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Fertile Material
Fertile material is a material that, although not fissile itself, can be converted into a fissile material by neutron absorption. 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- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Sasahara
Sasahara (written: lit. "bamboo field") is a Japanese surname. Notable people with the surname include: *, Japanese judoka *, Japanese Paralympic athlete *, Japanese anime director *, Japanese sport wrestler *, Japanese footballer *, Japanese racing driver *, Japanese footballer *, Japanese voice actress *, Japanese skeleton racer Fictional characters *, protagonist of the manga series ''Genshiken'' {{surname Japanese-language surnames ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Uranium-236
Uranium-236 ( or U-236) is an isotope of uranium that is neither fissile with thermal neutrons, nor very good fertile material, but is generally considered a nuisance and long-lived radioactive waste. It is found in spent nuclear fuel and in the reprocessed uranium made from spent nuclear fuel. Creation and yield The fissile isotope uranium-235 fuels most nuclear reactors. When 235U 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 236U. Thus, the yield of 236U per 235U+n reaction is about 14.5%, and the yield of fission products is about 85.5%. In comparison, the yields of the most abundant individual fission products like caesium-137, strontium-90, and technetium-99 are between 6% and 7%, and the combined yield of medium-lived (10 years and up) and long-lived fission products is about 32%, or a few percent less as some are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Fast Breeder Reactor
A breeder reactor is a nuclear reactor that generates more fissile material than it consumes. These reactors can be Nuclear fuel, fueled with more-commonly available isotopes of uranium and Isotopes of thorium, thorium, such as uranium-238 and thorium-232, as opposed to the rare uranium-235 which is used in conventional reactors. These materials are called fertile materials since they can be bred into fuel by these breeder reactors. Breeder reactors achieve this because their neutron economy is high enough to create more fissile fuel than they use. These extra neutrons are absorbed by the fertile material that is loaded into the reactor along with fissile fuel. This Irradiation, irradiated fertile material in turn transmutes into fissile material which can undergo Nuclear fission, fission reactions. Breeders were at first found attractive because they made more complete use of uranium fuel than light-water reactors, but interest declined after the 1960s as more uranium reserves ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
MOX Fuel
Mixed oxide fuel (MOX fuel) is nuclear fuel that contains more than one oxide of fissile material, usually consisting of plutonium blended with natural uranium, reprocessed uranium, or depleted uranium. MOX fuel is an alternative to the low-enriched uranium fuel used in the light-water reactors that predominate nuclear power generation. For example, a mixture of 7% plutonium and 93% natural uranium reacts similarly, although not identically, to low-enriched uranium fuel (3 to 5% uranium-235). MOX usually consists of two phases, UO2 and PuO2, and/or a single phase solid solution (U,Pu)O2. The content of PuO2 may vary from 1.5 wt.% to 25–30 wt.% depending on the type of nuclear reactor. One attraction of MOX fuel is that it is a way of utilizing surplus weapons-grade plutonium, an alternative to storage of surplus plutonium, which would need to be secured against the risk of theft for use in nuclear weapons. On the other hand, some studies warned that normalizing the global com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Thorium Fuel Cycle
The thorium fuel cycle is a nuclear fuel cycle that uses an isotope of thorium, , as the fertile material. In the reactor, is transmuted into the fissile artificial uranium isotope which is the nuclear fuel. Unlike natural uranium, natural thorium contains only trace amounts of fissile material (such as ), which are insufficient to initiate a nuclear chain reaction. Additional fissile material or another neutron source is necessary to initiate the fuel cycle. In a thorium-fuelled reactor, absorbs neutrons to produce . This parallels the process in uranium breeder reactors whereby fertile absorbs neutrons to form fissile . Depending on the design of the reactor and fuel cycle, the generated either fissions in situ or is chemically separated from the used nuclear fuel and formed into new nuclear fuel. The thorium fuel cycle has several potential advantages over a uranium fuel cycle, including thorium's greater abundance, superior physical and nuclear properties, reduc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Thermal Reactor
A thermal-neutron reactor is a nuclear reactor that uses slow or thermal neutrons. ("Thermal" does not mean hot in an absolute sense, but means in thermal equilibrium with the medium it is interacting with, the reactor's fuel, moderator and structure, which is much lower energy than the fast neutrons initially produced by fission.) A fast-neutron reactor, on the other hand, operates using high-energy neutrons that are not slowed by a moderator. These reactors can efficiently use a broader range of fuels, including plutonium and other heavy atoms, and have the capability to breed more fissile material, such as uranium-238 into plutonium-239, which is not possible in thermal reactor. In contrast to thermal-neutron reactors, integral fast reactors (IFRs) operate using fast neutrons and are designed for increased fuel efficiency. These reactors are capable of recycling nuclear waste and breeding new fuel, which enhances sustainability. Additionally, IFRs incorporate passive safet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Fuel Rod
