And like a controlled flame, a nuclear reaction can provide useful energy.
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The answer lies in some basic understanding of how a nuclear reaction is being created.
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Russian officials have said the crew contained the fire and isolated the submarine's nuclear reaction.
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The proposed new nuclear cruise missile would shorten nuclear reaction times and risk miscalculation in a crisis.
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Related: North Korea Claims It Just Successfully Detonated a Hydrogen Bomb The other flavor of nuclear reaction is fusion.
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DOE focuses upon the science of the nuclear reaction itself, exploring what's possible, and how it can be used.
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In it, he hypothesised that what makes the sun shine—then a matter of much debate—was some sort of nuclear reaction.
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In general, nuclear power works by using the heat from a nuclear reaction to generate steam, which drives a turbine to generate electricity.
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LAUNCHING NUCLEAR WASTE INTO THE SUN How about launching it into the Sun, which is, after all, just a giant sustained nuclear reaction?
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"Kessler Syndrome is global warming; it's not a nuclear reaction—it's this relatively slow accumulation that has accelerating negative effects in the future," Weeden said.
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CNBC explains… A hydrogen bomb is a type of nuclear bomb, just like an atomic bomb, where the explosive energy comes from as nuclear reaction.
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It helped a local firm that had previously made boilers learn how to make the hulking metre-thick metal vessels that can safely contain a nuclear reaction.
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Instead, all that energy is created through a nuclear reaction, which slams hydrogen atoms together to create larger helium atoms and some extra energy on the side.
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In the meantime, Shaughnessy has moved on to other projects studying nuclear reaction rates studying other heavier elements, this time relevant both to astrophysics and to national security.
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The boron control rods used to slow reactions were tipped with graphite, meaning that during an emergency shutdown, the rods would briefly stoke the nuclear reaction before damping it down.
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The experiments at issue are known as subcritical tests, because when neutrons from fissile materials interact fiercely enough to initiate a self-sustaining nuclear reaction, they've achieved a critical state.
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The authority was referring to ruthenium 106, the radioactive isotope identified by the monitoring stations that does not occur naturally and is the product of splitting atoms in a nuclear reaction.
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The bottom of the reactor looked like a collection of huge bolts — the access points for control rods used to speed up and slow down the nuclear reaction inside a healthy reactor.
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For his achievement, Dr. Goldwasser received a gift of Chianti wine, the same brand with which Enrico Fermi and his team celebrated when they created the first controlled nuclear reaction in 1942.
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Commonwealth Fusion expects to have its smallest possible reactor built by 2025 thanks to the research that MIT has done on proprietary magnet technology that the company uses to confine its nuclear reaction.
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"The United States has determined that the explosion near Nyonoksa, Russia, was the result of a nuclear reaction that occurred during the recovery of a Russian nuclear-powered cruise missile," the official wrote.
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It is at this point that the matter eventually collapses in on itself and goes through a nuclear reaction called fusion, when the material which has collapsed inwards begins to resemble a bright star.
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Sometimes a massive cloud will collapse in on itself and pull in more materials, causing the core of the cloud to grow so dense and so hot that it begins the nuclear reaction that births a star.
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An August 8 nuclear accident near Nyonoksa, Russia, was caused by a nuclear reaction that occurred while Russians were attempting to recover a nuclear-powered cruise missile submerged in the White Sea after a failed test last year.
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Under the nuclear deal, Iran is allowed to stockpile up to 300 kilograms (660 pounds) of low-enriched uranium, which has somewhere between a 3% and 4% concentration of the fissile isotope needed to set off a nuclear reaction.
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Instead of simulating solitaire games or neutrons in a nuclear reaction, the company's future stock price is simulated thousands of times, following a standard random model for how stock prices evolve over time, using data on the stock's historical performance.
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Given the PR aspects of the mission, US officials likely would have wanted to make sure the nuclear reaction was visible from Earth, and it likely would have been, according to Areg Danagoulian, an assistant professor of nuclear science and engineering at MIT.
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In late summer, she was in Washington, D.C., lobbying for the military to promote an alternative (and scientifically dubious) clean energy source called low-energy nuclear reaction, when she heard of a military veteran who was a forceful advocate for environmental conservation.
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Industry advocates say that by removing sources of clean electricity — a nuclear reaction produces no carbon dioxide or other greenhouse gases — the closings could affect the government's ability to fulfill its pledge, made at the Paris climate talks last year, to reduce emissions.
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Thomas DiNanno, a senior U.S. State Department official, said last week that Washington had determined that the explosion was the result of a nuclear reaction that had occurred during the recovery of a Russian nuclear-powered cruise missile after a failed test.
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After arriving in the US, Fermi led the world's first self-sustaining nuclear reaction at the University of Chicago and played an indispensable role in the Manhattan Project, which led to the end of World War II in the Pacific and laid the groundwork for a new world order and America's prominent role.
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In a report presented to the UN General Assembly this month, the US State Department said the nuclear accident near Nyonoksa, Russia, was caused by a nuclear reaction that occurred while Russians were attempting to recover a nuclear-powered cruise missile submerged in the White Sea after a failed test last year.
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To get a better understanding of the statistical behavior of neutrons in a nuclear explosion, Ulam and von Neumann used the early computers available to the Manhattan Project to simulate the random behavior of a large number of individual neutrons, averaging that behavior together to better understand the workings of the nuclear reaction.
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The (n-p) reaction, or (n,p) reaction, is an example of a nuclear reaction. It is the reaction which occurs when a neutron enters a nucleus and a proton leaves the nucleus simultaneously. For example, sulfur-32 (32S) undergoes an (n,p) nuclear reaction when bombarded with neutrons, thus forming phosphorus-32 (32P). The nuclide nitrogen-14 (14N) can also undergo an (n,p) nuclear reaction to produce carbon-14 (14C).
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Thus, for high-energy neutrons, beryllium is a neutron multiplier, releasing more neutrons than it absorbs. This nuclear reaction is: : + n → 2 + 2 n Neutrons are liberated when beryllium nuclei are struck by energetic alpha particles producing the nuclear reaction : + → + n where is an alpha particle and is a carbon-12 nucleus. Beryllium also releases neutrons under bombardment by gamma rays. Thus, natural beryllium bombarded either by alphas or gammas from a suitable radioisotope is a key component of most radioisotope-powered nuclear reaction neutron sources for the laboratory production of free neutrons.
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In this symbolic representing of a nuclear reaction, lithium-6 () and deuterium () react to form the highly excited intermediate nucleus which then decays immediately into two alpha particles of helium-4 (). Protons are symbolically represented by red spheres, and neutrons by blue spheres. In nuclear physics and nuclear chemistry, a nuclear reaction is semantically considered to be the process in which two nuclei, or a nucleus and an external subatomic particle, collide to produce one or more new nuclides. Thus, a nuclear reaction must cause a transformation of at least one nuclide to another.
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The tumor cells are strongly positive for vimentin, CD34, and sometimes with CD99. There is often (up to 2/3rds) a nuclear reaction with β-catenin.
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One of the many projects of JINA-CEE is the maintenance of an up-to-date nuclear reaction rate library called REACLIB. REACLIB contains over 75,000 thermonuclear reaction rates.
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Nuclear reaction analysis (NRA) is a nuclear method of nuclear spectroscopy in materials science to obtain concentration vs. depth distributions for certain target chemical elements in a solid thin film.
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In 1977, researchers at the Joint Institute for Nuclear Research bombarded plutonium-244 atoms with calcium-48, but were again unsuccessful. This nuclear reaction was repeated in 1998, this time successfully.
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The nuclear reaction theorised by Meitner and Frisch. Nuclear fission was discovered in December 1938 by physicists Lise Meitner and Otto Robert Frisch and chemists Otto Hahn and Fritz Strassmann. Fission is a nuclear reaction or radioactive decay process in which the nucleus of an atom splits into two or more smaller, lighter nuclei. The fission process often produces gamma rays and releases a very large amount of energy, even by the energetic standards of radioactive decay.
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He stayed on at Surrey to pursue a Doctor of Philosophy degree in nuclear reaction theory, which he obtained in 1989, rather than accepting a job offer from the National Physical Laboratory.
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13N decays by positron emission with a half-life of 9.97 min. It is produced by the nuclear reaction :1H + 16O → 13N + 4He 13N is used in positron emission tomography (PET scan).
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Neutron capture therapy, which depends on a secondary nuclear reaction, is also not considered here. Muon therapy, a rare type of particle therapy not within the categories above, has also been attempted.
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High energy electrons of >50 MeV may cause the same phenomenon, by coupling to the nucleus via a "virtual gamma photon", in a nuclear reaction that is the inverse (i.e., reverse) of internal conversion decay.
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PWR reactors are very stable due to their tendency to produce less power as temperatures increase; this makes the reactor easier to operate from a stability standpoint. PWR turbine cycle loop is separate from the primary loop, so the water in the secondary loop is not contaminated by radioactive materials. PWRs can passively scram the reactor in the event that offsite power is lost to immediately stop the primary nuclear reaction. The control rods are held by electromagnets and fall by gravity when current is lost; full insertion safely shuts down the primary nuclear reaction.
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A reaction with a negative Q value is endothermic, i.e. requires a net energy input, since the kinetic energy of the final state is less than the kinetic energy of the initial state. Observe that a chemical reaction is exothermic when it has a negative enthalpy of reaction, in contrast a positive Q value in a nuclear reaction. The Q value can also be expressed in terms of the binding energies of the nuclear species as: Q=B_f- B_i Proof: Note that the count of nucleons is conserved in a nuclear reaction.
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As a result of its extreme rarity in nature, most francium is synthesised in the nuclear reaction 197Au + 18O → 210Fr + 5 n, yielding francium-209, francium-210, and francium-211. The greatest quantity of francium ever assembled to date is about 300,000 neutral atoms, which were synthesised using the nuclear reaction given above. When the only natural isotope francium-223 is specifically required, it is produced as the alpha daughter of actinium-227, itself produced synthetically from the neutron irradiation of natural radium-226, one of the daughters of natural uranium-238.
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A nucleogenic isotope, or nuclide, is one that is produced by a natural terrestrial nuclear reaction, other than a reaction beginning with cosmic rays (the latter nuclides by convention are called by the different term cosmogenic). The nuclear reaction that produces nucleogenic nuclides is usually interaction with an alpha particle or the capture of fission or thermal neutrons. Some nucleogenic isotopes are stable and others are radioactive. An example of a nucleogenic nuclide is neon-21 produced from neon-20 that absorbs a thermal neutron (though some neon-21 is also primordial).
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Paris (série D), 264, 1967, p. 292-295 and perform boron imagingMartini, F., Thellier, M., « Use of a (n,α) nuclear reaction to study the long-distance transport of boron in Trifolium repens after foliar application », Planta, 150, 1980, p. 197-205 in plant samples. He generalized the Li, N and O method for animal and plant samples, obtaining in particular the first image of the distribution of lithiumThellier, M., Wissocq, J.C., Heurteaux, C., « Quantitative location of lithium in the brain by a (n,α) nuclear reaction », Nature, 283, 1980, p.
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The reactor vessel is the first layer of shielding around the nuclear fuel and usually is designed to trap most of the radiation released during a nuclear reaction. The reactor vessel is also designed to withstand high pressures.
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This nuclear reaction 14N (n,p) 14C continually happens in the Earth's atmosphere, forming equilibrium amounts of the radionuclide 14C. Most (n,p) reactions have threshold neutron energies below which the reaction cannot take place as a result of the charged particle in the exit channel requiring energy (usually more than a MeV) to overcome the Coulomb barrier experienced by the emitted proton. The (n,p) nuclear reaction 14N (n,p) 14C is an exception to this rule, and is exothermic – it can take place at all incident neutron energies. The 14N (n,p) 14C nuclear reaction is responsible for most of the radiation dose delivered to the human body by thermal neutrons – these thermal neutrons are absorbed by the nitrogen 14N in proteins, causing a proton to be emitted; the emitted proton deposits its kinetic energy over a very short distance in the body tissue, thereby depositing radiation dose.
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The mineral is being used for detection of solar neutrino via a certain nuclear reaction involving thallium. It has a monoclinic crystal structure consisting of spiral chains of AsS3 tetrahedra interconnected by thallium atoms, and can be synthesized in the laboratory.
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If irradiated with select projectile nuclei at kinetic energies Ekin, target solid thin-film chemical elements can undergo a nuclear reaction under resonance conditions for a sharply defined resonance energy. The reaction product is usually a nucleus in an excited state which immediately decays, emitting ionizing radiation. To obtain depth information the initial kinetic energy of the projectile nucleus (which has to exceed the resonance energy) and its stopping power (energy loss per distance traveled) in the sample has to be known. To contribute to the nuclear reaction the projectile nuclei have to slow down in the sample to reach the resonance energy.
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Irène Curie and Frédéric Joliot in their Paris laboratory in 1935. Patrick Blackett was able to accomplish nuclear transmutation of nitrogen into oxygen in 1925, using alpha particles directed at nitrogen. In modern notation for the atomic nuclei, the reaction was: : + → + p This was the first observation of a nuclear reaction, that is, a reaction in which particles from one decay are used to transform another atomic nucleus. A fully artificial nuclear reaction and nuclear transmutation was achieved in April 1932 by Ernest Walton and John Cockcroft, who used artificially accelerated protons against lithium, to break this nucleus into two alpha particles.
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Although the Chernobyl accident had dire off-site effects, much of the radioactivity remained within the building. If the building were to fail and dust were to be released into the environment, the release of a given mass of fission products that have aged for almost thirty years would have a smaller effect than the release of the same mass of fission products (in the same chemical and physical form) that had only undergone a short cooling time (such as one hour) after the nuclear reaction had terminated. If a nuclear reaction were to occur again within the Chernobyl plant (for instance if rainwater were to collect and act as a moderator), however, then the new fission products would have a higher specific activity and thus pose a greater threat if they were released. To prevent a post-accident nuclear reaction, steps have been taken, such as adding neutron poisons to key parts of the basement.
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If a nucleus interacts with another nucleus or particle and they then separate without changing the nature of any nuclide, the process is simply referred to as a type of nuclear scattering, rather than a nuclear reaction. In principle, a reaction can involve more than two particles colliding, but because the probability of three or more nuclei to meet at the same time at the same place is much less than for two nuclei, such an event is exceptionally rare (see triple alpha process for an example very close to a three-body nuclear reaction). The term "nuclear reaction" may refer either to a change in a nuclide induced by collision with another particle, or to a spontaneous change of a nuclide without collision. Natural nuclear reactions occur in the interaction between cosmic rays and matter, and nuclear reactions can be employed artificially to obtain nuclear energy, at an adjustable rate, on demand.
