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Reactor-grade Plutonium
Reactor-grade plutonium (RGPu) is the isotopic grade of plutonium that is found in spent nuclear fuel after the uranium-235 primary fuel that a nuclear power reactor uses has burnt up. The uranium-238 from which most of the plutonium isotopes derive by neutron capture is found along with the U-235 in the low enriched uranium fuel of civilian reactors. In contrast to the low burnup of weeks or months that is commonly required to produce weapons-grade plutonium (WGPu/ 239Pu), the long time in the reactor that produces reactor-grade plutonium leads to transmutation of much of the fissile, relatively long half-life isotope 239Pu into a number of other isotopes of plutonium that are less fissile or more radioactive. When absorbs a neutron, it does not always undergo nuclear fission. Sometimes neutron absorption will instead produce at the neutron temperatures and fuel compositions present in typical light water reactors, with the concentration of steadily rising with longer irradi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spent Nuclear Fuel
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. The term "fuel" is slightly confusing, as it implies a combustion of some type, which does not occur in a nuclear power plant. Nevertheless, this term is generally accepted. Nature of spent fuel Nanomaterial properties In the oxide fuel, intense temperature gradients exist that cause fission products to migrate. The zirconium tends to move to the centre of the fuel pellet where the temperature is highest, while the lower-boiling fission products move to the edge of the pellet. The pellet is likely to contain many small bubble-like pores that form during use; the fission product xenon migrates to these voids. Some of this xeno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal-neutron Reactor
A thermal-neutron reactor is a nuclear reactor that uses slow or thermal neutrons. ("Thermal" does not mean hot in an absolute sense, but means in thermal equilibrium with the medium it is interacting with, the reactor's fuel, moderator and structure, which is much lower energy than the fast neutrons initially produced by fission.) Most nuclear power plant reactors are thermal reactors and use a neutron moderator to slow neutrons until they approach the average kinetic energy of the surrounding particles, that is, to reduce the speed of the neutrons to low-velocity, thermal neutrons. Neutrons are uncharged, this allows them to penetrate deep in the target and close to the nuclei,Squires, G.L. (2012, March 29). Introduction of the Theory of Thermal Neutron Scattering. https://books.google.com/books?hl=en&lr=&id=KUVD8KJt7_0C&oi=fnd&pg=PR9&dq=thermal-neutron+reactor&ots=1tn_4dppSF&sig=QDWkMU5-iW8_4GCXjItypUchKBQ#v=onepage&q=thermal-neutron%20reactor&f=false thus scattering neutrons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weapons Grade
Weapons-grade nuclear material is any fissionable nuclear material that is pure enough to make a nuclear weapon or has properties that make it particularly suitable for nuclear weapons use. Plutonium and uranium in grades normally used in nuclear weapons are the most common examples. (These nuclear materials have other categorizations based on their purity.) Only fissile isotopes of certain elements have the potential for use in nuclear weapons. For such use, the concentration of fissile isotopes uranium-235 and plutonium-239 in the element used must be sufficiently high. Uranium from natural sources is enriched by isotope separation, and plutonium is produced in a suitable nuclear reactor. Experiments have been conducted with uranium-233 (the fissile material at the heart of the thorium fuel cycle). Neptunium-237 and some isotopes of americium might be usable, but it is not clear that this has ever been implemented. The latter substances are part of the minor actinides in spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plutonium-239
Plutonium-239 (239Pu or Pu-239) is an isotope of plutonium. Plutonium-239 is the primary fissile isotope used for the production of nuclear weapons, although uranium-235 is also used for that purpose. Plutonium-239 is also one of the three main isotopes demonstrated usable as fuel in thermal spectrum nuclear reactors, along with uranium-235 and uranium-233. Plutonium-239 has a half-life of 24,110 years. Nuclear properties The nuclear properties of plutonium-239, as well as the ability to produce large amounts of nearly pure 239Pu more cheaply than highly enriched weapons-grade uranium-235, led to its use in nuclear weapons and nuclear power plants. The fissioning of an atom of uranium-235 in the reactor of a nuclear power plant produces two to three neutrons, and these neutrons can be absorbed by uranium-238 to produce plutonium-239 and other isotopes. Plutonium-239 can also absorb neutrons and fission along with the uranium-235 in a reactor. Of all the common nuclear fuels ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plutonium-240
Plutonium-240 ( or Pu-240) is an isotope of plutonium formed when plutonium-239 captures a neutron. The detection of its spontaneous fission led to its discovery in 1944 at Los Alamos and had important consequences for the Manhattan Project. 240Pu undergoes spontaneous fission as a secondary decay mode at a small but significant rate. The presence of 240Pu limits plutonium's use in a nuclear bomb, because the neutron flux from spontaneous fission initiates the chain reaction prematurely, causing an early release of energy that physically disperses the core before full implosion is reached. It decays by alpha emission to uranium-236. Nuclear properties About 62% to 73% of the time when 239Pu captures a neutron, it undergoes fission; the remainder of the time, it forms 240Pu. The longer a nuclear fuel element remains in a nuclear reactor, the greater the relative percentage of 240Pu in the fuel becomes. The isotope 240Pu has about the same thermal neutron capture cross secti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plutonium
