A quality control method for nuclear instrumentation and control systems based on software safety prediction

In the case of safety-related applications like nuclear instrumentation and control (NI&C), safety-oriented quality control is required. The objective of this paper is to present a software safety classification method as a safety-oriented quality control tool. Based on this method, we predict the risk (and thus safety) of software items that are at the core of NI&C systems. Then we classify the software items according to the degree of the risk. The method can be used earlier than at the detailed design phase. Furthermore, the method can also be used in all the development phases without major changes. The proposed method seeks to utilize the measures that can be obtained from the safety analysis and requirements analysis. Using the measures proved to be desirable in a few aspects. The authors have introduced fuzzy approximate reasoning to the classification method because experts' knowledge covers the vague frontiers between good quality and bad quality with linguistic uncertainty and fuzziness. Fuzzy Colored Petri Net (FCPN) is introduced in order to offer a formal framework for the classification method and facilitate the knowledge representation, modification, or verification. Through the proposed quality control method, high-quality NI&C systems can be developed effectively and used safely.