A control safety system for use in nuclear plants, comprising: a plurality of identical safety channels, each said channel includes process signal input/output stations IOS 1-n, actuation mechanism priority control stations PCS 1-m that are connected with the main control room MCR and emergency control room ECR, safety features automation controller SF AC, safety features input/output bus SF IOB for SF AC controller data exchange with IOS and PCS stations, and is cross-connected with other safety channels by means of duplex optical fiber communication paths, characterized in that the said IOS station contains modules of communication with the process MCP 1-k and communication module - converter of communication interfaces CIC of SF IOB bus; said PCS station contains actuation mechanism priority control modules PCM 1-e and communication modules: voting communication module VCM and voting module VM of SF IOB bus; said automation controller SF AC contains safety feature automation processor module SF APM and communication modules - branching modules BM-4 1-p of SF IOB bus; said safety feature automation processor module SF APM of each safety channel is cross-connected with the SF APM of other safety channels by communication paths implemented using interprocessor interfaces IPI of 'point-to-point' type based on Ethernet interface and data-level communication protocol; said safety channel SF IOB bus has a 'tree'-type structure, the upper root node of which is the SF APM of the safety channel, the low end nodes are modules of communication with the process MCP 1-k of IOS 1-n stations and priority control modules PCM 1-e of PCS 1-m stations of its own safety channel, and priority control modules PCM 1-e of PCS 1-m stations of other safety channels, and intermediate nodes are communication modules: BM-4 1-p of automation controller, CIC of I/O stations, and VCM and VM of priority control stations; communication paths between the modules being in the SF IOB bus nodes are implemented as the lines of a serial duplex interface of 'point-to-point' type; interchannel communication lines between automation controller SF AC of each safety channel and priority control stations PCS 1-e of other safety channels are implemented using optical fiber cables; each safety channel is implemented based on one processor located in the automation processor module APM; and majority redundancy according to '2 out of N' principle of commands and data selection, where N is a number of safety channels, is implemented here at the two levels of interchannel communications: at the level of the processors of SF APM modules when receiving by the SF APM module processor of each safety channel the commands and measured parameters from the processors of the SF APM modules of other safety channels via interprocessor interfaces IPI, and at the level of priority control stations in communication modules VM of PCS 1-m stations, when receiving by PCS 1-m the control commands from the processors of the SF APM modules of all the safety channels via SF IOB buses; in said PCM modules of said PCS stations outputs of programmable logic circuits of actuation mechanisms priority control logic - PCL PLC - are connected to AM input and via feedback paths to SF AC controller of the safety channel via SF PLC and SF IOB bus; AM outputs are connected to PCL PLC and via SF PLC to MCR, ECR, and SF AC controllers; SF AC controllers of safety channels are connected with MCR and ECR via interprocessor interfaces IPI of 'point-to-point' type implemented based on Ethernet interface and data-level communication protocol; automation controllers SF AC of all safety channels are connected to the normal operation system via redundant bus EN built based on switched Ethernet interface, ring structure of net switch connection, and data-level communication protocol.