Search results
Results From The WOW.Com Content Network
Uranium-235 (235 U or U-235) is an isotope of uranium making up about 0.72% of natural uranium. Unlike the predominant isotope uranium-238, it is fissile, i.e., it can sustain a nuclear chain reaction. It is the only fissile isotope that exists in nature as a primordial nuclide. Uranium-235 has a half-life of 703.8 million years.
In a fission nuclear reactor, uranium-238 can be used to generate plutonium-239, which itself can be used in a nuclear weapon or as a nuclear-reactor fuel supply. In a typical nuclear reactor, up to one-third of the generated power comes from the fission of 239 Pu, which is not supplied as a fuel to the reactor, but rather, produced from 238 U. [5] A certain amount of production of 239
While the natural abundance of uranium has been supplemented by the decay of extinct 242 Pu (half-life 375,000 years) and 247 Cm (half-life 16 million years), producing 238 U and 235 U respectively, this occurred to an almost negligible extent due to the shorter half-lives of these parents and their lower production than 236 U and 244 Pu, the ...
Uranium-235 makes up about 0.72% of natural uranium. Unlike the predominant isotope uranium-238, it is fissile, i.e., it can sustain a fission chain reaction. It is the only fissile isotope that is a primordial nuclide or found in significant quantity in nature. Uranium-235 has a half-life of 703.8 million years.
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%).
Enrichment processes generate uranium with a higher-than-natural concentration of lower-mass-number uranium isotopes (in particular 235 U, which is the uranium isotope supporting the fission chain reaction) with the bulk of the feed ending up as depleted uranium. Natural uranium metal contains about 0.71% 235 U, 99.28% 238 U, and about 0.0054% ...
The isotope 238 U is also important because it absorbs neutrons to produce a radioactive isotope that subsequently decays to the isotope 239Pu (plutonium), which also is fissile. Uranium in its natural state comprises just 0.71% 235 U and 99.3% 238 U, and the main focus of uranium metallurgy is the enrichment of uranium through isotope separation.
Pu-239 is produced artificially in nuclear reactors when a neutron is absorbed by U-238, forming U-239, which then decays in a rapid two-step process into Pu-239. [22] It can then be separated from the uranium in a nuclear reprocessing plant. [23] Weapons-grade plutonium is defined as being predominantly Pu-239, typically about 93% Pu-239. [24]