No this is not an Alien discovery or humans being around a lot longer than otherwise thought.
There is basically a region in Okla, Gabon that was discovered in 1972 by nuclear scientists which had abnormal levels of Uranium 235.
A bit of background about Uranium, there are three types of Uranium:
Uranium 238 which is the most abundant
Uranium 234 which is the rarest
Uranium 235 which fuels nuclear chain reactions.
Normally uranium 235 when found is composed of 0.720% uranium 235, these samples contained 0.717% a slight discrepency. This meant back at the mine there was 440 pounds of missing uranium 235.
To start a natural nuclear reactor (ie nuclear fission) the following has to take place.
- Some uranium 235 needs to be used as fuel.
- Uranium 235 has to decay, become thorium and release neutrons. This neutron fuses with the other Uranium 235 and creates Uranium 236.
- Uranium 236 is unstable and therefore splits creating smaller, stable atoms and some neutrons. Which continues the chain reaction over and over again.
How it happened in Okla, Gabon was that there was a source of groundwater nearby. This allowed for the nuclear fission process to happen as the Uranium 235/236 would heat up the groundwater causing it to evaporate. This would happen over and over again until the groundwater evaporated completely and therefore resulted in the 0.717% uranium composition from the mine.
Scientists believed this watery cycle played out over hundreds of thousands of years.
Just sharing, I thought it was neat and it is REALITY.
You are right, it is real, and quite interesting. The reason it ran is that about 2 billion years ago, the ratio of U235 to U238 was quite different - there was a lot more U235 around due to the difference in half-lives between these two isotopes. The result was that you could basically run a "light water" reactor from natural uranium, which you can't do today. Now that U235 has decayed away we require enrichment for regular water to work in a reactor, or we require "heavy" water, such as in a CANDU reactor to make our current natural uranium work. The Youtuber "SciShow" did a great ~4 min vid on this topic as well.