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Scram
A scram or SCRAM is an emergency shutdown of a nuclear reactor effected by immediately terminating the fission reaction. It is also the name that is given to the manually operated kill switch that initiates the shutdown. In commercial reactor operations, this type of shutdown is often referred to as a "scram" at boiling water reactors (BWR), a "reactor ''trip''" at pressurized water reactors and at a CANDU reactor. In many cases, a scram is part of the routine shutdown procedure, which serves to test the emergency shutdown system. The etymology of the term is a matter of debate. United States Nuclear Regulatory Commission historian Tom Wellock notes that '' scram'' is English-language slang for leaving quickly and urgently, and cites this as the original and most likely accurate basis for the use of ''scram'' in the technical context. A persistent alternative explanation posits that ''scram'' is an acronym for "safety control rod axe man", which was supposedly coined by En ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scram
A scram or SCRAM is an emergency shutdown of a nuclear reactor effected by immediately terminating the fission reaction. It is also the name that is given to the manually operated kill switch that initiates the shutdown. In commercial reactor operations, this type of shutdown is often referred to as a "scram" at boiling water reactors (BWR), a "reactor ''trip''" at pressurized water reactors and at a CANDU reactor. In many cases, a scram is part of the routine shutdown procedure, which serves to test the emergency shutdown system. The etymology of the term is a matter of debate. United States Nuclear Regulatory Commission historian Tom Wellock notes that '' scram'' is English-language slang for leaving quickly and urgently, and cites this as the original and most likely accurate basis for the use of ''scram'' in the technical context. A persistent alternative explanation posits that ''scram'' is an acronym for "safety control rod axe man", which was supposedly coined by En ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boiling Water Reactor Safety Systems
Boiling water reactor safety systems are nuclear safety systems constructed within boiling water reactors in order to prevent or mitigate environmental and health hazards in the event of accident or natural disaster. Like the pressurized water reactor, the BWR reactor core continues to produce heat from radioactive decay after the fission reactions have stopped, making a core damage incident possible in the event that all safety systems have failed and the core does not receive coolant. Also like the pressurized water reactor, a boiling water reactor has a negative void coefficient, that is, the neutron (and the thermal) output of the reactor decreases as the proportion of steam to liquid water increases inside the reactor. However, unlike a pressurized water reactor which contains no steam in the reactor core, a sudden increase in BWR steam pressure (caused, for example, by the actuation of the main steam isolation valve (MSIV) from the reactor) will result in a sudden decr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chicago Pile-1
Chicago Pile-1 (CP-1) was the world's first artificial nuclear reactor. On 2 December 1942, the first human-made self-sustaining nuclear chain reaction was initiated in CP-1, during an experiment led by Enrico Fermi. The secret development of the reactor was the first major technical achievement for the Manhattan Project, the Allied effort to create atomic bombs during World War II. Developed by the Metallurgical Laboratory at the University of Chicago, CP-1 was built under the west viewing stands of the original Stagg Field. Although the project's civilian and military leaders had misgivings about the possibility of a disastrous runaway reaction, they trusted Fermi's safety calculations and decided they could carry out the experiment in a densely populated area. Fermi described the reactor as "a crude pile of black bricks and wooden timbers". The reactor was assembled in November 1942, by a team that included Fermi, Leo Szilard (who had previously formulated an idea for no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boiling Water Reactor
A boiling water reactor (BWR) is a type of light water nuclear reactor used for the generation of electrical power. It is a design different from a Soviet graphite-moderated RBMK. It is the second most common type of electricity-generating nuclear reactor after the pressurized water reactor (PWR), which is also a type of light water nuclear reactor. The main difference between a BWR and PWR is that in a BWR, the reactor core heats water, which turns to steam and then drives a steam turbine. In a PWR, the reactor core heats water, which does not boil. This hot water then exchanges heat with a lower pressure system, which turns water into steam that drives the turbine. The BWR was developed by the Argonne National Laboratory and General Electric (GE) in the mid-1950s. The main present manufacturer is GE Hitachi Nuclear Energy, which specializes in the design and construction of this type of reactor. Overview A boiling water reactor uses demineralized water as a coolant and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pressurized Water Reactor
A pressurized water reactor (PWR) is a type of light-water nuclear reactor. PWRs constitute the large majority of the world's nuclear power plants (with notable exceptions being the UK, Japan and Canada). In a PWR, the primary coolant (water) is pumped under high pressure to the reactor core where it is heated by the energy released by the fission of atoms. The heated, high pressure water then flows to a steam generator, where it transfers its thermal energy to lower pressure water of a secondary system where steam is generated. The steam then drives turbines, which spin an electric generator. In contrast to a boiling water reactor (BWR), pressure in the primary coolant loop prevents the water from boiling within the reactor. All light-water reactors use ordinary water as both coolant and neutron moderator. Most use anywhere from two to four vertically mounted steam generators; VVER reactors use horizontal steam generators. PWRs were originally designed to serve as nuclear marine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Fission
