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Nuclear Energy For Propulsion Of Aircraft
The Aircraft Nuclear Propulsion (ANP) program and the preceding Nuclear Energy for the Propulsion of Aircraft (NEPA) project worked to develop a nuclear propulsion system for aircraft. The United States Army Air Forces initiated Project NEPA on May 28, 1946. NEPA operated until May 1951, when the project was transferred to the joint Atomic Energy Commission (AEC)/USAF ANP. The USAF pursued two different systems for nuclear-powered jet engines, the Direct Air Cycle concept, which was developed by General Electric, and Indirect Air Cycle, which was assigned to Pratt & Whitney. The program was intended to develop and test the Convair X-6, but was canceled in 1961 before that aircraft was built. The total cost of the program from 1946 to 1961 was about $1 billion. Types Direct air cycle Direct cycle nuclear engines resemble a conventional jet engine without combustion chambers. The air gained from the compressor section is sent to a plenum that directs the air into the nuclea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aircraft Reactors Arco ID 2009
An aircraft ( aircraft) is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or the dynamic lift of an airfoil, or, in a few cases, direct downward thrust from its engines. Common examples of aircraft include airplanes, rotorcraft (including helicopters), airships (including blimps), gliders, paramotors, and hot air balloons. Part 1 (Definitions and Abbreviations) of Subchapter A of Chapter I of Title 14 of the U. S. Code of Federal Regulations states that aircraft "means a device that is used or intended to be used for flight in the air." The human activity that surrounds aircraft is called ''aviation''. The science of aviation, including designing and building aircraft, is called ''aeronautics.'' Crewed aircraft are flown by an onboard pilot, whereas unmanned aerial vehicles may be remotely controlled or self-controlled by onboard computers. Aircraft may be classified by different criteria, such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turbopump
A turbopump is a fluid pump with two main components: a rotodynamic pump and a driving gas turbine, usually both mounted on the same shaft, or sometimes geared together. They were initially developed in Germany in the early 1940s. The most common purpose of a turbopump is to produce a high-pressure fluid for feeding a combustion chamber. While other use cases exist, they are most commonly found in liquid rocket engines. There are two common types of pumps used in turbopumps: a centrifugal pump, where the pumping is done by throwing fluid outward at high speed, or an axial-flow pump, where alternating rotating and static blades progressively raise the pressure of a fluid. Axial-flow pumps have small diameters but give relatively modest pressure increases. Although multiple compression stages are needed, axial flow pumps work well with low-density fluids. Centrifugal pumps are far more powerful for high-density fluids but require large diameters for low-density fluids. Histo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutron Moderator
In nuclear engineering, a neutron moderator is a medium that reduces the speed of fast neutrons, ideally without capturing any, leaving them as thermal neutrons with only minimal (thermal) kinetic energy. These thermal neutrons are immensely more susceptible than fast neutrons to propagate a nuclear chain reaction of uranium-235 or other fissile isotope by colliding with their atomic nucleus. Water (sometimes called "light water" in this context) is the most commonly used moderator (roughly 75% of the world's reactors). Solid graphite (20% of reactors) and heavy water (5% of reactors) are the main alternatives. Beryllium has also been used in some experimental types, and hydrocarbons have been suggested as another possibility. Moderation Neutrons are normally bound into an atomic nucleus and do not exist free for long in nature. The unbound neutron has a half-life of 10 minutes and 11 seconds. The release of neutrons from the nucleus requires exceeding the binding ener ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Fuel
Nuclear fuel refers to any substance, typically fissile material, which is used by nuclear power stations or other atomic nucleus, nuclear devices to generate energy. Oxide fuel For fission reactors, the fuel (typically based on uranium) is usually based on the metal oxide; the oxides are used rather than the metals themselves because the oxide melting point is much higher than that of the metal and because it cannot burn, being already in the oxidized state. Uranium dioxide Uranium dioxide is a black semiconductor, semiconducting solid. It can be made by heating uranyl nitrate to form . : This is then converted by heating with hydrogen to form UO2. It can be made from Enriched uranium, enriched uranium hexafluoride by reacting with ammonia to form a solid called ammonium diuranate, . This is then heated (Calcination, calcined) to form and U3O8 which is then converted by heating with hydrogen or ammonia to form UO2. The UO2 is mixed with an organic binder and pressed in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uranium Tetrafluoride
Uranium tetrafluoride is the inorganic compound with the formula UF4. It is a green solid with an insignificant vapor pressure and low solubility in water. Uranium in its tetravalent ( uranous) state is important in various technological processes. In the uranium refining industry it is known as green salt. Production UF4 is prepared from UO2 in a fluidized bed by reaction with Hydrogen fluoride. The UO2 is derived from mining operations. Around 60,000 tonnes are prepared in this way annually. A common impurity is UO2F2. UF4 is susceptible to hydrolysis as well. UF4 is formed by the reaction of UF6 with hydrogen gas in a vertical tube-type reactor. The bulk density of UF4 varies from about 2.0 g/cm3 to about 4.5 g/cm3 depending on the production process and the properties of the starting uranium compounds. A molten salt reactor design, a type of nuclear reactor where the working fluid is a molten salt, would use UF4 as the core material. UF4 is generally chosen over relate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zirconium Tetrafluoride
