NUCLEAR FUEL ASSEMBLY HAVING A PROTECTIVE GRID TO PREVENT FLOW-INDUCED VIBRATION

The present invention relates to a nuclear fuel assembly capable of reducing flow-induced vibration by improving the combination structure between a protection spacer grid and a lower fixing body. The nuclear fuel assembly includes: a plurality of fuel rods which are arranged in the axial direction; a plurality of spacer grids which support the fuel rods; a plurality of guide pipes which are fixed to the spacer grids and form the frame of the assembly; an upper fixing body which supports the upper part of the guide pipes; and a lower fixing body which supports the lower part of the guide pipes and has a plurality of passage holes. Among the spacer grids, a protection spacer grid (100) includes: multiple outer grid plates (110) which make up the border; and multiple inner grid plates (120) which are arranged and fixed in a grid form inside the outer grid plates. The lower end of each inner grid plate is inserted and fixed into a fixing slot (220) formed on the lower fixing body to restrict the protection space grid by the combination between the lower end of the grid plate of the protection spacer grid and the lower fixing body. By doing so, it is possible to suppress the vibration of the protection spacer grid due to cooling water and thus prevent damage to the protection spacer grid due to flow-induced vibration.