Recent advances in digital system reliability prediction

Nuclear power plants (NPPs) traditionally relied upon analog instrumentation and control (I&C) systems for monitoring, control, and protection functions. With a shift in technology from analog systems to digital systems with their functional advantages, plants have begun such replacement, while new plant designs fully incorporate digital I&C systems. However, digital systems have some unique characteristics, such as using software, and may have different failure causes and/or modes than the analog systems; hence, their incorporation into NPP probabilistic safety assessments (PSA) entails special challenges. This paper highlights our recent work in incorporating contribution of software in digital I&C reliability analysis.