DYNAMIC RELIABILITY ANALYSIS OF A DIGITAL CONTROL SYSTEM

摘要

Digital systems offer the potential to improve plant safety and reliability through features such as increased hardware reliability and stability, and improved failure detection capability. Many new and old nuclear power plants are intended to upgrade/refurbish the aging control systems from analog to digital technology. However, this transition in technology is expected to cause immense challenges due to currently limited guidance on reliability modelling of digital systems. This paper discusses the dynamic reliability analysis of a digital steam generator level control (SGLC) system using the dynamic flowgraph method (DFM). A reliable operation of SGLC system is important for reactor safety. A control system failure to maintain water level within reasonable bounds typically results in a reactor trip. DFM offers a promising way to model/analyze interactions within a digital control system, and its interaction with process variables. The prime implicants of the analysis can be used to identify, prioritize and eliminate unanticipated system faults, resulting in increased overall availability and reliability of a plant.