Uranium isotopic data in uraninite spent fuel from the Bangombe natural nuclear reactor (Gabon) and its surroundings

In the framework of the "Oklo-Natural Analogue Phase II" Project, uraninite from the Bangombe natural reactor and samples from its host rock were anal yzed to determine their uranium isotopic composition by thermal ionisation mass spectrometry, inductively coupled plasma mass spectrometry and alpha s pectrometry. There were several objectives for this work: (i) to validate t he U-235/U-238 isotopic ratios obtained by these techniques; (ii) to test t he use of the U-235/U-238 ratio of uraninite as a tracer of migration/reten tion processes of uranium from the source term to the far field; (iii) to e valuate the most recent migration/retention processes of uranium in the sys tem by U-series disequilibrium. (C) 2000 Elsevier Science Ltd. All rights r eserved.