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The decrease in the critical size of core required is known as the reflector savings. Neutron reflectors reduce neutron leakage, i.e., to reduce the neutron fluence on a reactor pressure vessel. Neutron reflectors reduce a coolant flow bypass of a core. Neutron reflectors serve as a thermal and radiation shield of a reactor core.
The reflection is usually described in terms of a momentum transfer vector, denoted , which describes the change in momentum of a neutron after reflecting from the material. Conventionally the z {\displaystyle z} direction is defined to be the direction normal to the surface, and for specular reflection, the scattering vector has only a z ...
Moderation is the process of the reduction of the initial high speed (high kinetic energy) of the free neutron. Since energy is conserved, this reduction of the neutron speed takes place by transfer of energy to a material called a moderator. The probability of scattering of a neutron from a nucleus is given by the scattering cross section. The ...
A neutron supermirror is a highly polished, layered material used to reflect neutron beams. Supermirrors are a special case of multi-layer neutron reflectors with varying layer thicknesses. [1] The first neutron supermirror concept was proposed by Ferenc Mezei, [2] inspired by earlier work with X-rays.
The pits of the first nuclear weapons were solid, with an urchin neutron initiator in their center. The Gadget and Fat Man used pits made of 6.2 kg of solid hot pressed plutonium-gallium alloy (at 400 °C and 200 MPa in steel dies – 750 °F and 29,000 psi) half-spheres of 9.2 cm (3.6 in) diameter, with a 2.5 cm (1 in) internal cavity for the initiator.
Neutron radiography is a powerful non-destructive imaging technique for the internal evaluation of materials or components. It involves the attenuation of a neutron beam by an object to be radiographed, and registration of the attenuation process (as an image) digitally or on film.
Flattop is a benchmark critical assembly that is used to study the nuclear characteristics of uranium-233, uranium-235, and plutonium-239 in spherical geometries surrounded by a relatively thick natural uranium neutron reflector. Flattop assemblies are used to measure neutron activation and reactivity coefficients. Since the neutron energies ...
Lead cooled fast reactor scheme. The lead-cooled fast reactor is a nuclear reactor design that uses molten lead or lead-bismuth eutectic coolant.These materials can be used as the primary coolant because they have low neutron absorption and relatively low melting points.