Reliability Analysis Of Reactor Emergency Shutdown System

The reactor emergency shutdown system is the most important type of safety equipment in nuclear power plants,and the analysis and evaluation of its reliability has always been paid much attention.However,there is currently no uniform standard and a consensus reliability evaluation method for nuclear power plant control system design in the field of nuclear power.Taking the ISO26262international standard of the automobile manufacturing industry as a reference,this paper proposes a hybrid reliability analysis method that combines deductive and inductive analysis.Its characteristic is that reliability analysis methods such as FMEA,FTA,FMEDA and common cause evaluation are based on it.The internal time logic sequence is integrated and runs through the entire process of reactor emergency shutdown system design.Using the hybrid reliability analysis method proposed in this paper,taking the emergency shutdown system of a domestic reactor under construction as the analysis object,the effectiveness of the method is verified.According to the design process sequence of the reactor emergency shutdown system,this paper first starts from the conceptual design stage and analyzes the overall structure,composition,characteristics,working mode and work flow of the system;then,in the system design stage,the reliability analysis adopts the FMEA method to conduct self-reliability analysis.Bottom-up summary analysis is mainly to qualitatively analyze the main controller,communication module,analog input board,digital output board,power supply module,and execution module of the emergency shutdown system.Then,in the process design stage,a fault tree model of the reactor emergency shutdown system is established,and the reliability analysis uses FTA quantitative analysis for top-down deductive analysis.The refusal rate and the misoperation rate are calculated to verify whether it meets the requirements of the"Reactor Protection System"The indicator requirements in the Safety Guidelines.Entering the hardware design stage,FMEDA analysis and common cause evaluation are used to perform FMEDA analysis on the controller SCU9020 of the system,and key reliability parameters such asλ_D,λ_DD,andλ_DUare calculated from the failure analysis.After detailed common cause analysis,the results are obtained The common cause moleculeβ,according to the main controller 3 to take 2 is logical,and the rejection rate can be accurately calculated.At the end of this paper,the proposed hybrid reliability analysis method is summarized.The system failure based on the hardware system’s refusal and hardware misoperation as the data basis,and the software reliability analysis in the system,so as to further improve the complete reliability analysis of the system at the hardware and software level.