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Lead-cooled Fast Reactor
The lead-cooled fast reactor is a nuclear reactor design that features a fast neutron spectrum and molten lead or lead-bismuth eutectic coolant. Molten lead or lead-bismuth eutectic can be used as the primary coolant because especially lead, and to a lesser degree bismuth have low neutron absorption and relatively low melting points. Neutrons are slowed less by interaction with these heavy nuclei (thus not being neutron moderators) and therefore, help make this type of reactor a fast-neutron reactor. In simple terms, if a neutron hits a particle with a similar mass (such as hydrogen in a Pressurized Water Reactor PWR), it tends to lose kinetic energy. In contrast, if it hits a much heavier atom such as lead, the neutron will "bounce off" without losing this energy. The coolant does, however, serve as a neutron reflector, returning some escaping neutrons to the core. Fuel designs being explored for this reactor scheme include fertile uranium as a metal, metal oxide or metal nitr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Small, Sealed, Transportable, Autonomous Reactor
Small, sealed, transportable, autonomous reactor (SSTAR) is a proposed lead-cooled nuclear reactor being primarily researched and developed in the United States by Lawrence Livermore National Laboratory. It is designed as a fast breeder reactor that is passively safe. It has a self-contained fuel source of uranium-235 and uranium-238 which will be partly consumed by fast-neutron fission and, more importantly, converted into more fissile material ("breeding" plutonium). It should have an operative life of 30 years, providing a constant power source between 10 and 100 megawatts. The 100 megawatt version is expected to be 15 meters high by 3 meters wide, and weigh 500 tonnes. A 10 megawatt version is expected to weigh less than 200 tonnes. To obtain the desired 30 year life span, the design calls for a movable neutron reflector to be placed surrounding part of a column of fuel. The reflector's slow downward travel through the entire length of the column would cause the fuel to b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Decay
Alpha decay or α-decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus) and thereby transforms or 'decays' into a different atomic nucleus, with a mass number that is reduced by four and an atomic number that is reduced by two. An alpha particle is identical to the nucleus of a helium-4 atom, which consists of two protons and two neutrons. It has a charge of and a mass of . For example, uranium-238 decays to form thorium-234. While alpha particles have a charge , this is not usually shown because 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. 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 maximum and the nuclides are therefore unstable toward spontaneou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutron Economy
Neutron economy is defined as the ratio of an adjoint weighted average of the excess neutron production divided by an adjoint weighted average of the fission production. The distribution of neutron energies in a nuclear reactor differs from the fission neutron spectrum due to the slowing down of neutrons in elastic and inelastic collisions with fuel, coolant and construction material. Neutrons slow down in elastic and inelastic collisions, until they are absorbed via Neutron capture or lost by leakage. Neutron economy is the balanced account, in a reactor, of the neutrons created and the neutrons lost through absorption by non-fuel elements, resonance absorption by fuel, and leakage while fast and thermal energy ranges. Heavy water is an extremely efficient moderator. As a result, reactors using heavy water, such as the CANDU, also have a high neutron economy. The quantity that indicates how much the neutron economy is out of balance is given the term reactivity. If a reactor i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moderate
Moderate is an ideological category which designates a rejection of radical or extreme views, especially in regard to politics and religion. A moderate is considered someone occupying any mainstream position avoiding extreme views. In American politics, a moderate is considered someone occupying a centre position on the left–right political spectrum. Political position Japan Japan's right-wing Liberal Democratic Party (LDP) has traditionally been divided into two main factions: the based on bureaucratic "conservative mainstream" (保守本流) and the hawkish nationalist "conservative anti-mainstream" (保守傍流). Among them, "conservative mainstream" is also considered a moderate wing within the LDP. The LDP's faction ''Kōchikai'', is considered a moderate wing. The current LDP has conflicts between moderate patriotist and extreme nationalist supporters. Democratic Socialist Party (DSP) is formed by a group of politicians who splintered off of the Japan Socia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potable Water
Drinking water is water that is used in drink or food preparation; potable water is water that is safe to be used as drinking water. The amount of drinking water required to maintain good health varies, and depends on physical activity level, age, health-related issues, and environmental conditions. This 2004 article focuses on the USA context and uses data collected from the US military. Recent work showed that the most important driver of water turnover which is closely linked to water requirements is energy expenditure. For those who work in a hot climate, up to a day may be required. Typically in developed countries, tap water meets drinking water quality standards, even though only a small proportion is actually consumed or used in food preparation. Other typical uses for tap water include washing, toilets, and irrigation. Greywater may also be used for toilets or irrigation. Its use for irrigation however may be associated with risks. Water may also be unacceptable due to l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, and highly combustible. Hydrogen is the most abundant chemical substance in the universe, constituting roughly 75% of all normal matter.However, most of the universe's mass is not in the form of baryons or chemical elements. See dark matter and dark energy. Stars such as the Sun are mainly composed of hydrogen in the plasma state. Most of the hydrogen on Earth exists in molecular forms such as water and organic compounds. For the most common isotope of hydrogen (symbol 1H) each atom has one proton, one electron, and no neutrons. In the early universe, the formation of protons, the nuclei of hydrogen, occurred during the first second after the Big Bang. The emergence of neutral hydrogen atoms throughout the universe occurred about 370,000 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distributed Generation
