The interaction between nuclear power plant operators and high-level automatic systems has been addressed by the OECD Halden Reactor Project (HRP) in four simulator studies across the last decade. The general motivation for the studies has been to obtain better insights into how operators work with automatic systems to contribute to safe and efficient nuclear process control. This chapter reviews the four studies to assess the lessons learned about operators’ ability to work with high-level automatic systems. The studies suggest that assessment of operators’ ability to recover unforeseen events should be prioritized when evaluating the adequacy of human-automation interaction. When unforeseen events occur, the mitigation and recovery process cannot be guided by operating procedures alone, and the operators heavily depend on the information provided in the human-system interface. The studies, further, suggest that explicit representation of the automatic system’s activity, including the use of verbal feedback from the automatic system on its activity, facilitate operators’ ability to work efficiently with high-level automatic systems. Finally, the studies suggest that even with the above characteristics, an automatic system cannot replace the need for a co-located human colleague in a recovery situation.