Outer strip, location grid of nuclear reactor fuel subassembly, and nuclear reactor fuel subassembly

Abstract

The invention discloses an outer strip, a location grid of a nuclear reactor fuel subassembly, and the nuclear reactor fuel subassembly. According to the outer strip, in the longitudinal direction, the outer strip comprises an upper edge part, a middle part, and a lower edge part which are connected; on the upper edge part and / or the lower edge part, a plurality of guiding parts are formed via protruding towards the same side of the plane of the middle part; the guiding parts are arranged at intervals along the length direction of the outer strip; the middle part is used for connecting the upper edge part and the lower edge part in a plate shaped manner; buckling of the middle part, shaping like a plate, of the outer strip is not caused, so that the buckling strength of the location grid entire body is increased, and safe operation surplus capacity of the nuclear reactor fuel subassembly under reactor accident conditions is increased; the gaps between the outer strips of the adjacent location grids are narrowed, so that it is ensured that more cooling agent flows into the interior of the location grids for blending, better cooling agent blending performance is achieved, and reactor thermal working condition safe operation surplus capacity is increased.

Description

technical field [0001] The invention relates to the technical field of nuclear reactors, in particular to an outer strip, a positioning grid for nuclear reactor fuel assemblies and nuclear reactor fuel assemblies. Background technique [0002] At present, the fuel assemblies used in nuclear power plants at home and abroad are generally composed of skeletons and fuel rods. They are fixed on the guide pipe and instrumentation pipe at a certain distance along the axial direction of the fuel assembly. All the positioning grids have the same arrangement and number of grid units. The fuel rods, guide pipes and instrumentation pipes pass through each Locate the grid unit at the same position as the grid. [0003] In an existing spacer grid, the transverse section of the outer strip on the outer circumference is a bending structure that periodically bends inwards of the grid unit, because the bending structure runs through the axial height of the entire outer strip , which reduces...

AI Technical Summary

Problems solved by technology

[0003] In an existing spacer grid, the transverse section of the outer strip on the outer circumference is a bending structure that periodically bends inwards of the grid unit, because the bending structure runs through the axial height of the entire outer strip , which reduces the overall buckling strength of the spacer, which leads to the following problems:

[0004] 1. If the reactor has an accident such as an earthquake, the collision between the fuel assemblies in the core will cause the spacer grid to be subjected to collision force in the horizontal direction, so that it is easier to cause the spacer grid to buckle in the bending area and destroy the spacer grid

[0005] 2. When hoisting and hoisting the fuel assemblies in the reactor core, when the adjacent fuel assemblies are staggered by 1 / 2 cell in the horizontal position, the planar area of ​​the strip outside the grid (the non-bent structure between the bending structures) is positioned. Bending area) is easy to embed in the middle area of ​​the fuel rod of the adjacent fuel assembly, and then it is easy to cause the adjacent fuel assembly to be hooked

[0006] 3. After the fuel assemblies are adjacently placed inside the core, because of the lower flow resistance between the spacer grids, more coolant will flow between the outer strips of the adjacent spacer grids without participating in the mixing. will reduce the cooling effect of the fuel assembly, and ultimately reduce the thermal safety operating margin of the reactor

[0007] In addition, the outer strip area of ​​the existing positioning grid basically has no vertical projected area (excluding the projection of the strip thickness), so the outer strip basically does not have a mixing effect on the coolant

Images