摘要:
A spacer grid for nuclear fuel rods includes a plurality of unit spacer grids stacked one on top of another. Each unit spacer grid includes a plurality of unit spacer grid straps disposed at regular intervals in a row, and a plurality of fixing grid straps connected to respective opposite ends of the unit spacer grid straps so as to fix the unit spacer grid straps. Each unit spacer grid strap has convexities alternating with each other on opposite sides thereof at regular intervals, and at least one of the convexities has a diameter greater than the others. The unit spacer grids are rotated in one direction by a 90 or 180 degree angle when being stacked.
摘要:
Disclosed herein is a guide thimble of a nuclear fuel assembly, which is capable of improving the cooling performance and the stability of a nuclear fuel, preventing a flow split in dual-cooling nuclear fuel rod and guide thimble sub channels for obtaining high combustion degree and high power, and minimizing a neutron absorption section in a reaction degree region. Since the guide thimble having the dual tube type structure is adopted, a flow split in the fuel rod and guide thimble sub channels can be reduced, and the degradation in performance of nuclear fuel due to increase of a neutron absorption section can be prevented. In order for compatibility with an existing control rod, a typical guide tube is used as an inner guide thimble, and an outer guide thimble is provided outside the inner guide thimble. Thus, the guide thimble has the dual tube type structure as a whole, and is coupled to the upper and lower end fittings so that it can prevent a flow unbalance due to the flow split in the fuel rod and guide thimble sub channels.
摘要:
A perforated plate support supports dual-cooled fuel rods, each of which has concentric outer and inner tubes and is coupled with upper and lower end plugs at upper and lower ends thereof, and guide thimbles, each of which is used as a passage for a control rod. The perforated plate support is formed as a support plate having the shape of a flat plate, which includes internal channel holes, each of which has a diameter corresponding to an outer diameter of the inner tube, guide thimble holes, each of which has a diameter corresponding to an outer diameter of the guide thimble, and sub-channel holes around each internal channel hole. The upper or lower end of the dual-cooled fuel rod is coupled to the support plate such that the outer diameter of the inner tube is matched with the diameter of the internal channel hole.
摘要:
A duct-type spacer grid for nuclear fuel assemblies is disclosed. In this spacer grid, a plurality of duct-shaped grid elements, individually having an octagonal cell, are closely arranged in parallel and are welded together, thus forming a matrix structure. The grid elements do not pass across the center of the subchannel of the assembly, thus effectively reducing pressure loss. Each of the grid elements is formed as an independent cell, and so they effectively resist against a lateral impact. A plurality of integral type swirl flow vanes, having different heights or same height, axially extend from the top of the grid to be positioned within each subchannel. The swirl flow vanes are bent outwardly, and so they do not contact the fuel rods during an insertion of the fuel rods into the cells. In the spacer grid, the fuel rods are supported within the cells by line contact springs without using any dimple. The spacer grid thus uniformly distributes its spring force on the fuel rods and almost completely prevents damage of the fuel rods due to fretting wear.
摘要:
A truss-reinforced spacer grid and a method of manufacturing the same are provided, in which truss members having a small diameter are woven to form a truss structure surrounded by an external plate, and the truss structure is joined to the external plate to thereby improve the strength of the mechanical structure. The truss-reinforced spacer grid includes a truss structure in which horizontal trusses formed by horizontally weaving a plurality of truss members are vertically disposed at regular intervals, and an external plate is joined with ends of the horizontal trusses and surrounds the truss structure.
摘要:
A dual-cooled fuel rod's spacer grid with upper and lower dimples, including a blocking area of a flow passage that coolant flows through is reduced and dual-cooled fuel rods are supported, and reduces a turbulent flow of the coolant as well as vibrations of the dual-cooled fuel rods, thereby lessening fretting damage done to the rods. The spacer grid includes a plurality of unit grid straps, each of which includes a body disposed in a vertical direction, an upper dimple protruding from an upper portion of the body, and a lower dimple spaced apart from the upper dimple in a downward direction and protruding from a lower portion of the body. The unit grid straps form a grid structure that have inner grid holes into which the dual-cooled fuel rods are held, and the held dual-cooled fuel rods are each supported in four directions by the upper and lower dimples.
摘要:
A truss-reinforced spacer grid and a method of manufacturing the same are provided, in which truss members having a small diameter are woven to form a truss structure surrounded by an external plate, and the truss structure is joined to the external plate to thereby improve the strength of the mechanical structure. The truss-reinforced spacer grid includes a truss structure in which horizontal trusses formed by horizontally weaving a plurality of truss members are vertically disposed at regular intervals, and an external plate is joined with ends of the horizontal trusses and surrounds the truss structure.
摘要:
A spacer grid used for placing and supporting fuel rods in nuclear reactor fuel assemblies is disclosed. The spacer grid of this invention has a plurality of inner strips intersecting each other to form a plurality of guide tube cells and a plurality of fuel rod cells, with a plurality of mixing blades projecting upward from the inner strips at intersections of the inner strips. The spacer grid further includes a plurality of perimeter strips to encircle the intersecting inner strips. Each of the perimeter strips is fabricated with a plurality of unit intermediate strips and a plurality of unit corner strips, with a grid spring provided on each of the unit strips. The grid spring includes a vertical opening formed at a central area of each of the unit strips, a vertical support part extending vertically between the central portions of top and bottom edges of the vertical opening, and a fuel rod support part provided at a central portion of the vertical support part while being bent to have an outward rounded cross-section. The vertical support part is bent at two steps, and the fuel rod support part is bent to be in equiangular contact with each of the fuel rods, thus accomplishing a uniform contact pressure distribution when the fuel rod support part is in contact with each of the fuel rods.
摘要:
A porous plenum spacer is inserted into the plenum of a dual-cooled fuel rod having concentric inner and outer cladding tubes. The porous plenum spacer includes a hollow cylindrical body inserted into the annular space between the inner and outer cladding tubes. The hollow cylindrical body includes a plurality of through-holes formed in an outer circumference thereof or at least one groove formed in one of outer and inner circumferences thereof in a lengthwise direction. Pores formed by the through-holes or the grooves of the hollow cylindrical body of the porous plenum spacer are allowed to secure a space containing fission gas inevitably generated by a nuclear reaction.
摘要:
Disclosed herein is a guide thimble of a nuclear fuel assembly, which is capable of improving the cooling performance and the stability of a nuclear fuel, preventing a flow split in dual-cooling nuclear fuel rod and guide thimble sub channels for obtaining high combustion degree and high power, and minimizing a neutron absorption section in a reaction degree region. Since the guide thimble having the dual tube type structure is adopted, a flow split in the fuel rod and guide thimble sub channels can be reduced, and the degradation in performance of nuclear fuel due to increase of a neutron absorption section can be prevented. In order for compatibility with an existing control rod, a typical guide tube is used as an inner guide thimble, and an outer guide thimble is provided outside the inner guide thimble. Thus, the guide thimble has the dual tube type structure as a whole, and is coupled to the upper and lower end fittings so that it can prevent a flow unbalance due to the flow split in the fuel rod and guide thimble sub channels.