Nuclear safety and security called a nuclear meltdown. After shutting down, for some time the reactor still needs external energy to power its cooling systems. Normally this energy is provided by the power grid to which that plant is connected, or by emergency diesel generators. Failure to provide power for the cooling systems, as happened in Fukushima I, can cause serious accidents. Nuclear safety rules in the United States "do not adequately weigh the risk of a single event that would knock out electricity from the grid and from emergency generators, as a quake and tsunami recently did in Japan", Nuclear Regulatory Commission officials
Chain of events (accident analysis) Chain of events (accident analysis) In accident analysis, a chain of events (or error chain) consists of the contributing factors leading to an undesired outcome. In aviation accidents and incidents, these contributing actions typically stem from human factor-related mistakes and pilot error, rather than mechanical failure. A study conducted by Boeing found that 55% of airline accidents between 1959 and 2005 were caused by such human related factors, while only 17% of accidents were caused by mechanical issues with the aircraft. The Tenerife airport disaster, the worst accident in aviation history, is a prime example of an accident in which