The Oklo Natural Reactor
In 1972, scientists found uranium from a mine in Gabon that had already been 'used', as if by a nuclear reactor two billion years ago.
What was reported
In 1972, workers at a French processing plant noticed that uranium from the Oklo mine in Gabon contained slightly less of a key type of uranium, uranium-235, than uranium from anywhere else. It looked as if some of it had already been burned in a nuclear reactor.
The finding caused alarm at first, and inspired later claims of an ancient civilisation with nuclear power.
Explanations offered
Scientists found the answer in the rock itself. About two billion years ago, when natural uranium was richer in uranium-235, groundwater seeping into the deposit slowed down neutrons enough for natural nuclear chain reactions to start. They ran on and off for hundreds of thousands of years. Oklo is the only known natural reactor on Earth.
- When
- About 2 billion years ago; found in 1972
- Where
- Oklo, Haut-Ogooué, Gabon
- Witnesses
- French nuclear scientists
- Status
- Confirmed
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