An investigation on unintended reactor trip events in terms of human error hazards of Korean nuclear power plants

• A methodology to identify human error hazards has been established.
• The proposed methodology is a preventive approach to identify not only human error causes but also its hazards.
• Using the HFACS framework we tried to find out not causations but all of the hazards and relationships among them.
• We determined countermeasures against human errors through dealing with latent factors such as organizational influences.

A new approach for finding the hazards of human errors, and not just their causes, in the nuclear industry is currently required. This is because finding causes of human errors is really impossible owing to the multiplicity of causes in each case. Thus, this study aims at identifying the relationships among human error hazards and determining the strategies for preventing human error events by means of a reanalysis of the reactor trip events in Korea NPPs. We investigated human errors to find latent factors such as decisions and conditions in all of the unintended reactor trip events during the last dozen years. In this study, we applied the HFACS (Human Factors Analysis and Classification System), which is a commonly utilized tool for investigating human contributions to aviation accidents under a widespread evaluation scheme. Using the HFACS framework, we tried to find out not the causations but all of the hazards and their relationships in terms of organizational factors. Through the trial, we proposed not only meaningful frequencies of each hazards also correlations of them. Also, considering the correlations of each hazards, we suggested useful strategies to prevent human error event. A method to investigate unintended nuclear reactor trips by human errors and the results will be discussed in more detail.