Two billion years ago, parts of an African uranium deposit spontaneously underwent nuclear fission. Scientists estimate that this nuclear reactor –whch consists of 16 sites—has been operational for at least 500,000 years in the distant past. Incredibly, compared with this massive nuclear reactor, our modern-day nuclear reactors are not comparable both in design and functionality.
The nuclear reactor consists of 16 sites. As it is noted in Scientific American, “It is truly amazing that more than a dozen natural reactors spontaneously sprang into existence and that they managed to maintain a modest power output for perhaps a few hundred millennia.”
The discovery is so fascinating that researchers said that “the discovery of the Oklo natural nuclear reactor in Gabon (West Africa) in 1972 was possibly one of the most momentous events in reactor physics since 1942 when Enrico Fermi and his team achieved an artificial self-sustained fission chain reaction.
This mind-bending discovery was made in 1972 when French scientists took uranium ore from the mine in Gabon to test its uranium content. Uranium ore is composed of three isotopes of uranium, and each one of them contains a different number of neutrons. There is Uranium 238, uranium 234, and uranium 235.
Uranium 235 is the one which scientists are most interested in because it can sustain nuclear chain reactions.
What is surprising is that a nuclear reaction had occurred in a way that the plutonium, the by-product, was created, and the nuclear reaction itself had been moderated. This is something considered as a “holy grail” of atomic science. The ability to moderate the reaction means that once the reaction was initiated, it was possible to leverage the output power in a controlled way, with the capacity to prevent catastrophic explosions or the release of the energy at a single time.