Levels of Automation and User Control - Evaluation of a Turbine Automation Interface

Report, 2008

The study was performed during the annual operator training at the Studsvik nuclear power plant simulator facility in Nyköping, Sweden. The participating operators came from the Oskarshamn 3 nuclear power plant. In the study, seven nuclear power plant turbine operators were interviewed concerning their use of the automatic turbine system. A field study approach together with a heuristic usability evaluation was made to assess how the operators’ are affected by use of automation in the control room setting. The purpose of the study was to examine how operator performance is affected by varying levels of automation in nuclear power plant turbine operation. The Automatic Turbine System (ATS) was evaluated to clarify how the ATS interface design supports the operators’ work. The results show that during manual control the operators experience loss of speed and accuracy in performing actions together with difficulty of dividing attention between performing a task and overall monitoring, as the major problems. The positive aspects of manual operations lie in increased feeling of being in control when performing actions by hand. With higher levels of automation the problems shift to issues concerning difficulty of following the automatic sequences and loosing track in procedures. As the level of automation gets higher, the need of feedback increases which means that information presentation also becomes more important. The use of the semiautomatic, step-mode is often preferred by the operators since it combines the speed and accuracy of the automation with the ability of maintaining the feeling of being in control. Further, a number of usability related concerns was found in the ATS interface. The operators especially experience the presentation of the conditions that manage the automatic sequences as difficult to perceive.