Dynamic Reliability Analysis of DCS in HTR-PM Considering Fault Self-Check Rate Based on Petri Net

Abstract

Digital distributed control system (DCS) is the most important monitoring and control platform in a nuclear power plant (NPP). The reliability and availability modeling and analysis of digital DCS are of great significance to ensure the stable and reliable operation of NPPs and to improve the economy of NPPs. With the continuous development of control system technology, the fault self-check rate of DCS equipment is getting higher and higher. It is necessary to consider the influence of this factor in the DCS reliability model and improve the model architecture. In this paper, a dynamic reliability model of DCS based on Petri Net is proposed by considering the factor of fault self-check rate. The DCS of High Temperature Gas-Cooled Reactor -Pebble bed Module (HTR-PM) was adopted for model verification, and the reliability of the DCS was calculated by Monte Carlo method. The calculation results show that the higher the fault self-check rate, the lower the unavailability of the DCS. When the fault self-check rate exceeds 40%, the unavailability of DCS will be reduced by an order of magnitude. This conclusion has important engineering practical significance.