Abstract: A drive mechanism for a control rod of a nuclear reactor adapted for rapid refueling is disclosed which electromechanically grips and moves a control rod in a step-by-step manner. Locking apparatus is included with the drive mechanism which locks the control rod in position when it is fully withdrawn from the core. The locking apparatus prevents the drive mechanism from inadvertently dropping the control rod. Therefore, during rapid refueling of a core, when the control rods are withdrawn and stored within an upper core supporting structure, there is no possibility of a control rod being accidentally dropped so as to interface with the rapid refueling operations.