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The Coulomb barrier, named after Coulomb's law, which is in turn named after physicist Charles-Augustin de Coulomb, is the energy barrier due to electrostatic interaction that two nuclei need to overcome so they can get close enough to undergo a nuclear reaction.
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The site was named a Chicago Landmark on October 27, 1971. A Henry Moore sculpture, Nuclear Energy, in a small quadrangle commemorates the location of the nuclear experiment.Site of First Self-Sustaining Nuclear Reaction, NHL Database, National Historic Landmarks Program. Retrieved 11 February 2007.
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Some scientists reported excess heat, neutrons, tritium, helium and other nuclear effects in so-called cold fusion systems, which for a time gained interest as showing promise. Hopes fell when replication failures were weighed in view of several reasons cold fusion is not likely to occur, the discovery of possible sources of experimental error, and finally the discovery that Fleischmann and Pons had not actually detected nuclear reaction byproducts. By late 1989, most scientists considered cold fusion claims dead, and cold fusion subsequently gained a reputation as pathological science. However, a small community of researchers continues to investigate cold fusion claiming to replicate Fleischmann and Pons' results including nuclear reaction byproducts.
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Nitrogen-14 is the source of naturally-occurring, radioactive, carbon-14. Some kinds of cosmic radiation cause a nuclear reaction with nitrogen-14 in the upper atmosphere of the Earth, creating carbon-14, which decays back to nitrogen-14 with a half-life of 5,730 ± 40 years.
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A reactor protection system is designed to immediately terminate the nuclear reaction. By breaking the nuclear chain reaction, the source of heat is eliminated. Other systems can then be used to remove decay heat from the core. All nuclear plants have some form of reactor protection system.
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It is also used as a means to record ionizing radiation exposure from gamma rays, beta particles, and neutrons (indirectly, using the (n,alpha) nuclear reaction) in thermoluminescent dosimeters. 6LiF nanopowder enriched to 96% has been used as the neutron reactive backfill material for microstructured semiconductor neutron detectors (MSND).
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Nuclear collision length is the mean free path of a particle before undergoing a nuclear reaction, for a given particle in a given medium. The collision length is smaller than the nuclear interaction length because the latter excludes the elastic and quasi-elastic (diffractive) reactions from its definition.
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Ernest Rutherford commented in the article that inefficiencies in the process precluded use of it for power generation. However, the neutron had been discovered in 1932, shortly before, as the product of a nuclear reaction. Szilárd, who had been trained as an engineer and physicist, put the two nuclear experimental results together in his mind and realized that if a nuclear reaction produced neutrons, which then caused further similar nuclear reactions, the process might be a self- perpetuating nuclear chain-reaction, spontaneously producing new isotopes and power without the need for protons or an accelerator. Szilárd, however, did not propose fission as the mechanism for his chain reaction, since the fission reaction was not yet discovered, or even suspected.
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Human antimicrobial peptides which are toxic to viruses, fungi, bacteria and cancerous cells are considered a part of the immune system. In nuclear physics, a poison is a substance that obstructs or inhibits a nuclear reaction. For an example, see nuclear poison. Environmentally hazardous substances are not necessarily poisons, and vice versa.
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Small amounts of tritium are liberated when nuclei absorb low energy neutrons in the three- step nuclear reaction : + n → + , → + β−, \+ n → + Note that has a half- life of only 0.8 seconds, β− is an electron, and has a high neutron absorption cross-section. Tritium is a radioisotope of concern in nuclear reactor waste streams.
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Topical Conferences - Type B These concentrate on broad sub- fields (e.g. nuclear spectroscopy, nuclear reaction mechanisms, heavy ion physics, are possible sub-fields in the field of Nuclear Physics). They would normally be scheduled in the years between the corresponding Type A General conferences. Attendance in the range of 300-600 would be anticipated.
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Fuel is discharged not because fissile material is fully used-up, but because the neutron-absorbing fission products have built up and the fuel becomes significantly less able to sustain a nuclear reaction. Some natural uranium fuels use chemically active cladding, such as Magnox, and need to be reprocessed because long-term storage and disposal is difficult.
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Nuclear Energy is on Ellis Avenue, between the Max Palevsky West dormitory and the Mansueto Library in the Hyde Park community area of Chicago. It sits on the very spot where the Manhattan Project team built a nuclear reactor to produce the first self-sustaining controlled nuclear reaction, under the now-demolished west stands of the old Stagg Field.
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In nuclear physics and chemistry, the Q value for a reaction is the amount of energy absorbed or released during the nuclear reaction. The value relates to the enthalpy of a chemical reaction or the energy of radioactive decay products. It can be determined from the masses of reactants and products. Q values affect reaction rates.
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Exposure to radiation causes chemical changes in gases. The least susceptible to damage are noble gases, where the major concern is the nuclear transmutation with follow-up chemical reactions of the nuclear reaction products. High-intensity ionizing radiation in air can produce a visible ionized air glow of telltale bluish-purplish color. The glow can be observed e.g.
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Like cosmic rays, as noted, this secondary muon radiation is also directional. The same nuclear reaction described above (i.e. hadron-hadron impacts to produce pion beams, which then quickly decay to muon beams over short distances) is used by particle physicists to produce muon beams, such as the beam used for the muon g−2 experiment.
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Although the foundations of nuclear astrophysics appear clear and plausible, many puzzles remain. One example from nuclear reaction physics is helium fusion (specifically the 12C(α,γ)16O reaction), others are the astrophysical site of the r-process, anomalous lithium abundances in Population III stars, and the explosion mechanism in core-collapse supernovae and the progenitors of thermonuclear supernovae.
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In 1919, Ernest Rutherford was able to accomplish transmutation of nitrogen into oxygen at the University of Manchester, using alpha particles directed at nitrogen 14N + α → 17O + p. This was the first observation of an induced nuclear reaction, that is, a reaction in which particles from one decay are used to transform another atomic nucleus. Eventually, in 1932 at Cambridge University, a fully artificial nuclear reaction and nuclear transmutation was achieved by Rutherford's colleagues John Cockcroft and Ernest Walton, who used artificially accelerated protons against lithium-7, to split the nucleus into two alpha particles. The feat was popularly known as "splitting the atom", although it was not the modern nuclear fission reaction later discovered in heavy elements, in 1938 by the German scientists Otto Hahn, Lise Meitner, and Fritz Strassmann.
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However, the University of Chicago says it is only in height. The Henry Moore Foundation lists its height at 3.66m. The sculpture was erected for and dedicated at the celebration of the 25th anniversary of the initiation of the first self-sustaining controlled nuclear reaction by Enrico Fermi on December 2, 1942. It was unveiled at precisely 3:36 p.m.
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This often activates the nucleus, putting it into an excited, unstable, short-lived energy state which causes it to quickly emit some kind of radiation to bring it back down to a stable or ground state. Alpha, beta, gamma, and protons may be emitted. Particles scattered in this type of nuclear reaction may cause the nucleus to recoil in the other direction.
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Meitner, and her nephew Otto Robert Frisch, correctly interpreted these results as being nuclear fission.Lise Meitner and O. R. Frisch Disintegration of Uranium by Neutrons: a New Type of Nuclear Reaction, Nature, Volume 143, Number 3615, 239-240 (11 February 1939). The paper is dated 16 January 1939. Meitner is identified as being at the Physical Institute, Academy of Sciences, Stockholm.
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Refractory metals are used in lighting, tools, lubricants, nuclear reaction control rods, as catalysts, and for their chemical or electrical properties. Because of their high melting point, refractory metal components are never fabricated by casting. The process of powder metallurgy is used. Powders of the pure metal are compacted, heated using electric current, and further fabricated by cold working with annealing steps.
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Z is not decremented but incremented. This was the first reported nuclear reaction, 14N + α → 17O + p. Depending on one's perspective, either 1919 or 1925 may be regarded as the moment when the proton was 'discovered'. Rutherford knew hydrogen to be the simplest and lightest element and was influenced by Prout's hypothesis that hydrogen was the building block of all elements.
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Later, he fought in Volkhov Front. In March 1942 he was ordered to leave the army and join evacuated Radium Institute scientists in Kazan. In 1943, Petrzhak studied neutron induced fission of uranium under the supervision of professor Piotr Lukirski. In 1944, Petrzhak proposed a method to determine the number of neutrons present during a nuclear reaction, based on the number of protons.
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From 1928 Pose was an unsalaried assistant and from 1930 a regular assistant to the physicist Gerhard Hoffmann, who was doing research in nuclear reaction measurements.G. Hoffmann Zur Methodik der Atomzertrümmerungsmessungen, Zeitschrift für Physik Volume 73, Numbers 9-10, 578-579 (1932). The author was identified as being at Halle in Saale (Halle University). The article was received on 6 December 1931.
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Post-primordial isotopes were created by cosmic ray bombardment as cosmogenic nuclides (e.g., tritium, carbon-14), or by the decay of a radioactive primordial isotope to a radioactive radiogenic nuclide daughter (e.g. uranium to radium). A few isotopes are naturally synthesized as nucleogenic nuclides, by some other natural nuclear reaction, such as when neutrons from natural nuclear fission are absorbed by another atom.
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A pebble bed reactor using high mass-flow gaseous nitrogen coolant near normal atmospheric pressures is a possible heat source. Power generation could be accomplished with gas turbine technology, which is well developed. Nuclear fuel would be highly enriched uranium encapsulated in low- boron graphite balls probably 5–10 cm in diameter. The graphite would also moderate the neutrons of the nuclear reaction.
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52 he patented such a device made with a multi-anode vacuum tube in 1943."Electronic switching device", Wilcox P. Overbeck's US Patent No. 2427533, filed in 1943 At the Met Lab in Chicago, he used such counters to scale the rate of detected ionization events, to estimate the rate of the nuclear reaction in the Chicago Pile-1, Enrico Fermi's famous first critial nuclear reactor.
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Spent fuel pool at a nuclear power plant Spent nuclear fuel, occasionally called used nuclear fuel, is nuclear fuel that has been irradiated in a nuclear reactor (usually at a nuclear power plant). It is no longer useful in sustaining a nuclear reaction in an ordinary thermal reactor and depending on its point along the nuclear fuel cycle, it may have considerably different isotopic constituents.
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In order to start up a controllable fission reaction, the assembly must be delayed-critical. In other words, k must be greater than 1 (supercritical) without crossing the prompt-critical threshold. In nuclear reactors this is possible due to delayed neutrons. Because it takes some time before these neutrons are emitted following a fission event, it is possible to control the nuclear reaction using control rods.
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Electrochemical, metallurgy, nuclear reaction in condensed matter, elucidation of the peculiar behavior of hydrogen in the metal, hydrogen penetration in metals, hydrogen embrittlement, hydrogen production, hydrogen separation and purification, power conversion of hydrogen, elucidation of hydrogen behavior, development of unique methods using hydrogen isotopes, studying the behavior of hydrogen on metal. Mizuno has also written Numerous books representing the interaction between hydrogen and the metals.
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Safety concepts rely on a negative temperature coefficient of reactivity and a large possible temperature rise to limit reactivity excursions. As an additional method for shutdown, a separate, passively cooled container below the reactor can be included. In case of problems and for regular maintenance the fuel is drained from the reactor. This stops the nuclear reaction and acts as a second cooling system.
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Viewed as a nuclear reaction it would belong to a class in which only photons were involved in creating and destroying states of nuclear excitation. It is a class usually overlooked in traditional discussions. In 1939 Pontecorvo and Lazard reported the first example of this type of reaction. Indium was the target and in modern terminology describing nuclear reactions it would be written 115In(γ,γ')115mIn.
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In February 2011, Rosatom announced that one of the reactor's four main cooling pumps, from the original German reactor, had suffered damage. Thoroughly cleaning the reactor of metal particles required the removal of the fuel core, resulting in a startup delay. The reactor achieved a sustained nuclear reaction at 11:12 on 8 May 2011 and ran at a minimum power level for final commissioning tests.
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Nuclear power is conducted by the released nuclear energy from nuclear reactions. The power is ignited heat from reactions, which is most commonly used in the powering of electricity-producing steam turbines, located in nuclear power plants. Nuclear fission is a type of nuclear reaction that is a leading form of low carbon power generation. The commercialization of entire power stations was first introduced in the 1970s.
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"Hoyle's Equation" Science 318, 1876 (2007) The second of Hoyle's nucleosynthesis papers also introduced an interesting use of the anthropic principle, which was not then known by that name. In trying to work out the routes of stellar nucleosynthesis, Hoyle calculated that one particular nuclear reaction, the triple-alpha process, which generates carbon from helium, would require the carbon nucleus to have a very specific resonance energy and spin for it to work. The large amount of carbon in the universe, which makes it possible for carbon-based life-forms of any kind to exist, demonstrated to Hoyle that this nuclear reaction must work. Based on this notion, Hoyle therefore predicted the values of the energy, the nuclear spin and the parity of the compound state in the carbon nucleus formed by three alpha particles (helium nuclei), which was later borne out by experiment.
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When temperature returns to an acceptable level, the hydrogen will again combine with the uranium metal, forming uranium hydride, restoring moderation and the nuclear reaction will start again. Uranium zirconium hydride (UZrH), a combination of uranium hydride and zirconium(II) hydride, is used as a fuel/moderator in the TRIGA-class reactors. On heating with diborane, uranium hydride produces uranium boride. With bromine at 300 °C, uranium(IV) bromide is produced.
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It was much more difficult to understand how it worked or why it failed. Designers gathered as much data as possible during the explosion, before the device destroyed itself, and used the data to calibrate their models, often by inserting fudge factors into equations to make the simulations match experimental results. They also analyzed the weapon debris in fallout to see how much of a potential nuclear reaction had taken place.
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The transmutation of lithium atoms to helium in 1932 was the first fully man-made nuclear reaction, and lithium deuteride serves as a fusion fuel in staged thermonuclear weapons.Nuclear Weapon Design. Federation of American Scientists (21 October 1998). fas.org Lithium and its compounds have several industrial applications, including heat-resistant glass and ceramics, lithium grease lubricants, flux additives for iron, steel and aluminium production, lithium batteries, and lithium-ion batteries.
