The Canary, the Ostrich, and the Black Swan: A Historical Perspective on our Understanding of BWR Severe Accidents and Their Mitigation

Between 1980 and 1995, Oak Ridge National Laboratory (ORNL) was engaged in an intense effort to understand commercial boiling water reactor severe accident phenomenology, severe accident progression, and the potential role of the reactor operator in severe accident mitigation. This paper presents a summary of the major findings and conclusions from that period. Both detailed accident- and plant-specific results are discussed. The author, who was a member of the ORNL research team that performed the work, offers a historical perspective on lessons learned, lessons ignored, and lessons forgotten from that period. The relevancy of these findings in the post-Fukushima world is addressed. The author discusses the evolution of the current risk-informed regulatory framework, and identifies some key questions to be addressed and critical steps to be taken to inform the development of the new nuclear safety construct required in the wake of the Fukushima Daiichi accident. Finally, the author closes by sharing an ethos of nuclear reactor safety that can guide a new generation of reactor safety professionals in the post-Fukushima era.