Retaining grid and fuel assembly with such retaining grid

Abstract

The invention discloses a holding grille. The holding grille comprises a plurality of inner strips and a plurality of outer strips, the plurality of inner strips are intersected to form a gridding grille structure and form a plurality of hollow grille units, the outer strips are circumferentially arranged on the periphery of the grille structure and fixedly connected with the inner strips, and the holding grille also comprises a plurality of clamping pieces, the clamping pieces are fixed onto the inner strips in a clamping manner, each clamping piece comprises a first strip and a second strip, which are respectively arranged on two sides of the inner strip, the first strip is protruded towards the inside of the grille unit to form an arch bulge, the second strip is protruded towards the inside of the adjacent grille unit to form a plane bulge, a fuel rod which is arranged in the grille unit is collectively clamped by the arch bulge and the plane bulge in the same grille unit, and the arch projection and the plane projection extend along the axial direction of the fuel rod. The holding grille is low in machining difficulty, small in pressure loss, balanced in water stress and high in stability.

Description

technical field [0001] The invention relates to the technical field of nuclear reactors, in particular to a holding grid and a fuel assembly with the holding grid. Background technique [0002] A certain number of fuel rods are arranged at certain intervals (such as: 15×15 or 16×16, etc.) and fixed into a bundle, which is called a reactor fuel assembly. The reactor fuel assembly is mainly composed of an upper nozzle, a lower nozzle, and a holding grid ( Also known as mixing grid or positioning grid), control rod guide tube and fuel rods. Among them, the holding grid is used for loading and positioning fuel rods and is composed of a plurality of inner strips and outer strips, and the plurality of inner strips are orthogonal to each other to form a grid-like grid structure with a plurality of grid units, while the outer The straps are fixedly surrounded by the inner straps. Except a few grid units are used to set the control rod guide tubes, each of the remaining grid units ...

AI Technical Summary

Problems solved by technology

[0004] The holding grid with this structure in the prior art has the following disadvantages: first, the rigid convex a is directly made on the inner strip by stamping, the stamping process is relatively complicated, the processing difficulty is relatively high, and it is easy to be lost during the stamping process. Cracks are generated on the inner strip; secondly, the existing rigid convex a is a bridge structure perpendicular to the fuel rod, and it has a certain length of flat area after forming to ensure the resistance to the fuel rod, thus resulting in the rigid convex a The length is relatively large, thereby increasing the front flow area of ​​the grille, increasing the pressure loss, which is not conducive to the flow and heat dissipation of the coolant; The front-flow area of ​​the spring b is different, which leads to the unbalanced hydraulic force of the grid under the impact of the coolant inside the reactor, and it is easy to vibrate when running in the reactor

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