Abstract: The probability of a number of basic events itself was uncertain and fuzzy when the traditional FTA method was used in the practical quantitative analysis quite. It was difficult to obtain the exact probability from failures, which violated the premise of exact probability selected. In order to solve the traditional fault tree analysis (FTA) of the probability the basic event fuzzy and uncertain problems, the concept of fuzzy theory were introduced, and the fuzzy probability was used to deal with the basic events lack of statistical data. The basic events of fuzzy probability were described by using a clear triangular fuzzy number, the fuzzy probability distribution of top event layer by layer was obtained, and the fuzzy importance of each basic event was determined by using fuzzy numbers value method. And the sort of top event of failure factors was obtained, the main factors influencing the accident were identified and effective measures from fundamentally preventive and the key points to control the top event were proposed.

Key words: The fuzzy theory, Triangular fuzzy number, FTA model, The fuzzy importance, Safety evaluation

摘要： 传统事故树分析法应用于实际量化分析时，相当一部分基本事件的概率本身是不确定的、模糊的，因此获得故障的精确概率比较困难，违背了精确概率选取的前提。为了处理传统事故树分析法中基本事件概率的模糊和不确定问题，引入了模糊数学理论的概念，对缺乏统计资料的基本事件进行模糊处理。运用一种能解决模糊性并且意义明确的三角模糊数来描述基本事件的模糊概率，逐层求得各事件发生的模糊概率分布，同时通过模糊数的中值法求出各基本事件的模糊重要度，得到顶上事件故障影响因素的排序，找出导致事故的主要因素，提出能从根本上预防、从关键点控制顶上事件发生的有效措施。

关键词: 模糊理论, 三角模糊数, FTA模型, 模糊重要度, 安全评价