Uranium-233 is produced by the neutron irradiation of thorium-232. It has a half-life of around 160,000 years. It has been used successfully in experimental nuclear reactors and has been proposed for much wider use as a nuclear fuel. It was occasionally tested but never deployed in nuclear weapons and has not been used commercially as a nuclear fuel. Uranium-233 was investigated for use in nuclear weapons and as a reactor fuel. Uranium-233 is a fissile isotope of uranium that is bred from thorium-232 as part of the thorium fuel cycle. ^ Neutron capture product, parent of trace quantities of 237Np. ![]() ^ Intermediate decay product of 244Pu, also produced by neutron capture of 235U.^ a b # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).^ ( ) spin value – Indicates spin with weak assignment arguments.^ Bold symbol as daughter – Daughter product is stable.^ Bold italics symbol as daughter – Daughter product is nearly stable.^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).^ ( ) – Uncertainty (1 σ) is given in concise form in parentheses after the corresponding last digits.Uranium-238 is also important because it is fertile: it absorbs neutrons to produce a radioactive isotope that subsequently decays to the isotope plutonium-239, which also is fissile. ![]() A chain reaction can be sustained with a sufficiently large ( critical) mass of uranium-235. Uranium-235 is important for both nuclear reactors (energy production) and nuclear weapons because it is the only isotope existing in nature to any appreciable extent that is fissile in response to thermal neutrons, i.e., thermal neutron capture has a high probability of inducing fission. Uranium-233 is made from thorium-232 by neutron bombardment. The constant rates of decay in these series makes comparison of the ratios of parent-to-daughter elements useful in radiometric dating. The decay series of uranium-235 (historically called actino-uranium) has 15 members and ends in lead-207. Uranium-238 is an alpha emitter, decaying through the 18-member uranium series into lead-206. All three isotopes are radioactive (i.e., they are radioisotopes), and the most abundant and stable is uranium-238, with a half-life of 4.4683 ×10 9 years (close to the age of the Earth). The standard atomic weight of natural uranium is 238.028 91(3). In addition to isotopes found in nature or nuclear reactors, many isotopes with far shorter half-lives have been produced, ranging from 214U to 242U (with the exception of 220U). ![]() Other isotopes such as uranium-233 have been produced in breeder reactors. The decay product uranium-234 is also found. It has two primordial isotopes, uranium-238 and uranium-235, that have long half-lives and are found in appreciable quantity in the Earth's crust. Some of them produce neutrons, called delayed neutrons, which contribute to the fission chain reaction.Uranium ( 92U) is a naturally occurring radioactive element that has no stable isotope. A critical chain reaction can be achieved at low concentrations of U-235 if the neutrons from fission are moderated to lower their speed, since the probability for fission with slow neutrons is greater.Ī fission chain reaction produces intermediate mass fragments which are highly radioactive and produce further energy by their radioactive decay. If the reaction will sustain itself, it is said to be "critical", and the mass of U-235 required to produced the critical condition is said to be a " critical mass". If an least one neutron from U-235 fission strikes another nucleus and causes it to fission, then the chain reaction will continue. If at least one neutron from each fission strikes another U-235 nucleus and initiates fission, then the chain reaction is sustained. Uranium-235 Fission Example Initiation of this processĮnergy From Uranium Fission Form of Energy ReleasedĮnergy of decay products of fission fragments Uranium-235 Chain Reaction Uranium-235 Fission Detailed example
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