Research On Station Blackout Accident And Fault Tree Analysis Method

Station Blackout(SBO),with important research significance,is one of the severe events which can lead to core melting.This paper adopts the modular accident analysis program for modeling the SBO accident in CPR1000.Accident process of the SBO is analyzed in detail by the calculation of relevant parameters,such as primary circuit pressure,water level of the vessel,core temperature,etc.On this basis,in view of the problem that main pump is easy to break at high temperature and pressure,this paper selects the early period,middle period and late period,thus three periods of accident sequences to do the sensitivity analysis of the occurring time.The result shows that seal LOCA in the early period will accelerate the process of vessel failure,and in the later period,especially in the middle period,seal LOCA can delay the accident process.We hope that data in this paper will provide a reference for relevant personnel for the prevention and mitigation of serious accidents.Probability Safety Analysis(PSA)method is an important supplement to the analysis of severe accidents.Due to the large number of different systems and events in SBO accident,obtaining the minimal cut sets efficiently has been an important research area of PSA.Due to low efficiency of the traditional methods,this paper uses C language to develop a Fault Tree(FT)analysis program based on the Binary Decision Diagram(BDD)and ITE algorithm.At same time,it is applied to a simplified example of vessel failure mode.As for the problem that logical loops are easily found in the process of building FT for SBO accident,this paper carries out a further research.In order to make the process of dealing with logical loops more intuitive and easy to implement programming,this paper improves the improved analytical method by using the multi-tree structure and combining the advantage of the iterative method.This method is applied to the typical logical loops in SBO situation and software implementation of this method is realized by using C#language.