Africa's Natural Nuclear Reactors

Image: United States Geological Survey and the Mineral Information Institute via Scientific American

Hat tip to Beam Me Up for finding this unusual story from Scientific American about a cache of uranium in a mine in Oklo (in Gabon) in western Africa that, in prehistoric times, had output a steady stream of energy for thousands of years. Now we're not talking Three-Mile Island here, it's more like 100 kilowatts of energy, but still, I find the idea of a "natural" nuclear power plant really intriguing.

From the Scientific American article by researcher Alex P. Meshik, PhD, who's studied the phenomenon:

Physicists confirmed the basic idea that natural fission reactions were responsible for the depletion in uranium 235 at Oklo quite soon after the anomalous uranium was discovered. Indisputable proof came from an examination of the new, lighter elements created when a heavy nucleus is broken in two. The abundance of these fission products proved so high that no other conclusion could be drawn. A nuclear chain reaction very much like the one that Enrico Fermi and his colleagues famously demonstrated in 1942 had certainly taken place, all on its own and some two billion years before.

Shortly after this astonishing discovery, physicists from around the world studied the evidence for these natural nuclear reactors and came together to share their work on “the Oklo phenomenon” at a special 1975 conference held in Libreville, the capital of Gabon. The next year George A. Cowan, who represented the U.S. at that meeting (and who, incidentally, is one of the founders of the renowned Santa Fe Institute, where he is still affiliated), wrote an article for Scientific American [see “A Natural Fission Reactor,” by George A. Cowan, July 1976] in which he explained what scientists had surmised about the operation of these ancient reactors.

Fascinating! Seems like fodder for a sci-fi story, doesn't it? Ancient astronauts plunder prehistoric earth for natural nuclear energy to power their spaceships and rayguns!