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
Office of Nuclear Reactor Regulation crisis zone in person in order to demonstrate that the dangers were not as high as many believed. These events occurred at approximately the same time as the beginning of the J. Samuel Walker term of service as the official historian of the NRC and are documented by him in "". Office of Nuclear Reactor Regulation The Office of Nuclear Reactor Regulation, usually known by the acronym NRR, is a subordinate part of the United States Nuclear Regulatory Commission. The Office should not be confused with the NRC's Nuclear Regulatory Research. The Office's current Director is William Dean. It has