Control unit of a nuclear reactor

Control unit comprising multiple leak-tight vessels, in communication with the inside of the reactor vessel, extending this vessel above its cover, in the vertical direction and each one enclosing a mechanism for moving a cluster of material absorbing the neutrons in the reactor core, actuated by a motor. This control unit is of reduced height above the vessel cover and provides efficient protection of the leak tight containments and the mechanisms in the event of earthquakes, easy removal and refitting of the vessel cover, good ventilation of the power devices of the mechanisms without the use of a complex ventilation system, efficient thermal insulation of the leak-tight containments assembly, as well as easy access to the motors and mechanism located in the leak-tight containment for carrying out any maintenance and repairs that might be required