Cask for receiving control rod drives

Object: To position a gate valve between an upper receiving vessel and a lower receiving vessel of a cask so that it may be used disconnecting the upper receiving vessel when necessary to efficiently perform maintenance and repair work of the upper portion of a control rod drive. Structure: A lower receiving vessel whose periphery is surrounded by a shield and an upper receiving vessel whose periphery has no shield are separably mounted so that when the respective receiving vessels are separated, a gate valve for sealing the upper receiving vessel is mounted on the upper receiving vessel. When the upper receiving vessel is withdrawn from the reactor for purposes of maintenance and repair, a sleeve is mounted between the structure and a pit cover, and a bed incorporating therein a fixed valve is mounted. Next, the upper receiving vessel provided with the gate valve and a winch means are separated from the lower part and connected onto the bed, and both the valves are opened to remove the upper receiving vessel from the reactor so that it may be carried into a maintenance room for maintenance and repair. (Hanada, M.)