A trap for catching debris carried by coolant flowing from the bottom nozzle of a fuel assembly to the bottom or lowermost one of the grids of the assembly which support the fuel rods in an organized array therein includes a structure disposed between the bottom nozzle and the bottom grid and generally aligned with the lower end plugs of the fuel rods. The structure forms a multiplicity of hollow cells each being open at opposite ends and defining a central cavity which receives one of the fuel rod lower end plugs while providing for passage of coolant flow therethrough from the bottom nozzle to the bottom grid. Also, the trap includes means in the form of dimples defined in each of the cells for catching debris carried into the cells by the coolant flowing therethrough. The dimples are formed from the wall portions defining the cells and extend into the cavities of the cells. Each dimple has a configuration generally arched outwardly from the wall portion which is oriented in alignment with the direction of coolant flow through the cell. The distance between those dimples formed on oppositely-disposed ones of the wall portions is slightly greater than the diameter of the fuel rod lower end plug disposed in the cavity of each cell. Additionally, the debris trap further includes structure support means in the form of a plurality of hanger straps attached at their lower ends to the structure adjacent the corners thereof and at their upper ends to the bottom grid so as to locate the structure in the spaced relationship below the bottom grid and support the structure adjacent the corners thereof from the bottom grid.