Causes of Uncertainty in FTA Method and Use of Fuzzy Logic to Solve this Problem


Nowadays increasing the number of chemical industries leads to more industrial accidents. Due to consequences of accidents imposed high costs to industry, society and environment. This makes safety analysis more important. Therefore qualitative and quantitative hazard analyses are essential for identification and quantification of hazards. Fault tree analysis (FTA) is an established technique in hazard identification. People when using FTA often suffers from a lack of detailed data on failure rates, uncertainties in available data, imprecision and vagueness. This may lead to uncertainty in results and process risk level. Fuzzy logic deals with uncertainty and imprecision, and is an efficient tool for solving problems where knowledge of uncertainty may occur. In this paper traditional FTA was combined with fuzzy set theory. In fuzzy method, all variables are replaced by fuzzy numbers in the process of fuzzification and subsequently fuzzy probability of the top event is used for fault tree.

Keywords: Fault Tree Analysis, Uncertainty, Fuzzy Logic, Fuzzy Operator.

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