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Enriched uranium is a type of uranium in which the percent composition of uranium-235 (written 235 U) has been increased through the process of isotope separation.Naturally occurring uranium is composed of three major isotopes: uranium-238 (238 U with 99.2732–99.2752% natural abundance), uranium-235 (235 U, 0.7198–0.7210%), and uranium-234 (234 U, 0.0049–0.0059%).
The use of the nuclides produced is varied. The largest variety is used in research (e.g. in chemistry where atoms of "marker" nuclide are used to figure out reaction mechanisms). By tonnage, separating natural uranium into enriched uranium and depleted uranium is the largest application. In the following text, mainly uranium enrichment is ...
Infrared absorption spectra of the two UF 6 isotopes at 300 and 80 K. Schematic of a stage of an isotope separation plant for uranium enrichment with laser. An infrared laser with a wavelength of approx. 16 μm radiates at a high repetition rate onto a UF6 carrier gas mixture, which flows supersonically out of a laval nozzle.
Gaseous diffusion is a technology that was used to produce enriched uranium by forcing gaseous uranium hexafluoride (UF 6) through microporous membranes. This produces a slight separation (enrichment factor 1.0043) between the molecules containing uranium-235 ( 235 U) and uranium-238 ( 238 U).
Other methods of separation were more practical at that time, but this method was designed and used in South Africa for producing reactor fuel with a uranium-235 content of around 3–5%, and 80–93% enriched uranium for use in nuclear weapons. The Uranium Enrichment Corporation of South Africa, Ltd. (UCOR) developed the process, operating a ...
Natural uranium consists of three isotopes; the majority (99.274%) is U-238, while approximately 0.72% is U-235, fissile by thermal neutrons, and the remaining 0.0055% is U-234. If natural uranium is enriched to 3% U-235, it can be used as fuel for light water nuclear reactors. If it is enriched to 90% uranium-235, it can be used for nuclear ...
These problems were gradually overcome. The first shipments of enriched uranium to the Manhattan Project's Los Alamos Laboratory were made in March 1944, consisting of Alpha product enriched to 13 to 15 percent uranium-235. While of no use in a bomb, it was urgently required for experiments with enriched uranium. The last shipment of Alpha ...
The increased percentage of 234 U in enriched natural uranium is acceptable in current nuclear reactors, but (re-enriched) reprocessed uranium might contain even higher fractions of 234 U, which is undesirable. [30] This is because 234 U is not fissile, and tends to absorb slow neutrons in a nuclear reactor—becoming 235 U. [29] [30]