Study on CCF Detection Methods for Digital I&C

APR1400 I&C system features an advanced control room and digital control systems. This I&C system architecture of APR1400 consists of independent and diverse platforms such as Distributes Control System (DCS) platform, Qualified Programmable Logic Controller (PLC) platform. This diversity is important to address the CCF concern of DI&C systems. However, it is difficult for operators to quickly recognize the situation of CCF in DI&C systems. This paper presents methods for the operator to detect the situation of CCF occurrence in APR1400 DI&C systems. Generally, diversity I&C systems can provide effective protection against CCF for digital protection system. Diversity in redundant I&C divisions may help prevent CCFs, and diverse backup system can be used to mitigate a failure or CCF after it occurs. It is even more important for the operator to recognize and respond to this situation. Therefore, it is necessary to improve the design to recognize the CCF situations by using the online self-diagnostic function of the digital system.