Diagnosis expert system for nuclear power plant control system electronic components

An expert system for nuclear power plant control system diagnosis was developed. The system, named LODIA (LOgical DIagnostic Adviser), is built on top of an AI tool named PLEXSYS (PLant EXpert SYStem) developed by Electric Power Research Institute (USA) and Toshiba Corporation (Japan). The distinguishing feature of PLEXSYS is 'Model Based Reasoning' and it provides functions to build knowledge base of specific domain (domain model) and search among this model to derive various conclusions. The diagnosis expert system developed consists of knowledge base of a typical BWR PLR flow control system and can locate a failed electronic board from plan process data collected at a certain point of time. Major characteristics for the fault locating process in this system are combination of qualitative and quantitative reasoning. Actual diagnosis methods are implemented with logical search mechanism for PLEXSYS without using any rules. The diagnosis system was tested with simulated plant status data. (author)