to other elements. Therefore, any natural deposits that may have been in the earth’s crust when it formed, would have degraded over time through geological processes. The plutonium available today is found only in trace amounts within uranium deposits and is extracted by burning the uranium, which is the process used in nuclear reactors.
In 1972, a French physicist discovered evidence of nuclear waste products in an underground uranium deposit in Oklo (Gabon, Africa). This discovery proved a previous theory that nuclear reaction could occur naturally during the earth’s formation. It was surmised that 2 billion years ago a large uranium deposit was affected by a series of natural phenomena, including water saturation, causing nuclear fission to occur and produce the known by-products associated with nuclear reactors. It is thought that this process produced approximately one tonne of plutonium, all of which is no longer available due to its degradation over time.
Visit our Rocks, Metals and Gems
page for more articles on mining. You can find information on Energy in our Oil and Gas, Energy
page or our section on Alternative Energy
• World Nuclear Association
• Safe ultimate disposal of nuclear waste (in Germany)
Visit our Oil, Gas and Energy
page for more information about the Oil and Gas industry.
Image courtesy of Wikipedia.