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Proton capture is a nuclear reaction in which an atomic nucleus and one or more protons collide and merge to form a heavier nucleus. Since protons have positive electric charge, they are repelled electrostatically by the positively charged nucleus. Therefore, it is more difficult for protons to enter the nucleus compared to neutrally charged neutrons . Proton capture plays an important role in the cosmic nucleosynthesis of proton rich isotopes.
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Scandium-44 (44Sc) is a radioactive isotope of scandium that decays by positron emission to stable 44Ca with a half-life of 4.042 hours. 44Sc can be obtained as a daughter radionuclide of long-lived 44Ti (t1/2 60.4 a) from 44Ti /44Sc generator or can be produced by nuclear reaction 44Ca ( p, n)44Sc in small cyclotrons. This isotope is of potential interest for clinical PET imaging.
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The G-III experiment was a small-scale design, but it generated an exceptionally high rate of neutron production. The G-III model was superior to nuclear fission chain reaction experiments that had been conducted at the KWIP in Berlin-Dahem, the University of Heidelberg, or the University of Leipzig.Walker, 1993, 94-104. Herrmann also participated in work to explore the initiation of a nuclear reaction through the detonation of explosives.
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Lise Meitner and O. R. Frisch Disintegration of Uranium by Neutrons: a New Type of Nuclear Reaction, Nature, Volume 143, Number 3615, 239-240 (11 February 1939). The paper is dated 16 January 1939. Meitner is identified as being at the Physical Institute, Academy of Sciences, Stockholm. Frisch is identified as being at the Institute of Theoretical Physics, University of Copenhagen. Frisch confirmed this experimentally on 13 January 1939.
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Frank Spedding (B.S. 1925, M.S. 1926) (deceased), directed the chemistry phase of the Manhattan Project in World War II, which led to the world's first controlled nuclear reaction. He was Iowa State's second member of the National Academy of Sciences and the first director of the Ames Laboratory. Dr. Spedding won the Langmuir Award in 1933, Only Oscar K. Rice and Linus Pauling preceded him in this achievement.
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The prototype KRUSTY 1 kWe Kilopower reactor weighs 134 kg and contains 28 kg of . The space rated 10 kWe Kilopower for Mars is expected to mass 1500 kg in total (with a 226 kg core) and contain 43.7 kg of . Nuclear reaction control is provided by a single rod of boron carbide, which is a neutron absorber. The reactor is intended to be launched cold, preventing the formation of highly radioactive fission products.
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At Brookhaven National Laboratories, 40 MeV proton irradiation of a gallium metal target produces germanium-68 by proton capture and double neutron knockout, from gallium-69 (the most common of two stable isotopes of gallium). This reaction is: 69Ga(p,2n)68Ge. A Russian source produces germanium-68 from accelerator-produced helium ion (alpha) irradiation of zinc-66, again after knockout of two neutrons, in the nuclear reaction 66Zn(α,2n)68Ge.
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Spider-Man falls unconscious, allowing Octavius to deliver him to Harry. As Octavius leaves with the tritium, Harry prepares to kill Spider- Man, only to be shocked to see Peter under the mask. Peter convinces Harry to direct him to Octavius' lair, as bigger things are at stake. As Peter arrives at Octavius's waterfront laboratory and attempts to rescue Mary Jane discreetly, Octavius discovers him, and they battle as the nuclear reaction swells.
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Spider-Man falls unconscious, allowing Octavius to deliver him to Harry. As Octavius leaves with the tritium, Harry prepares to kill Spider-Man, only to be shocked to see Peter under the mask. Peter convinces Harry to direct him to Octavius' lair, as bigger things are at stake. As Peter arrives at Octavius's waterfront laboratory and attempts to rescue Mary Jane discreetly, Octavius discovers him, and they battle as the nuclear reaction swells.
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The order was fulfilled within a couple of months. By early 1942, there was another order from Arthur H. Compton of the Metallurgical Laboratory for three short tons of the uranium metal for the Chicago Pile-1. A woman is shown unveiling the new street sign of MacArthur Avenue and MacArthur Plaza. The project was done in secrecy by not revealing any connection of the work there to the ongoing research on the nuclear reaction.
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It also provides a means for attaining necessary elements that otherwise are difficult to find in nature. prior to this discovery, the cost per neutron in a nuclear reaction was relatively high. The patent concerning the prompt negative temperature coefficient was groundbreaking because it provided a markedly safer reactor even in the event of misuse. With the negative temperature coefficient, the reactor can mitigate sudden surges of reactivity propelled into the system.
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In inelastic scattering, neutrons are readily absorbed in a type of nuclear reaction called neutron capture and attributes to the neutron activation of the nucleus. Neutron interactions with most types of matter in this manner usually produce radioactive nuclei. The abundant oxygen-16 nucleus, for example, undergoes neutron activation, rapidly decays by a proton emission forming nitrogen-16, which decays to oxygen-16. The short-lived nitrogen-16 decay emits a powerful beta ray.
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In engineered nuclear devices, essentially all nuclear fission occurs as a "nuclear reaction" — a bombardment-driven process that results from the collision of two subatomic particles. In nuclear reactions, a subatomic particle collides with an atomic nucleus and causes changes to it. Nuclear reactions are thus driven by the mechanics of bombardment, not by the relatively constant exponential decay and half-life characteristic of spontaneous radioactive processes. Many types of nuclear reactions are currently known.
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Throughout his career at Argonne, Benioff conducted research in many fields, including mathematics, physics and chemistry. While in the Chemistry Division, he conducted research on nuclear reaction theory, as well as the relationship between the foundations of physics and mathematics. After joining Argonne's Environmental Impact Division in 1978, Benioff continued work on quantum computing and on foundational issues. This included descriptions of quantum robots, quantum mechanical models of different types of numbers, and other topics.
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The Big Bang is thought to be the origin of the hydrogen (including all deuterium) and helium in the universe. Hydrogen and helium together account for 98% of the mass of ordinary matter in the universe, while the other 2% makes up everything else. The Big Bang also produced small amounts of lithium, beryllium and perhaps boron. More lithium, beryllium and boron were produced later, in a natural nuclear reaction, cosmic ray spallation.
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ZEEP (left), NRX (right) and NRU (back) reactors at Chalk River, 1954. In 1944, approval was given to proceed with the construction of the smaller ZEEP (Zero Energy Experimental Pile) test reactor at Chalk River, Ontario and on September 5, 1945, at 3:45 p.m., the 10-watt ZEEP achieved the first self-sustained nuclear reaction outside the United States. In 1946, the Montreal Laboratory was closed, and the work continued at the Chalk River Nuclear Laboratories.
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Checking for radioactive contamination on nearby Highway 20 There were no other people at the reactor site. The ending of the nuclear reaction was caused solely by the design of the reactor and the basic physics of heated water and core elements melting, separating the core elements and removing the moderator. Heat sensors above the reactor set off an alarm at the central test site security facility at 9:01 p.m. MST, the time of the accident.
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In carbon dioxide-cooled reactors such as the AGR, if the solid control rods fail to arrest the nuclear reaction, nitrogen gas can be injected into the primary coolant cycle. This is because nitrogen has a larger absorption cross-section for neutrons than carbon or oxygen; hence, the core then becomes less reactive. As the neutron energy increases, the neutron cross section of most isotopes decreases. The boron isotope 10B is responsible for the majority of the neutron absorption.
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Selective ActiNide EXtraction. As part of the management of minor actinides it has been proposed that the lanthanides and trivalent minor actinides should be removed from the PUREX raffinate by a process such as DIAMEX or TRUEX. In order to allow the actinides such as americium to be either reused in industrial sources or used as fuel, the lanthanides must be removed. The lanthanides have large neutron cross sections and hence they would poison a neutron driven nuclear reaction.
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He did not envision fission as one of these neutron-producing reactions, since this reaction was not known at the time. Experiments he proposed using beryllium and indium failed. Later, after fission was discovered in 1938, Szilárd immediately realized the possibility of using neutron-induced fission as the particular nuclear reaction necessary to create a chain-reaction, so long as fission also produced neutrons. In 1939, with Enrico Fermi, Szilárd proved this neutron-multiplying reaction in uranium.
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Fermi reluctantly moved, and his team became part of the new Metallurgical Laboratory there. The possible results of a self-sustaining nuclear reaction were unknown, so it seemed inadvisable to build the first nuclear reactor on the University of Chicago campus in the middle of the city. Compton found a location in the Argonne Woods Forest Preserve, about from Chicago. Stone & Webster was contracted to develop the site, but the work was halted by an industrial dispute.
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Proton-rich nuclides can be produced by sequentially adding one or more protons to an atomic nucleus. Such a nuclear reaction of type (p,γ) is called proton capture reaction. By adding a proton to a nucleus, the element is changed because the chemical element is defined by the proton number of a nucleus. At the same time the ratio of protons to neutrons is changed, resulting in a more neutron-deficient isotope of the next element.
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The atoms undergoing fission are at a temperature of millions of degrees, which is then spread out into the surrounding fuel, resulting in an overall temperature of a few thousand. By physically arranging the fuel into very thin layers or particles, the fragments of a nuclear reaction, can boil off the surface. Since they will be ionized due to the high temperatures of the reaction, they can then be handled magnetically and channeled to produce thrust. Numerous technological challenges still remain, however.
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Although specifics were not published, its existence was known by both Congressional Representatives such as Flora Hamburger Blackford and journalists such as Ophelia Clemens. The program was supervised by the Assistant Secretary of War, Franklin D. Roosevelt. The Confederate nuclear program began in 1942, when intelligence indicated the U.S. was developing the facilities to separate uranium-235 from -238. The Confederate program was able to start a self-sustaining nuclear reaction at the program at Washington University in Lexington, Virginia, in 1943.
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A graphic depiction of a nuclear fusion reaction. Two nuclei fuse into one, emitting a neutron. Reactions that created new elements to this moment were similar, with the only possible difference that several singular neutrons sometimes were released, or none at all. A superheavy atomic nucleus is created in a nuclear reaction that combines two other nuclei of unequal size into one; roughly, the more unequal the two nuclei in terms of mass, the greater the possibility that the two react.
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Richter worked in Germany, England and France. In preparing his dissertation for a doctorate from the University of Prague, Richter worked at Falkenau Chemiewerke in his home town of Falkenau an der Eger (now known as Sokolov) in the Czech Republic. There he went to with electric arc furnaces looking to develop accurate methods for measurement and control of temperatures. Richter discovered that the injection of heavy Hydrogen (Deuterium) caused a nuclear reaction which he could measure and gauge with Geiger counters.
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After very slow neutrons are generated by the reflector, producer, moderator, and so forth, they encounter a nucleus in the proportional counter and cause it to disintegrate. This nuclear reaction produces energetic charged particles that ionize gas in the proportional counter, producing an electrical signal. In the early Simpson monitors, the active component in the gas was 10B, which produced a signal via the reaction (n + 10B → α + 7Li). Recent proportional counters use the reaction (n + 3He → 3H + p) which yields 764 keV.
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Work was also done to explore the initiation of a nuclear reaction through the detonation of explosives.W. Herrmann, Georg Hartwig, H. Rockwitz, W. Trinks, and H. Schaub Versuche über die Einleitung von Kernreaktionen durch die Wirkung explodierender Stoffe G-303 (1944). In the latter part of World War II, in addition to his other responsibilities, Diebner was a Reich Planning Officer.Kurt Diebner Listing of Nuclear Research Commissions Enclosed with a Letter to the President of the Reich Research Council [April 18.
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With a source of high-energy neutrons and a detector sensitive to low-energy neutrons (thermal neutrons), the detection rate will be governed by the water content of the soil between the source and the detector. The neutron source typically contains a small amount of a radionuclide. Sources may emit neutrons during spontaneous fission, as with californium; alternatively, an alpha emitter may be mixed with a light element for a nuclear reaction yielding excess neutrons, as with americium in a beryllium matrix.
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Nuclear propulsion includes a wide variety of propulsion methods that use some form of nuclear reaction as their primary power source. The idea of using nuclear material for propulsion dates back to the beginning of the 20th century. In 1903 it was hypothesized that radioactive material, radium, might be a suitable fuel for engines to propel cars, planes, and boats.Some practical uses of radium rays, The Republic, Sunday, September 13, 1903 H. G. Wells picked up this idea in his 1914 fiction work The World Set Free.
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The couple race to meet Walter and Bell at the Opera House, where Fauxlivia and a team of Fringe Commandos catch up with them. Bell and Olivia hold off the assault while Peter and Walter set up the dimensional device to enable their return home. Lacking a fuel source for the device, Bell sacrifices himself to create a nuclear reaction, using his body's unstable molecular state. Close to death, Bell reveals that he removed Walter's memories at his own request, and he and Walter are reconciled.
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Several experiments have been performed between 2000–2004 at the Flerov Laboratory of Nuclear Reactions in Dubna studying the fission characteristics of the compound nucleus 292Fl. The nuclear reaction used is 244Pu+48Ca. The results have revealed how nuclei such as this fission predominantly by expelling closed shell nuclei such as 132Sn (Z=50, N=82). It was also found that the yield for the fusion-fission pathway was similar between 48Ca and 58Fe projectiles, indicating a possible future use of 58Fe projectiles in superheavy element formation.
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It uses neutron reflector panels around the perimeter to maintain neutron density. These reflector panels replace complicated control rods, yet keep the ability to shut down the nuclear reaction in case of an emergency. Additionally, the Toshiba 4S utilizes liquid sodium as a coolant, allowing the reactor to operate 200 degrees hotter than if it used water. Although water would readily boil at these temperatures, sodium remains a liquid; the sodium coolant therefore exerts very low pressure on the reactor vessel even at extremely high temperatures.
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Received 22 December 1938. simultaneously, they communicated these results to Lise Meitner, who had in July of that year fled to The Netherlands and then went to Sweden.Ruth Lewin Sime Lise Meitner's Escape from Germany, American Journal of Physics Volume 58, Number 3, 263- 267 (1990). Meitner, and her nephew Otto Robert Frisch, correctly interpreted these results as being nuclear fission.Lise Meitner and O. R. Frisch Disintegration of Uranium by Neutrons: a New Type of Nuclear Reaction, Nature, Volume 143, Number 3615, 239–240 (11 February 1939).
