Reliability Analysis And Application Of Safety Instrument And Control System For Nuclear Power Plant Based On Dynamic Fault Tree

With increasing pressure on the environment and depletion of coal resources,transformation of energy system is imperative.Compared with wind power and solar power,nuclear power has advantages of cleanliness,stability,high utilization,and abundant resources,so it makes sense for optimization of Chinese Strategic layout of energy.The number of nuclear power plants under construction in China in recent years has also proved the importance of nuclear power.However,due to the severity of damage to surrounding environment caused by accidents of nuclear power plants,safety of nuclear power plants is critical.Safety instrument and control system ensures normal operation of nuclear power plants and maintain nuclear power plants in a safe shutdown state by implementing corresponding safety functions.In China,due to the introduction of previous technologies,in-depth research on safety I&C systems just begins.The operating logic under different accident conditions,failure probability and design concept of safety I&C systems are the focus of nuclear power research.The research object is safety I&C system of third-generation nuclear power plant,develop dynamic link library with C++ language under Visio platform is used to realize configuration and simulation.The internal operation logic of safety I&C systems for nuclear power plant is analyzed,which include process from receiving safety parameter signal to activating corresponding driving signal of safety facility by simulating changes in value of safety parameters and operator's manual operation under accident conditions.At the same time,the way to switch the safety function of system during different operation phases through the lock signal and summarizes operation mechanism of safety I&C system is obtained through simulation platform.Combining operation mechanism,hardware composition and work flow of safety I&C system,failure mechanism of system is analyzed.The top event of dynamic fault is failure of reactor trip function,reactor coolant pump trip function,automatically depressurization system,dynamic fault tree modeling of safety I&C system is completed.Through modularization method,dynamic fault tree model is simplified into dynamic subtree and static subtree.Dynamic subtree with dynamic logic gates is solved by Markov mode,then dynamic subtree can be treated as basis event of the static subtree.Down-way method and quantitative analysis method is applied to obtain the minimum cut set and reliability parameters of dynamic fault tree,the reliability of safety I&C systems is verified.Finally,failure mode of safety I&C system and the most dangerous components is obtained.Fault tree analysis software and risk assessment platform is developed,it receives real-time data from nuclear power plants and monitor faulty components in safety I&C system,and calculates real-time failure characteristics of the nuclear power plant in fault tree analysis software,then feed assessment results back to the operator.Based on results of simulation analysis and reliability analysis,differences between different nuclear power technology's safety I&C system are obtained through comparison.Design concept of safety I&C system for nuclear power plant is summarized from the perspective of safety and reliability,which provides comprehensive theoretical support to operators and designers.