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 safety system heat removal system (RHR or RHS). LPCI is generally not a stand-alone system. This system uses spargers (pipes fitted with an array of many small spray nozzles) within the reactor pressure vessel to spray water directly onto the fuel rods, suppressing the generation of steam. Reactor designs can include core spray in high-pressure and low-pressure modes. This system consists of a series of pumps and spargers that spray coolant into the upper portion of the primary containment structure. It is designed to condense the steam into liquid within the primary containment structure in order to prevent overpressure and overtemperature, which