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Because of this, a reasonably sized gun-type weapon would suffer nuclear reaction (predetonation) before the masses of plutonium would be in a position for a full-fledged explosion to occur. Instead, the plutonium is present as a subcritical sphere (or other shape), which may or may not be hollow. Detonation is produced by exploding a shaped charge surrounding the sphere, increasing the density (and collapsing the cavity, if present) to produce a prompt critical configuration. This is known as an implosion type weapon.
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William David Arnett (born 1940) is a Regents Professor of Astrophysics at Steward Observatory, University of Arizona, known for his research on supernova explosions, the formation of neutron stars or black holes by gravitational collapse, and the synthesis of elements in stars; he is author of the monograph Supernovae and Nucleosynthesis which deals with these topics. Arnett pioneered the application of supercomputers to astrophysical problems, including neutrino radiation hydrodynamics, nuclear reaction networks, instabilities and explosions, supernova light curves, and turbulent convective flow in two and three dimensions.
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After giving Octavius the tritium, Harry prepares to kill Spider-Man, only to be shocked to see Peter under the mask. Peter convinces Harry to direct him to Octavius' lair, as bigger things are at stake. As Peter arrives at the doctor's waterfront laboratory and attempts to rescue Mary Jane discreetly, Octavius discovers him, and they battle as the nuclear reaction swells and starts threatening the city. Peter ultimately subdues Octavius, reveals his identity, and persuades Octavius to let his dream go for the greater good.
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Chart of nuclides showing thermal neutron capture cross section values Neutron capture is a nuclear reaction in which an atomic nucleus and one or more neutrons collide and merge to form a heavier nucleus. Since neutrons have no electric charge, they can enter a nucleus more easily than positively charged protons, which are repelled electrostatically. Neutron capture plays an important role in the cosmic nucleosynthesis of heavy elements. In stars it can proceed in two ways: as a rapid (r-process) or a slow process (s-process).
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It still holds the record for the largest fission explosion ever tested (as the Ivy King device tested during Operation Ivy), producing over 500 kilotons of TNT equivalent. Taylor was credited with developing multiple techniques that improved the fission bomb. For example, he was largely responsible for the development of fusion boosting, which is a technique that improves the reaction yield and efficiency of a nuclear reaction. This technique was a re-invention of the implosion mechanism used in the bomb detonated at Nagasaki.
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They unsuccessfully try to protect him when Octavius returns to capture Peter, whom Octavius delivers to Harry. After giving Octavius the tritium, Harry prepares to kill Spider-Man, only to be shocked to see Peter under the mask. Peter convinces Harry to direct him to Octavius' lair, as bigger things are at stake. As Peter arrives at the doctor's waterfront laboratory and attempts to rescue Mary Jane discreetly, Octavius discovers him, and they battle as the nuclear reaction swells and starts threatening the city.
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The iodine pit, also called the iodine hole or xenon pit, is a temporary disabling of a nuclear reactor due to buildup of short-lived nuclear poisons in the reactor core. The main isotope responsible is 135Xe, mainly produced by natural decay of 135I. 135I is a weak neutron absorber, while 135Xe is the strongest known neutron absorber. When 135Xe builds up in the fuel rods of a reactor, it significantly lowers their reactivity, by absorbing a significant amount of the neutrons that provide the nuclear reaction.
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This new, heavier isotope may be either stable or unstable (radioactive), depending on the chemical element involved. Because free neutrons disintegrate within minutes outside of an atomic nucleus, free neutrons can be obtained only from nuclear decay, nuclear reaction, and high- energy interaction, such as cosmic radiation or particle accelerator emissions. Neutrons that have been slowed through a neutron moderator (thermal neutrons) are more likely to be captured by nuclei than fast neutrons. A less common form of induced radioactivity results from removing a neutron by photodisintegration.
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In 1934 Frédéric and Irène Joliot-Curie bombarded aluminium with alpha particles to effect the nuclear reaction + → + , and observed that the product isotope emits a positron identical to those found in cosmic rays by Carl David Anderson in 1932. This was the first example of decay (positron emission). The Curies termed the phenomenon "artificial radioactivity," since is a short-lived nuclide which does not exist in nature. The discovery of artificial radioactivity would be cited when the husband and wife team won the Nobel Prize.
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Georg Robert Döpel (3 December 1895 - 2 December 1982) was a German experimental nuclear physicist. He was a participant in a group known as the "first Uranverein", which was spawned by a meeting conducted by the Reichserziehungsministerium, in April 1939, to discuss the potential of a sustained nuclear reaction. He worked under Werner Heisenberg at the University of Leipzig, and he conducted experiments on spherical layers of uranium oxide surrounded by heavy water. He was a contributor to the German nuclear weapon project (Uranprojekt).
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Within a nuclear fission reactor, the neutron flux is the primary quantity measured to control the reaction inside. The flux shape is the term applied to the density or relative strength of the flux as it moves around the reactor. Typically the strongest neutron flux occurs in the middle of the reactor core, becoming lower toward the edges. The higher the neutron flux the greater the chance of a nuclear reaction occurring as there are more neutrons going through an area per unit time.
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In the nuclear reaction that occurs, a beryllium nucleus is transmuted into carbon-12, and one free neutron is emitted, traveling in about the same direction as the alpha particle was heading. Such alpha decay driven beryllium neutron sources, named "urchin" neutron initiators, were used in some early atomic bombs. Neutron sources in which beryllium is bombarded with gamma rays from a gamma decay radioisotope, are also used to produce laboratory neutrons.Byrne, J. Neutrons, Nuclei, and Matter, Dover Publications, Mineola, NY, 2011, , pp. 32–33.
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Either of those interactions will cause the ejection of an electron from an atom at relativistic speeds, turning that electron into a beta particle (secondary beta particle) that will ionize many other atoms. Since most of the affected atoms are ionized directly by the secondary beta particles, photons are called indirectly ionizing radiation. Photon radiation is called gamma rays if produced by a nuclear reaction, subatomic particle decay, or radioactive decay within the nucleus. It is otherwise called x-rays if produced outside the nucleus.
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General Hau Pei-tsun claimed that scientists in Taiwan had already produced a controlled nuclear reaction. Under pressure from the U.S., the program was halted. During the 1995–1996 Taiwan Strait crisis, ROC President Lee Teng-hui proposed to reactivate the program, but was forced to back down a few days later after drawing intense criticism from the U.S. government. With the unbalanced military equation across the Taiwan Strait, Taipei may choose nuclear weapons as a deterrent against the military encirclement by the People's Republic of China.
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Measurements are used to test our understanding: Astronomical constraints are obtained from stellar and interstellar abundance data of elements and isotopes, and other multi-messenger astronomical measurements of the cosmic object phenomena help to understand and model these. Nuclear properties can be obtained from terrestrial nuclear laboratories such as accelerators with their experiments. Theory and simulations are needed to understand and complement such data, providing models for nuclear reaction rates under the variety of cosmic conditions, and for the structure and dynamics of cosmic objects.
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It contains of conventional high explosives and highly enriched uranium. The Air Force maintains that its nuclear capsule, used to initiate the nuclear reaction, was removed before its flight aboard B-47. As noted in the Atomic Energy Commission "Form AL-569 Temporary Custodian Receipt (for maneuvers)", signed by the aircraft commander, the bomb contained a simulated 150-pound cap made of lead.The Nuclear Information Project , Form AL-569, "Temporary Custodian Receipt (for maneuvers)," to U.S. Atomic Energy Commission, Albuquerque Operations, from James W. Twitty, Col.
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His knowledge of chemistry and nuclear physics experience provided expertise on a number of things necessary to the Manhattan Project. In 1942, Wigner, Cowan, and several others transferred to the Metallurgy Lab at the University of Chicago where the first atomic pile was being developed under Enrico Fermi. Starting as a junior member, Cowan became a jack-of-all-trades, capable of such skills as machining graphite blocks used for control of the pile's reaction rate and in casting uranium metal. In 1942, the Chicago Pile 1 (CP-1) generated the first controlled nuclear reaction.
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The Ion Beam Laboratory at IOP The experimental physics group encompasses accelerator-based research for advanced chemical and radioisotope analysis. The ion beam laboratory (IBL) is equipped with a 3MV tandem accelerator (NEC 9SDH-2). Research at the IBL includes Rutherford back scattering, Particle-induced X-ray emission, accelerator mass spectrometry, channeling, ion implantation, surface modification and characterization, microbeam analysis and nuclear reaction studies. The 3 million volt NEC 9SDH-2 pelletron accelerator of the Accelerator Mass Spectrometry lab is a multi-disciplinary research accelerator for various physics experiments.
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The Great Migration, which had been on pause due to the Depression, resumed at an even faster pace in the second wave, as hundreds of thousands of blacks from the South arrived in the city to work in the steel mills, railroads, and shipping yards. On December 2, 1942, physicist Enrico Fermi conducted the world's first controlled nuclear reaction at the University of Chicago as part of the top- secret Manhattan Project. This led to the creation of the atomic bomb by the United States, which it used in World War II in 1945.
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Several experiments have been performed between 2001 and 2004 at the Flerov Laboratory of Nuclear Reactions in Dubna studying the fission characteristics of the compound nucleus 286Cn. The nuclear reaction used is 238U+48Ca. The results have revealed how nuclei such as this fission predominantly by expelling closed shell nuclei such as 132Sn (Z=50, N=82). It was also found that the yield for the fusion-fission pathway was similar between 48Ca and 58Fe projectiles, indicating a possible future use of 58Fe projectiles in superheavy element formation.
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Mysterio reveals that he was a distraction for Spider-Man and that Octavius is at the subway station, before restoring the city to normal and vanishing, implying that it was all an illusion. Spider-Man arrives at the subway station and battles Octavius on top of a New York City Subway train. Octavius sabotages the controls and leaves Peter to save the passengers whilst he escapes. Later, Spider-Man finds Octavius's waterfront laboratory and attempts to rescue Mary Jane discreetly, but Octavius discovers him, and they battle as the nuclear reaction swells.
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While in a non-nuclear chemical reaction the number and kind of atoms on both sides of the equation are equal, for a nuclear reaction this holds true only for the nuclear particles viz. protons and neutrons.Chemical Reaction Equation – IUPAC Goldbook The sequence of steps in which the reorganization of chemical bonds may be taking place in the course of a chemical reaction is called its mechanism. A chemical reaction can be envisioned to take place in a number of steps, each of which may have a different speed.
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After leaving the Army, Bachelder became a research chemist at the University of Chicago, where the first self-sustaining nuclear reaction had been achieved in 1942. Nobel Laureate James Franck had been Director of the Chemistry Division of the Metallurgical Laboratory during the earlier phases of the Manhattan Project. Bachelder joined the University's Institute for the Study of Metals (renamed as the James Franck Institute in 1967), and she conducted further research in metallochemistry. Among other achievements, Bachelder developed methods for the purification of the rare elements tellurium and indium.
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Nuclear reaction kinematics are customarily performed in units involving the electron volt, a consequence of accelerator technology. The combination of this practical point with the theoretical relation E = mc2 makes units of mega electron volts over the speed of light squared (MeV/c2) a convenient form to express nuclear mass. However, the numerical values of nuclear masses in MeV/c2 are quite large (even the proton mass is ~938.27 MeV/c2), while mass excesses range in the tens of MeV/c2. This makes tabulated mass excess less cumbersome for use in calculations.
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This process is also known as inductive reasoning or the use of specific observations to make generalizations. Data mining is the most common tool used in discovery science, and is applied to data from diverse fields of study such as DNA analysis, climate modeling, nuclear reaction modeling, and others. The use of data mining in discovery science follows a general trend of increasing use of computers and computational theory in all fields of science, and newer methods of data mining employ specialized machine learning algorithms for automated hypothesis forming and automated theorem proving.
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The thin-walled sphere was a commonly used design, which ensured that the fissile material remained sub-critical until imploded. The HEU sphere was then enclosed in a natural-uranium neutron reflector. To physically prevent the HEU sphere collapsing into a critical condition if the surrounding explosives were detonated accidentally, or if the sphere was crushed following an aircraft accident, the hollow center was filled with a chain made from aluminum and boron, which was pulled out to arm the bomb. The boron-coated chain also absorbed the neutrons needed to drive the nuclear reaction.
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Native sulfur crystals. Sulfur occurs naturally as elemental sulfur, in sulfide and sulfate minerals and in hydrogen sulfide. An element is a chemical substance made up of a particular kind of atom and hence cannot be broken down or transformed by a chemical reaction into a different element, though it can be transmuted into another element through a nuclear reaction. This is so because all of the atoms in a sample of an element have the same number of protons, though they may be different isotopes, with differing numbers of neutrons.
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They further reported measuring small amounts of nuclear reaction byproducts, including neutrons and tritium. ("It is inconceivable that this [amount of heat] could be due to anything but nuclear processes... We realise that the results reported here raise more questions than they provide answers...") The small tabletop experiment involved electrolysis of heavy water on the surface of a palladium (Pd) electrode. The reported results received wide media attention and raised hopes of a cheap and abundant source of energy. Many scientists tried to replicate the experiment with the few details available.
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Diagram of the D-T reaction The easiest nuclear reaction, at the lowest energy, is: : + → (3.5 MeV) + (14.1 MeV) This reaction is common in research, industrial and military applications, usually as a convenient source of neutrons. Deuterium is a naturally occurring isotope of hydrogen and is commonly available. The large mass ratio of the hydrogen isotopes makes their separation easy compared to the difficult uranium enrichment process. Tritium is a natural isotope of hydrogen, but because it has a short half-life of 12.32 years, it is hard to find, store, produce, and is expensive.
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The Oppenheimer–Phillips process or strip reaction is a type of deuteron- induced nuclear reaction. In this process the neutron half of an energetic deuteron (a stable isotope of hydrogen with one proton and one neutron) fuses with a target nucleus, transmuting the target to a heavier isotope while ejecting a proton. An example is the nuclear transmutation of carbon-12 to carbon-13. The process allows a nuclear interaction to take place at lower energies than would be expected from a simple calculation of the Coulomb barrier between a deuteron and a target nucleus.
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The "Sausage" device casing of the Ivy Mike H bomb, attached to instrumentation and cryogenic equipment. The 20-ft-tall bomb held a cryogenic Dewar flask with room for 160 kg of liquid deuterium. The 62-ton Ivy Mike device built by the United States and exploded on 1 November 1952, was the first fully successful "hydrogen bomb" (thermonuclear bomb). In this context, it was the first bomb in which most of the energy released came from nuclear reaction stages that followed the primary nuclear fission stage of the atomic bomb.
