As a support tool of risk management, an approach to the reliability analysis system for the complex technical systems and its application to LNG (liquefied natural gas) receiving terminals are described. We have developed a tool capable of quantitative evaluation of the reliability of LNG facilities based on FTA (fault tree analysis) method and have implemented it in Gensym's G2. A key feature of the system is it constructs a fault tree automatically from diagrams such as process flow diagrams, and sequence block diagrams. The system has actually been used in the evaluation of existing LNG receiving terminals, and has also contributed to cost reduction in constructing a new terminal.