Fukushima Case Studies on Risk-Taking Behavior in Accident Management

Risk-taking behavior (RTB) in accident management (AM) is exploratively addressed here by case studies addressing the 2011 Fukushima Daiichi accident. 17 RTB cases are identified in the time window after the staff’s diagnosis of failure of core cooling; three of them are analyzed in detail. In one case, the prioritization of a goal (core cooling) typical for core damage (CD) prevention in a situation with little or no margin to CD had a negative impact on CD consequence mitigation. Two cases have in common that the prioritization of a goal (containment venting or containment isolation, respectively) typical for CD consequence mitigation in a situation with a notable margin to CD had a negative impact on CD prevention. A scenario at the cliff edge to a severe accident deserves therefore particular attention in HRA (human reliability analysis). The results of innovative HRAs of the decision-making constraints in the three RTB cases show that the preferences observed in the accident are, by and large, in compliance with the data underlying the consolidated prospect theory. Analyses of additional cases in the same manner would be therefore promising for achieving progress in the difficult area of HRA of decision-making in the context of system safety.