A device for supplementing structural integrity of a spent nuclear fuel assembly during handling is provided. The spent nuclear fuel assembly includes spacer grids for supporting fuel rods, guide tubes, and top and bottom nozzles for supporting upper and lower ends of the guide tubes. The device includes a housing, a rod member and fixing members. The housing includes a plurality of free end portions, stopper protrusions formed at an end of each of the free end portions, a first male thread formed on an outer surface, and a female thread formed on an inner surface. The rod member includes a pressurization protrusion at one end and a second male thread for engaging with the female thread of the housing. The fixing members are configured engage with the first male thread to secure the device to the top nozzle of the spent nuclear fuel assembly.