A Study on How Time Pressure and Information Load Affects Operators Performance in Accident Scenarios (PSAM-0344)


The purpose of this study was to explore how additional tasks, that intended to cause high time pressure, high information load and high masking, added to a base case scenario affected the operators' performance of a main task. The experiment was run in the Halden Man-Machine Laboratories' (HAMMLAB), Boiling Water Reactor simulator. Seven crews participated each for one week. There were three operators in each crew; one shift supervisor, one reactor operator and one turbine operator. Five main scenarios and 20 scenario variants were run. The data from the experiment was analyzed with completion time for important actions and by in-depth qualitative analysis of the crews' communication. In this paper the main results from the manipulation of time pressure and information load are presented. It was concluded that the manipulated time pressure had different effects in the different scenario types and for the different actions. Time pressure decreased performance of some of the actions for some of the crews. The results showed that if a crew had a problem in solving one failure in the scenario they got more time pressure to solve other tasks, and then performance on the following tasks also decreased. The results also showed that the combinations of high time pressure and “inadequate team work” had relatively large effects on performance, compared to crews with better teamwork. It was observed that in the scenario with time pressure it was important that the crews communicated well and allocated the tasks in the scenarios between the operators in a good way. High information load did not affect the operators' performance much and in general the crews were very good at selecting the most important information first. In this paper it is discussed that there exist no method to identify the presence of a performance shaping factor (PSF) and the level of the PSF. Most of the HRA methods describe absolute time as a way to identify time pressure. However, the effect of time pressure on performance is very dependent of the nature of the tasks, the operators' strategies, and on other PSF that are present at the same time. This identification analysis is left to each HRA analyst's knowledge and experience and is not formalized in any method. It was suggested that data, as those presented here, could be used in such a formalization of a method to analyze the presence of a PSF(s) and its effect on performance. Also, in order to develop such a method further research on the effects of PSFs in realistic settings are needed.

  • Summary/Abstract
  • Introduction
  • Method
  • Result and Discussion
  • Conclusion
  • References

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