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Helikon Vortex Separation Process
The Helikon vortex separation process is an aerodynamic uranium enrichment process designed around a device called a vortex tube. Paul Dirac thought of the idea for isotope separation and tried creating such a device in 1934 in the lab of Peter Kapitza at Cambridge. Other methods of separation were more practical at that time, but this method was designed and used in South Africa for producing reactor fuel with a uranium-235 content of around 3–5%, and 80–93% enriched uranium for use in nuclear weapons. The Uranium Enrichment Corporation of South Africa, Ltd. (UCOR) developed the process, operating a facility at Pelindaba (known as the 'Y' plant) to produce hundreds of kilograms of HEU. Aerodynamic enrichment processes require large amounts of electricity and are not generally considered economically competitive because of high energy consumption and substantial requirements for removal of waste heat. There are other ways in which it is advantageous, e.g. In simplicity, lack ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enriched Uranium
Enriched uranium is a type of uranium in which the percent composition of uranium-235 (written 235U) has been increased through the process of isotope separation. Naturally occurring uranium is composed of three major isotopes: uranium-238 (238U with 99.2739–99.2752% natural abundance), uranium-235 (235U, 0.7198–0.7202%), and uranium-234 (234U, 0.0050–0.0059%). 235U is the only nuclide existing in nature (in any appreciable amount) that is fissile with thermal neutrons. Enriched uranium is a critical component for both civil nuclear power generation and military nuclear weapons. The International Atomic Energy Agency attempts to monitor and control enriched uranium supplies and processes in its efforts to ensure nuclear power generation safety and curb nuclear weapons proliferation. There are about 2,000 tonnes of highly enriched uranium in the world, produced mostly for nuclear power, nuclear weapons, naval propulsion, and smaller quantities for research reactors ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plumbing
Plumbing is any system that conveys fluids for a wide range of applications. Plumbing uses pipes, valves, plumbing fixtures, tanks, and other apparatuses to convey fluids. Heating and cooling (HVAC), waste removal, and potable water delivery are among the most common uses for plumbing, but it is not limited to these applications. The word derives from the Latin for lead, ''plumbum'', as the first effective pipes used in the Roman era were lead pipes. In the developed world, plumbing infrastructure is critical to public health and sanitation. Boilermakers and pipefitters are not plumbers although they work with piping as part of their trade and their work can include some plumbing. History Plumbing originated during ancient civilizations, as they developed public baths and needed to provide potable water and wastewater removal for larger numbers of people. The Mesopotamians introduced the world to clay sewer pipes around 4000 BCE, with the earliest examples found i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uranium
Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weakly radioactive because all isotopes of uranium are unstable; the half-lives of its naturally occurring isotopes range between 159,200 years and 4.5 billion years. The most common isotopes in natural uranium are uranium-238 (which has 146 neutrons and accounts for over 99% of uranium on Earth) and uranium-235 (which has 143 neutrons). Uranium has the highest atomic weight of the primordially occurring elements. Its density is about 70% higher than that of lead, and slightly lower than that of gold or tungsten. It occurs naturally in low concentrations of a few parts per million in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite. In nature, uranium is found as uranium-238 (99. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotope Separation
Isotope separation is the process of concentrating specific isotopes of a chemical element by removing other isotopes. The use of the nuclides produced is varied. The largest variety is used in research (e.g. in chemistry where atoms of "marker" nuclide are used to figure out reaction mechanisms). By tonnage, separating natural uranium into enriched uranium and depleted uranium is the largest application. In the following text, mainly the uranium enrichment is considered. This process is crucial in the manufacture of uranium fuel for nuclear power plants, and is also required for the creation of uranium-based nuclear weapons. Plutonium-based weapons use plutonium produced in a nuclear reactor, which must be operated in such a way as to produce plutonium already of suitable isotopic mix or ''grade''. While different chemical elements can be purified through chemical reaction, chemical processes, isotopes of the same element have nearly identical chemical properties, which makes this ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Materials
Nuclear material refers to the metals uranium, plutonium, and thorium, in any form, according to the IAEA. This is differentiated further into "source material", consisting of natural and depleted uranium, and "special fissionable material", consisting of enriched uranium (U-235), uranium-233, and plutonium-239. Uranium ore concentrates are considered to be a "source material", although these are not subject to safeguards under the Nuclear Non-Proliferation Treaty. According to the Nuclear Regulatory Commission(NRC), there are four different types of regulated nuclear materials: special nuclear material, source material, byproduct material and radium. Special nuclear materials have plutonium, uranium-233 or uranium with U233 or U235 that has a content found more than in nature. Source material is thorium or uranium that has a U235 content equal to or less than what is in nature. Byproduct material is radioactive material that is not source or special nuclear material. It can be a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Technology
