A fuel assembly, a method of operating a pressurized water reactor and an auxiliary device (20) for a fuel assembly of the reactor are disclosed. The fuel assembly (2a) comprises fuel rods (10) and a plurality of guide thimbles (11). The auxiliary device comprises a carrying structure (21), and rods (22) suspended in the carrying structure to extend in parallel with each other in a direction away from the carrying structure. Each of the rods comprises a cladding tube defining an inner space. The rods are inserted into a respective one of some of the guide thimbles. Each of the rods comprises a major amount of a fissile material of enriched uranium in the inner space of the cladding tube, and a minor amount of a neutron absorbing material in the inner space of the cladding tub.
G21C 3/32 - Bundles of parallel pin-, rod-, or tube-shaped fuel elements
G21C 3/322 - Means to influence the coolant flow through or around the bundles
G21C 3/326 - Bundles of parallel pin-, rod-, or tube-shaped fuel elements comprising fuel elements of different compositionComprising, in addition to the fuel elements, other pin-, rod-, or tube-shaped elements, e.g. control rods, grid support rods, fertile rods, poison rods or dummy rods
G21C 7/04 - Control of nuclear reaction by using self-regulating properties of reactor materials of burnable poisons
2.
Fuel assembly for a nuclear power boiling water reactor
The present invention concerns a fuel assembly for a nuclear power boiling water reactor. The fuel assembly comprises fuel rods. At least 95% of the fuel rods comprise nuclear fuel material in the form of U enriched in 235U. At least 20% of the fuel rods belong to a first set of fuel rods. The fuel rods in this first set comprise both U enriched in 235U and Th. The first set comprises a first and a second subset of fuel rods. The ratio, with regard to weight, between Th and U, in each fuel rod of said first subset, is higher than the ratio, with regard to weight, between Th and U, in each fuel rod of said second subset. The invention also concerns a nuclear power boiling water reactor and a manner of operating such a reactor.
G21C 7/06 - Control of nuclear reaction by application of neutron-absorbing material, i.e. material with absorption cross-section very much in excess of reflection cross-section
G21C 3/326 - Bundles of parallel pin-, rod-, or tube-shaped fuel elements comprising fuel elements of different compositionComprising, in addition to the fuel elements, other pin-, rod-, or tube-shaped elements, e.g. control rods, grid support rods, fertile rods, poison rods or dummy rods
The present invention concerns a fuel assembly (12) for a nuclear power boiling water reactor. The fuel assembly comprises fuel rods (23). At least 95% of the fuel rods comprise nuclear fuel material in the form of U enriched in 235U. At least 20% of the fuel rods belong to a first set of fuel rods (41, 32, 26, 9). The fuel rods in this first set comprise both U enriched in 235U and Th. The first set comprises a first and a second subset of fuel rods (41, 32). The ratio, with regard to weight, between Th and U, in each fuel rod (41) of said first subset, is higher than the ratio, with regard to weight, between Th and U, in each fuel rod (32) of said second subset. The invention also concerns a nuclear power boiling water reactor and a manner of operating such a reactor.
G21C 3/326 - Bundles of parallel pin-, rod-, or tube-shaped fuel elements comprising fuel elements of different compositionComprising, in addition to the fuel elements, other pin-, rod-, or tube-shaped elements, e.g. control rods, grid support rods, fertile rods, poison rods or dummy rods
A fuel assembly (1) for a nuclear reactor comprises a bundle of fuel rods (3) with a first group of fuel rods (5a) and a second group of fuel rods (5b). Each fuel rod comprises a cladding tube (15) and stack of fuel pellets (12) enclosed within the cladding tube. At least a main portion (13) of the fuel stack comprises a fissile nuclear material comprising Plutonium and Thorium, and is arranged with an axial hole (22). Said main portion (13) of the fuel stack of each fuel rod (5a) of the first group comprises a first axial hole (22a) constituting a first volume and said main portion of the fuel stack of each fuel rod (5b) of the second group comprises a second axial hole (22b) constituting a second volume. The first volume and the second volume are different.
G21C 3/16 - Details of the construction within the casing
G21C 3/326 - Bundles of parallel pin-, rod-, or tube-shaped fuel elements comprising fuel elements of different compositionComprising, in addition to the fuel elements, other pin-, rod-, or tube-shaped elements, e.g. control rods, grid support rods, fertile rods, poison rods or dummy rods
G21C 3/328 - Relative disposition of the elements in the bundle lattice
A nuclear fuel element for use in water-cooled nuclear power reactors. The fuel element includes a multilayered silicon carbide cladding tube. The multilayered silicon carbide cladding tube preferably includes an inner layer and a central layer. Also, in one embodiment, the ends further include hermetically sealed end caps. The cladding tube is sized to receive a stack of individual fissionable fuel pellets. In one embodiment, the fuel pellets comprise a mixture of thorium oxide and plutonium oxide.
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