Oklo

Oklo is a region near the town of

For 40 years, France mined uranium in Gabon. Once extracted, the uranium was used for electricity production in France and much of Europe. Today the uranium deposits are exhausted, and the mine is no longer worked. Currently, mine reclamation work is ongoing in the region affected by the mine operations.

Natural nuclear fission reactor

Some of the mined uranium was found to have a lower concentration of uranium-235 than expected, as if it had already been in a reactor. When geologists investigated they also found products typical of a reactor. They concluded that the deposit had been in a reactor: a natural nuclear fission reactor, around 1.8 to 1.7 billion years BP – in the Paleoproterozoic Era during Precambrian times, during the Statherian period – and continued for a few hundred thousand years, probably averaging less than 100 kW of thermal power during that time. At that time the natural uranium had a concentration of about 3% ²³⁵U, and could have reached criticality with natural water as neutron moderator allowed by the special geometry of the deposit.^{[1][2][3][4][5][6][7]}

See also

• Oklo Mine
• Deep geological repository
• List of uranium mines
• Mounana

References