Role of organic matter in the Proterozoic Oklo natural fission reactors, Gabon, Africa

Journal Article · Thu Jul 01 04:00:00 EDT 1993 · Geology

DOI:https://doi.org/10.1130/0091-7613(1993)021<0655:ROOMIT>2.3.CO;2· OSTI ID:140074

Nagy, B; Rigali, M J ^[1]; Gauthier-Lafaye, F ^[2]; Holliger, P ^[3]; Mossman, D J ^[4]; Leventhal, J S ^[5]

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1. Univ. of Arizona, Tucson (United States)
2. Centre de Geochemie de la Surface, Strasbourg (France)
3. Centre d`Etudes Nucleaires de Cadarache (France)
4. Mount Allison Univ., Sackville, New Brunswick (Canada)
5. Geological Survey, Denver, CO (United States)

Of the sixteen known Oklo and the Bangombe natural fission reactors (hydrothermally altered elastic 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. Reactors 7 to 9 are the subjects of this study. These organic-rich reactors may serve as time-tested analogues for anthropogenic nuclear-waste containment strategies. Organic matter helped to concentrate quantities of uranium sufficient to initiate the nuclear chain reactions. Liquid bitumen was generated from organic matter by hydrothermal reactions during nuclear criticality. 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. This mechanism prevented major loss of uranium and fission products from the natural nuclear reactors for 1.2 b.y. 24 refs., 4 figs.

• OSTI ID: 140074
• Journal Information: Geology, Journal Name: Geology Journal Issue: 7 Vol. 21; ISSN 0091-7613; ISSN GLGYBA
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
22 GENERAL STUDIES OF NUCLEAR REACTORS
58 GEOSCIENCES
BITUMENS
EXPLORATION
GABON
GRAPHITE
HYDROTHERMAL ALTERATION
NATURAL NUCLEAR REACTORS
OKLO PHENOMENON
ORGANIC MATTER
POLYCYCLIC AROMATIC HYDROCARBONS
URANINITES
Yucca Mountain Project