Distributed generation, also distributed energy, on-site generation (OSG), or district/decentralized energy, is electrical generation and storage performed by a variety of small, grid-connected or distribution system-connected devices referred to as distributed energy resources (DER). Conventional power stations, such as coal-fired, gas, and nuclear powered plants, as well as hydroelectric dams and large-scale solar power stations, are centralized and often require electric energy to be transmitted over long distances. By contrast, DER systems are decentralized, modular, and more flexible technologies that are located close to the load they serve, albeit having capacities of only 10 megawatts (MW) or less. These systems can comprise multiple generation and storage components; in this instance, they are referred to as hybrid power systems. DER systems typically use renewable energy sources, including small hydro, biomass, biogas, solar power, wind power, and geothermal power, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turnkey
A turnkey, a turnkey project, or a turnkey operation (also spelled turn-key) is a type of project that is constructed so that it can be sold to any buyer as a completed product. This is contrasted with build to order, where the constructor builds an item to the buyer's exact specifications, or when an incomplete product is sold with the assumption that the buyer would complete it. A turnkey project or contract as described by Duncan Wallace (1984) is: Turnkey contract is typically a construction contract under which a contractor is employed to plan, design and build a project or an infrastructure and do any other necessary development to make it functional or ‘ready to use’ at an agreed price and by a fixed date. In Turnkey contracts, most of the time employer provides the primary design. The contractor must follow the primary design provided by the employer. A turnkey computer system is a complete computer including hardware, operating system and application(s) designed a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Generation IV Reactor
Generation IV reactors (Gen IV) are six nuclear reactor designs recognized by the Generation IV International Forum. The designs target improved safety, sustainability, efficiency, and cost. The most developed Gen IV reactor design is the sodium fast reactor. It has received the greatest share of funding that supports demonstration facilities, as well as two commercial reactors in Russia. One of these has been in commercial operation since 1981. Its principal Gen IV features relates its sustainable closed fuel cycle. Moir and Teller consider the molten-salt reactor, a less developed technology, as potentially having the greatest inherent safety of the six models. The very-high-temperature reactor designs operate at much higher temperatures than prior generations. This allows for high temperature electrolysis or for sulfur–iodine cycle for the efficient production of hydrogen and the synthesis of carbon-neutral fuels. The first commercial plants are not expected before 2040–2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Submarine
A nuclear submarine is a submarine powered by a nuclear reactor, but not necessarily nuclear-armed. Nuclear submarines have considerable performance advantages over "conventional" (typically diesel-electric) submarines. Nuclear propulsion, being completely independent of air, frees the submarine from the need to surface frequently, as is necessary for conventional submarines. The large amount of power generated by a nuclear reactor allows nuclear submarines to operate at high speed for long periods, and the long interval between refuelings grants a range virtually unlimited, making the only limits on voyage times being imposed by such factors as the need to restock food or other consumables. The limited energy stored in electric batteries means that even the most advanced conventional submarine can only remain submerged for a few days at slow speed, and only a few hours at top speed, though recent advances in air-independent propulsion have somewhat ameliorated this disadv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium-cooled Fast Reactor
A sodium-cooled fast reactor is a fast neutron reactor cooled by liquid sodium. The initials SFR in particular refer to two Generation IV reactor proposals, one based on existing liquid metal cooled reactor (LMFR) technology using mixed oxide fuel (MOX), and one based on the metal-fueled integral fast reactor. Several sodium-cooled fast reactors have been built and some are in current operation, particularly in Russia. Others are in planning or under construction. For example in 2022, in the USA, TerraPower (using its Traveling Wave technology) is planning to build its own reactors along with molten salt energy storage in partnership with GEHitachi's PRISM integral fast reactor design, under the ''Natrium'' appellation in Kemmerer, Wyoming. Aside from the Russian experience, Japan, India, China, France and the USA are investing in the technology. Fuel cycle The nuclear fuel cycle employs a full actinide recycle with two major options: One is an intermediate-size (150–600 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