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Several heavy elements, such as uranium, thorium, and plutonium, undergo both spontaneous fission, a form of radioactive decay and induced fission, a form of nuclear reaction. Elemental isotopes that undergo induced fission when struck by a free neutron are called fissionable; isotopes that undergo fission when struck by a slow-moving thermal neutron are also called fissile. A few particularly fissile and readily obtainable isotopes (notably 233U, 235U and 239Pu) are called nuclear fuels because they can sustain a chain reaction and can be obtained in large enough quantities to be useful.
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Such steam explosions would be typical of the very diffuse assembly of materials in a nuclear reactor, even under the worst conditions. In addition, other steps can be taken for safety. For example, power plants licensed in the United States require a negative void coefficient of reactivity (this means that if water is removed from the reactor core, the nuclear reaction will tend to shut down, not increase). This eliminates the possibility of the type of accident that occurred at Chernobyl (which was due to a positive void coefficient).
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A few of these women were Leona Woods, Maria Goeppert Mayer, Chien- Shiung Wu, Isabella Karle, Naomi Livesay, Lilli Hornig, Floy Agnes Lee, and many more unnamed women. Leona Woods was the only woman working at the Hanford site and assisted John Wheeler in determining the cause of the reactor shutdown to be xenon poisoning. Woods also worked under Enrico Fermi on the Chicago Pile, the first self-sustaining nuclear reaction. Along with Leona Woods, Chien-Shiung Wu helped in determining the cause of the Hanford reactor poisoning.
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Nucleogenic isotopes, as noted, are the result of a more complicated nuclear reaction, although such reactions may begin with a radioactive decay event. Alpha particles that produce nucleogenic reactions come from natural alpha particle emitters in uranium and thorium decay chains. Neutrons to produce nucleogenic nuclides may be produced by a number of processes, but due to the short half- life of free neutrons, all of these reactions occur on Earth. Among the most common are cosmic ray spallation production of neutrons from elements near the surface of the Earth.
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A secret program was revealed when Colonel Chang Hsien-yi, deputy director of nuclear research at INER, who was secretly working for the CIA, defected to the U.S. in December 1987 and produced a cache of incriminating documents. General Hau Pei-tsun claimed that scientists in Taiwan had already produced a controlled nuclear reaction. Under pressure from the U.S., the program was halted. A study into the secret program concluded that at the time of Chang's defection, Taiwan was one or two years away from being able to complete a nuclear bomb.
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Returning one of several US Mark 4 nuclear bombs secretly deployed at Goose AFB in Labrador, a USAF Boeing B-50 Superfortress had engine trouble and jettisoned the weapon at . The crew set the bomb to self-destruct at , and released it over the St. Lawrence River. The non-nuclear explosion shook area residents and scattered nearly of radioactive uranium (U-238) used in the weapon's tamper. The plutonium core ("pit"), which is the key component for a nuclear reaction and detonation, was not installed in the bomb at the time.
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During World War II, the university's Metallurgical Laboratory made ground-breaking contributions to the Manhattan Project. The university was the site of the first isolation of plutonium and of the creation of the first artificial, self-sustained nuclear reaction by Enrico Fermi in 1942. It has been noted that the university did not provide standard oversight regarding Bruno Bettelheim and his tenure as director of the Orthogenic School for Disturbed Children from 1944 to 1973.Genius Or Fraud? Bettelheim's Biographers Can't Seem To Decide , Chicago Tribune, Ron Grossman, January 23, 1997.
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There are three neutron sources at ORNL; the High Flux Isotope Reactor (HFIR), the Oak Ridge Electron Linear Accelerator (ORELA) and the Spallation Neutron Source. HFIR provides neutrons in a stable beam resulting from a constant nuclear reaction whereas ORELA and SNS produce pulses of neutrons as they are particle accelerators. HFIR went critical in 1965 and has been used for materials research and as a major source of medical radioisotopes since. As of 2013, HFIR provides the world's highest constant neutron flux as a result of various upgrades.
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The spacecraft variant of the gaseous fission reactor is called the gas core reactor rocket. There are two approaches: the open and closed cycle. In the open cycle, the propellant, most likely hydrogen, is fed to the reactor, heated up by the nuclear reaction in the reactor, and exits out the other end. Unfortunately, the propellant will be contaminated by fuel and fission products, and although the problem can be mitigated by engineering the hydrodynamics within the reactor, it renders the rocket design completely unsuitable for use in atmosphere.
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The channel gas outlet temperature, the temperature at which the CO2 leaves the fuel channels in the reactor core, had to be reduced, initially dropping the power output to 840 MW, which was later raised to 980 MW as more experience accumulated. A considerable portion of the output, up to 255 MW, was consumed by the nearby Anglesey Aluminium smelting plant. The graphite cores each weigh ; 6,156 vertical fuel channels contain over 49,248 natural uranium magnox-clad fuel elements, hence the name magnox reactor. A further 200 channels allow boron control rods to enter the reactor and control the nuclear reaction.
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In December 1983, when Ignalina Unit 1 came online, a design flaw of the RBMK was noticed for the first time. When the graphite-moderated tips on its control rods were entered into the reactor, they immediately caused a power excursion. Unit 1's control rods did not get stuck; they reached the bottom of the reactor, and the boron in the control rods stopped the nuclear reaction. Other nuclear organizations and RBMK plants were informed of the problem, but it was not addressed until after a similar power surge partly caused the 1986 Chernobyl Disaster.
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On December 2, 1942, the world's first controlled nuclear reaction was conducted at the University of Chicago as part of the top secret Manhattan Project. During World War II, the steel mills in the city of Chicago alone accounted for 20% of all steel production in the United States and 10% of global production. The city produced more steel than the United Kingdom during the war, and surpassed Nazi Germany's output in 1943 (after barely missing in 1942). The city's diversified industrial base made it second only to Detroit in the value—$24 billion—of war goods produced.
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On May 19, 2010, a team of astronomers released a report on the discoveries made in their research of SN 2005E. The articles were published in the British journal Nature."A faint type of supernova from a white dwarf with a helium-rich companion", Nature, 465, 322–325 (20 May 2010), ; Received 17 May 2009; Accepted 23 March 2010. The researchers have determined that the blast emitted a large amount of calcium and titanium, which is evidence of a nuclear reaction involving helium, instead of the carbon and oxygen that is characteristic of Type Ia supernovae.
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Copper-64 can be technically reproduced by several different reactions with the most common methods using either a reactor or an accelerator. Thermal neutrons can produce 64Cu in low specific activity (the number of decays per second per amount of substance) and low yield through the 63Cu(n,γ)64Cu reaction. At the University of Missouri Research Reactor Center (MURR) 64Cu was produced using high-energy neutrons via the 64Zn(n,p)64Cu reaction in high specific activity but low yield. Using a biomedical cyclotron the 64Ni(p,n)64Cu nuclear reaction can produce large quantities of the nuclide with high specific activity.
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In 1952, he received a degree in Physical and Mathematical Sciences with a thesis on kinetic processes of neutrons. This work on neutrons and efficiency continued, along with calculations on nuclear reaction kinetics and energy release of the Soviet Union's first thermonuclear weapon, the RDS-6, tested in 1953; for this he was awarded the Stalin Prize, the first of several awards. He was a leading developer of the RDS-37 - the first Soviet two-stage thermonuclear weapon - most specifically concerned with the power output. Romanov transferred to the new Scientific Research Institute-1011 as head of the theoretical department in 1955.
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A nuclear chain reaction was proposed by Leo Szilard in 1933, shortly after the neutron was discovered, yet more than five years before nuclear fission was first discovered. Szilárd knew of chemical chain reactions, and he had been reading about an energy-producing nuclear reaction involving high-energy protons bombarding lithium, demonstrated by John Cockcroft and Ernest Walton, in 1932. Now, Szilárd proposed to use neutrons theoretically produced from certain nuclear reactions in lighter isotopes, to induce further reactions in light isotopes that produced more neutrons. This would in theory produce a chain reaction at the level of the nucleus.
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Fermi and Szilárd collaborated on a design of a device to achieve a self-sustaining nuclear reaction—a nuclear reactor. Owing to the rate of absorption of neutrons by the hydrogen in water, it was unlikely that a self-sustaining reaction could be achieved with natural uranium and water as a neutron moderator. Fermi suggested, based on his work with neutrons, that the reaction could be achieved with uranium oxide blocks and graphite as a moderator instead of water. This would reduce the neutron capture rate, and in theory make a self-sustaining chain reaction possible.
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Nuclear fission was discovered by Otto Hahn and Fritz Strassmann in December 1938Lise Meitner: Otto Hahn - the discoverer of nuclear fission. In: Forscher und Wissenschaftler im heutigen Europa. Stalling Verlag, Oldenburg/Hamburg 1955. and explained theoretically in January 1939 by Lise Meitner and her nephew Otto Robert Frisch.Lise Meitner & O. R. Frisch, "Disintegration of Uranium by Neutrons: A New Type of Nuclear Reaction," Nature 143, 3615 (1939-02-11): 239, , ; O. R. Frisch, "Physical Evidence of Division of Heavy Nuclei under Neutron Bombardment," Nature 143, 3616 (1939-02-18): 276, . The paper is dated 16 January 1939.
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Today this might seem ill-considered, since approximately 40,000 people lived within a 1 km radius. It was risky, but was deemed tolerable since the reactor was an important research tool for scientists at the Royal Swedish Academy of Engineering Sciences (Ingenjörsvetenskapsakademien). At 18:59 on 13 July 1954, the reactor reached critical mass and sustained Sweden's first nuclear reaction. R1 was to be the main site for almost all Swedish nuclear research until 1970 when the reactor was finally decommissioned, mostly due to the increased awareness of the risks associated with operating a reactor in a densely populated area of Stockholm.
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Control rods are a series of rods that can be quickly inserted into the reactor core to absorb neutrons and rapidly terminate the nuclear reaction. They are typically composed of actinides, lanthanides, transition metals, and boron, in various alloys with structural backing such as steel. In addition to being neutron absorbent, the alloys used also are required to have at least a low coefficient of thermal expansion so that they do not jam under high temperatures, and they have to be self-lubricating metal on metal, because at the temperatures experienced by nuclear reactor cores oil lubrication would foul too quickly.
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The rates of the various nuclear reactions are estimated from particle physics experiments at high energies, which are extrapolated back to the lower energies of stellar interiors (the Sun burns hydrogen rather slowly). Historically, errors in the nuclear reaction rates have been one of the biggest sources of error in stellar modelling. Computers are employed to calculate the varying abundances (usually by mass fraction) of the nuclear species. A particular species will have a rate of production and a rate of destruction, so both are needed to calculate its abundance over time, at varying conditions of temperature and density.
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Liquid hydrogen served as the propellant that was supplied to the reactor core by turbopumps and also provided regenerative cooling. The cylindrical graphite core was surrounded by twelve rotating control drums with beryllium on one side to reflect neutrons and boral on the other side to absorb neutrons to control the rate of the nuclear reaction in the core. The core consisted of clusters of hexagonal graphite fuel elements containing pyrographite-coated beads of uranium pellets coated with niobium carbide to prevent corrosion by exposure to the hydrogen propellant. Each fuel rod cluster was supported by an inconel tie rod.
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For the initial start up of the reactor neutron sources were located within the core to provide sufficient neutrons to initiate the nuclear reaction. Other aspects of the design included the use of flux shaping or flattening bars or controls rods to even out (to some extent) the neutron flux density across the core. If not used, the flux in the centre would be very high relative to the outer areas leading to excessive central temperatures and lower power output limited by the temperature of the central areas. Each fuel channel would have several elements stacked one upon another to form a stringer.
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BADGER, fired on April 18, 1953 at the Nevada Test Site, as part of the Operation Upshot–Knothole nuclear test series. Greenhouse George test early fireball. Upshot–Knothole Grable test (film) A nuclear explosion is an explosion that occurs as a result of the rapid release of energy from a high- speed nuclear reaction. The driving reaction may be nuclear fission or nuclear fusion or a multi-stage cascading combination of the two, though to date all fusion-based weapons have used a fission device to initiate fusion, and a pure fusion weapon remains a hypothetical device.
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In a nuclear power reactor, the main sources of radioactivity are fission products, alongside actinides and activation products. Fission products are the largest source of radioactivity for the first several hundred years, while actinides are dominant roughly 103 to 105 years after fuel use. Fission occurs in the nuclear fuel, and the fission products are primarily retained within the fuel close to where they are produced. These fission products are important to the operation of the reactor because some fission products contribute delayed neutrons that are useful for reactor control while others are neutron poisons that tend to inhibit the nuclear reaction.
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As matter is processed as such within stars and stellar explosions, some of the products are ejected from the nuclear-reaction site and end up in interstellar gas. Then, it may form new stars, and be processed further through nuclear reactions, in a cycle of matter. This results in compositional evolution of cosmic gas in and between stars and galaxies, enriching such gas with heavier elements. Nuclear astrophysics is the science to describe and understand the nuclear and astrophysical processes within such cosmic and galactic chemical evolution, linking it to knowledge from nuclear physics and astrophysics.
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As part of the management of minor actinides, it has been proposed that the lanthanides and trivalent minor actinides should be removed from the PUREX raffinate by a process such as DIAMEX or TRUEX. In order to allow the actinides such as americium to be either reused in industrial sources or used as fuel the lanthanides must be removed. The lanthanides have large neutron cross sections and hence they would poison a neutron-driven nuclear reaction. To date, the extraction system for the SANEX process has not been defined, but currently, several different research groups are working towards a process.
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Units 1 through 4 at the plant At the time of the earthquake, Unit 4 had been shut down for shroud replacement and refueling since 29 November 2010. All 548 fuel assemblies had been transferred in December 2010 from the reactor to the spent fuel pool on an upper floor of the reactor building where they were held in racks containing boron to damp down any nuclear reaction. The pool is used to store rods for some time after removal from the reactor and contains 1,331 rods. Recently active fuel rods produce more decay heat than older ones.
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Arguably the principal Isotope Separator On Line (ISOL) is ISOLDE at CERN, which is a joint European facility spread across the Franco-Swiss border near the city of Geneva. This laboratory uses mainly proton spallation of uranium carbide targets to produce a wide range of radioactive fission fragments that are not found naturally on earth. During spallation (bombardment with high energy protons), a uranium carbide target is heated to several thousand degrees so that radioactive atoms produced in the nuclear reaction are released. Once out of the target, the vapour of radioactive atoms travels to an ionizer cavity.