Nuclear fission is a nuclear reaction, reaction in which the atomic nucleus, nucleus of an atom splits into two or more smaller atomic nucleus, nuclei. The fission process often produces gamma ray, gamma photons, and releases a very large amount of energy even by the energetic standards of radioactive decay. Nuclear fission of heavy elements was discovered on Monday 19 December 1938, by German chemist Otto Hahn and his assistant Fritz Strassmann in cooperation with Austrian-Swedish physicist Lise Meitner. Hahn understood that a "burst" of the atomic nuclei had occurred. Meitner explained it theoretically in January 1939 along with her nephew Otto Robert Frisch. Frisch named the process by analogy with fission (biology), biological fission of living cells. For heavy nuclides, it is an exothermic reaction which can release large amounts of energy both as electromagnetic radiation and as kinetic energy of the fragments (heating the bulk material where fission takes place). Li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Reactor
A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat from nuclear fission is passed to a working fluid (water or gas), which in turn runs through steam turbines. These either drive a ship's propellers or turn electrical generators' shafts. Nuclear generated steam in principle can be used for industrial process heat or for district heating. Some reactors are used to produce isotopes for Nuclear medicine, medical and industrial radiography, industrial use, or for production of weapons-grade plutonium. , the International Atomic Energy Agency reports there are 422 nuclear power reactors and 223 nuclear research reactors in operation around the world. In the early era of nuclear reactors (1940s), a reactor was known as a nuclear pile or atomic pile (so-called because the graphite moderator blocks of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Control Rod
Control rods are used in nuclear reactors to control the rate of fission of the nuclear fuel – uranium or plutonium. Their compositions include chemical elements such as boron, cadmium, silver, hafnium, or indium, that are capable of absorbing many neutrons without themselves decaying. These elements have different neutron capture cross sections for neutrons of various energies. Boiling water reactors (BWR), pressurized water reactors (PWR), and heavy-water reactors (HWR) operate with thermal neutrons, while breeder reactors operate with fast neutrons. Each reactor design can use different control rod materials based on the energy spectrum of its neutrons. Control rods have been used in nuclear aircraft engines like Project Pluto as a method of control. Operating principle Control rods are inserted into the core of a nuclear reactor and adjusted in order to control the rate of the nuclear chain reaction and, thereby, the thermal power output of the reactor, the rate o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutron
The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons behave similarly within the nucleus, and each has a mass of approximately one atomic mass unit, they are both referred to as nucleons. Their properties and interactions are described by nuclear physics. Protons and neutrons are not elementary particles; each is composed of three quarks. The chemical properties of an atom are mostly determined by the configuration of electrons that orbit the atom's heavy nucleus. The electron configuration is determined by the charge of the nucleus, which is determined by the number of protons, or atomic number. The number of neutrons is the neutron number. Neutrons do not affect the electron configuration, but the sum of atomic and neutron numbers is the mass of the nucleus. Atoms of a chemical element t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Borax
Borax is a salt (chemistry), salt (ionic compound), a hydration (chemistry), hydrated borate of sodium, with chemical formula often written . It is a colorless crystalline solid, that dissolves in water to make a base (chemistry), basic aqueous solution, solution. It is commonly available in powder or granular form, and has many industrial and household uses, including as a pesticide, as a metal soldering flux (metallurgy), flux, as a component of glass, Enamelled glass, enamel, and glaze (pottery), pottery glazes, for tanning (leather), tanning of skins and hide (skin), hides, for artificial aging of wood, as a preservative against wood fungus, and as a pharmaceutic alkalizer. In chemical laboratories, it is used as a buffer solution, buffering agent. The compound is often called sodium tetraborate decahydrate, but that name is not consistent with its structure. The anion is not tetraborate but tetraborate, tetrahydroxy tetraborate , so the more correct formula should be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boric Acid
Boric acid, more specifically orthoboric acid, is a compound of boron, oxygen, and hydrogen with formula . It may also be called hydrogen borate or boracic acid. It is usually encountered as colorless crystals or a white powder, that dissolves in water, and occurs in nature as the mineral sassolite. It is a weak acid that yields various borate anions and salts, and can react with alcohols to form borate esters. Boric acid is often used as an antiseptic, insecticide, flame retardant, neutron absorber, or precursor to other boron compounds. The term "boric acid" is also used generically for any oxoacid of boron, such as metaboric acid and tetraboric acid . History Orthoboric acid was first prepared by Wilhelm Homberg (1652–1715) from borax, by the action of mineral acids, and was given the name ("sedative salt of Homberg"). However boric acid and borates have been used since the time of the ancient Greeks for cleaning, preserving food, and other activities. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EBR-I - SCRAM Button
Experimental Breeder Reactor I (EBR-I) is a decommissioned research reactor and U.S. National Historic Landmark located in the desert about southeast of Arco, Idaho. It was the world's first breeder reactor. At 1:50 p.m. on December 20, 1951, it became one of the world's first electricity-generating nuclear power plants when it produced sufficient electricity to illuminate four 200-watt light bulbs. EBR-I subsequently generated sufficient electricity to power its building, and continued to be used for experimental purposes until it was decommissioned in 1964. The museum is open for visitors from late May until early September. History As part of the National Reactor Testing Station (since 2005 Idaho National Laboratory), EBR-I's construction started in late 1949. The reactor was designed and constructed by a team led by Walter Zinn at the Argonne National Laboratory Idaho site, known as Argonne-West. In its early stages, the reactor plant was referred to as Chicago Pil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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