Removable top nozzle and tool for a nuclear reactor fuel assembly

摘要

A top nozzle subassembly having a hold-down device incorporated therewithin is provided for a nuclear reactor fuel assembly. The subassembly is slidably mounted on the upper ends of the control rod guide thimbles and is removably attached by internally threaded collars which threadably mate with external threads provided on the upper ends of the guide thimbles. Unthreading of the collars allows the subassembly to be removed from the fuel assembly to gain top access to the fuel rods within the fuel assembly. The invention also includes a special tool for threading and unthreading of the collars.