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Earlier experiments theorized this but had been unable to confirm it. In late 2019, Hahn became the founding director of the IBS Center for Exotic Nuclear Studies. Divided into four groups; experimental nuclear astrophysics, experimental nuclear structure, experimental nuclear reaction and theoretical nuclear physics, research of the center uses rare isotope beams from overseas RI accelerators and later the Rare Isotope Science Project's (RISP) RAON accelerator in Korea, specifically RISP's KOrea Broad acceptance Recoil spectrometer and Apparatus (KOBRA) with a focus on discovering rare isotopes and investigating the origins of heavy elements. His work will help direct collaborations among universities and research groups studying rare isotope accelerator sciences in South Korea.
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PNNL engineer testing a timed neutron detector. Since the late 1940s, a lot of research has examined the potential of nuclear techniques for detecting landmines and there have been several reviews of the technology. According to a RAND study in 2003, "Virtually every conceivable nuclear reaction has been examined, but ... only a few have potential for mine detection." In particular, reactions that emit charged particles can be eliminated because they do not travel far in the ground, and methods involving transmission of neutrons through the medium (useful in applications such as airport security) are not feasible because the detector and receiver cannot be placed on opposite sides.
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In December, the regents awarded the construction contract to Jentoft & Forbes, paying $308,082 (equivalent to $ in dollars) for the project. A site at the eastern edge of the campus was chosen for its proximity to various academic engineering buildings and its visibility to the public. The AEC granted an operating license for the reactor to the university in April 1961, and the reactor began operating with a self- sustained nuclear reaction on April 10. It was officially dedicated on June 1, in a ceremony attended by Argonne National Laboratory director Norman Hilberry, a physicist who worked on Chicago Pile-1, the world's first nuclear reactor to achieve criticality.
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Whereas Godzilla defense measures had by 1995 become the role of G-Force, the multipurpose fighter plane Super X-III was not designed exclusively as an anti-Godzilla weapon, but rather (as with the original Super X) to respond to a nuclear accident or attack. The winged V/STOL craft's central features are its cooling weapons, the Super-Low Temperature Beam and Freezing Missiles. Also like the original, it is piloted and operated by a three-person crew and equipped with cadmium missiles intended for long-range nuclear reaction control. Artificial diamond is incorporated into its alloy armor, making it strong enough to withstand repeated hits from Godzilla's ray.
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Inverse beta decay, commonly abbreviated to IBD, is a nuclear reaction involving electron antineutrino scattering off a proton, creating a positron and a neutron. This process is commonly used in the detection of electron antineutrinos in neutrino detectors, such as the first detection of antineutrinos in the Cowan–Reines neutrino experiment, or in neutrino experiments such as KamLAND and Borexino. It is an essential process to experiments involving low-energy neutrinos (< 60 MeV) such as those studying neutrino oscillation, reactor neutrinos, sterile neutrinos, and geoneutrinos. The IBD reaction can only be used to detect antineutrinos (rather than normal matter neutrinos, such as from the Sun) due to lepton conservation.
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The 12C standard makes it useful to think about nuclear mass in atomic mass units for the definition of the mass excess. However, its usefulness arises in the calculation of nuclear reaction kinematics or decay. Only a small fraction of the total energy associated with atomic nuclei by mass-energy equivalence, on the order of 0.01% to 0.1% of the total mass, may be absorbed or liberated as radiation. Thus by working in terms of the mass excess, one has effectively removed much of the mass changes which arise from the mere transfer or release of nucleons, making more obvious the scale of the net energy difference.
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Neutrons may be emitted from nuclear fusion or nuclear fission, or from other nuclear reactions such as radioactive decay or particle interactions with cosmic rays or within particle accelerators. Large neutron sources are rare, and usually limited to large-sized devices such as nuclear reactors or particle accelerators, including the Spallation Neutron Source. Neutron radiation was discovered from observing an alpha particle colliding with a beryllium nucleus, which was transformed into a carbon nucleus while emitting a neutron, Be(α, n)C. The combination of an alpha particle emitter and an isotope with a large (α, n) nuclear reaction probability is still a common neutron source.
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The painter and photographer Eugene Von Bruenchenhein painted the artwork “Atomic age” in 1955, and other apocalyptical and post apocalyptical paintings up to 1965. The British sculptor Henry Moore created a bronze public sculpture entitled Nuclear Energy (sculpture) (1967), which both depicted the fatality of nuclear weapons and celebrated the invention of nuclear energy for use as electrical power. The sculpture is located on the grounds of the University of Chicago, where the first self-sustaining nuclear reaction was produced at the Chicago Pile-1, under the oversight of the Manhattan Project and Enrico Fermi. The sculpture is in the form of a hybrid mushroom cloud and human skull.
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He performed the first artificially induced nuclear reaction in 1917 in experiments where nitrogen nuclei were bombarded with alpha particles. As a result, he discovered the emission of a subatomic particle which, in 1919, he called the "hydrogen atom" but, in 1920, he more accurately named the proton. Rutherford became Director of the Cavendish Laboratory at the University of Cambridge in 1919. Under his leadership the neutron was discovered by James Chadwick in 1932 and in the same year the first experiment to split the nucleus in a fully controlled manner was performed by students working under his direction, John Cockcroft and Ernest Walton.
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Nuclear power is any nuclear technology designed to extract usable energy from atomic nuclei via controlled nuclear reactions. The only controlled method now practical uses nuclear fission in a fissile fuel (with a small fraction of the power coming from subsequent radioactive decay). Use of the nuclear reaction nuclear fusion for controlled power generation is not yet practical, but is an active area of research. Nuclear power is usually used by using a nuclear reactor to heat a working fluid such as water, which is then used to create steam pressure, which is converted into mechanical work for the purpose of generating electricity or propulsion in water.
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The Chicago example is on display in North Stanley McCormick Memorial Court (AKA north garden) north of the Art Institute of Chicago Building in the Loop community area of Chicago, Illinois. In Chicago, Moore has a total of four public sculptures on display that are listed on the Smithsonian Institution's Research Information System (SIRIS). He also has Nuclear Energy situated at the National Historic Landmark, National Register of Historic Places, Chicago Landmark Site of First Self-Sustaining Nuclear Reaction. Moore also has a sundial installation (visible here) outside the National Historic Landmark, National Register of Historic Places Adler Planetarium called Man Enters the Cosmos.
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In this episode, Mulder and Scully run into a pair of doppelgangers, who, whenever they draw near to one another, cause disaster to unfold. Splitting up, the agents try to find out "why" and "what" they are doing. "Fight Club" was inspired by a "long-lost nugget" of a story that series creator Chris Carter had thought up a while back about "mis- matched twins that had an almost nuclear reaction when they were around each other." Steve Kiziak and Arlene Pileggi—David Duchovny's stunt double and Mitch Pileggi's wife, respectively—were chosen to play the Mulder and Scully look-alikes at the start of the episode.
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A Generation III nuclear reactor has a 72-hour capability of passive cooling to prevent damage to its core should the plant face a total blackout after an emergency shut down. If core overheating and meltdown became unavoidable, these reactors have core catchers that will trap the molten fuel and stop the nuclear reaction (although Lungmen, as other ABWR does not have a core catcher but rely on passive cooling of the corium). Finally, a tight containment ensures that no evacuation zone is required around a Generation III nuclear power plant. The ABWR was designed to a 0.3G earthquake acceleration standard with the Lungmen units seismic hardening increased to 0.4G.
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Salted versions of both fission and fusion weapons can be made by surrounding the core of the explosive device with a material containing an element that can be converted to a highly radioactive isotope by neutron bombardment. When the bomb explodes, the element absorbs neutrons released by the nuclear reaction, converting it to its radioactive form. The explosion scatters the resulting radioactive material over a wide area, leaving it uninhabitable far longer than an area affected by typical nuclear weapons. In a salted hydrogen bomb, the radiation case around the fusion fuel, which normally is made of some fissionable element, is replaced with a metallic salting element.
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Also, the philosophy oriented Committee on Social Thought, an institution distinctive of the university, was created. Some of the University of Chicago team that worked on the production of the world's first human-caused self-sustaining nuclear reaction, including alt=A group of people in suits standing in three rows on the steps in front of a stone building. Money that had been raised during the 1920s and financial backing from the Rockefeller Foundation helped the school to survive through the Great Depression. Nonetheless, in 1933, Hutchins proposed an unsuccessful plan to merge the University of Chicago and Northwestern University into a single university.
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That generally means higher temperatures, although lower densities, than for less massive stars. To get the right figures for a particular mass, and a particular stage of evolution, it is necessary to use a numerical stellar model computed with computer algorithms. Such models are continually being refined based on nuclear physics experiments (which measure nuclear reaction rates) and astronomical observations (which include direct observation of mass loss, detection of nuclear products from spectrum observations after convection zones develop from the surface to fusion-burning regions – known as dredge-up events – and so bring nuclear products to the surface, and many other observations relevant to models).
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In 1934, Frédéric and Irène Joliot-Curie bombarded aluminium with alpha particles to effect the nuclear reaction + → + , and observed that the product isotope emits a positron identical to those found in cosmic rays (discovered by Carl David Anderson in 1932). This was the first example of decay (positron emission), which they termed artificial radioactivity since is a short-lived nuclide which does not exist in nature. In recognition of their discovery the couple were awarded the Nobel Prize in Chemistry in 1935. The theory of electron capture was first discussed by Gian-Carlo Wick in a 1934 paper, and then developed by Hideki Yukawa and others.
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In this technique, a thin uranium target is bombarded with protons and nuclear reaction products recoil out of the target in a charged state. The recoils are stopped in a gas cell and then exit through a small hole in the side of the cell where they are accelerated electrostatically and injected into a mass separator. This method of production and extraction takes place on a shorter timescale compared to the standard ISOL technique and isotopes with short half-lives (sub millisecond) can be studied using an IGISOL. An IGISOL has also been combined with a laser ion source at the Leuven Isotope Separator On Line (LISOL) in Belgium.
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In nature, sixteen repositories were discovered at the Oklo mine in Gabon where natural nuclear fission reactions took place 1.7 billion years ago. The fission products in these natural formations were found to have moved less than 10 ft (3 m) over this period, though the lack of movement may be due more to retention in the uraninite structure than to insolubility and sorption from moving ground water; uraninite crystals are better preserved here than those in spent fuel rods because of a less complete nuclear reaction, so that reaction products would be less accessible to groundwater attack.Krauskopf, Konrad B. 1988. Radioactive waste and geology.
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A schematic representation of the target area of the International Fusion Material Irradiation Facility (IFMIF). A small target area is irradiated by a pair of deuteron beams to study the effects of intense neutron flux (produced by the interaction of deuterons with a stream of lithium) on materials. The International Fusion Materials Irradiation Facility, also known as IFMIF, is a projected material testing facility in which candidate materials for the use in an energy producing fusion reactor can be fully qualified. IFMIF will be an accelerator-driven neutron source producing a high intensity fast neutron flux with a spectrum similar to that expected at the first wall of a fusion reactor using a deuterium-lithium nuclear reaction.
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This leaves emission of radiation from targets and scattering of neutrons. For neutron detectors to be portable, they must be able to detect landmines efficiently with low-intensity beams so that little shielding is needed to protect human operators. One factor that determines the efficiency is the cross section of the nuclear reaction; if it is large, a neutron does not have to come as close to a nucleus to interact with it. One possible source of neutrons is spontaneous fission from a radioactive isotope, most commonly californium-252. Neutrons can also be generated using a portable particle accelerator (a sealed neutron tube) that promotes the fusion of deuterium and tritium, producing helium-4 and a neutron.
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Simplified illustration of some nuclear weapon safety mechanisms The conventional explosives needed to start the chain reaction are tailored to the characteristics of the fissile material in the core of the weapon. If the detonation does not occur exactly as planned, such as in the case of a misfire, a nuclear reaction is unlikely to occur—the explosion will be no greater than the amount of conventional explosive (although radioactive material—the unreacted nuclear fuel—may be dispersed). Computer simulations have assisted in calculating the likelihood of a chain reaction still occurring in a misfire. The odds of a nuclear chain reaction after a misfire of the conventional explosives is estimated to be one in one million.
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His Nuclear Energy is situated on the campus of the University of Chicago at the site of the first self-sustaining nuclear reaction, which is listed in the National Register of Historic Places. The site is also listed as a National Historic Landmark, and Chicago Landmark. Other Chicago works include Large Interior Form, which is located in the north garden at the Art Institute of Chicago, and Reclining Figure, which is on loan to the University of Chicago and which is located in the Cochrane-Woods Art Center courtyard. The Henry Moore Foundation lists several other indoor Chicago works at locations such as the Art Institute of Chicago and The Smart Museum.
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In any reactor, a SCRAM is achieved by inserting large amounts of negative reactivity mass into the midst of the fissile material, to immediately terminate the fission reaction. In light-water reactors, this is achieved by inserting neutron-absorbing control rods into the core, although the mechanism by which rods are inserted depends on the type of reactor. In PWRs, the control rods are held above a reactor's core by electric motors against both their own weight and a powerful spring. A SCRAM is designed to release the control rods from those motors and allows their weight and the spring to drive them into the reactor core, rapidly halting the nuclear reaction by absorbing liberated neutrons.
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When temperature returns to an acceptable level, the hydrogen will again combine with the uranium metal, forming uranium hydride, restoring moderation and the nuclear reaction will start again. This makes the reactor a self-regulating, dynamic system, as with a rise in temperature, nuclear reactivity will substantially decrease, and with a fall in temperature, nuclear reactivity will substantially increase. Thus, this reactor design is self-regulating, meltdown is impossible, and the design is inherently safe. From a safety point of view, the design leverages the technology used in the TRIGA reactor, which uses uranium zirconium hydride (UZrH) fuel and is the only reactor licensed by the U.S. Nuclear Regulatory Commission for unattended operation.
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The remaining 6 transient elements (technetium, promethium, astatine, francium, neptunium, and plutonium) occur only rarely, as products of rare decay modes or nuclear reaction processes involving uranium or other heavy elements. No radioactive decay has been observed for elements with atomic numbers 1 through 82, except 43 (technetium) and 61 (promethium). Observationally stable isotopes of some elements (such as tungsten and lead), however, are predicted to be slightly radioactive with very long half-lives: for example, the half-lives predicted for the observationally stable lead isotopes range from 1035 to 10189 years. Elements with atomic numbers 43, 61, and 83 through 94 are unstable enough that their radioactive decay can readily be detected.
