Consideration was given to the design of the top-level system of the nuclear power plant process control system with regard for the impact on its safety. This system is aimed at centralizing process instrumentation and control. The top-level system is a sophisticated hardware complex supported by the computer-aided design and adjustment system and intended for integrating all subsystems of the process control system. The top-level system executes the informational, control, service, and auxiliary functions of the nuclear power-plant process control system. Consideration was given to the structure of the top-level system, the structure of its software, and the principles of design providing high performance of the top-level system.