A simplified risk effect analysis of digital reactor protection system

In recent days rapid development of digital technology over both hardware and software stimulates the application of digital equipment to the safety systems of nuclear power plants. The risk effect analysis of these application are, however, not yet performed in Korea. In this paper, we perform and present the quantitative analysis of the risk effect of digital reactor protection system on the total nuclear plant. The safety assessment under the assumption of no operator action for the manual initiation of emergency systems are also performed. The results show that if the manual initiation is ignored, the effect of digital safety-critical systems no the plant safety is quite serious. The results in this paper are calculated with a simplified fault-tree model of digital reactor protection system and digital engineered safety feature actuation system. Therefore, the more detailed model of these systems are required in order to get the more realistic results. We expect that the simplified model could also present the outline of risk effect analysis results of digital reactor protection system