Hostname: page-component-586b7cd67f-rdxmf Total loading time: 0 Render date: 2024-11-29T11:16:47.887Z Has data issue: false hasContentIssue false
  • English
  • Français

Uraninite: a 2 Ga Spent Nuclear Fuel from the Natural Fission Reactor at Bangombé in Gabon, West Africa

Published online by Cambridge University Press:  03 September 2012

K. A. Jensen ,
R. C. Ewing  and
F. Gauthier-Lafaye
K. A. Jensen
Affiliation:
Department of Earth Sciences, Aarhus University, DK-8000 Aarhus C, [email protected]
R. C. Ewing
Affiliation:
Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM 87131
F. Gauthier-Lafaye
Affiliation:
Centre National de la Recherche Scientifique, Centre de Geochemie de la Surface, 67084 Strasbourg Cedex, France
Get access

Abstract

Uraninites from the Bangombé natural fission reactor (RZB) and “normal” uranium-ore occur as fine veins in the sandstone host-rock as well as altered, broken, and slightly displaced grains in an illitic matrix, and in nodules and veins of solid bitumen. Inclusions of galena, (Y,Gd)-rich phosphates, a Pb-oxide and a Ti-oxide? were observed. Uraninites just below RZB were partially altered to a uranyl-sulfate. Three generations of uraninite were identified based on their PbO-contents of 8–11.06 wt%, 6 wt% (the largest population), and a younger generation with 3 wt%. The high Pb-uraninites may be the precursor to the low Pb-uraninites. Diffusional loss of Pb is indicated by the presence of a Pb-oxide at the interface to the uraninites. The behaviour of the metallic fission products, incompatible with the uraninite structure, may mimic the behaviour of Pb in these uraninites. The averaged impurity-content ranges from 4.29 to 6.89 wt%, and consists mainly of SiO2, TiO2, ZrO2, FeO, CaO, Al2O3 and P2O5. The averaged content of Y2O3 and the Ln's is less than 0.78 wt% and there is a scattered positive correlation with P2O5. The content of Y + Ln's is generally highest in the uraninites from RZB. Uraninite hydration and the formation of “uranopelite/zippeite” have caused complete loss of Y and the Ln's. These elements seems also to be partially lost by weak phosphatian coffinitization. The analytical results indicate that Y and the Ln's, which are high yield fission products, may be released from uraninite during alteration in the presence of P.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 465: Symposium II – Scienfific Basis for Nuclear Waste Management XX , 1996 , 1209
Copyright
Copyright © Materials Research Society 1997

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

[1] Gauthier-Lafaye, F. and Weber, F., Econ. Geol., 84, 2267–2285 (1989)Google Scholar
[2] Gauthier-Lafaye, F., Weber, F., and Ohmoto, H., Econ. Geol., 84, 2286–2295 (1989)Google Scholar
[3] Gauthier-Lafaye, F., Rapport final; Volume 2: Les Reacteurs de Fission et les Systèmes Geochemiques; 2éme partie: Geologie des réacteurs, études des épontes et transferts anciens, Commissariata l'Energie Atomique. Institution de Protection et de Sûreté Nucléaire, 105–118 (1995).Google Scholar
[4] Blanc, P.-L., Final report: Volume 1: Acquierements of the natural analogy programme. Commissariat á l'Energie Atomique, Institut de Protection et de Sûreté Nucléaire, 135 pp. (1995)Google Scholar
[5] Janeczek, J. and Ewing, R.C., Geochim. Cosmochim. Acta, 59, 1917–1931 (1995)Google Scholar
[6] Bros, R., Gauthier-Lafaye, F., Larque, P., and Stille, P., Mineralogy and isotope geochemistry of Bangombé reaction zone - Migrations of U, Th and fission products. Internal report for SKB-CNRS “Oklo - Analogues Naturels”, Centre National e la Recherche Scientifique, Centre de Geochemie de la Surface, 1, rue Blessig, 67084 Strasborg Cedex, France, 14 p. (1993)Google Scholar
[7] Janeczek, J. and Ewing, R.C., Am. Min., 81, 1263–1269 (1996)Google Scholar
[8] Toulhaut, P., Gallien, J.P., Louvat, D., Moulin, V., I'Henoret, P., Guerin, R., Ledoux, E., Gurban, I., Smellie, J.A.T., and Winberg, A., Fourth International Conference on the Chemistry and Migration Behaviour of Actinides and Fission Products in the Geosphere. Charleston, SC USA, December 12–17, 1993), 383–390.Google Scholar
[9] Eberly, P.O., Ewing, R.C., Janeczek, J., and Furiano, A.. Radiochim. Acta, 74, 271–275 (1996).Google Scholar
[10] Holliger, Ph., Terme Source: Caracterisation Isotopique Paramètres Nucléaires et Modélisation. Commissariat a l'Energie Atomique, Institut de Protection et de Sûreté Nucléaire, p. 40 (1994)Google Scholar
[11] Bonhomme, M.G., Gauthier-Lafaye, F., and Weber, F., Precambrian Research, 18, 87–102 (1982)Google Scholar
[12] Gauthier-Lafaye, F., Holliger, P., and Blanc, P.-L., Geochim. Cosmochim. Acta, in press (1996)Google Scholar
[13] Eberly, P.O., Janeczek, J., and Ewing, R.C., Radiochim. Acta, 66/67, 455–461 (1994)Google Scholar
[14] Nagy, B., Gauthier-Lafaye, F., Holliger, Ph., Davis, D.W., Mossman, D.J., Leventhal, J.S., Rigali, M.J., and Parnell, J., Nature, 354, 472–475 (1991)Google Scholar
[15] Gancarz, A.J., Natural Fission Reactors, (Proc. Tech. Comm. Meet., Paris, December 1977, International Atomic Energy Agency: Vienna), 513–520 (1978)Google Scholar
[16] Janeczek, J., and Ewing, R.C., In Nuclear Science and Technology - Report EUR 16098 edited by H. von Marevic (Oklo Working Group - Proceedings of the third joint EC-CEA progress meeting held in Brussels on 11 and 12 October 1993, 181–211 (1995)Google Scholar
[17] Nagy, B., In Nuclear Science and Technology - Report EUR 16098 edited by H. von Marevic (Oklo Working Group - Proceedings of the third joint EC-CEA progress meeting held in Brussels on 11 and 12 October 1993, 169–179 (1995).Google Scholar
[18] Kleykamp, H., J. of Nucl. Mat., 206, 82–86 (1993)Google Scholar
[19] Hidaka, H., Takahashi, K., and Holliger, Ph., Radiochim. Acta, 66/67, 463–468 (1994).Google Scholar
[20] Janeczek, J., and Ewing, R.C., J. Nucl. Mat, 190, p. 157 (1992).Google Scholar
[21] Ewing, R.C. and Janeczek, J., In Nuclear Science and Technology - Report EUR 14877 EN edited by von Marevic, H. (Oklo Working Group - Proceedings of the second joint CEC-CEA progress meeting held in Brussels on 6 and 7 April 1992, 177–188 (1993).Google Scholar