Nuclear fission differs from other forms of radioactive decay in that it can be harnessed and controlled via a chain reaction: free neutrons released by each fission event can trigger yet more events, which in turn release more neutrons and cause more fissions. Chemical isotopes that can sustain a fission chain reaction are called nuclear fuels, and are said to be fissile. The most common nuclear fuels are 235U (the isotope of uranium with an atomic mass of 235) and 239Pu (the isotope of plutonium with an atomic mass of ...

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Nuclear fission, Nuclear fission - Physical overview, Nuclear fission - Spontaneous and induced fission; chain reactions, Nuclear fission - Fission reactors, Nuclear fission - Fission bombs, Nuclear fission - History, Nuclear fission - Links

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Nuclear fission, Nuclear fission - Physical overview, Nuclear fission - Spontaneous and induced fission; chain reactions, Nuclear fission - Fission reactors, Nuclear fission - Fission bombs, Nuclear fission - History, Nuclear fission - Links

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Nuclear fission differs from other forms of radioactive decay in that it can be harnessed and controlled via a chain reaction: free neutrons released by each fission event can trigger yet more events, which in turn release more neutrons and cause more fissions. Chemical isotopes that can sustain a fission chain reaction are called nuclear fuels, and are said to be fissile. The most common nuclear fuels are 235U (the isotope of uranium with an atomic mass of 235) and 239Pu (the isotope of plutonium with an atomic mass of ...

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Nuclear fission, Nuclear fission - Physical overview, Nuclear fission - Spontaneous and induced fission; chain reactions, Nuclear fission - Fission reactors, Nuclear fission - Fission bombs, Nuclear fission - History

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Nuclear fission (in nuclear physics, simply fission) is a process in which the nucleus of an atom splits into two or more smaller nuclei (fission products) and usually some by-product particles. Hence, fission is a form of elemental transmutation. The by-products include free neutrons, photons (usually gamma rays), and other nuclear fragments such as beta particles and alpha particles. Fission of heavy elements can release substantial amounts of useful energy both ...

Including:

Nuclear fission - Physical overview
Nuclear fission - Fission reactors Nuclear fission - Fission bombs
Nuclear fission - History Nuclear fission - Links

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In general fission is a splitting or breaking up into parts. In physics, nuclear fission is a process where a large nucleus such as uranium is split into two smaller nuclei. In biology, binary fission refers to the process whereby a prokaryote reproduces by cell division. It is similar to mitosis and meiosis in eukaryotes. In anthropology, fission refers to the process whereby a nationstate divides and becomes multiple states (example: Yugoslavia). ...

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Some of the fission products generated during a nuclear reaction have a high neutron absorption capacity, such as xenon-135 and samarium-149. Because these two fission product poisons remove neutrons from the reactor, they will have an impact on the thermal utilization factor and thus the reactivity. The poisoning of a reactor core by these fission products may become so serious that the chain reaction comes to a standstill. 135Xe in particular has a tremendous impact on the operation of a nuclear reactor. The inability of ...

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Nuclear poison, Nuclear poison - Fission Product Poison, Nuclear poison - Decay Poisons, Nuclear poison - Control Poisons, Nuclear poison - Burnable poisons, Nuclear poison - Non-burnable poison, Nuclear poison - Soluble poisons

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A chain reaction is a sequence of reactions where a reactive product or by-product causes additional reactions. The neutron-fission chain reaction: a neutron plus a fissionable atom causes a fission resulting in a larger number of neutrons than was consumed in the initial reaction. Chemical reactions, where a product of a reaction is itself a reactive particle which can cause more similar reactions. For example, every step of H2 + Cl2 chain reaction consumes one molecule of H

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Binary fission is the form of asexual reproduction used by most prokaryotes to reproduce. This process results in the reproduction of a living cell by division into two equal or near-equal parts. Binary fission begins when the DNA replication occurs. Each circular DNA strand then attaches to the plasma membrane. The cell elongates, causing the two chromosomes to separate. The plasma membrane then invaginates (grows inwards) and splits the cell into two daughter cells through a process called cytokinesis. Organisms that reproduce ...

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In physics, nuclear fusion is the process by which two nuclei join together to form a heavier nucleus. It is accompanied by the release or absorption of energy depending on the masses of the nuclei involved. Iron and nickel nuclei have the largest binding energies of all nuclei and therefore are the most stable. The fusion of two nuclei to produce a nucleus lighter than iron or nickel generally gives off energy while t ...

Including:

Nuclear fusion - Requirements for fusion
Nuclear fusion - Methods of fuel confinement
Nuclear fusion - Important fusion reactions
Nuclear fusion - Astrophysical reaction chains Nuclear fusion - Criteria and candidates for terrestrial reactions Nuclear fusion - Neutronicity confinement requirement and power density Nuclear fusion - Bremsstrahlung losses

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A nuclear weapon is a weapon which derives its destructive force from the nuclear reactions of nuclear fission and/or fusion. As a result, even a nuclear weapon with a small yield is significantly more powerful than the largest conventional explosives, and a single weapon can be capable of destroying or seriously disabling an entire city. In the history of warfare, nuclear weapons have been used on two occasions, both during the closing days of World War II. The first event occurred on the morning of 6 August 1945, when the Uni ...

