Abstract: A control rod driving apparatus adapted to drive a control rod assembly for a nuclear reactor is disposed in a housing mounted to a reactor pressure vessel of the nuclear reactor and includes a guide tube disposed in the housing, a connection pipe disposed inside the guide tube coaxially therewith and having one end to which a control rod assembly is connected, a ball spindle disposed inside the connection pipe and supported thereby so as to be rotatable by a ball nut assembly engaged with the ball spindle so as to be axially movable along the ball spindle, the ball nut assembly supporting another end of the connection pipe, a hydraulic drive operatively connected to the ball spindle to rotate the ball spindle, and a transmission mechanism operatively connected to the drive for transmitting a power of the drive to the ball spindle.

Abstract: A control rod driving system for controlling a reactor core disposed in a reactor pressure vessel comprises a control rod and a control rod driving mechanism. The control rod has an inner hollow portion extending in a longitudinal direction thereof and the control rod driving mechanism is inserted into the inner hollow portion of the control rod for driving the control rod.