Reactor fuel elements and their assemblies Selection of substances for use as reactor fuel elements

GPHYSICS G21Nuclear engineering G21CNUCLEAR REACTORS

G21C3/00Reactor fuel elements and their assemblies Selection of substances for use as reactor fuel elements

G21C3/02Fuel elements G21C3/04Constructional details G21C3/041Means for removal of gases from fuel elements G21C3/042Fuel elements comprising casings with a mass of granular fuel with coolant passages through them G21C3/044Fuel elements with porous or capillary structure G21C3/06Casings Jackets G21C3/07characterised by their material G21C3/08provided with external means to promote heat-transfer G21C3/10End closures; Means for tight mounting therefor G21C3/105Flattened end-closures G21C3/12Means forming part of the element for locating it within the reactor core G21C3/14Means forming part of the element for inserting it into, or removing it from, the core Means for coupling adjacent elements G21C3/16Details of the construction within the casing G21C3/17Means for storage or immobilisation of gases in fuel elements G21C3/18Internal spacers or other non-active material within the casing G21C3/20with coating on fuel or on inside of casing with non-active interlayer between casing and active material with multiple casings or multiple active layers G21C3/22with fissile or breeder material in contact with coolant G21C3/24with fissile or breeder material in fluid form within a non-active casing G21C3/26with fissile or breeder material in powder form within a non-active casing G21C3/28with fissile or breeder material in solid form within a non-active casing G21C3/30Assemblies of a number of fuel elements in the form of a rigid unit G21C3/32Bundles of parallel pin-, rod-, or tube-shaped fuel elements G21C3/3206Means associated with the fuel bundle for filtering the coolant G21C3/3213Means for the storage or removal of fission gases G21C3/322Means to influence the coolant flow through or around the bundles G21C3/324Coats or envelopes for the bundles G21C3/3245made of moderator material G21C3/326comprising fuel elements of different composition comprising, in addition to the fuel elements, other pin-, rod-, or tube-shaped elements G21C3/328Relative disposition of the elements in the bundle lattice G21C3/33Supporting or hanging of elements in the bundle Means forming part of the bundle for inserting it into, or removing it from, the core Means for coupling adjacent bundles G21C3/3305Lower nozzle G21C3/331Comprising hold-down means G21C3/3315Upper nozzle G21C3/332Supports for spacer grids G21C3/334Assembling , maintenance or repair of the bundles G21C3/335Exchanging elements in irradiated bundles G21C3/336Spacer elements for fuel rods in the bundle G21C3/338Helicoidal spacer elements G21C3/34Spacer grids G21C3/3408Compact spacer grids G21C3/3416Spacer grids formed by metallic wires G21C3/3424Fabrication of spacer grids G21C3/344formed of assembled tubular elements G21C3/348formed of assembled non-intersecting strips G21C3/352formed of assembled intersecting strips G21C3/356being provided with fuel element supporting members G21C3/3563Supporting members formed only by deformations in the strips G21C3/3566Supporting members formed only of elements fixed on the strips G21C3/36Assemblies of plate-shaped fuel elements or coaxial tubes G21C3/38Fuel units consisting of a single fuel element in a supporting sleeve or in another supporting element G21C3/40Structural combination of fuel element with thermoelectric element for direct production of electric energy from fission heat or with another arrangement for direct production of electric energy G21C3/42Selection of substances for use as reactor fuel G21C3/44Fluid or fluent reactor fuel G21C3/46Aqueous compositions G21C3/48True or colloidal solutions of the active constituent G21C3/50Suspensions of the active constituent Slurries G21C3/52Liquid metal compositions G21C3/54Fused salt, oxide or hydroxide compositions G21C3/56Gaseous compositions Suspensions in a gaseous carrier G21C3/58Solid reactor fuel Pellets made of fissile material G21C3/60Metallic fuel Intermetallic dispersions G21C3/62Ceramic fuel G21C3/623Oxide fuels G21C3/626Coated fuel particles G21C3/64Ceramic dispersion fuel