Plutonium is a radioactive chemical element with the symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation states. It reacts with carbon, halogens, nitrogen, silicon, and hydrogen. When exposed to moist air, it forms oxides and hydrides that can expand the sample up to 70% in volume, which in turn flake off as a powder that is pyrophoric. It is radioactive and can accumulate in bones, which makes the handling of plutonium dangerous. Plutonium was first synthetically produced and isolated in late 1940 and early 1941, by a deuteron bombardment of uranium-238 in the cyclotron at the University of California, Berkeley. First, neptunium-238 ( half-life 2.1 days) was synthesized, which subsequently beta-decayed to form the new element with atomic number 94 and atomic weight 238 (half-life 88 years). Since ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Department Of Energy
The United States Department of Energy (DOE) is an executive department of the U.S. federal government that oversees U.S. national energy policy and manages the research and development of nuclear power and nuclear weapons in the United States. The DOE oversees the U.S. nuclear weapons program, nuclear reactor production for the United States Navy, energy-related research, and domestic energy production and energy conservation. The DOE was created in 1977 in the aftermath of the 1973 oil crisis. It sponsors more physical science research than any other U.S. federal agency, the majority of which is conducted through its system of National Laboratories. The DOE also directs research in genomics, with the Human Genome Project originating from a DOE initiative. The department is headed by the Secretary of Energy, who reports directly to the president of the United States and is a member of the Cabinet. The current Secretary of Energy is Jennifer Granholm, who has served ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sasahara
Sasahara (written: lit. "bamboo field") is a Japanese surname. Notable people with the surname include: *, Japanese judoka *, Japanese Paralympic athlete *, Japanese anime director *, Japanese sport wrestler *, Japanese footballer *, Japanese racing driver *, Japanese footballer *, Japanese voice actress *, Japanese skeleton racer Fictional characters *, protagonist of the manga series ''Genshiken'' {{surname Japanese-language surnames ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Proliferation
Nuclear proliferation is the spread of nuclear weapons, fissionable material, and weapons-applicable nuclear technology and information to nations not recognized as " Nuclear Weapon States" by the Treaty on the Non-Proliferation of Nuclear Weapons, commonly known as the ''Non-Proliferation Treaty'' or ''NPT''. Proliferation has been opposed by many nations with and without nuclear weapons, as governments fear that more countries with nuclear weapons will increase the possibility of nuclear warfare (up to and including the so-called countervalue targeting of civilians with nuclear weapons), de-stabilize international or regional relations, or infringe upon the national sovereignty of nation states. Four countries besides the five recognized Nuclear Weapons States have acquired, or are presumed to have acquired, nuclear weapons: India, Pakistan, North Korea, and Israel. None of these four is a party to the NPT, although North Korea acceded to the NPT in 1985, then withdrew in 200 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thin Man (nuclear Bomb)
"Thin Man" was the code name for a proposed plutonium gun-type nuclear bomb that the United States was developing during the Manhattan Project. Its development was abandoned when it was discovered that the spontaneous fission rate of nuclear reactor-bred plutonium was too high for use in a gun-type design due to the high concentration of the isotope plutonium-240. Early decisions In 1942, prior to the United States Army taking over control of wartime atomic research in what became known as the Manhattan Project, Robert Oppenheimer held conferences in Chicago in June and Berkeley, California in July, at which physicists discussed nuclear bomb design issues. A gun-type design was chosen, in which two sub-critical masses of plutonium would be brought together by firing a "bullet" into a "target". The idea of an implosion-type nuclear weapon was suggested by Richard Tolman, but it attracted scant consideration, being far more complex. Oppenheimer reviewed his options in early 1943 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plutonium-240
Plutonium-240 ( or Pu-240) is an isotope of plutonium formed when plutonium-239 captures a neutron. The detection of its spontaneous fission led to its discovery in 1944 at Los Alamos and had important consequences for the Manhattan Project. 240Pu undergoes spontaneous fission as a secondary decay mode at a small but significant rate. The presence of 240Pu limits plutonium's use in a nuclear bomb, because the neutron flux from spontaneous fission initiates the chain reaction prematurely, causing an early release of energy that physically disperses the core before full implosion is reached. It decays by alpha emission to uranium-236. Nuclear properties About 62% to 73% of the time when 239Pu captures a neutron, it undergoes fission; the remainder of the time, it forms 240Pu. The longer a nuclear fuel element remains in a nuclear reactor, the greater the relative percentage of 240Pu in the fuel becomes. The isotope 240Pu has about the same thermal neutron capture cross secti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transuranium
The transuranium elements (also known as transuranic elements) are the chemical elements with atomic numbers greater than 92, which is the atomic number of uranium. All of these elements are unstable and decay radioactively into other elements. With the exception of neptunium and plutonium (which have been found in trace amounts in nature), all do not occur naturally on Earth and are synthetic. Overview Of the elements with atomic numbers 1 to 92, most can be found in nature, having stable isotopes (such as hydrogen) or very long-lived radioisotopes (such as uranium), or existing as common decay products of the decay of uranium and thorium (such as radon). The exceptions are elements 43, 61, 85, and 87; all four occur in nature, but only in very minor branches of the uranium and thorium decay chains, and thus all save element 87 were first discovered by synthesis in the laboratory rather than in nature (and even element 87 was discovered from purified samples of its parent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
