Cyber security analysis of reactor protection system

In the process of DCS platform developing and engineering implementation of nuclear power plant Reactor Protection System (RPS), to enhance Cyber security of RPS, RPS access paths were analyzed, and security level and zone were set by graded approach and zone model. The attack tree model for RPS was established to analyze the attack ways. The paper put forward systematic cyber security analysis method and countermeasures mentioned which can be referenced by the project of RPS platform developing, engineering implementation and operating maintenance. (authors)