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Uranium-238 (238 U or U-238) is the most common isotope of uranium found in nature, with a relative abundance of 99%. Unlike uranium-235, it is non-fissile, which means it cannot sustain a chain reaction in a thermal-neutron reactor. However, it is fissionable by fast neutrons, and is fertile, meaning it can be transmuted to fissile plutonium-239.
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 ...
Natural uranium is made weapons-grade through isotopic enrichment. Initially only about 0.7% of it is fissile U-235, with the rest being almost entirely uranium-238 (U-238). They are separated by their differing masses. Highly enriched uranium is considered weapons-grade when it has been enriched to about 90% U-235. [citation needed]
The radiative capture cross section for thorium-232 is more than three times that of uranium-238, yielding a higher conversion to fissile fuel than that from uranium-238. Due to the absence of uranium in the fuel, there is no second generation plutonium produced, and the amount of plutonium burnt will be higher than in mixed oxide fuels.
thorium-232 which converts into uranium-233; uranium-234 which converts into uranium-235; uranium-238 which converts into plutonium-239; Artificial isotopes formed in the reactor which can be converted into fissile material by one neutron capture include: plutonium-238 which converts into plutonium-239; plutonium-240 which converts into ...
Uranium-238 is predominantly an alpha emitter, decaying to thorium-234. It ultimately decays through the uranium series, which has 18 members, into lead-206. [17] Uranium-238 is not fissile, but is a fertile isotope, because after neutron activation it can be converted to plutonium-239
The first step to enriching uranium begins by converting uranium oxide (created through the uranium milling process) into a gaseous form. This gas is known as uranium hexafluoride, which is created by combining hydrogen fluoride, fluorine, and uranium oxide. Uranium dioxide is also present in this process and is sent off to be used in reactors ...
The situation with uranium-233 is more complicated, [1] as U-233 is difficult to store safely, which is both an advantage and a disadvantage. Decay of the associated uranium-232 produces thorium-228 with a radioactive half-life of 1.9 years and several short-lived daughter nuclides; these daughters include some very hard gamma-ray emitters like ...