![]() The Journal of Chemical Physics, 25, 781–782. On the nuclear physical stability of the uranium minerals. ![]() Geochimica et Cosmochimica Acta, 59, 1917–1931. Mechanisms of lead release in the natural fission reactors in Gabon. Earth and Planetary Science Letters, 52, 76–84. Contribution a l’etude de la temperature dans Jes reacteurs fossiles d’Oklo par la mesure du rapport isotopique du lutetium. Proceedings of the Joint Commission European Communities-Commissariat a l'Energie Atomique, 2nd Meeting, Brussels, EUR, pp. Geochemical and isotopic characterization of the reaction zones (uranium, transuranium, lead and fission products). Earth and Planetary Science Letters, 122, 173–182. Isotopic evidence for the retention of 90Sr from excess Zr in the Oklo natural fission reactors: implication for geochemical behavior of fissiogenic Rb, Sr, Cs and Ba. Hidaka, H., Sugiyama, T., Ebihara, M., and Holliger, P., 1994. Geochimica et Cosmochimica Acta, 72, 4123–4135. Ba isotopic signature for early differentiation between Cs and Ba in natural fission reactors. Hidaka, H., and Gauthier-Lafaye, F., 2008. Gauthier-Lafaye, F., Weber, F., and Ohmoto, H., 1989. The Francevillian (Lower Proterozoic) uranium ore deposits of Gabon. Gauthier-Lafaye, F., and Weber, F., 1989. 2 billion year old natural analogs for nuclear waste disposal: the natural nuclear fission reactors in Gabon (Africa). Fission product retention in the Oklo natural fission reactors. Scientific American, 235, 36–47.Ĭurtis, D., Benjamin, T., Gancarz, A., Loss, R., Rosman, K., and DeLaeter, J., 1989. Occurrence of Pu and fissiogenic REE in hydrothermal apatites from the fossil nuclear reactor 16 at Oklo. Geochimica et Cosmochimica Acta, 57, 1351–1358.īros, R., Carpena, J., Sere, V., and Beltritti, A., 1996. Occurrence of naturally enriched 235 uranium: the implications for Pu behavior in a natural environment. IEEE Transactions on Nuclear Science, 60, 278–283.īros, R., Turpin, L., Gauthier-Lafaye, F., Holliger, P., and Stille, P., 1993. ![]() Criticality of Oklo natural reactors: realistic model of reactor zone 9. This process is experimental and the keywords may be updated as the learning algorithm improves.īentridi, S.-E., Gall, B., Gauthier-Lafaye, F., Seghour, A., Pape, A., and Medjadi, D.-E., 2013. These keywords were added by machine and not by the authors. Today, these natural nuclear reactors serve as useful analogs for on-going research in the development of nuclear waste containment strategies. ![]() The reactors were discovered in 1972 when it was realized that 235U was consumed and fission products were produced within seventeen high-grade uranium ore bodies, the Oklo and the associated Okelobondo and Bangombe uranium ore deposits. The primary fuel for the natural reactors was a fissionable isotope of uranium, 235U. They operated for as long as 140,000 years. The natural reactors reached criticality and began fission reactions 1.95 billion years ago. The reactors occur as small lenticular bodies of high-grade uranium ore (20–60% by weight) in the uranium ore deposits. This mechanism prevented major loss of uranium and fission products from the natural nuclear reactors for 1.2 b.y.Natural nuclear reactors have been discovered in the Oklo and the associated Okelobondo and Bangombe uranium ore deposits in the Republic of Gabon on the coast of Equatorial West Africa. The bitumen soon became a solid, consisting of polycyclic aromatic hydrocarbons and an intimate mixture of cryptocrystalline graphite, which enclosed and immobilized uraninite and the fission-generated isotopes entrapped in uraninite. Liquid bitumen was generated from organic matter by hydrothermal reactions during nuclear criticality. Organic matter helped to concentrate quantities of uranium sufficient to initiate the nuclear chain reactions. ![]() These organic-rich reactors may serve as time- tested analogues for anthropogenic nuclear-waste containment strategies. Reactors 7 to 9 are the subjects of this study. Of the sixteen known Oklo and the Bangombé natural fission reactors (hydro-thermally altered clastic sedimentary rocks that contain abundant uraninite and authigenic clay minerals), reactors 1 to 6 at Oklo contain only traces of organic matter, but the others are rich in organic substances. ![]()
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