page_title: Isotope separation
section_title: Centrifugal
hierarchical_section_title: Isotope separation / Practical methods of separation / Centrifugal
caption_attribution_description: English: Cascade of gas centrifuges used to produce enriched uranium. This photograph is of the U.S. gas centrifuge plant in Piketon, Ohio from 1984.
context_page_description: Isotope separation is the process of concentrating specific isotopes of a chemical element by removing other isotopes. The use of the nuclides produced is various. The largest variety is used in research. By tonnage, separating natural uranium into enriched uranium and depleted uranium is the largest application. In the following text, mainly the uranium enrichment is considered. This process is a crucial one in the manufacture of uranium fuel for nuclear power stations, and is also required for the creation of uranium based nuclear weapons. Plutonium-based weapons use plutonium produced in a nuclear reactor, which must be operated in such a way as to produce plutonium already of suitable isotopic mix or grade.
  While different chemical elements can be purified through chemical processes, isotopes of the same element have nearly identical chemical properties, which makes this type of separation impractical, except for separation of deuterium.
context_section_description: Centrifugal schemes rapidly rotate the material allowing the heavier isotopes to go closer to an outer radial wall. This too is often done in gaseous form using a Zippe-type centrifuge.
  The centrifugal separation of isotopes was first suggested by Aston and Lindemann in 1919 and the first successful experiments were reported by Beams and Haynes on isotopes of chlorine in 1936. However attempts to use the technology during the Manhattan project were unproductive. In modern times it is the main method used throughout the world to enrich uranium and as a result remains a fairly secretive process, hindering a more widespread uptake of the technology. In general a feed of UF₆ gas is connected to a cylinder that is rotated at high speed. Near the outer edge of the cylinder heavier gas molecules containing U-238 collect, while molecules containing U-235 concentrate at the center and are then fed to another cascade stage. Use of gaseous centrifugal technology to enrich isotopes is desirable as power consumption is greatly reduced when compared to more conventional techniques such as diffusion plants since fewer cascade steps are required to reach similar degrees of separation. In fact, gas centrifuges using uranium hexafluoride have largely replaced gaseous diffusion technology for uranium enrichment. As well as requiring less energy to achieve the same separation, far smaller scale plants are possible, making them an economic possibility for a small nation attempting to produce a nuclear weapon. Pakistan is believed to have used this method in developing its nuclear weapons.
  Vortex tubes were used by South Africa in their Helikon vortex separation process. The gas is injected tangentially into a chamber with special geometry that further increases its rotation to a very high rate, causing the isotopes to separate. The method is simple because vortex tubes have no moving parts, but energy intensive, about 50 times greater than gas centrifuges. A similar process, known as jet nozzle, was created in Germany, with a demonstration plant built in Brazil, and they went as far as developing a site to fuel the country's nuclear plants.
caption: A cascade of gas centrifuges at a U.S. uranium enrichment plant.
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