LAUSR

Abstract Automatic Control System (ACS) has been more widely applied in nuclear power plants (NPP) in order to achieve better performance, convenience and economics. Some new challenges are also emerging in reliability analysis of ACS because of its complexity and strict regulatory requirements of NPP. The dynamic behavior of ACS is difficult to be expressed by traditional system reliability analysis techniques such as fault tree analysis and/or event tree which are widely applied for probabilistic safety assessment in NPPs. This paper presents an extended GO-FLOW methodology by introducing several supplementary operators for modelling control logic generally used in NPP systems. A Chemical and Volume Control System (CVCS) in Pressurized Water Reactor (PWR) NPP is taken as an example to demonstrate the usage of improved GO-FLOW methodology in modeling and reliability estimation of a process system coupled with automatic control functions.