The ubiquity of nuclear fission reactors throughout time and space

Abstract

The evidence for a natural uranium fission reactor in Oklo, Gabon (Africa) begs the question as to whether this was the only one to have ever occurred on earth or elsewhere. Modern nuclear terminology classifies uranium as highly enriched uranium when the U235 content exceeds 20% which is shown comparable to projecting back ca 4.5e9 yr for terrestrial uranium isotopic abundances. At that time, the natural uranium content of the earth would have been classified as highly enriched uranium. With one verified natural criticality event, more events are postulated both on earth and throughout our galaxy. The latter effect should result in some background contribution to gamma ray burst events placing nuclear reactors as an expected ubiquitous natural phenomenon throughout time and space.