Deregulation forces Nuclear Power Plants (NPPs) to operate not only safely, but also more economically. Instrumentation and Control (I&C) systems in NPPs play an important role to reduce operational related costs. Therefore, a well-planned test and maintenance (T&M) strategy for I&C systems is more important then ever in this deregulated energy market. This paper presents a general T&M framework for digital I&C systems in NPPs. There are three main parts within this framework: probabilistic safety assessment (PSA), reliability analysis, and costs evaluation. PSA is used to set risk-informed unavailability limits. Reliability analysis is used to derive the relation between the unavailability and the T&M interval. Costs associated with not only T&M, but also reactor mal-shutdowns are evaluated. The Shutdown System Number One (SDSI) in Canadian Deuterium-Uranium (CANDU) based NPPs is used as an example system to illustrate the proposed framework.
Models for the Reliability Analysis of Digital Instrumentation and Control Systems for Nuclear Power Plants