A Domain-Specific Safety Analysis for Digital Nuclear Plant Protection Systems

Rigorous safety demonstration through safety analysis is strongly mandated for safety-critical systems. Nuclear plant protection systems often use techniques such as FTA, FMEA and HAZOP. Safety experts perform them manually, and quality of the analysis totally depends on the ability and experience of the experts. If we restrict the application domain of safety analysis into specific critical failures, we could automate a large part of the analysis and also improve its quality too. This paper proposes a domain-specific safety analysis technique, NuFTA, for nuclear plant protection systems. NuFTA mechanically constructs a software fault tree of nuclear reactor protection systems specified with NuSCR requirement formal specification language. The root failures of the fault tree constructed through NuFTA are restricted into ´shutdown´ events of nuclear reactors, which is the most important event in the domain. Within the domain specific restrictions, NuFTA can construct software fault trees mechanically and aid safety experts´ analyses efficiently.