Nuclear meltdown derived from a 1967 report by a group of nuclear physicists, headed by W. K. Ergen. In the event, Lapp’s hypothetical nuclear accident was cinematically adapted as "The China Syndrome" (1979). Nuclear meltdown A nuclear meltdown (core melt accident or partial core melt) is a severe nuclear reactor accident that results in core damage from overheating. The term "nuclear meltdown" is not officially defined by the International Atomic Energy Agency or by the Nuclear Regulatory Commission. However, it has been defined to mean the accidental melting of the core of a nuclear reactor, and is in common usage a reference
Natural nuclear fission reactor had operated as a natural fission reactor. Other observations led to the same conclusion, and on September 25, 1972, the CEA announced their finding that self-sustaining nuclear chain reactions had occurred on Earth about 2 billion years ago. Later, other natural nuclear fission reactors were discovered in the region. Neodymium and other elements were found with isotopic compositions different from what is usually found on Earth. For example, Oklo contained less than 6% of the isotope while natural neodymium contains 27%; however Oklo contained more of the isotope. Subtracting the natural isotopic Nd abundance from the Oklo-Nd, the isotopic composition