Findings From an Operator-In-The-Loop Study on System Overview Displays in a Modernized Nuclear Power Plant

The second Operator Study of System Overviews (OSSO-2) was conducted with a three-person reactor operator crew in the Human Systems Simulation Laboratory (HSSL) at Idaho National Laboratory (INL) in August, 2017. The study supported control room modernization at a nuclear power plant and featured a benchmark comparison of three variants of a turbine control system (TCS): the existing analog TCS, a proposed standalone digital TCS with two displays, and the digital TCS with the addition of a third display depicting a system overview screen. TCS prototypes were developed at INL to allow evaluation of operator performance and preferences during realistic turbine scenarios in the full-scope simulator. The study revealed that completion of turbine startup was several minutes faster with the digital TCS variants than with the conventional analog TCS. Eye tracking revealed visual fixations were more widely distributed in the overview vs. standalone TCS condition, suggesting the overview screen may have cued reactor operators to verify values across the boards. Reviewing key plant parameters showed smoother transitions during load following for the digital vs. analog TCS. The study provides evidence that the new digital TCS could be used successfully by operators without extensive training or rewriting of the operating procedures, suggesting high usability for the digital TCS design. Further advantages were realized through the addition of the system overview screen to provide crews with at-a-glance indicators of key turbine parameters.