Nuclear technology is technology that involves the nuclear reactions of atomic nuclei. Among the notable nuclear technologies are nuclear reactors, nuclear medicine and nuclear weapons. It is also used, among other things, in smoke detectors and gun sights. History and scientific background Discovery The vast majority of common, natural phenomena on Earth only involve gravity and electromagnetism, and not nuclear reactions. This is because atomic nuclei are generally kept apart because they contain positive electrical charges and therefore repel each other. In 1896, Henri Becquerel was investigating phosphorescence in uranium salts when he discovered a new phenomenon which came to be called radioactivity. He, Pierre Curie and Marie Curie began investigating the phenomenon. In the process, they isolated the element radium, which is highly radioactive. They discovered that radioactive materials produce intense, penetrating rays of three distinct sorts, which they labeled al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Power
Nuclear power is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced by nuclear ''fission'' of uranium and plutonium in nuclear power plants. Nuclear ''decay'' processes are used in niche applications such as radioisotope thermoelectric generators in some space probes such as ''Voyager 2''. Generating electricity from fusion power, ''fusion'' power remains the focus of international research. Most nuclear power plants use thermal reactors with enriched uranium in a Nuclear fuel cycle#Once-through nuclear fuel cycle, once-through fuel cycle. Fuel is removed when the percentage of neutron poison, neutron absorbing atoms becomes so large that a nuclear chain reaction, chain reaction can no longer be sustained, typically three years. It is then cooled for several years in on-site spent fuel pools before being tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Fuel Cycle
The nuclear fuel cycle, also called nuclear fuel chain, is the progression of nuclear fuel through a series of differing stages. It consists of steps in the ''front end'', which are the preparation of the fuel, steps in the ''service period'' in which the fuel is used during reactor operation, and steps in the ''back end'', which are necessary to safely manage, contain, and either reprocess or dispose of spent nuclear fuel. If spent fuel is not reprocessed, the fuel cycle is referred to as an ''open fuel cycle'' (or a ''once-through fuel cycle''); if the spent fuel is reprocessed, it is referred to as a ''closed fuel cycle''. Basic concepts Nuclear power relies on fissionable material that can sustain a chain reaction with neutrons. Examples of such materials include uranium and plutonium. Most nuclear reactors use a moderator to lower the kinetic energy of the neutrons and increase the probability that fission will occur. This allows reactors to use material with far lower con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Reprocessing
Nuclear reprocessing is the chemical separation of fission products and actinides from spent nuclear fuel. Originally, reprocessing was used solely to extract plutonium for producing nuclear weapons. With commercialization of nuclear power, the reprocessed plutonium was recycled back into MOX nuclear fuel for thermal reactors. The reprocessed uranium, also known as the spent fuel material, can in principle also be re-used as fuel, but that is only economical when uranium supply is low and prices are high. A breeder reactor is not restricted to using recycled plutonium and uranium. It can employ all the actinides, closing the nuclear fuel cycle and potentially multiplying the energy extracted from natural uranium by about 60 times. Reprocessing must be highly controlled and carefully executed in advanced facilities by highly specialized personnel. Fuel bundles which arrive at the sites from nuclear power plants (after having cooled down for several years) are completely dissolv ... [...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] |
Criticality Accident
A criticality accident is an accidental uncontrolled nuclear fission chain reaction. It is sometimes referred to as a critical excursion, critical power excursion, or divergent chain reaction. Any such event involves the unintended accumulation or arrangement of a critical mass of fissile material, for example enriched uranium or plutonium. Criticality accidents can release potentially fatal radiation doses, if they occur in an unprotected environment. Under normal circumstances, a critical or supercritical fission reaction (one that is self-sustaining in power or increasing in power) should only occur inside a safely shielded location, such as a reactor core or a suitable test environment. A criticality accident occurs if the same reaction is achieved unintentionally, for example in an unsafe environment or during reactor maintenance. Though dangerous and frequently lethal to humans within the immediate area, the critical mass formed would not be capable of producing a massi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heat Exchanger
A heat exchanger is a system used to transfer heat between a source and a working fluid. Heat exchangers are used in both cooling and heating processes. The fluids may be separated by a solid wall to prevent mixing or they may be in direct contact. They are widely used in space heating, refrigeration, air conditioning, power stations, chemical plants, petrochemical plants, petroleum refineries, natural-gas processing, and sewage treatment. The classic example of a heat exchanger is found in an internal combustion engine in which a circulating fluid known as engine coolant flows through radiator coils and air flows past the coils, which cools the coolant and heats the incoming air. Another example is the heat sink, which is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant. Flow arrangement Image:Heat_exc_1-1.svg, Fig. 1: Shell and tube heat exchanger, single pass (1–1 parallel f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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