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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.
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. Experiments have been conducted with uranium-233 (the fissile material at the heart of the ...
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%).
Many contemporary uses of uranium exploit its unique nuclear properties. Uranium is used in nuclear power plants and nuclear weapons because it is the only naturally occurring element with a fissile isotope – uranium-235 – present in non-trace amounts.
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.
Uranium hexafluoride is the feedstock used to separate uranium-235 from natural uranium. All uranium fluorides are created using uranium tetrafluoride (UF 4); UF 4 itself is prepared by hydrofluorination of uranium dioxide. [6] Reduction of UF 4 with hydrogen at 1000 °C produces uranium trifluoride (UF 3).
Approximately 2.2% of its radioactivity comes from uranium-235, 48.6% from uranium-238, and 49.2% from uranium-234. Natural uranium can be used to fuel both low- and high-power nuclear reactors . Historically, graphite-moderated reactors and heavy water -moderated reactors have been fueled with natural uranium in the pure metal (U) or uranium ...
The "special nuclear materials" are also plutonium-239, uranium-233, and enriched uranium (U-235). Note that the 1980 Convention on the Physical Protection of Nuclear Material definition of nuclear material does not include thorium. [4] The NRC has a regulatory process for nuclear materials with five main components. [5]