Computer-aided Fault Tree Synthesis for Quantitative Risk Assessments

PresentationFault tree analysis (FTA) has been used in the chemical process industry (CPI) for systematic safety and reliability analysis during the past decades. Once constructed, the fault tree can be of considerable value in determining the paths for propagation of basic events through the system to cause the top event. Algorithms exist that determine which basic events, or combinations of primal events (minimum cut set analysis), will cause the top event for a given fault tree. While much of the statistical and cut set analysis has been automated, construction of a fault tree is usually done by hand. Manual construction of the tree can be extremely time consuming and vulnerable to human errors. No entirely-satisfactory algorithm has been published for fault tree synthesis, especially when control loops are encountered. Ideally the system failure models should be independent of the synthesis method, but in practice they are strongly interdependent. The object of this research is to develop an efficient and practical computer algorithm for the synthesis of fault trees. The fault tree is deduced based on a mini-fault tree model of the analyzed system. The correctness of this algorithm will be examined for control loops. Serial and parallel consistency also will be considered and discussed