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

In the framework of the “Oklo-Natural Analogue Phase II” Project, uraninite from the Bangombé natural reactor and samples from its host rock were analyzed to determine their uranium isotopic composition by thermal ionisation mass spectrometry, inductively coupled plasma mass spectrometry and alpha spectrometry. There were several objectives for this work: (i) to validate the 235U/238U isotopic ratios obtained by these techniques; (ii) to test the use of the 235U/238U ratio of uraninite as a tracer of migration/retention processes of uranium from the source term to the far field; (iii) to evaluate the most recent migration/retention processes of uranium in the system by U-series disequilibrium.