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Fertile material is a material that, although not itself fissionable by thermal neutrons, can be converted into a fissile material by neutron absorption and subsequent nuclei conversions. ==Naturally occurring fertile materials== Naturally occurring fertile materials that can be converted into a fissile material by irradiation in a reactor include: *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 plutonium-241 Some other actinides need more than one neutron capture before arriving at an isotope which is both fissile and long-lived enough to probably be able to capture another neutron and fission instead of decaying. *plutonium-242 to americium-243 to curium-244 to curium-245 *uranium-236 to neptunium-237 to plutonium-238 to plutonium-239 *americium-241 to curium-242 to curium-243 (or, more likely, curium-242 decays to plutonium-238, which also requires one additional neutron to reach a fissile nuclide) Since these require a total of 3 or 4 thermal neutrons to eventually fission, and a thermal neutron fission generates only about 2 to 3 neutrons, these nuclides represent a net loss of neutrons. In a fast reactor, they may require fewer neutrons to achieve fission, as well as producing more neutrons when they do fission. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Fertile material」の詳細全文を読む スポンサード リンク
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