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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.
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 ...
The critical mass can be greatly reduced by the use of a tamper. The following table lists the values for common neutron reflectors, where λ tamp is the mean free path of a neutron within the tamper material before an elastic scattering. In nuclear weapon design, natural uranium is primarily used.
Cold, thermal, and hot neutron radiation is commonly employed in neutron scattering facilities for neutron diffraction, small-angle neutron scattering, and neutron reflectometry. Slow neutron matter waves exhibit properties similar to geometrical and wave optics of light, including reflection, refraction, diffraction, and interference. [ 123 ]
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.
Nuclear graphite is any grade of graphite, usually synthetic graphite, manufactured for use as a moderator or reflector within a nuclear reactor.Graphite is an important material for the construction of both historical and modern nuclear reactors because of its extreme purity and ability to withstand extremely high temperatures.
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.
Zirconium(II) hydride is used as a thermal neutron moderator in nuclear reactors and as a material for neutron reflectors in fast reactors. [5] Zirconium(II) hydride in the form of a powder is used in powder metallurgy as a hydrogenation catalyst, vacuum tube getter, foaming agent in the production of metal foams and as a reducing agent. [5]