Office of Nuclear Regulatory Research

Digital I&C (DI&C) systems have been used to upgrade or replace some analog I&C systems in current nuclear power plants (NPPs). In addition, new and advanced NPPs of various technologies extensively employ DI&C systems. These systems are very flexible and can be used to implement many useful features. However, like any other system in an NPP, common cause failure (CCF) may happen among the redundant components in this type of system. Therefore, the potential exists for CCFs to occur among the hardware components and among the software components of a DI&C system. This digital exhibit will describe the issues encountered in quantifying the probability of CCF in this type of system.