Nuclear and radiation accidents and incidents involving HEU or plutonium trafficking: A nuclear meltdown is a severe nuclear reactor accident that results in reactor core damage from overheating. It has been defined as the accidental melting of the core of a nuclear reactor, and refers to the core's either complete or partial collapse. A core melt accident occurs when the heat generated by a nuclear reactor exceeds the heat removed by the cooling systems to the point where at least one nuclear fuel element exceeds its melting point. This differs from a fuel element failure, which is not caused by high temperatures. A meltdown may be
Nuclear power in the United States in 2005, which was still a factor of 14.6 less than the 3.5 number for all manufacturing industries. However, more than a quarter of U.S. nuclear plant operators "have failed to properly tell regulators about equipment defects that could imperil reactor safety", according to a Nuclear Regulatory Commission report. As of February 2009, the NRC requires that the design of new power plants ensures that the reactor containment would remain intact, cooling systems would continue to operate, and spent fuel pools would be protected, in the event of an aircraft crash. This is an issue that has gained attention since