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 reactor heat removal total heat produced in the nuclear reactor is: formula_5 where formula_6 is the mean neutronic flux and V is the fuel volume (normally measured in formula_7). Recovery of this amount of heat is achieved by using cooling fluids whose temperature at the entrance to the reactor channel formula_8 will increase with the distance traveled in the channel. The thermal balance of the channel is expressed by the relationship: formula_9 where formula_10 is the flow rate of the cooling agent, formula_11 is the specific heat at constant pressure, formula_12 is the increase in the temperature of the fluid after passing a