Dynamic human reliability analysis ⎼ A stakeholder survey and an empirical study

Dynamic human reliability analysis is an approach to human errors, their identification, and estimation of their probabilities that takes into account the changing situation that affects human errors. This report documents two studies on dynamic HRA.
The first study is a survey, the aim of which was to find out how familiar Nordic HRA professionals are with the dynamic HRA concept; what are their opinions and experiences on it; and what further research on it would be interesting or important. Six Finnish and Swedish human reliability analysis experts from five different organizations replied to the query. In general, the respondents’ view is that the greatest potential benefit of dynamic HRA is increased realism. On the other hand, they emphasized that deployment of dynamic HRA methods should not lead to increased complexity of models and workload in analysis, because resources available for HRA are limited and the models are already complex. Dynamicity is involved in long time windows and annual maintenance break scenarios, among others. The respondents identified also several interesting future research topics.
The second study is an interview of main control-room operators to shed light on dynamic HRA related phenomena qualitatively, in the form of asking operators’ opinions on error possibility in various operational, possibly error-prone situations in the main control room. There was only a small number of interviewees, limiting the conclusions to be made. However, even this small sample provided a lot of information and variation, which can also reflect the true variation, possibly realised also with a larger sample. Whether this is the case, calls for a new study with more interviewees.