Nuclear Gabon

It may seem unlikely that all these conditions could have been met, but at least one deposit of uranium ore has characteristics indicating that, long ago, it operated as a natural nuclear reactor. At Oklo in the Gabon Republic near the western coast of equatorial Africa (see photo), there are uranium deposits of high purity... 

Radioactivity, radioactive elements and nuclear reactors are found in nature. There are at least 14 natural fission reactors in the Oklo-Okelobon-do natural uranium formation in Gabon on the west coast of Africa. These fossil reactors had sufficient amounts of U-235 to allow chain reactions to... 

Gauthier-Lafaye, F., 2002, 2 billion year old natural analogs for nuclear waste disposal the natural nuclear fission reactors in Gabon (Africa). C. R. Physiquee 3 839-849. 

Brookins, D. G. 1990. Radionuclide behavior at the Oklo nuclear reator, Gabon. Waste Management, 10, 285-296. 

Bros, R., Carpena, J., Sere, V. Beltritti, A. 1996. Occurence of Pu and fissiogenic rare earth elements in hydrothermal apatites from the fossil natural nuclear reactor 16 of Oklo (Gabon). Radio-chimica Acta, 74, 277-282. 

Dymkov, Y. M, Holliger, P Pagel, M., Gorshkov, A. Artyukhina, A. 1997. Characterization of a La-Ce-Sr-C aluminous hydroxy phosphate in nuclear zone 13 in the Oklo uranium deposit (Gabon). Mineralium Deposita, 32, 617-620. 

Eberly, P., Janeczek, J. Ewing, R. C. 1995. Precipitation of uraninite in chlorite-bearing veins of the hydrothermal alteration zone (argiles de pile) of the natural nuclear reactor at Bangombe, Republic of Gabon. Proceedings of Material Research Society Symposium, 353, 1195-1202. 

Uraninite a 2 Ga spent nuclear fuel from the natural fission reactor at Bangombe in Gabon, West Aftrica. Proceedings of Materia Research Society Symposium, 465, 1209-1218. 

Jensen, K. A. Ewing, R. C. 2001. The Oklelobondo natural fission reactor, southeast Gabon Geology, mineralogy and retardation of nuclear reaction... 

Salah, S. 2000. Weathering Processes at the Natural Nuclear Reactor of Bangombe Gabon). Identification and Geochemical Modeling of the Retention and Migration Mechanisms of Uranium and Rare Earth Elements. PhD thesis, Universite Louis Pasteur, Strasbourg, France. 

Information on the interaction of radionuclides with ground-water in deeply-buried, high-level, long-term "waste repositories" is available at only a few locations. One is the OKLO natural reactor in Gabon which has for over 1. 7 billion years retained some of the radionuclides also present in nuclear wastes (5). Another is the Nevada test Site, where radionuclides were first deposited underground on September 19, 1967 during the 1.7 kt... 

We should not leave our discussion of nuclear reactors without mentioning the Oklo phenomenon. In 1972, French scientists analyzing uranium ore from the Oklo uranium mine in Gabon found ore that was depleted in 235U. Further investigation showed the presence of high abundances of certain Nd isotopes, which are formed as fission products. The relative isotopic abundances of these isotopes were very different from natural abundance patterns. The conclusion was that a natural uranium chain reaction had occurred 1.8 billion years ago. 

Beyond radioactivity, nuclear energy occurred spontaneously on Earth when sustained fission reactions developed spontaneously in the uranium mine of Oklo in Gabon in Africa, showing the path towards fission reactors about 2 billion years ahead. 

In 1972, evidence of a past "natural nuclear reactor" was found by a French mining geologist while assaying uranium samples in a uranium mine at Oklo, Gabon, West Africa It "went critical" about 1.7 billion years ago, released 15,000 megawatt-years of energy by consuming six tons of uranium, and was critical (at low power) for several hundred thousand years. 

In 1972 it was found that uranium in ore deposits at Oklo, Gabon, contains significantly smaller concentrations of than other deposits of natural uranium (<0.5% compared with 0.72%). At these places, the isotopic composition of other elements is also different from the mean composition in nature. For instance, natural Nd contains 27% " Nd and xl2% " Nd, whereas Nd at Oklo contains <2% Nd and up to 24% Comparison with the yields of nuclear fission leads to... 

Jensen K. and Ewing R. (2001) The Okelobondo natural fission reactor, southeast Gabon geology, mineralogy, and retardation of nuclear-reaction products. Geol. Soc. Am. Bull. 113(1), 32-62. 

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