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The extra rod worth was in part due to the decision to load only 40 of the 59 fuel assemblies with nuclear fuel, thus making the prototype reactor core more active in the center. In normal operation control rods are withdrawn only enough to cause sufficient reactivity for a sustained nuclear reaction and power generation. In this accident, however, the reactivity addition was sufficient to take the reactor prompt critical within a time estimated at 4 milliseconds. That was too fast for the heat from the fuel to get through the aluminum cladding and boil enough water to fully stop the power growth in all parts of the core via negative moderator temperature and void feedback.
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Especially energetic alpha particles deriving from a nuclear process are produced in the relatively rare (one in a few hundred) nuclear fission process of ternary fission. In this process, three charged particles are produced from the event instead of the normal two, with the smallest of the charged particles most probably (90% probability) being an alpha particle. Such alpha particles are termed "long range alphas" since at their typical energy of 16 MeV, they are at far higher energy than is ever produced by alpha decay. Ternary fission happens in both neutron-induced fission (the nuclear reaction that happens in a nuclear reactor), and also when fissionable and fissile actinides nuclides (i.e.
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To do this they allowed alpha particles to penetrate a very thin glass wall of an evacuated tube, thus capturing a large number of the hypothesized helium ions inside the tube. They then caused an electric spark inside the tube, which provided a shower of electrons that were taken up by the ions to form neutral atoms of a gas. Subsequent study of the spectra of the resulting gas showed that it was helium and that the alpha particles were indeed the hypothesized helium ions. Because alpha particles occur naturally, but can have energy high enough to participate in a nuclear reaction, study of them led to much early knowledge of nuclear physics.
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Defect formation in gallium arsenide was studied during implantation of N, Al, P, As, and Sb ions under conditions of controlled energy density released in cascades of atomic collisions at temperatures from 40 K to several hundred degrees Celsius with ion current density from hundredths to units of μA / cm2. Using the Rutherford backscattering (RBS), the distribution profiles of the implanted As, Sb were established using the 27Al (p,γ)28Si resonance nuclear reaction of aluminum profiles in gallium arsenide. These results, as well as the results of studies of the modification of the catalytic properties of nickel electrodes for water alkaline electrolysis for the production of hydrogen, formed the basis for a doctoral dissertation.
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The idea of chemical chain reactions was first suggested in 1913 by the German chemist Max Bodenstein for a situation in which two molecules react to form not just the final reaction products, but also some unstable molecules which can further react with the original substances to cause more to react. The concept of a nuclear chain reaction was first hypothesized by the Hungarian scientist Leo Szilard on 12 September 1933. Szilard realized that if a nuclear reaction produced neutrons or dineutrons, which then caused further nuclear reactions, the process might be self-perpetuating. Szilard proposed using mixtures of lighter known isotopes which produced neutrons in copious amounts, and also entertained the possibility of using uranium as a fuel.
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Alpha particles have a charge , but as a nuclear equation describes a nuclear reaction without considering the electrons – a convention that does not imply that the nuclei necessarily occur in neutral atoms – the charge is not usually shown. Alpha decay typically occurs in the heaviest nuclides. Theoretically, it can occur only in nuclei somewhat heavier than nickel (element 28), where the overall binding energy per nucleon is no longer a minimum and the nuclides are therefore unstable toward spontaneous fission-type processes. In practice, this mode of decay has only been observed in nuclides considerably heavier than nickel, with the lightest known alpha emitters being the lightest isotopes (mass numbers 104–109) of tellurium (element 52).
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Uranium-235 tends to capture neutrons because of multiple resonances Excitation function is a term used in nuclear physics to describe a graphical plot of the yield of a radionuclide or reaction channel as a function of the bombarding projectile energy or the calculated excitation energy of the compound nucleus. The excitation function typically resembles a Gaussian bell curve. Mathematically, it is described as a Breit-Wigner function, owing to the resonant nature of the production of the compound nucleus. A nuclear reaction should be described by a complete study of the exit channel (1n,2n,3n etc) excitation functions in order to allow a determination of the optimum energy to be used to maximize the yield.
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The B Reactor had its first nuclear chain reaction in September, 1944, the D Reactor in December 1944 and the F Reactor in February 1945. The reactor produced plutonium-239 by irradiating uranium-238 with neutrons generated by the nuclear reaction. It was one of three reactors - along with the D and F reactors - built about six miles (10 km) apart on the south bank of the Columbia River. Each reactor had its own auxiliary facilities that included a river pump house, large storage and settling basins, a filtration plant, large motor-driven pumps for delivering water to the face of the pile, and facilities for emergency cooling in case of a power failure.
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Reactions that created new elements to this moment were similar, with the only possible difference that several singular neutrons sometimes were released, or none at all. A superheavy atomic nucleus is created in a nuclear reaction that combines two other nuclei of unequal size into one; roughly, the more unequal the two nuclei in terms of mass, the greater the possibility that the two react. The material made of the heavier nuclei is made into a target, which is then bombarded by the beam of lighter nuclei. Two nuclei can only fuse into one if they approach each other closely enough; normally, nuclei (all positively charged) repel each other due to electrostatic repulsion.
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Twenty years later, Bethe and von Weizsäcker independently derived the CN cycle, the first known nuclear reaction that accomplishes this transmutation. The interval between Eddington's proposal and derivation of the CN cycle can mainly be attributed to an incomplete understanding of nuclear structure. The basic principles for explaining the origin of elements and energy generation in stars appear in the concepts describing nucleosynthesis, which arose in the 1940s, led by George Gamow and presented in a 2-page paper in 1948 as the Alpher–Bethe–Gamow paper. A complete concept of processes that make up cosmic nucleosynthesis was presented in the late 1950s by Burbidge, Burbidge, Fowler, and Hoyle, and by Cameron.
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Estimates of the stability of the elements on the island are usually around a half-life of minutes or days; some estimates predict half-lives of millions of years. Although the nuclear shell model predicting magic numbers has existed since the 1940s, the existence of long- lived superheavy nuclides has not been definitively demonstrated. Like the rest of the superheavy elements, the nuclides on the island of stability have never been found in nature; thus, they must be created artificially in a nuclear reaction to be studied. Scientists have not found a way to carry out such a reaction, for it is likely that new types of reactions will be needed to populate nuclei near the center of the island.
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In such an event, reactor power can grow rapidly without any negative feedback from the expansion or boiling of the water, even if it is in a channel just away. Dramatic heating will occur to the nuclear fuel, leading to melting and vaporization of the metals within the core. Rapid expansion, increases in pressure, and failure of core components may lead to the destruction of the nuclear reactor, as was the case with SL-1. As the energy of expansion and heat travel from the nuclear fuel to the water and the vessel, it becomes likely that the nuclear reaction will shut down, either from the lack of sufficient moderator or from the fuel expanding beyond the realm of a critical mass.
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The ground state of helium-5-Lambda, for example, must resemble helium-4 more than it does helium-5 or lithium-5 and must be stable, apart from the eventual weak decay of the lambda with a mean lifetime of 278±11 ps. Sigma hypernuclei have been sought, as have doubly-strange nuclei containing Cascade baryons. Hypernuclei can be made by a nucleus capturing a Lambda or a K meson and boiling off neutrons in a compound nuclear reaction, or, perhaps most easily, by the direct strangeness exchange reaction. : + nucleus -> \+ hypernucleus A generalized mass formula developed for both the non-strange normal nuclei and strange hypernuclei can estimate masses of hypernuclei containing Lambda, Lambda-Lambda, Sigma, Cascade and Theta+ hyperon(s).
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Initial studies of homogeneous reactors took place toward the close of World War II. It pained chemists to see precisely fabricated solid-fuel elements of heterogeneous reactors eventually dissolved in acids to remove fission products—the "ashes" of a nuclear reaction. Chemical engineers hoped to design liquid-fuel reactors that would dispense with the costly destruction and processing of solid fuel elements. The formation of gas bubbles in liquid fuels and the corrosive attack on materials (in uranyl sulfate base solutions), however, presented daunting design and materials challenges. Enrico Fermi advocated construction at Los Alamos of what was to become the world’s third reactor, the first homogeneous liquid-fuel reactor, and the first reactor to be fueled by uranium enriched in uranium-235.
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Diagram of an open-type calorimeter used at the New Hydrogen Energy Institute in Japan Cold fusion is a hypothesized type of nuclear reaction that would occur at, or near, room temperature. It would contrast starkly with the "hot" fusion that is known to take place naturally within stars and artificially in hydrogen bombs and prototype fusion reactors under immense pressure and at temperatures of millions of degrees, and be distinguished from muon-catalyzed fusion. There is currently no accepted theoretical model that would allow cold fusion to occur. In 1989, two electrochemists, Martin Fleischmann and Stanley Pons, reported that their apparatus had produced anomalous heat ("excess heat") of a magnitude they asserted would defy explanation except in terms of nuclear processes.
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Hopes faded with the large number of negative replications, the withdrawal of many reported positive replications, the discovery of flaws and sources of experimental error in the original experiment, and finally the discovery that Fleischmann and Pons had not actually detected nuclear reaction byproducts., , , By late 1989, most scientists considered cold fusion claims dead,, , , and cold fusion subsequently gained a reputation as pathological science. In 1989 the United States Department of Energy (DOE) concluded that the reported results of excess heat did not present convincing evidence of a useful source of energy and decided against allocating funding specifically for cold fusion. A second DOE review in 2004, which looked at new research, reached similar conclusions and did not result in DOE funding of cold fusion.
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Some engines convert heat from noncombustive processes into mechanical work, for example a nuclear power plant uses the heat from the nuclear reaction to produce steam and drive a steam engine, or a gas turbine in a rocket engine may be driven by decomposing hydrogen peroxide. Apart from the different energy source, the engine is often engineered much the same as an internal or external combustion engine. Another group of noncombustive engines includes thermoacoustic heat engines (sometimes called "TA engines") which are thermoacoustic devices which use high-amplitude sound waves to pump heat from one place to another, or conversely use a heat difference to induce high-amplitude sound waves. In general, thermoacoustic engines can be divided into standing wave and travelling wave devices.
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In nuclear physics, a stripping reaction is a nuclear reaction in which part of the incident nucleus combines with the target nucleus, and the remainder proceeds with most of its original momentum in almost its original direction. This reaction was first described by Stuart Thomas Butler in 1950. Deuteron stripping reactions have been extensively used to study nuclear reactions and structure, this occurs where the incident nucleus is a deuteron and only a proton emerges from the target nucleus. A simple one-step stripping reaction can be represented as :A+a →B+b :A + (b+x)a→(A+x)b+b :where A represents the target core, b represents the projectile core, and x is the transferred mass which may represent any number of particles.
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The nuclear exclusion clause is a clause which excludes damage caused by nuclear and radiation accidents from regular insurance policies of, for example, home owners. : Example: Notwithstanding anything to the contrary herein, it is hereby understood and agreed that this policy shall not apply to any loss, damage or expense due to or arising out of, directly or indirectly, nuclear reaction, radiation or radioactive contamination regardless of how it was caused. As operators of nuclear power plants often have limited third- party liability, in the case of a nuclear accident it is possible that private property damage would be covered neither by the operator of the nuclear power plant nor by the property owners' insurance. There is no nuclear exclusion clause in health insurance policies.
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Neutron cross section of boron (top curve is for 10B and bottom curve for 11B) Enriched boron or 10B is used in both radiation shielding and is the primary nuclide used in neutron capture therapy of cancer. In the latter ("boron neutron capture therapy" or BNCT), a compound containing 10B is incorporated into a pharmaceutical which is selectively taken up by a malignant tumor and tissues near it. The patient is then treated with a beam of low energy neutrons at a relatively low neutron radiation dose. The neutrons, however, trigger energetic and short-range secondary alpha particle and lithium-7 heavy ion radiation that are products of the boron + neutron nuclear reaction, and this ion radiation additionally bombards the tumor, especially from inside the tumor cells.
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For an observer in the rest frame, or center of momentum frame, removing energy is the same as removing mass and the formula indicates how much mass is lost when energy is removed. In a nuclear reaction, the mass of the atoms that come out is less than the mass of the atoms that go in, and the difference in mass shows up as heat and light with the same relativistic mass as the difference. In this case, the in the formula is the energy released and removed, and the mass is how much the mass decreases. In the same way, when any energy is added to an isolated system, the increase in the mass is equal to the added energy divided by .
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Particle-induced gamma emission (PIGE) is a form of nuclear reaction analysis, one of the ion beam analysis thin-film analytical techniques. Typically, an MeV proton beam is directed onto a sample which may be tens of microns thick, and the fast protons may excite the target nuclei such that gamma rays are emitted. These may be used to characterise the sample. For example, sodium in glass is of great importance but can be hard to measure non destructively: X-ray fluorescence (XRF) and particle-induced X-ray emission (PIXE) are both sensitive only to the surface few microns of the sample because of the low energy (and consequent high absorption coefficient) of the Na K X-rays (1.05 keV).
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The 54-m3 detector tank was filled with 101 tons of gallium trichloride-hydrochloric acid solution, which contained 30.3 tons of gallium. The gallium in this solution acted as the target for a neutrino-induced nuclear reaction, which transmuted it into germanium through the following reaction: : νe \+ 71Ga → 71Ge + e−. The threshold for neutrino detection by this reaction is very low (233.2 keV), and this is also the reason why gallium was chosen: other reactions (as with chlorine-37) have higher thresholds and are thus unable to detect low-energy neutrinos. In fact, the low energy threshold makes the reaction with gallium suitable to the detection of neutrinos emitted in the initial proton fusion reaction of the proton-proton chain reaction, which have a maximum energy of 420 keV.
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In 1993, at Dubna, Yuri Lazarev and his team announced the discovery of long-lived 266Sg and 265Sg produced in the 4n and 5n channels of this nuclear reaction following the search for seaborgium isotopes suitable for a first chemical study. It was announced that 266Sg decayed by 8.57 MeV alpha-particle emission with a projected half-life of ~20 s, lending strong support to the stabilising effect of the Z=108,N=162 closed shells. This reaction was studied further in 1997 by a team at GSI and the yield, decay mode and half-lives for 266Sg and 265Sg have been confirmed, although there are still some discrepancies. In the recent synthesis of 270Hs (see hassium), 266Sg was found to undergo exclusively SF with a short half-life (TSF = 360 ms).
