ABSTRACT
In order to identify error types observed in the dynamic operational environment, the following material was analysed: (i) 13 human factors analyses of US nuclear power events, and (ii) 40 cases of errors made in the simplified plant simulator. In the resulting analysis, the most frequently identified cognitive process associated with error production was situation assessment, and following varieties were knowledge based (KB) processes and response planning. This suggested that the more significant human errors originated in the conscious thought processes. The error mechanisms were judged to fall into three categories: psychological bias, arousal and KB problems. In conclusion, several of the most frequent error patterns identified in each cognitive process were modelled with regard to their relationship between performance shaping factors, biases and error types.
