Search results
Results From The WOW.Com Content Network
Uranium-238 is not fissile, but is a fertile isotope, because after neutron activation it can be converted to plutonium-239, another fissile isotope. Indeed, the 238 U nucleus can absorb one neutron to produce the radioactive isotope uranium-239.
Moreover, different isotopes have different critical masses, and the critical mass for many radioactive isotopes is infinite, because the mode of decay of one atom cannot induce similar decay of more than one neighboring atom. For example, the critical mass of uranium-238 is infinite, while the critical masses of uranium-233 and uranium-235 are ...
Uranium is a silvery-gray, weakly radioactive metallic chemical element.It has the chemical symbol U and atomic number 92. The most common isotopes in natural uranium are 238 U (99.274%) and 235 U (0.711%).
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 ...
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
Natural uranium (NU or U nat [1]) is uranium with the same isotopic ratio as found in nature. It contains 0.711% uranium-235 , 99.284% uranium-238 , and a trace of uranium-234 by weight (0.0055%). Approximately 2.2% of its radioactivity comes from uranium-235, 48.6% from uranium-238, and 49.2% from uranium-234.
Natural uranium contains about 0.72% 235 U. Depleted uranium has lower mass fractions—up to three times less—of 235 U and 234 U than natural uranium. Since 238 U has a much longer half-life than the lighter isotopes, DU is about 40% less radioactive than natural uranium.
Uranium's radioactivity can present health and environmental issues in the case of nuclear waste produced by nuclear power plants or weapons manufacturing. Uranium is weakly radioactive and remains so because of its long physical half-life (4.468 billion years for uranium-238).