In 1972, A French factory imported uranium ore from Gabon, and found surprisingly that the uranium had already been extracted!
Natural uranium contains 0.7202% of uranium-235, the fissionable isotope contained in nuclear fuel, but the uranium in Oklo, Gabon contained less then 0.3%.
So scientists around the world gathered in Gabon to explore this phenomenon. They have found that it is a highly technically designed underground nuclear reactor which is beyond the capabilities of our present scientific knowledge. This nuclear reactor came into being 1.8 billion years ago, and was operational for about 500 thousand years.
Scientists investigated the uranium mine and the results were made public at a conference of the International Atomic Energy Agency. The uranium indeed had been used. One may wonder what exactly happened at Oklo?
French scientists found traces of fission products and fuel wastes at various locations within the mine area. These observations were puzzling at first because it is not possible for natural uranium to go critical, except under very special circumstances such as the presence of graphite or heavy water as a moderator, neither of which could reasonably be expected to have been present in the vicinity of Oklo.
The half-life of U235 is 7.13E8 years, which is considerably shorter than the half-life of U238 at 4.51E9 years. Since the original formation of the earth, more of the U235 had decayed than the U238. This means that the natural uranium ore had a much higher uranium concentration many years ago than it does today. Indeed, it is easy to show that about 3 billion years ago the U235 concentration was in the neighborhood of 3 w%, sufficiently high to reach the critical point for a chain reaction to occur in ordinary water, which was present near Oklo at that time.
Surprisingly, this uranium mine's nuclear reactor was well designed. Studies indicate that this reactor was several miles in length. However, for such a huge nuclear reactor, the thermal impact to its environment was limited to 40 meters on all sides. Even more astonishing is the fact that the radioactive wastes have still not migrated outside the mine site. They are held in place by the surrounding geology.
Faced with these findings, scientists considered the mine to be a 'naturally occurring' nuclear reactor. The Oklo reactor has been documented for its importance as an analogue (a structural derivative of a parent compound) in the disposal of nuclear fuel wastes. But few people are bold enough to go one step further.
Rene Noorbergen, in his book Secrets of the Lost Races, says: "Following the publication of Dr. Perrin's report by the French Academy of Sciences, however, questions concerning his conclusions were raised by many experts. Glenn T. Seaborg, former head of the United States Atomic Energy Commission and Nobel prize winner for his work in the synthesis of heavy elements, pointed out that for uranium to "burn" in a reaction, conditions must be exactly right.
This water most be extremely pure. Even a few parts per million of any contaminant will "poison" the reaction, bringing it to a halt. The problem is that no water that pure exists naturally anywhere in the world!"
A second objection to Dr. Perrin's report involved the uranium itself. Several specialists in reactor engineering remarked that at no time in the geologically estimated history of the Oklo deposits was the uranium ore rich enough in U 235 for a natural reaction to have taken place.
Even when the deposits supposedly were first formed, because of the slow rate of radioactive disintegration of U 235, the fissionable material would have constituted only 3 per cent of the deposits—far too low a level for a "bum," Yet a reaction did take place, suggesting that the original uranium was far richer in U 235 than a natural formation could have been.
If nature was not responsible, then the reaction must have been produced artificially. Is it possible that the Oklo uranium is the residue from an antediluvian reactor that was destroyed by the Flood and redeposited in West Africa?"
As a matter of fact, many people today know that the reactor is a relic from a prehistoric civilization. It's probable that two billion years ago there was a fairly advanced civilization living at a place now called Oklo. This civilization was technologically superior to today's civilization. Compared to this huge 'natural' nuclear reactor, our current nuclear reactors are far less impressive.