A Soft Control Model for Human Reliability Analysis in APR-1400 Advanced Control Rooms (ACRs)

Abstract

Human reliability analyses play very important roles in safety analyses for NPP operations. However, scarcity of the basic human error probability data of soft control human actions has been considered as a main bottleneck for HRAs of the soft control tasks in NPPs. In this study, the soft control tasks are analyzed and modelled to be used for development of the basic human reliability data and quantification of human error probability. Sub-tasks comprising a soft control are modelled to be observable and distinguishable as unit tasks so that the basic human error probabilities for the sub-tasks could be observed and calculated in simulator-based experimental or real field operational studies. Safety-grade and non-safety grade soft controls are modelled for controls of safety and non-safety components, respectively. Possible error modes and propagation to another unintended control action, impact on soft control operation, and final error type are analyzed to provide helpful information for applications to the final human error quantification and reduction. Considerations are provided for the soft control models developed to be used in HRAs. The results of this study would be used for development of a human reliability model and basic human reliability data and quantification and reduction of human error probability during the soft control in various large-scale process control systems such as nuclear power plant (NPPs), chemical processing plants, oil processing plant, and large military systems.