What if you were told that all the while process have been done to fabricate a nuclear reactor, the natural nuclear reactor, have always been there! And, that too for almost 2 billion years ago! You are bound to be taken by surprise. However, it’s time you believe it.
Indeed, there is a realm of natural Uranium within the Earth’s crust, found in Oklo, Gabon. This is the natural reactor. You must be aware of the fact, that Uranium is naturally radioactive.
It did come as a surprise to the scientists.
The first nuclear reactor, which produced electricity, was initiated in 1951. This could give rise to a very less amount of energy. Simply compare it with the ground in Oklo. The latter, has been producing nuclear power for almost 2 billion years ago.
What led to the discovery of a natural nuclear reactor?
The natural nuclear reactor was discovered in 1972. It so happened that French scientists took samples from the mine in Gabon to test the content of Uranium.
It is important in here for the readers to get acknowledged by the fact that uranium consists of 3 isotopes of Uranium. Each isotope has a different number of neutrons:-
- Uranium 238-most abundant
- Uranium 234-rarest
- Uranium 235- can sustain chain reactions.
Going with the expectation, the Uranium should have had 0.720% of Uranium 235. It is because that is the ideal percentage available with the rock samples. However, the French scientists found that it only contained 0.717% of Uranium 235.
While, you as a reader might feel that what is the big deal with the discrepancy of 0.003%, however, for the scientists this was of paramount significance!
The implication was the almost 200 kg of Uranium was missing back then.
The acumen associated with the missing Uranium was, that 0.003% of Uranium had undergone nuclear fission and split into other atoms.
What are the conditions that ensured the fabrication of a natural nuclear reactor?
- It had a good percentage of Uranium 235, which managed to fuel the reaction.
- It was a good source of neutrons. Uranium 235 decayed into thorium and released neutron. It is this neutron, which in turn, started the fission process when reacting with another Uranium 235 atom.
- The neutron fused with Uranium 235, leading to formation of Uranium 236. The Uranium 236 was unstable.
- The Uranium 236, then split. It created a variety of smaller and stable atoms along with neutron.
- The neutron in turn continued the chain reaction, by shooting towards other atoms.
- The naturally occurring nuclear reactor had an immense supply of regulating substance too, in the form of the flow of natural ground water.
- The water would slow down the neutrons.
- However, the energy would heat the water, making it boil.
- So, gradually no more water would be left to slow down the neutrons.
- The neutrons would start shooting off, without pursuing any reaction.
- Finally, the wait for the water cycle would initiate, and then the whole process would restart.
And, this is what exactly happened with a natural nuclear reactor. Gradually, it slowed down and presently has ceased to exist.