# US 10,770,188 B2 · Nuclear reactor fuel assembly and method for producing same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,770,188 B2 - Document ID: US10770188B2 - Status: Granted - Kind: B2 - Application number: 16/473,868 - Filed: 2017-11-03 - Published: 2019-10-24 - Granted: 2020-09-08 - Earliest claimed: 2016-12-26 - Assignees: State Atomic Energy Corporation "Rosatom" On Behalf of the Russian Federation - Applicants: State Atomic Energy Corporation “Rosatom” On Behalf of the Russian Federation - Inventors: Vladimir Aleksandrovich Forstman - Web page: https://patentgrep.com/patent/US10770188B2 ## CPC - G21C 3/336: Spacer elements for fuel rods in the bundle (spacer grids G21C3/34) - G21C 3/338: Helicoidal spacer elements - G21C 3/32: Bundles of parallel pin-, rod-, or tube-shaped fuel elements - G21C 3/334: Assembling {, maintenance or repair of} the bundles {(assembling, maintenance or repair of other reactor components G21C19/207)} - Y02E 30/30: Nuclear fission reactors - G21C: NUCLEAR REACTORS (fusion reactors, hybrid fission-fusion reactors G21B; nuclear explosives G21J) - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract A fuel assembly design for nuclear reactors that is used in fast neutron reactor cores to provide more reliable spacing of a fuel element bundle in a fuel assembly and reduced local stress in the cladding of the fuel elements in the region where the elements are in contact with spacing elements. The fuel assembly has a top nozzle and a bottom nozzle which are connected to one another by a jacket. A bundle of rod-type fuel is elements arranged in the fuel assembly with the aid of a grid and spiral spacer elements wrapped around the cladding of each fuel element. At least the peripheral fuel elements in the bundle are provided with spacer elements in the form of thin-walled tubes with longitudinal through slots, wherein the elements have a substantially oval cross section in the regions where they are in contact with the jacket. ## Claims ### Claim 1 A nuclear reactor fuel assembly, comprising: a top nozzle and a bottom nozzle connected to one another with the aid of a jacket; a bundle of rod-type fuel elements arranged in the jacket with the aid of a grid and spacing elements, wherein the fuel elements comprise peripheral fuel elements in a peripheral row, and internal fuel elements, the spacing elements are spiral shaped and wrapped around cladding of each fuel element and fixed at ends of the fuel elements, wherein the spacing elements comprise peripheral spacing elements and internal spacing elements, wherein at least the peripheral fuel elements in the bundle are provided with the peripheral spacing elements formed as tubes with longitudinal through slots, wherein the peripheral spacing elements have a substantially oval cross section in regions where the peripheral spacing elements are in contact with the jacket. ### Claim 2 (depends on 1) The fuel assembly of claim 1, wherein the width of the slot in the spacing elements is between 0.1 and 0.35 of a spacing element diameter. ### Claim 3 (depends on 1) The fuel assembly of claim 1, wherein a thickness of a wall of the spacing elements is between 0.25 and 1 of the thickness of the cladding. ### Claim 4 (depends on 1) The fuel assembly of claim 1, wherein the peripheral spacing elements of the peripheral fuel elements have reduced resistance to deformation in the transverse direction compared to the internal spacing elements of the internal fuel elements in the bundle. ### Claim 5 (depends on 4) The fuel assembly of claim 4, wherein a width of the slots in the peripheral spacing elements is between 0.20 and 0.35, and a width of slots in internal spacing elements is between 0.1 and 0.30 of a spacing element diameter. ### Claim 6 (depends on 4) The fuel assembly of claim 4, wherein a thickness of the walls of peripheral spacing elements is between 0.25 and 0.6 of a thickness of the cladding, and a thickness of walls of internal spacing elements is between 0.4 and 1 of the thickness of the cladding. ### Claim 7 (depends on 1) The fuel assembly of claim 1, wherein the internal spacing elements are generally round tubes with longitudinal through slots. ### Claim 8 (depends on 1) The fuel assembly of claim 1, wherein the internal fuel elements are provided with wire spacing elements. ### Claim 9 (depends on 1) A method of producing the fuel assembly of claim 1, comprising: creating the bundle of internal and peripheral fuel elements with the internal and peripheral spacing elements; inserting the bundle in the jacket; and connecting the jacket with the top nozzle and bottom nozzle of the fuel assembly, compressing at least the peripheral spacing elements to assume the substantially oval cross section in the regions where the peripheral spacing elements are in contact with the jacket through compression of the bundle in the transverse plane. ### Claim 10 (depends on 9) The method of claim 9, wherein the compressing is carried out while inserting the bundle into the jacket. ### Claim 11 (depends on 9) The method of claim 9, wherein the compressing comprises, prior to inserting the bundle into the jacket, compressing the bundle in the transverse plane with several hexagonal compressing rims, which are removed from the bindle one by one as the bundle is inserted in the jacket. ### Claim 12 (depends on 9) The method of claim 9, wherein compressing the bundle is carried out within the limits of elastic deformation of the spacing elements.