Analysis and Improvement of Safety Class DCS Network Structure in a Nuclear Power Plant

Based on the design basis accident of degraded operation of ACPR1000 nuclear power unit caused by instrument and control system fault, five kinds of specific common cause faults are proposed. According to the connection robustness indicator, the improved method of the arrangement of the ring network nodes in the safety level DCS is summarized, and the common cause failure table is made for the network nodes with common cause faults, the adjacent sequencing is carried out according to the probability of common cause faults and the ring network structure is arranged to improve the connection robustness indicator of the network. The method is used to adjust the distribution of safety level DCS network in nuclear power plant, which improves the robustness of the network structure and contributes to the safety and reliability of nuclear power unit operation.