An anonymous reader writes from a report via MIT Technology Review: Spencer Wheatley and Didier Sornette at ETH Zurich in Switzerland and Benjamin Sovacool at Aarhus University in Denmark have compiled the most comprehensive list of nuclear accidents ever created and used it to calculate the chances of future accidents. They say there is a 50:50 chance that a major nuclear disaster will occur somewhere in the world before 2050. "There is a 50 percent chance that a Chernobyl event (or larger) occurs in the next 27 years," they conclude. Since the International Atomic Energy Agency doesn't publish a historical database of the nuclear accidents it rates using the International Nuclear Event Scale, others, like Wheatley and co, have to compile their own list of accidents. They define an accident as "an unintentional incident or event at a nuclear energy facility that led to either one death (or more) or at least $50,000 in property damage." Each accident must have occurred during the generation, transmission, or distribution of nuclear energy, which includes accidents at mines, during transportation, or at enrichment facility, and so on. Fukushima was by far the most expensive accident in history at a cost of $166 billion, which is 60 percent of the total cost of all other nuclear accidents added together. Wheatley and co say their data suggests that the nuclear industry remains vulnerable to dragon king events, which are large unexpected events that are difficult to analyze because they follow a different statistical distribution, have unforeseen causes, and are few in number. "There is a 50% chance that a Fukushima event (or larger) occurs in the next 50 years," they say.