No. 121: Jan-Feb 1999
In 1972, French scientists discovered that several natural concentrations of uranium ore had become critical and flared up some 2 billion years ago at Oklo, Gabon. The concentration and configuration of the natural uranium and surrounding materials at that time had been just right to sustain fission. In fact, the analysis of the nuclear waste in the burned rocks demonstrated that plutonium had also been created. This implies that natural breeder reactors are also possible, raising the possibility of hitherto unappreciated, long-lived heat sources deep in the earth, in the other planets, and inside some of the stars.
Don't worry that the Oklo phenomenon might occur today on the earth's surface. The concentration of fissionable U-235 has fallen considerably in the last 2 billion years due to its radioactive decay. But, deep inside the earth and other astronomical bodies, nuclear criticality might still be possible due to different pressures, densities, etc.
In a stimulating and generally overlooked paper in Eos, J.M. Herndon proffers four important natural phenomena that may involve natural fission reactors.
(Herndon, J. Marvin; "Examining the Overlooked Implications of Natural Nuclear Reactors," Eos, 79:451, 1998.)
Comments. Two additions to Herndon's list.
|Disposition of six of the Oklo 2-billion-year-old natural nuclear reactors. (From: Anomalies in Geology).|