Zirconium(IV) fluoride describes members of a family inorganic compounds with the formula Zr F4(H2O)x. All are colorless, diamagnetic solids. Anhydrous Zirconium(IV) fluoride is a component of ZBLAN fluoride glass. Structure Three crystalline phases of ZrF4 have been reported, α (monoclinic), β (tetragonal, Pearson symbol tP40, space group P42/m, No 84) and γ (unknown structure). β and γ phases are unstable and irreversibly transform into the α phase at 400 °C. Zirconium(IV) fluoride forms several hydrates. The trihydrate has the structure . Preparation and reactions Zirconium fluoride can be produced by several methods. Zirconium dioxide reacts with hydrogen fluoride and hydrofluoric acid to afford the anhydrous and monohydrates: : The reaction of Zr metal reacts at high temperatures with HF as well: : Zirconium dioxide reacts at 200 °C with solid ammonium bifluoride to give the heptafluorozirconate salt, which can be converted to the tetrafluoride at 500  ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Fluoride
Sodium fluoride (NaF) is an inorganic compound with the formula . It is a colorless or white solid that is readily soluble in water. It is used in trace amounts in the fluoridation of drinking water to prevent tooth decay, and in toothpastes and topical pharmaceuticals for the same purpose. In 2022, it was the 221st most commonly prescribed medication in the United States, with more than 1million prescriptions. It is also used in metallurgy and in medical imaging. Uses Dental caries Fluoride salts are often added to municipal drinking water (as well as to certain food products in some countries) for the purpose of maintaining dental health. The fluoride enhances the strength of teeth by the formation of fluorapatite, a naturally occurring component of tooth enamel. Although sodium fluoride is used to fluoridate water and is the standard by which other water-fluoridation compounds are gauged, hexafluorosilicic acid (H2SiF6) and its salt sodium hexafluorosilicate (Na2Si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molten Salt Reactor
A molten-salt reactor (MSR) is a class of nuclear fission reactor in which the primary nuclear reactor coolant and/or the fuel is a mixture of molten salt with a fissile material. Two research MSRs operated in the United States in the mid-20th century. The 1950s Aircraft Reactor Experiment (ARE) was primarily motivated by the technology's compact size, while the 1960s Molten-Salt Reactor Experiment (MSRE) aimed to demonstrate a nuclear power plant using a thorium fuel cycle in a breeder reactor. Increased research into Generation IV reactor designs renewed interest in the 21st century with multiple nations starting projects. On October 11, 2023, China's TMSR-LF1 reached Criticality (status), criticality, and subsequently achieved full power operation, as well as breeder reactor, Thorium breeding. Properties MSRs eliminate the nuclear meltdown scenario present in water-cooled reactors because the fuel mixture is kept in a molten state. The fuel mixture is designed to drain with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soviet Union
The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet Union, it dissolved in 1991. During its existence, it was the list of countries and dependencies by area, largest country by area, extending across Time in Russia, eleven time zones and sharing Geography of the Soviet Union#Borders and neighbors, borders with twelve countries, and the List of countries and dependencies by population, third-most populous country. An overall successor to the Russian Empire, it was nominally organized as a federal union of Republics of the Soviet Union, national republics, the largest and most populous of which was the Russian SFSR. In practice, Government of the Soviet Union, its government and Economy of the Soviet Union, economy were Soviet-type economic planning, highly centralized. As a one-party state go ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deterrence Theory
Deterrence theory refers to the scholarship and practice of how threats of using force by one party can convince another party to refrain from initiating some other course of action. The topic gained increased prominence as a military strategy during the Cold War with regard to the use of nuclear weapons and is related to but distinct from the concept of mutual assured destruction, according to which a full-scale nuclear attack on a power with second-strike capability would devastate both parties. The central problem of deterrence revolves around how to credibly threaten military action or nuclear punishment on the adversary despite its costs to the deterrer. Deterrence in an international relations context is the application of deterrence theory to avoid conflict. Deterrence is widely defined as any use of threats (implicit or explicit) or limited force intended to dissuade an actor from taking an action (i.e. maintain the status quo). Deterrence is unlike compellence, which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power Density
Power density, defined as the amount of power (the time rate of energy transfer) per unit volume, is a critical parameter used across a spectrum of scientific and engineering disciplines. This metric, typically denoted in watts per cubic meter (W/m3), serves as a fundamental measure for evaluating the efficacy and capability of various devices, systems, and materials based on their spatial energy distribution. The concept of power density finds extensive application in physics, engineering, electronics, and energy technologies. It plays a pivotal role in assessing the efficiency and performance of components and systems, particularly in relation to the power they can handle or generate relative to their physical dimensions or volume. In the domain of energy storage and conversion technologies, such as batteries, fuel cells, motors, and power supply units, power density is a crucial consideration. Here, power density often refers to the volume power density, quantifying how much ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Reactor
A nuclear reactor is a device used to initiate and control a Nuclear fission, fission nuclear chain reaction. They are used for Nuclear power, commercial electricity, nuclear marine propulsion, marine propulsion, Weapons-grade plutonium, weapons production and Research reactor, research. Fissile material, Fissile nuclei (primarily uranium-235 or plutonium-239) absorb single neutron, neutrons and split, releasing energy and multiple neutrons, which can induce further fission. Reactors stabilize this, regulating Neutron absorber, neutron absorbers and neutron moderator, moderators in the core. Fuel efficiency is exceptionally high; Enriched uranium#Low-enriched uranium (LEU), low-enriched uranium is 120,000 times more energy dense than coal. Heat from nuclear fission is passed to a working fluid Nuclear reactor#By coolant, coolant. In commercial reactors, this drives Turbine, turbines and electrical generator shafts. Some reactors are used for district heating, and isotopes, isoto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
