AUTOMATED FAULT-TREE SYNTHESIS BY SEMANTIC NETWORK MODELING, RULEBASED DEVELOPMENT AND RECURSIVE 3-VALUE PROCEDURE

A concept of flow is introduced to represent any material, information , energy, activity, or phenomenon which can move or propagate along fl ow paths to cause events specific to the system to be analyzed. A grap hical equipment library is given to represent typical types of 'genera tion rate' and 'aperture' controllers. The system is modeled by a sema ntic network with labeled arrows showing effect to cause (backward) re lationships between flow and equipment nodes. A correspondence between the equipment library and the system components is established, and t he semantic network is constructed by integrating network fragments in the library. Fixed and/or free boundary conditions can be specified e xplicitly for flow or equipment nodes. Forward-chaining event developm ent rules locally trace the labeled arrows, while a 3-value procedure guides the FT generation by recursive rule applications. The rules are obtained from tables and equipment definitions. The 3-value logic is used to truncate FTs according to the boundary conditions. Different F Ts are generated for different top events and boundary conditions, giv en a semantic network model. FT modules and their hierarchies can be i dentified by examining network theoretic properties of flow nodes. The proposed approach is demonstrated for a relay system, a hypothetical swimming pool reactor and a chemical reactor.