Digital Twin-Based Lifecycle Methodology for Ensuring Safety of NPP/SMR I&C Systems

This paper presents a digital twin-based lifecycle framework aimed at improving the safety and security of instrumentation and control (I&C) systems for nuclear power plants and small modular reactors. The approach formalizes DT components, functions, and stakeholder interactions across the entire lifecycle, enabling continuous V&V, accelerated commissioning, proactive fault detection, cyber-resilience, and faster and safer modification of I&C algorithms. The methodology is validated through case studies involving DT-supported V-model testing and Markov-based modeling of the intelligent diagnostic system of an NPP pump. The results show that the proposed DT-enabled lifecycle methodology increases test coverage, shortens verification time, and enhances proactive safety and security capabilities of I&C systems. The study outlines future research directions toward adaptive, explainable, and regulation-ready DTs for next-generation nuclear systems.