Fuel assemblies and their non-strip spacer grids and strips

Abstract

The invention relates to a fuel assembly and an outer-strip-free positioning grid frame and strips thereof. Each strip comprises a plate-shaped body and elastic arms arranged at at least one end of the body, wherein the tail ends of the elastic arms extend towards the side away from the body. The positioning grid frame comprises the first strips and the second strips, wherein the first strips and the second strips are arranged in a crossed mode. The ends, extending out of the same side of the corresponding first strip, of every two adjacent second strips are provided with the first elastic arm and the second elastic arm which extend outwards respectively, wherein the first elastic arm and the second elastic arm are bent towards the part between the two corresponding second strips, the first elastic arm, the second elastic arm, the parts, extending out of the first strip, of the two adjacent second strips and the part, located between the two corresponding second strips, of the first strip form a first clamping unit, and a fuel rod is arranged in the first clamping unit in a penetrating mode and clamped by the first clamping unit. No outer strip is arranged outside the positioning grid frame for enclosure, so that the pressure loss of a coolant in a reactor is reduced, and the operating efficiency of the reactor is improved; meanwhile, the risk of hooking between two adjacent positioning grid frames is avoided.

Description

technical field [0001] The invention relates to the field of nuclear power, and more specifically relates to a fuel assembly used for light water reactor fuel elements and its positioning grid and strips without outer strips. Background technique [0002] The core of a pressurized water reactor nuclear power plant consists of many fuel assemblies such as figure 1 As shown, the fuel assembly structure is composed of a rigid frame and fuel rods, and the fuel rods are arranged in parallel and evenly spaced in the rigid frame. The rigid skeleton includes a positioning grid 10 , a mixing grid 4 , an upper tube base 5 , a lower tube base 6 and a guide tube 7 . The mixing grid 4 and the spacer grid 10 are respectively composed of regularly arranged cells for accommodating and clamping fuel rods. The spacer grid 10 and the mixing grid 4 are arranged at intervals in the axial direction of the fuel rods, for the fuel rods to pass through and locate. The guide tube 7 is longer than ...

AI Technical Summary

Problems solved by technology

[0004] The guide wings of the above-mentioned spacer grid 10 are bent toward the inside of the spacer grid 10. At this time, the guide wings will produce a projected area in the flow direction of the coolant in the reactor, thereby causing a large pressure loss and reducing the operating efficiency of the reactor.

[0005] At the same time, during the loading and unloading process of nuclear fuel assemblies with the above-mentioned structural features, adjacent nuclear fuel assemblies are prone to collide. Due to the collision of adjacent fuel assemblies, the collision force in the direction of the guide wing to the inside of the grid is too large, and the It is easy to over-bend the guide fins to the inside of the spacer grid 10, which may cause interference with the fuel rods and cause damage to the fuel rods, thereby reducing the safety of the reactor operation

[0006] In addition, during the loading and unloading process of nuclear fuel assemblies with the above-mentioned structural features, if adjacent fuel assemblies are misaligned by half of the cells and squeeze each other, the guide fins of one of the adjacent fuel assemblies can be easily inserted into the other fuel assembly The area where the strips join between adjacent guide fins, allowing snagging to occur, which can easily lead to fuel assembly damage

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