Abstract
There is apparently virtually universal agreement that certain deposits found at the Oklo uranium mine in Gabon, Africa are the remains of "natural nuclear reactors." This paper examines the make-up and configuration of some of these reactors and shows that these deposits were not capable of a sustained nuclear fission chain reaction if the nuclear characteristics of the isotopes involved were the same as they are today. If these deposits really are the remains of natural nuclear reactors, then they appear to provide support for the hypothesis that nuclear constants have changed over time.