• Fukushima;
  • Nuclear risk thresholds;
  • Comparative risk assessment;
  • Systemic reasoning;
  • Risk aggregation;
  • Resilience in engineered systems


In the wake of the compound March 2011 nuclear disaster at the Fukushima I nuclear power plant in Japan, international public dialogue has repeatedly turned to questions of the accuracy of current risk assessment processes to assess nuclear risks and the adequacy of existing regulatory risk thresholds to protect us from nuclear harm. We confront these issues with an emphasis on learning from the incident in Japan for future US policy discussions. Without delving into a broader philosophical discussion of the general social acceptance of the risk, the relative adequacy of existing US Nuclear Regulatory Commission (NRC) risk thresholds is assessed in comparison with the risk thresholds of federal agencies not currently under heightened public scrutiny. Existing NRC thresholds are found to be among the most conservative in the comparison, suggesting that the agency's current regulatory framework is consistent with larger societal ideals. In turning to risk assessment methodologies, the disaster in Japan does indicate room for growth. Emerging lessons seem to indicate an opportunity to enhance resilience through systemic levels of risk aggregation. Specifically, we believe bringing systemic reasoning to the risk management process requires a framework that (i) is able to represent risk-based knowledge and information about a panoply of threats; (ii) provides a systemic understanding (and representation) of the natural and built environments of interest and their dependencies; and (iii) allows for the rational and coherent valuation of a range of outcome variables of interest, both tangible and intangible. Rather than revisiting the thresholds themselves, we see the goal of future nuclear risk management in adopting and implementing risk assessment techniques that systemically evaluate large-scale socio-technical systems with a view toward enhancing resilience and minimizing the potential for surprise. Integr Environ Assess Manag 2011;7:400–403. © 2011 SETAC