Nuclear Reactor Core

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Nuclear Reactor Core


the space in which the controlled chain reaction of nuclear fission of heavy elements (uranium, plutonium) takes place. The chain reaction is accompanied by the release of the kinetic energy of the fission fragments, as well as the energy of neutron radiation, γ-radiation, and β-decay. The core contains the fissionable material, most often fabricated in the form of slugs or rods; a moderator, if the reaction is basically a slow-neutron reaction (there is no moderator in fast-neutron reactors); a coolant for removing the heat produced during the reaction; and components, instruments, and devices of the systems for controlling, monitoring, and shielding the reactor. The fissionable material may be located either apart from the rest of the reactor core’s components (heterogeneous reactor) or in a mixture with those components (homogeneous reactor). Commonly used moderators are water, heavy water, graphite, beryllium, and organic fluids. Reliable heat transfer is necessary to prevent nuclear accidents caused by overheating resulting from the heat produced in the reactor and to improve reactor efficiency. Water, steam, heavy water, organic fluids, helium, and carbon dioxide gas serve as coolants in thermal neutron reactors. Liquid metal (predominantly sodium) is used as a coolant in fast-neutron reactors. The reactor core is usually surrounded on all sides by a neutron reflector to minimize neutron leakage; reflector materials are usually the same as the moderator materials.

From a physical standpoint, the best reactor core shape is a sphere, but design considerations often dictate a cylindrical shape.


References in periodicals archive ?
A team of commercial specialists led by Wragge & Co partner David Hamlett, and including senior associate Julia Holdright and solicitor Dermot McGirr, worked closely with the MOD to secure the supply of nuclear reactor cores for its submarines.
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Rolls-Royce is been selected to supply nuclear reactor cores for Britain's submarine fleet.
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s Fukushima Daiichi nuclear power plant was triggered by the March earthquake and tsunami and resulted in the suspected meltdowns of three nuclear reactor cores, in the worst nuclear catastrophe since Chernobyl, where a reactor exploded during a test run.
This volume provides a summary of the physical, chemical, and thermodynamic phenomena taking place in nuclear reactor cores during the progression of reactor accidents; the formation and physical and chemical properties of the resulting radioactive aerosols; the timing and duration of the aerosol release from the core to the coolant system and containment; and the physical, chemical, and thermal-hydraulic phenomena that govern the removal of aerosols within the containment or other plant volumes through natural or engineered processes.
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IN the 80s the Soviets dumped 60 nuclear reactor cores previously used in military satellites.
Among specific potential uses, Miles notes, is the deposit of repair materials in tiny cracks that form in teeth or even in nuclear reactor cores.

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