Mental causal models of incidents communicated in licensee event reports in a process industry

Abstract

The present investigation describes some mental causal models used in incident reports. Some of the models (e.g., single-cause models) are simpler than others (e.g., causal-tree models). The models are also associated with different ways of explaining an incident or accident and with different recommendations for increasing the safety of a system. In study 1, incident reports from Swedish nuclear power plants known to use human or organisational factors were analysed. The analysis showed that the most frequent model was a simple single-cause model. Two-step models and more complex models were less frequent. Study 2 analysed all licensee event reports (including those reports not related to human organisational factors) from four reactors assessed by regulators during the year. The results showed that single-cause and two-step accident models were more frequent than more complex models. The analyses also revealed that different detection modes were related to different models.

Appendix

Codings of mental causal models from study 2 distributed over categories and reactors are shown in Table 5. The data represent joint codings of two judges. Investigation means that the LER should be followed up by a more complete incident analysis.

Table 5. Codings of mental causal models from study 2 distributed over categories and reactors. The data represent joint codings of two judges. Investigation means that the LER should be followed up by a more complete incident analysis