A control drum system for a nuclear reactor including a reactor core, including an ex-core reflector including a plurality of cylindrical apertures, a plurality of control drum assemblies, each control drum assembly including a drive shaft, a drum cylinder affixed to a bottom end of the drive shaft, and a planetary gear attached to a top end of the drive shaft, wherein each drum cylinder is rotatably received in a cylindrical aperture, a first control drum drive motor operably connected to a first control drum assembly, and an annular ring gear that is operably connected to the planetary gear of each of the control drum assemblies so that all the control drum assemblies rotate simultaneously.