Reliability evaluation of digital instrumentation system of NPP safety system

Application of digital instrumentation and control system on the design of nuclear power plant was done gradually, especially for systems related to safety. For safety reason, the technology used for safety system must be proven technology with a reliability that meets the requirements. Another thing that distinguishes between and digital technology is the use of software in digital technology, which is not found in analog technology. In this paper, reliability evaluation of digital instrumentation system for nuclear power plant (NPP) safety systems is discussed. The research objective was to investigate the effect of the features of digital technology on the system reliability. The evaluation is done by fault tree analysis of the analog and digital instrumentation system that perform the same function. Evaluation results showed that the reliability of on the digital instrumentation systems, related to the application of software fault-tolerant and multitasking features, could be improved by using reliable watchdog timer and system redundancy configuration. (author)