"the number of years that all civilian nuclear reactors on the grid, divided by the number of existing core melt accidents in which large amounts of radioactivity were released. Of these so-called super-Gaussian, there were four: one in Chernobyl, and three in Fukushima. That's a disaster per 3625 years of operation, which round off the researcher on one to 5000. You look at it, the three events in Fukushima as independent because the reactors would each own separate security systems due to the common cause of accidents should be done.
If one of these record high in the future, could the 440 reactors that have 20 to 25 years remain on the network, producing in this period, two meltdowns. Previous safety analyzes from the 1990s, however, said there could be a probability of one percent of such an event. "We are therefore a factor of 200 about it," says Lelieveld."