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Nuclear weapon - Types of nuclear weapons Nuclear weapon - Effects of a nuclear explosion Nuclear weapon - Nuclear strategy Nuclear weapon - Weapons delivery Nuclear weapon - History Nuclear weapon - Media

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After iron the binding energy per nucleon begins decreasing, so it is possible for energy to be released if a heavy nucleus breaks apart into two lighter ones. This splitting of atoms is known as nuclear fission. This is the source of energy for nuclear power plants and conventional nuclear bombs like the two that the United States used to destroy the buildings and civilians of Hiroshima and Nagasaki. Nuclear reactions occur naturally on Earth, and are in fact quite common. These include alpha decay and beta decay, and heavy nuclei su ...

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Atomic nucleus, Atomic nucleus - Nuclear Makeup, Atomic nucleus - Isotopes, Atomic nucleus - Nuclear Decay, Atomic nucleus - Nucleus Size, Atomic nucleus - History, Atomic nucleus - Nuclear Fusion, Atomic nucleus - Nuclear Fission, Atomic nucleus - Production of Heavy Elements, Atomic nucleus - Nuclear Physics

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A criticality accident (also sometimes referred to as an "excursion" or "power excursion") occurs when a nuclear chain reaction is accidentally allowed to occur in fissile material, such as enriched uranium or plutonium. This releases neutron radiation which is highly dangerous to surrounding personnel and which causes induced radioactivity in the surroundings. When such incidents occur outside reactor cores and test facilities where fission is intended to occur, they pose a high risk both of injury or death to su ...

Including:

Criticality accident - Cause Criticality accident - Description
Criticality accident - Confusion with Cherenkov radiation and other effects
Criticality accident - Records

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The simplest nuclear weapons are pure fission bombs. These were the first types of nuclear weapons built during the Manhattan Project and they are a building block for all advanced nuclear weapons designs. Nuclear weapon design - Critical mass. A mass of fissile material is called critical when it is capable of a sustained chain reaction, which depends upon the size, shape and purity of the material as well as what surrounds the material. A numerical measure of whether a mass is critical or not is available as the neutron multiplication factor, k, w ...

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Nuclear weapon design, Nuclear weapon design - Fission weapons, Nuclear weapon design - Critical mass, Nuclear weapon design - Enriched materials, Nuclear weapon design - Efficiency, Nuclear weapon design - Combination methods, Nuclear weapon design - Gun method, Nuclear weapon design - Implosion method, Nuclear weapon design - Comparison of the two methods, Nuclear weapon design - Practical limitations of the fission bomb, Nuclear weapon design - Fusion weapons, Nuclear weapon design - Boosting, Nuclear weapon design - Staged thermonuclear weapons, Nuclear weapon design - Advanced thermonuclear weapons designs, Nuclear weapon design - Miniaturization, Nuclear weapon design - Stockpile stewardship

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The gun method has also been applied for nuclear artillery shells. An advantage is that it is easier to keep the diameter small. A US gun-type nuclear artillery weapon was tested on May 25, 1953 at the Nevada Test Site. Fired as part of Operation Upshot-Knothole and codenamed Shot GRABLE, a 280 mm shell was fired 10,000 m and detonated 160 m above the ground with an estimated yield of 15 kilotons. Thus it had approximately the same yield as Little Boy, although it weig ...

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Gun-type fission weapon, Gun-type fission weapon - Little Boy, Gun-type fission weapon - Proliferation and terrorism, Gun-type fission weapon - Comparison with the implosion method, Gun-type fission weapon - US nuclear artillery

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In a nuclear reactor, the buildup of fission products as reaction poisons in the fuel eventually leads to loss of efficiency, and in some cases to instability. They contribute most of the short and medium term radioactivity of high-level nuclear waste produced from spent reactor fuel. Depending on the quality of the fuel cladding can appear in the primary coolant. In a well designed power reactor running under normal conditions the radioactivity of the coolant is very low, in the BWR reactors the bulk of the activity in the coolant is due to ...

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Fission product, Fission product - Physical process of nuclear fission, Fission product - Mass vs. yield curve, Fission product - FPs in power reactors, Fission product - Fission products listed according to atomic number, Fission product - Krypton, Fission product - Strontium, Fission product - Zirconium, Fission product - Molybdenum, Fission product - Technetium, Fission product - Ruthenium, Fission product - Rhodium, Fission product - Palladium, Fission product - Tellurium-132, Fission product - Iodine, Fission product - Xenon, Fission product - Cesium, Fission product - Barium, Fission product - Lanthanides Lanthanum cerium neodymium and samarium, Fission product - Countermeasures against the worst fission products found in accident fallout, Fission product - Iodine, Fission product - Cesium, Fission product - Strontium, Fission product - Fission products within the back end of the nuclear fuel cycle

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Suppose a fission caused by a neutron hitting a nucleus produces 3 neutrons (i.e. 2 extra). Also suppose k > 1. The probability that a neutron causes a fission is k / 3. The probability that a free neutron does not cause a chain reaction is (1 - k / 3) (no fission at all) plus the probability of at least one fission, while none of the 3 neutrons produced causes a chain reaction. The latter has a probability of k / 3 times the cube of the first-mentioned probability that a free neutron does not cause a chain reaction. ...

