Control drum controller for nuclear reactor system

A nuclear reactor system, comprising:

• a pressure vessel;
• a nuclear reactor core disposed in the pressure vessel, the nuclear reactor core including a plurality of fuel elements and at least one moderator element;
• a plurality of control drums disposed longitudinally within the pressure vessel and laterally surrounding the plurality of fuel elements and the at least one moderator element to control reactivity of the nuclear reactor core, wherein each of the control drums includes a reflector material on a first portion of an outer surface of a respective control drum and an absorber material on a second portion of the outer surface of the respective control drum;
• and
• a control drum controller including:
• a counterweight that is external to a control drum of the plurality of control drums to impart a reverse torque on the control drum,
• a driven pulley coupled to the counterweight and to rotatably control the control drum based on a torque applied to the driven pulley,
• a tension member coupled to the driven pulley to rotatably control the driven pulley and apply the torque to the driven pulley, and
• an actuator powered by power from a power source and coupled to the tension member to apply a tension force to the tension member by winding or unwinding the tension member;
• wherein:
• the actuator counteracts the reverse torque of the counterweight with the applied tension force,
• the tension member applies the torque to the driven pulley in response to the applied tension force, and
• based on the torque applied to the driven pulley, the driven pulley rotatably controls the control drum.