Nuclear safety in the unexpected second nuclear era

Significance Despite great efforts to pursue a safe nuclear energy system during the first nuclear era, which was dominated by developed countries, severe nuclear accidents still occurred. Today, nuclear energy development has entered an unexpected second nuclear era, which is driven by developing countries. This may give rise to a great risk. Nuclear power plants are complex sociotechnical systems, and their safety has never been fully defined. We argue that social aspects, rather than just technical measures, must be involved to ensure nuclear safety. In this paper, the nature of nuclear safety is elucidated with identification of new challenges, and corresponding suggestions are proposed to improve nuclear safety in the unexpected second nuclear era.