Oklo stable isotopes

It is generally accepted that the fission reactions at Oklo resulted in convective circulation of the water heated up in the reactor zones. These convective currents were likely the main cause for the redistribution of some of the uranium of the reactor zones and most of the migration of the fission products possibly occurred at this stage. In order to derive generic conclusions applicable to the problems of nuclear waste disposal one has to identify the pattern of circulation of the convective currents and relate the observed distribution of elements around the reactor zones to the patterns left behind by the paleohydrogeological regime. The objective of this project is to discern and delineate the pathways of elemental migration by determining the deuterium and oxygen signature in the rocks confining the reactor zones. Furthermore the stable isotope analysis provides insights regarding water-rock interaction. In pursuit of this objective the Toronto team is concentrating on measurements of deuterium while F. Gauthier-Lafaye of Strasbourg is responsible for the analysis of the oxygen isotopes. In the final synthesis of the results beyond the main objective we intend to evaluate the differences in migration between the various members of the decay chains by means of a semi-analytical 3 dimensional model. (author). 8 refs., 1 fig., 1 tab., 2 appendices