Nuclear fuel refers to any substance, typically fissile material, which is used by nuclear power stations or other nuclear devices to generate energy. Oxide fuel For fission reactors, the fuel (typically based on uranium) is usually based on the metal oxide; the oxides are used rather than the metals themselves because the oxide melting point is much higher than that of the metal and because it cannot burn, being already in the oxidized state. Uranium dioxide Uranium dioxide is a black semiconducting solid. It can be made by heating uranyl nitrate to form . : This is then converted by heating with hydrogen to form UO2. It can be made from enriched uranium hexafluoride by reacting with ammonia to form a solid called ammonium diuranate, . This is then heated ( calcined) to form and U3O8 which is then converted by heating with hydrogen or ammonia to form UO2. The UO2 is mixed with an organic binder and pressed into pellets. The pellets are then fired at a much highe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Breeder Reactor
A breeder reactor is a nuclear reactor that generates more fissile material than it consumes. These reactors can be fueled with more-commonly available isotopes of uranium and thorium, such as uranium-238 and thorium-232, as opposed to the rare uranium-235 which is used in conventional reactors. These materials are called fertile materials since they can be bred into fuel by these breeder reactors. Breeder reactors achieve this because their neutron economy is high enough to create more fissile fuel than they use. These extra neutrons are absorbed by the fertile material that is loaded into the reactor along with fissile fuel. This irradiated fertile material in turn transmutes into fissile material which can undergo fission reactions. Breeders were at first found attractive because they made more complete use of uranium fuel than light-water reactors, but interest declined after the 1960s as more uranium reserves were foundHelmreich, J. E. ''Gathering Rare Ores: The D ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Fast Neutron
The neutron detection temperature, also called the neutron energy, indicates a free neutron's kinetic energy, usually given in electron volts. The term ''temperature'' is used, since hot, thermal and cold neutrons are moderated in a medium with a certain temperature. The neutron energy distribution is then adapted to the Maxwell distribution known for thermal motion. Qualitatively, the higher the temperature, the higher the kinetic energy of the free neutrons. The momentum and wavelength of the neutron are related through the de Broglie relation. The long wavelength of slow neutrons allows for the large cross section. Neutron energy distribution ranges The precise boundaries of neutron energy ranges are not well defined, and differ between sources, but some common names and limits are given in the following table. The following is a detailed classification: Thermal A thermal neutron is a free neutron with a kinetic energy of about 0.025 eV (about 4.0×10−21 J or 2. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Neutron Moderator
In nuclear engineering, a neutron moderator is a medium that reduces the speed of fast neutrons, ideally without capturing any, leaving them as thermal neutrons with only minimal (thermal) kinetic energy. These thermal neutrons are immensely more susceptible than fast neutrons to propagate a nuclear chain reaction of uranium-235 or other fissile isotope by colliding with their atomic nucleus. Water (sometimes called "light water" in this context) is the most commonly used moderator (roughly 75% of the world's reactors). Solid graphite (20% of reactors) and heavy water (5% of reactors) are the main alternatives. Beryllium has also been used in some experimental types, and hydrocarbons have been suggested as another possibility. Moderation Neutrons are normally bound into an atomic nucleus and do not exist free for long in nature. The unbound neutron has a half-life of 10 minutes and 11 seconds. The release of neutrons from the nucleus requires exceeding the binding ener ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Fast-neutron Reactor
A fast-neutron reactor (FNR) or fast-spectrum reactor or simply a fast reactor is a category of nuclear reactor in which the fission chain reaction is sustained by fast neutrons (carrying energies above 1 MeV, on average), as opposed to slow thermal neutrons used in thermal-neutron reactors. Such a fast reactor needs no neutron moderator, but requires fuel that is comparatively rich in fissile material. The fast spectrum is key to breeder reactors, which convert highly abundant uranium-238 into fissile plutonium-239, without requiring enrichment. It also leads to high burnup: many transuranic isotopes, such as of americium and curium, accumulate in thermal reactor spent fuel; in fast reactors they undergo fast fission, reducing total nuclear waste. As a strong fast-spectrum neutron source, they can also be used to transmute existing nuclear waste into manageable or non-radioactive isotopes. These characteristics also cause fast reactors to be judged a higher n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
