Oklo - A Nuclear Reactor 1800 Million Years Ago
A scientific conference about the so-called OKLO- phenomenon will take place in Gabon in West Africa from 23—27 June this year. The conference is arranged jointly by the International Atomic Energy Agency, the Gabonese authorities and the French Atomic Energy Commission (CEA). As the OKLO phenomenon, named after a uranium mine in Gabon, does not seem to be known outside specialist circles, it may be of interest to report on a few details about this discovery and the interesting conclusions that have been drawn about what happened during a short period of 100—500 000 years, in the earth's development 1 800 million years ago.
Natural uranium contains 0.7202% of uranium-235, the fissionable isotope contained in nuclear fuel. Until June 1972 this concentration had been found to be the same for all uranium that had been discovered until that time, regardless of the place of discovery, and the same concentration was encountered in the uranium of which traces have been found on the moon. In the French gaseous diffusion plant for enrichment of the isotope-235 at Pierrelatte, regular measurements are carried out on the concentration of uranium-235 in the uranium with which the plant is supplied. This is done primarily to ensure that the contained uranium really is of natural origin and does not come from a plant where some fraction of the uranium-235 has already been used. In the course of one such isotopic analysis it was found that the uranium-235 concentration was slightly less than what one would expect from natural uranium, namely 0.7171% instead of the value just mentioned.
Oklo- Anuclear reactor.pdf
