[en] Design of a hermetically sealed box for fuel recharging device used in liquid metal fast reactors is described. The box consists of a vessel, an upper port, and cavities for gathering of radioactive coolant outgoing from the fuel assembly unloaded from the core, connected between each other with hinges. To simplify service of the box cavities are connected between each other by steel rope haulages. The length of a medium cavity exceeds at least twice lengths of other cavities. After recharging, when cavities are filled with sodium, they are removed from the box. Removing of cavities is carried out simultaneously through an upper port. Box equipment mounting and dismounting is accomplished also through the above port