Oklo, natural reactor

Toulhoat, P., Gallien, J. P. et al. 1996. Preliminary studies of groundwater flow and migration of uranium isotopes around the Oklo Natural Reactors (Gabon). Journal of Contaminant Hydrology, 21, 3-17. 

The Oklo natural reactors in Gabon are the best natural analogues for assessing the geological behaviour of fission products and actinides (see also Gauthier-Lafaye et al. 2004). Elements that were compatible with the U ore structure were retained, whereas elements that... 

Indications from both microscopic analyses of metallic particles from corrosion tests and evidence from the Oklo natural reactors indicate that performance assessment calculations should not assume 99Tc is easily mobilized. It is entirely inappropriate to use "Tc release as a marker for fuel corrosion because Tc is not located in the fuel matrix. The TEM examinations of corroded e-particles have shown that Mo is preferentially leached from these phases, a behaviour that is similar to the one observed at Oklo. It is interesting to note that laboratory dissolution of billion-year old 4d-metallic particles for a chemical analysis required a corrosive mix of peroxide and acid (Hidaka Holliger 1998) similar to the experience at SNF reprocessing plants. It is doubtful that the oxidation potential at the surface of an aged fuel will be sufficient to move Tc(0) from the e-metal particles. 

Pourcelot, L. Gauthier-Lafaye, F. 1999. Hydrothermal and supergen clays of the Oklo natural reactors conditions of radionuclide release, migration and retention. Chemical Geology, 157, 155-174. 

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... 

Cuney M. and Mathieu R. (2000) Extreme fight rare earth element mobilization by diagenetic fluids in the geological environment of the Oklo natural reactor zones, EranceviUe Basin, Gabon. Geology 28, 743—746. 

The following section provides detailed information concerning the transport of radionuclides associated with two very different field analogues the Chernobyl reactor accident and the Oklo Natural Reactor. These examples span wide temporal and spatial scales and include the rapid geochemical and physical processes important to nuclear reactor accidents or industrial discharges as well as the slower processes important to the geologic disposal of nuclear waste. 

Long-term Behavior of Radionuclides in the Environment—The Oklo Natural Reactor... 

Hidaka H., Konishi T., and Masuda A. (1992) Reconstruction of cumulative fission yield curve and geochemical behaviors of fissiogenic nuclides in the Oklo natural reactors. Geochem. J. 26, 227-239. 

The Oklo natural reactor in Gabon, Africa, is a high-grade sandstone-hosted U deposit. It was formed about... 

The measurements at the Oklo natural reactor provide the best bound on the variation of Xs = ms/AgcD, where ms is the strange quark mass [8-10],... 

Plutonium does not exist as a naturally occurring element with the exception that small amount of Pu generated in the natural reactors (the Oklo natural reactor in Gabon). The primary input of Pu to environment is fallout from nuclear weapon tests and accident release (e.g., the Windscale accident in 1957 and the Chernobyl accident in 1986). Three of the most common of the 15 known Pu isotopes are Pu (94%), °Pu (6%), and Pu (0.4%). Pu has a half-life of 24,000 yr. Its (X-dccay results in production of (Tj/2 = 700 million yr). Pu has a half-life of 6560 yr, emits a particles and decays to U (T1/2 = 20 million yr). Due to (he long half... 

Bangombe, Oklo natural reactors, Gabon Natural Analogue 0.25 — 25-500 Presence of a weathered zone. Groundwater chemistry controlled by the Fe " /Fe(OH)3 equilibria. Fluids are not enriched in CO2. 

Curtis, D. B. Gancarz, A. J. 1983. Radiolysis in nature evidence from the Oklo natural reactors. Swedish Nuclear Fuel and Waste Management Co. (SKB) Technical Report Series, TR 83-10, Stockholm, Sweden. 

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