Uranium oxide remains are visible as the yellowish rock.
Oklo by-products are being used today to study the stability of the fundamental constants over cosmological timescales and to develop more effective means for disposing of human-manufactured nuclear waste.
In 1972, a French company imported some uranium ore from Oklo in the Gabon Republic in Africa.
Surprisingly the uranium concentration in the ore was as low as spent uranium fuel from a nuclear reactor.
The finding led scientists to believe that the uranium had already been used for energy production.
This discovery shocked the world and attracted scientists from many countries to go to Oklo for further investigation.
The results showed that the uranium mine was an ancient nuclear reactor.
The ancient reactor consisted of five hundred tons of utilized uranium ore in six different areas.
Its output power was estimated to be approximately one hundred kilowatts.
The reactor was perfectly preserved and its layout was very rational.
It is estimated that the reactor had been in operation for around 500,000 years.
Furthermore, nuclear wastes produced in this reactor had not spread all over the surrounding areas.
Instead, they were confined within the separate sections.
From the perspective of modern nuclear technology, this ancient reactor used very advanced techniques.
According to geological dating, the Oklo uranium mine was formed about 2 billion years ago.
Shortly after formation, the nuclear reactor commenced operation.
The research results made scientists seriously consider the possibility of a prehistoric civilization.
Such a nuclear reactor could be a product of a civilization from long ago, although scientists have proposed completely natural mechanisms by which the chain reactions could have taken place.
Human beings have only made use of nuclear power for a couple of decades.
This discovery raised the intriguing possibility that a technologically more advanced civilization existed two billion years ago, and it had advanced knowledge of nuclear fission.
But if this assumption were correct, one would ask why such an advanced civilization did not perpetuate its own existence.
Instead, it disappeared for unknown reasons, leaving only ancient relics.
How should we view such a discovery?
A large unaccounted-for time gap exists between two billion years ago and our present historical human civilization.
What could have happened during that time?
If we neglect relics of prehistoric civilization, there is no way we can broaden the scope of our present knowledge.
