Search results
Results From The WOW.Com Content Network
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 ...
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).
Commercial nuclear power plants use fuel that is typically enriched to around 3% uranium-235. [10] The CANDU and Magnox designs are the only commercial reactors capable of using unenriched uranium fuel. Fuel used for United States Navy reactors is typically highly enriched in uranium-235 (the exact values are classified).
Only fissile isotopes of certain elements have the potential for use in nuclear weapons. For such use, the concentration of fissile isotopes uranium-235 and plutonium-239 in the element used must be sufficiently high. Uranium from natural sources is enriched by isotope separation, and plutonium is produced in a suitable nuclear reactor.
Highly enriched uranium (HEU), which contains an even greater proportion of uranium-235, is sometimes used in the reactors of nuclear submarines, research reactors and nuclear weapons. If at least one neutron from uranium-235 fission strikes another nucleus and causes it to fission, then the chain reaction will continue.
Depleted uranium has an even higher concentration of 238 U, and even low-enriched uranium (LEU) is still mostly 238 U. Reprocessed uranium is also mainly 238 U, with about as much uranium-235 as natural uranium, a comparable proportion of uranium-236, and much smaller amounts of other isotopes of uranium such as uranium-234, uranium-233, and ...
Enriched uranium can be used on its own. Many designs surround the reactor core in a blanket of tubes that contain non-fissile uranium-238, which, by capturing fast neutrons from the reaction in the core, converts to fissile plutonium-239 (as is some of the uranium in the core), which is then reprocessed and used as nuclear fuel. Other FBR ...