Abstract: A hydraulic control unit (“HCU”) configured to control a control rod drive mechanism (“CRDM”) configured to control the nuclear flux produced by a nuclear reactor is disclosed herein. The HCU can include a plurality of valves configured to attenuate a fluid pressure within the CRDM, wherein the attenuation of the fluid pressure is configured to cause a control rod of the CRDM to be inserted or withdrawn from a reactor vessel of the nuclear reactor, and a control circuit including a plurality of relay interfaces, wherein each relay of the plurality of relay interfaces is electrically coupled to a valve of the plurality of valves, a controller electrically coupled to the plurality of relay interfaces, and a communications circuit communicably coupled to a header controller, wherein the communications circuit is configured to transmit and receive signals between the controller and the header controller.