Oklo Uranium deposit located in southeastern Gabon in equatorial Africa.

Oklo natural fossil reactors were first discovered on June 2nd 1972 by French nuclear analysts while working at Pierrelatte nuclear fuel processing plant during a routine job.

Oklo nuclear fission reaction took place 2 billion years ago, where as man made nuclear reaction took place on December 2nd, 1942, known as Manhattan project.

Oklo and Manhattan project used Uranium as nuclear fuel. Oklo used a water moderator while Chicago reactor used graphite. Manhattan project used Cadmium rods to control the reaction while Oklo did not use conventional means to control the reaction, rather, it lost the moderator through overheating.

In 1956, Dr. Paul Kuroda, a Japanese physicist described conditions needed for natural nuclear reactions to arise, when Oklo reactors were discovered in 1972, the conditions in Oklo were similar to Dr. Kuroda’s predictions.


Cowan, G. A. 1976. "A Natural Fission Reactor," Scientific American, 235:36.