Oklo

This article is about the region in Gabon. For the company, see Oklo Inc.

Region containing uranium ore in Haut-Ogooué, Gabon

The natural nuclear fission reactors of Oklo:

1. Nuclear reactor zones
2. Sandstone
3. Uranium ore layer
4. Granite

Oklo is a region near Franceville in the Haut-Ogooué province of Gabon. Several natural nuclear fission reactors were discovered in the uranium mines in the region in 1972.

## History

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Gabon was a French colony when prospectors from the French Alternative Energies and Atomic Energy Commission (the industrial parts, which later became Orano Cycle) discovered uranium in the remote region in 1956. France immediately opened mines operated by Comuf (Compagnie des Mines d'Uranium de Franceville) near Mounana village to exploit the vast mineral resources, and the state of Gabon was given a minority share in the company.

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 Today the uranium deposits are exhausted, and the mine is no longer active. Currently, mine reclamation work is ongoing in the region affected by the mine operations.

## Natural nuclear fission reactor

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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 nuclear 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

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* List of uranium mines

## References

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1. ^ Kean, Sam (12 July 2010). The Disappearing Spoon: And Other True Tales of Madness, Love, and the History of the World from the Periodic Table of the Elements. Little, Brown. pp. 324–. ISBN 978-0-316-05164-4.
2. ^ Lederman, Leon; Hill, Christopher (2004). Symmetry and the Beautiful Universe. Amherst: Prometheus Books. pp. 40-42. ISBN 9781591022428.
3. ^ Zoellner, Tom (2009). Uranium. Viking Penguin. pp. 291–292. ISBN 9780670020645.
4. ^ Cowan, George (1976). "A Natural Fission Reactor". Scientific American. Vol. 235, no. 1\. pp. 36–47. Bibcode:1976SciAm.235a..36C. doi:10.1038/scientificamerican0776-36. JSTOR 24950391. Archived from the original on 15 August 2023. Retrieved 15 August 2023.
5. ^ Cowan, George (1976). "Oklo – A Natural Fission Reactor" (PDF). Federation of American Scientists. Los Alamos Scientific Laboratory. Archived (PDF) from the original on 29 March 2024. Retrieved 15 August 2023.
6. ^ Gauthier-Lafaye, F.; Holliger, P.; Blanc, P.-L. (December 1996). "Natural fission reactors in the Franceville basin, Gabon: A review of the conditions and results of a 'critical event' in a geologic system". Geochimica et Cosmochimica Acta. 60 (23): 4831–4852. doi:10.1016/s0016-7037(96)00245-1. ISSN 0016-7037.
7. ^ Meshik, Alex P. (2005-11-01). "The Workings of an Ancient Nuclear Reactor". Scientific American. Vol. 293, no. 5\. pp. 82–91. doi:10.1038/scientificamerican1105-82. Archived from the original on 2024-03-25. Retrieved 2024-03-25.

## External links

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* Yucca Mountain Project (YMP) (Nov 2004). "Oklo: Natural Nuclear Reactors". Office of Civilian Radioactive Waste Management (OCRWM). Fact sheets. DOE. YMP-0010. Archived from the original on 2004-02-19.
* Manaugh, Geoff (Dec 8, 2009). "One Million Years of Isolation: An Interview With Abraham Van Lu". World Changing. Archived from the original (pdf) on December 12, 2009. Alt URL

1°23′40″S 13°9′39″E﻿ / ﻿1.39444°S 13.16083°E﻿ / -1.39444; 13.16083