Abstract
Probabilistic risk assessment (PRA) is a technique for evaluating the safety of nuclear power plants. In particular, the level 1PRA has general versatility and has been utilized in various fields. In the level 1PRA, the identification of accident scenarios is very important. It is performed by top-down analysis or bottom-up analysis. In the previous study, the marine accident in Akashi Strait was analyzed by the bottom-up analysis method. However, the identification of accident scenarios required a more effective analysis to extract factors without slipping. So, in this study, we discuss accident scenario identification methods from both top-down and bottom-up analysis method. An example of the analysis of marine accidents was shown by these methods. The bottom-up analysis was referred to the previous study. As a top-down analysis method, the Master Logic Diagrams (MLD) was performed. By comparing the analysis result of MLD to the previous study, we discuss the effectivity of the identified accident scenario by both top-down analysis and bottom-up analysis.
