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.
The heaviest elements such as uranium have close to 1.5 neutrons per proton (e.g. 1.587 in uranium-238). No nuclide heavier than lead-208 is stable; these heavier elements have to shed mass to achieve stability, mostly by alpha decay.
Decay Scheme of 210 Po. Here, to the left, we now have an alpha decay. It is the decay of the element Polonium [6] discovered by Marie Curie, with mass number 210. The isotope 210 Po is the penultimate member of the uranium-radium-decay series; it decays into a stable lead-isotope with a half-life of 138 days.
The fissile isotope uranium-235 fuels most nuclear reactors.When 235 U absorbs a thermal neutron, one of two processes can occur.About 85.5% of the time, it will fission; about 14.5% of the time, it will not fission, instead emitting gamma radiation and yielding 236 U. [1] [2] Thus, the yield of 236 U per 235 U+n reaction is about 14.5%, and the yield of fission products is about 85.5%.
234 U occurs in natural uranium as an indirect decay product of uranium-238, but makes up only 55 parts per million of the uranium because its half-life of 245,500 years is only about 1/18,000 that of 238 U. The path of production of 234 U is this: 238 U alpha decays to thorium-234. Next, with a short half-life, 234 Th beta decays to ...
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%).
Both plutonium-239 and uranium-235 are obtained from Natural uranium, which primarily consists of uranium-238 but contains traces of other isotopes of uranium such as uranium-235. The process of enriching uranium , i.e. increasing the ratio of 235 U to 238 U to weapons grade, is generally a more lengthy and costly process than the production of ...
Although thorium-232 mainly decays by alpha decay, it also undergoes spontaneous fission 1.1 × 10 −9 % of the time. [3] In addition, it is capable of cluster decay , splitting into ytterbium-182 , neon-24 , and neon-26 ; the upper limit for the branching ratio of this decay mode is 2.78 × 10 −10 %.