Thursday, November 18, 2010
Explanation: The remnants of nuclear reactors nearly two billion years old were found in the 1970s in Africa. These reactors are thought to have occurred naturally. No natural reactors exist today, as the relative density of fissile uranium has now decayed below that needed for a sustainable reaction. Pictured above is Fossil Reactor 15, located in Oklo, Gabon. Uranium oxide remains are visible as the yellowish rock. Oklo by-products are being used today to probe the stability of the fundamental constants over cosmological time and distance scales and to develop more effective means for disposing of human-manufactured nuclear waste.
-- Source: NASA Astronomy Picture of the Day Archives.
Comparison with modern nuclear reactors PDF.
Scientific American "The Workings of Ancient Nuclear Reactors"
Live Science "Natural Nuclear Reactor Powered Ancient Geyser"
Future Pundit "Earth Core Nuclear Reactor May Run Out of Nuclear Fuel"
CERN Document Server "Natural Nuclear Reactor Oklo and Variation of Fundamental Constants Part 1: Computation of Neutronic of Fresh Core"
Scientific Commons "Natural Nuclear Reactor Oklo and Variation of Fundamental Constants Part 1: Computation of Neutronics of Fresh Core (2005) "