Risk assessment of technological processes (chemical and power plants, electro-mechanical systems) is a complex process that requires enumeration of all possible failure modes, their probability of occurrence, and their consequences. Traditionally such studies have been performed by a committee of expert engineers with diverse backgrounds. This paper discusses the use of qualitative modeling techniques based on deriving behavior from structural descriptions and causal reasoning to aid automating and enhancing the risk analysis process. Hierarchical schemes are used for describing component structure, and system functionality is derived from a set of primitive functions and parameters defined for the domain. The system uses these models to automatically generate fault and event networks for hypothesized fault situations specified by users.