Cost evaluation of I&C upgrade approach in nuclear power plants

•Cost evaluation process for I&C system upgrade is built.•4 cost factors affecting I&C system upgrade are described.•Additional cost incurred by a phased upgrade is calculated.•Cost for system upgrade between upgrade implementations is compared. Utilities have recently been debating the respective pros and cons of implementation of a multi-phase upgrade during several normal outages versus a single major upgrade implementation during a prolonged outage. We have studied these approaches and have been developing the basic design of nuclear power plants (NPPs) instrumentation and control (I&C) upgrade since early 2008. As part of this study, analyses of the NPPs I&C systems were conducted and the need for upgrading the systems was raised. One of the primary concerns regarding the system upgrade is a cost-benefit implementation, which will influence the upgrade approach. From this viewpoint, the I&C upgrade must consider economic factors such as I&C vendor cost, architecture engineering cost, installation cost, utility cost, and other transition costs such as training and procedure development. This paper presents a comparison study of economical aspects including cost evaluation between the aforementioned upgrade implementations and suggests a solution for I&C upgrade approach.