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Post- accident analysis concluded that the final control method (i.e., dissipation of the prompt critical state and the end of the sustained nuclear reaction) occurred by means of catastrophic core disassembly: destructive melting, vaporization, and consequent conventional explosive expansion of the parts of the reactor core where the greatest amount of heat was being produced most quickly. It was estimated that this core heating and vaporization process happened in about 7.5 milliseconds, before enough steam had been formed to shut down the reaction, beating the steam shutdown by a few milliseconds. A key statistic makes it clear why the core blew apart: the reactor designed for a 3 MW power output operated momentarily at a peak of about 20 GW, a power density over 6,000 times higher than its safe operating limit.
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Transmutation of elements from one to another had been understood since 1901 as a result of natural radioactive decay, but when Rutherford projected alpha particles from alpha decay into air, he discovered this produced a new type of radiation which proved to be hydrogen nuclei (Rutherford named these protons). Further experimentation showed the protons to be coming from the nitrogen component of air, and the reaction was deduced to be a transmutation of nitrogen into oxygen in the reaction :14N + α → 17O + p This was the first discovered nuclear reaction. To the adjacent pictures: According to the energy-loss curve by Bragg, it is recognizable that the alpha particle indeed loses more energy on the end of the trace.Magazine "nuclear energy" (III/18 (203) special edition, Volume 10, Issue 2 /1967.
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Their article was published on 6 January 1939. On 19 December 1938, eighteen days before the publication, Otto Hahn communicated these results and his conclusion of a bursting of the uranium nucleus in a letter to his colleague and friend Lise Meitner, who had fled Germany in July to the Netherlands and then to Sweden.Ruth Lewin Sime Lise Meitner's Escape from Germany, American Journal of Physics Volume 58, Number 3, 263–267 (1990). Meitner and her nephew Otto Robert Frisch confirmed Hahn's conclusion of a bursting and correctly interpreted the results as "nuclear fission" – a term coined by Frisch.Lise Meitner and O. R. Frisch Disintegration of Uranium by Neutrons: a New Type of Nuclear Reaction, Nature, Volume 143, Number 3615, 239–240 (11 February 1939). The paper is dated 16 January 1939.
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The panel noted the large number of failures to replicate excess heat and the greater inconsistency of reports of nuclear reaction byproducts expected by established conjecture. Nuclear fusion of the type postulated would be inconsistent with current understanding and, if verified, would require established conjecture, perhaps even theory itself, to be extended in an unexpected way. The panel was against special funding for cold fusion research, but supported modest funding of "focused experiments within the general funding system". Cold fusion supporters continued to argue that the evidence for excess heat was strong, and in September 1990 the National Cold Fusion Institute listed 92 groups of researchers from 10 different countries that had reported corroborating evidence of excess heat, but they refused to provide any evidence of their own arguing that it could endanger their patents.
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The use of theoretical and applied physics were an extremely important part of Canada's war effort as reflected in activities involving the development of atomic energy. The Tizard Mission, a delegation of British scientists and military experts, visiting North America to promote wartime allied scientific cooperation, met with NRC nuclear physicist George Laurence in Ottawa in 1940. As a result of this meeting, beginning in 1942, a Montreal-based British-Canadian project under the aegis of the National Research Council undertook the construction of a heavy-water atomic reactor. An experimental device with graphite control rods, ZEEP, (Zero Energy Experimental Pile) was built at Chalk River Ontario before the end of the war, and on 5 September 1945 achieved "the first self-sustained nuclear reaction outside the United States".
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The Nuclear industry (as distinct from the uranium industry) in Canada dates back to 1942 when a joint British-Canadian laboratory was set up in Montreal, Quebec, under the administration of the National Research Council of Canada, to develop a design for a heavy-water nuclear reactor. This reactor was called National Research Experimental and would be the most powerful research reactor in the world when completed. In the meantime, in 1944, approval was given to proceed with the construction of the smaller ZEEP (Zero Energy Experimental Pile) test reactor at Chalk River, Ontario and on September 5, 1945 at 3:45 p.m., the 10 Watt ZEEP successfully achieved the first self-sustained nuclear reaction outside the United States. ZEEP operated for 25 years as a key research facility.
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The graphite composition was selected to moderate the nuclear reaction fueled by of uranium slugs approximately diameter long (the approximate size of a roll of quarters), sealed in aluminum cans, and loaded into the aluminum tubes. The reactor was water-cooled, with cooling water pumped from the Hanford Reach of the Columbia River through the aluminum tubes around the uranium slugs at the rate of per minute. The water was discharged into settling basins, then returned to the river after allowing time for the decay of radioactive materials, the settling out of particulate matter and for the water to cool so it could be returned to the Columbia River. Water returning to the river was prohibited from raising the temperature of the river by more than 11 °F.
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In nature, carbon exists as two stable, nonradioactive isotopes: carbon-12 (), and carbon-13 (), and a radioactive isotope, carbon-14 (), also known as "radiocarbon". The half-life of (the time it takes for half of a given amount of to decay) is about 5,730 years, so its concentration in the atmosphere might be expected to decrease over thousands of years, but is constantly being produced in the lower stratosphere and upper troposphere, primarily by galactic cosmic rays, and to a lesser degree by solar cosmic rays. These cosmic rays generate neutrons as they travel through the atmosphere which can strike nitrogen-14 () atoms and turn them into . The following nuclear reaction is the main pathway by which is created: : n + → + p where n represents a neutron and p represents a proton.
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Steam being less dense than water, it absorbs fewer neutrons, which required constant adjustments in the nuclear reaction and the turbine inlet valves in order to avoid reactor power running away and activating the shutdown systems. To alleviate this problem, engineers developed a new control system that was installed at the beginning of 1976, but the plant could then be operated at no more than two-thirds of its nominal capacity. On May 21 and 22, 1977, ten tonnes of heavy water containing 31,000 curies of tritium were released from the plant into the St. Lawrence River due to a failure in a moderator heat exchanger caused by corrosion. The plant ceased electricity production on the 1st of June, 1977, and remained the property of AECL, given that Hydro-Québec refused to take formal possession of it.
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The reactor design in question begins producing power when hydrogen gas at a sufficient temperature and pressure is admitted to the core (made up of granulated uranium metal) and reacts with the uranium metal to form uranium hydride. Uranium hydride is both a nuclear fuel and a neutron moderator; apparently it, like other neutron moderators, will slow neutrons sufficiently to allow for fission reactions to take place; the U-235 atoms within the hydride also serve as the nuclear fuel. Once the nuclear reaction has started, it will continue until it reaches a certain temperature, approximately , where, due to the chemical properties of uranium hydride, it chemically decomposes and turns into hydrogen gas and uranium metal. The loss of neutron moderation due to the chemical decomposition of the uranium hydride will consequently slow — and eventually halt — the reaction.
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An example of this kind of a nuclear reaction occurs in the production of cobalt-60 within a nuclear reactor: The cobalt-60 then decays by the emission of a beta particle plus gamma rays into nickel-60. This reaction has a half-life of about 5.27 years, and due to the availability of cobalt-59 (100% of its natural abundance), this neutron bombarded isotope of cobalt is a valuable source of nuclear radiation (namely gamma radiation) for radiotherapy.Manual for reactor produced radioisotopes from the International Atomic Energy Agency In other cases, and depending on the kinetic energy of the neutron, the capture of a neutron can cause nuclear fission—the splitting of the atomic nucleus into two smaller nuclei. If the fission requires an input of energy, that comes from the kinetic energy of the neutron.
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The first part takes place on Earth, almost a century after the "Great Crisis", where ecological and economic collapse reduced the world's population from six billion to two billion. Radiochemist Frederick Hallam discovers that a container's contents have been altered. He finds out that the sample, originally tungsten, has been transformed into plutonium 186—an isotope that cannot occur naturally in our universe. As this is investigated, Hallam gets the credit for suggesting that the matter has been exchanged by beings in a parallel universe; this leads to the development of a cheap, clean, and apparently endless source of energy: the "Pump", which transfers matter between our universe (where plutonium 186 decays into tungsten 186) and a parallel one governed by different physical laws (where tungsten 186 turns into plutonium 186), yielding a nuclear reaction in the process.
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Zubrin claimed in his design that the apparatus was created so that the liquid flow rate or velocity was what mattered most in the process, not the material. Therefore, he argued that if the proper velocity was chosen for the liquid traveling through the reaction chamber, the site of maximum fission release could then be located at the end of the chamber, thus allowing the system to remain intact and safe to operate. These claims have still not been proven due to no test of such a device having ever been conducted. For example, Zubrin argues that if diluted nuclear fuel flows into the chamber at speed similar to diffusion speed of thermal neutrons, then nuclear reaction is confined in the chamber and does not damage the rest of the system (it is a nuclear analog of gas burner).
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According to the aforementioned patent application, the reactor design in question begins producing power when hydrogen gas at a sufficient temperature and pressure is admitted to the core (made up of granulated uranium metal) and reacts with the uranium metal to form uranium hydride. Uranium hydride is both a nuclear fuel and a neutron moderator; apparently it, like other neutron moderators, will slow neutrons sufficiently to allow for fission reactions to take place; the uranium-235 atoms within the hydride also serve as the nuclear fuel. Once the nuclear reaction has started, it will continue until it reaches a certain temperature, approximately , where, due to the chemical properties of uranium hydride, it chemically decomposes and turns into hydrogen gas and uranium metal. The loss of neutron moderation due to the chemical decomposition of the uranium hydride will consequently slow — and eventually halt — the reaction.
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Mass change (decrease) in bound systems, particularly atomic nuclei, has also been termed mass defect, mass deficit, or mass packing fraction. The difference between the unbound system calculated mass and experimentally measured mass of nucleus (mass change) is denoted as Δm. It can be calculated as follows: :Mass change = (unbound system calculated mass) − (measured mass of system) :: e.g. (sum of masses of protons and neutrons) − (measured mass of nucleus) After a nuclear reaction occurs that results in an excited nucleus, the energy that must be radiated or otherwise removed as binding energy in order to decay to the unexcited state may be in one of several forms. This may be electromagnetic waves, such as gamma radiation; the kinetic energy of an ejected particle, such as an electron, in internal conversion decay; or partly as the rest mass of one or more emitted particles, such as the particles of beta decay.
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Rutherford went on to say: Szilard was so annoyed at Rutherford's dismissal that, on the same day, he conceived of the idea of nuclear chain reaction (analogous to a chemical chain reaction), using recently discovered neutrons. The idea did not use the mechanism of nuclear fission, which was not yet discovered, but Szilard realized that if neutrons could initiate any sort of energy-producing nuclear reaction, such as the one that had occurred in lithium, and could be produced themselves by the same reaction, energy might be obtained with little input, since the reaction would be self-sustaining. Szilard filed for a patent on the concept of the neutron-induced nuclear chain reaction in 1933, which was granted in 1936. Under section 30 of the Patents and Designs Act (1907, UK), Szilard was able to assign the patent to the British Admiralty to ensure its secrecy, which he did.
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Beyond the arts and sciences, Chicago is well known for its professional schools, which include the Pritzker School of Medicine, the Booth School of Business, the Law School, the School of Social Service Administration, the Harris School of Public Policy, the Divinity School and the Graham School of Continuing Liberal and Professional Studies, as well as the recently launched Pritzker School of Molecular Engineering. The university has additional campuses and centers in London, Paris, Beijing, Delhi, and Hong Kong, as well as in downtown Chicago. University of Chicago scholars have played a major role in the development of many academic disciplines, including economics, law, literary criticism, mathematics, religion, sociology, and the behavioralism school of political science, establishing the Chicago schools in various fields. Chicago's Metallurgical Laboratory produced the world's first man-made, self-sustaining nuclear reaction in Chicago Pile-1 beneath the viewing stands of the university's Stagg Field.
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Active in helioseismology for over twenty years beginning in the early 1980s. The efforts in which he was involved include the first determinations of the Sun’s internal rotation, its internal differential rotation and determining limits on buried magnetic field and demonstrating that the Sun rotates on a single axis, determining the Sun’s seismic radius. Observationally, Goode led the effort that ultimately showed solar oscillations are driven, in part, by the noise made in the ubiquitous, continuous collapses of the dark inter-granular lanes. Also in the 1990s, he teamed to develop a seismic model of the Sun's interior, which was used to place strong limits on solar opacities and nuclear-reaction cross sections in the p-p chain, as well as demonstrating that there is no astrophysical solution to the sun’s neutrino deficit but rather the deficit is in the province of particle physics, which was subsequently shown experimentally.
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An example of this kind of fission in a light element can occur when the stable isotope of lithium, lithium-7, is bombarded with fast neutrons and undergoes the following nuclear reaction: : + → + + + gamma rays + kinetic energy In other words, the capture of a neutron by lithium-7 causes it to split into an energetic helium nucleus (alpha particle), a hydrogen-3 (tritium) nucleus and a free neutron. The Castle Bravo accident, in which the thermonuclear bomb test at Enewetak Atoll in 1954 exploded with 2.5 times the expected yield, was caused by the unexpectedly high probability of this reaction. In the areas around a pressurized water reactors or boiling water reactors during normal operation, a significant amount of radiation is produced due to the fast neutron activation of coolant water oxygen via a (n,p) reaction. The activated oxygen-16 nucleus emits a proton (hydrogen nucleus), and transmutes to nitrogen-16, which has a very short life (7.13 seconds) before decaying back to oxygen-16 (emitting 6.13MeV beta particles).
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Some processes involving neutrons are notable for absorbing or finally yielding energy — for example neutron kinetic energy does not yield heat immediately if the neutron is captured by a uranium-238 atom to breed plutonium-239, but this energy is emitted if the plutonium-239 is later fissioned. On the other hand, so-called delayed neutrons emitted as radioactive decay products with half-lives up to several minutes, from fission-daughters, are very important to reactor control, because they give a characteristic "reaction" time for the total nuclear reaction to double in size, if the reaction is run in a "delayed-critical" zone which deliberately relies on these neutrons for a supercritical chain-reaction (one in which each fission cycle yields more neutrons than it absorbs). Without their existence, the nuclear chain-reaction would be prompt critical and increase in size faster than it could be controlled by human intervention. In this case, the first experimental atomic reactors would have run away to a dangerous and messy "prompt critical reaction" before their operators could have manually shut them down (for this reason, designer Enrico Fermi included radiation- counter-triggered control rods, suspended by electromagnets, which could automatically drop into the center of Chicago Pile-1).
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