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Nuclear chain reaction, Nuclear chain reaction - Numerical example for the probability of a chain reaction, Nuclear chain reaction - Predetonation

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For fission of Uranium-235 the most common radioactive fission products include isotopes of Iodine, Caesium, Strontium, Xenon and Barium. Many of the fission products decay through very shortlived isotopes to form stable isotopes, but also a considerable number of the radioisotopes have half lives longer than a day. Some fission products are useful as beta and gamma sources in medicine and industry, see common beta emitters and commonly used gamma emitting isotopes for more details. Few fission products are alpha particle emitters, but ...

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Fission product, Fission product - Physical process of nuclear fission, Fission product - Mass vs. yield curve, Fission product - FPs in power reactors, Fission product - Fission products listed according to atomic number, Fission product - Krypton, Fission product - Strontium, Fission product - Zirconium, Fission product - Molybdenum, Fission product - Technetium, Fission product - Ruthenium, Fission product - Rhodium, Fission product - Palladium, Fission product - Tellurium-132, Fission product - Iodine, Fission product - Xenon, Fission product - Cesium, Fission product - Barium, Fission product - Lanthanides Lanthanum cerium neodymium and samarium, Fission product - Countermeasures against the worst fission products found in accident fallout, Fission product - Iodine, Fission product - Cesium, Fission product - Strontium, Fission product - Fission products within the back end of the nuclear fuel cycle

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The mixture of radioactive fission products found in the fall out from a nuclear bomb are very different in nature to those found in spent power reactor fuel. This is because the reactor fuel will have had more time for the short lived isotopes to decay. Fission product - Iodine. At least three isotopes of iodine are important. 129I, 131I and 132I A counter measure against the shortlived iodine isotopes (such as 131I), is to take potassium iodide by mouth. ...

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Fission product, Fission product - Physical process of nuclear fission, Fission product - Mass vs. yield curve, Fission product - FPs in power reactors, Fission product - Fission products listed according to atomic number, Fission product - Krypton, Fission product - Strontium, Fission product - Zirconium, Fission product - Molybdenum, Fission product - Technetium, Fission product - Ruthenium, Fission product - Rhodium, Fission product - Palladium, Fission product - Tellurium-132, Fission product - Iodine, Fission product - Xenon, Fission product - Cesium, Fission product - Barium, Fission product - Lanthanides Lanthanum cerium neodymium and samarium, Fission product - Countermeasures against the worst fission products found in accident fallout, Fission product - Iodine, Fission product - Cesium, Fission product - Strontium, Fission product - Fission products within the back end of the nuclear fuel cycle

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If a graph of the mass or mole yield of fission products against the atomic mass of the fragments is drawn then it has two peaks, one in the area strontium through to palladium and one at iodine through to neodymium. This is due to the fact that the fission event causes the nucleus to split in an asymmetric manner.[1] Yield vs. Z - This is a typical distribution for the fission of uranium. Please note in the calculations used to make this graph the activation of fission products was ignored and the fission was assumed to occur in a single moment rather than a length of time. In this bar chart results are ...

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Fission product, Fission product - Physical process of nuclear fission, Fission product - Mass vs. yield curve, Fission product - FPs in power reactors, Fission product - Fission products listed according to atomic number, Fission product - Krypton, Fission product - Strontium, Fission product - Zirconium, Fission product - Molybdenum, Fission product - Technetium, Fission product - Ruthenium, Fission product - Rhodium, Fission product - Palladium, Fission product - Tellurium-132, Fission product - Iodine, Fission product - Xenon, Fission product - Cesium, Fission product - Barium, Fission product - Lanthanides Lanthanum cerium neodymium and samarium, Fission product - Countermeasures against the worst fission products found in accident fallout, Fission product - Iodine, Fission product - Cesium, Fission product - Strontium, Fission product - Fission products within the back end of the nuclear fuel cycle

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The method is roughly how the "Little Boy" weapon which was detonated over Hiroshima worked, using uranium-235 as its enriched material. In detail, it most likely utilized some arrangement of a uranium "bullet" powered by a cordite charge into a target of uranium rings, rather than using two hemispheres. The use of "rings" had two advantages: it allowed the target to confidently remain subcritical (the hollow column served to keep the material from having too much contact with other material), and it allowed sub-critical assemblies to be ...

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Gun-type fission weapon, Gun-type fission weapon - Little Boy, Gun-type fission weapon - Proliferation and terrorism, Gun-type fission weapon - Comparison with the implosion method, Gun-type fission weapon - US nuclear artillery

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