Black Swan Events: Black Swan events are highly unlikely occurrences that have big repercussions. Despite planning, nuclear power will always be vulnerable to black swan events: A rare event - especially one that has never occurred - is difficult to foresee, expensive to plan for and easy to discount with statistics. Just because something is only supposed to happen every 10,000 years does not mean that it will not happen tomorrow. Over the typical 40-year life of a plant, assumptions can also change, as they did on September 11, 2001, in August 2005 when Hurricane Katrina struck, and in March, 2011, after Fukushima. The list of potential black swan events is "damningly diverse": Nuclear reactors and their spent-fuel pools could be targets for terrorists piloting hijacked planes. Reactors may be situated downstream from dams that, should they ever burst, could unleash massive floods. Some reactors are located close to earthquake faults or shorelines, a dangerous scenario like that which emerged at Three Mile Island and Fukushima - a catastrophic coolant failure, the overheating and melting of the radioactive fuel rods, and a release of radioactive material