In 1956 Paul Kazuo, in a published academic paper, proposed that it was possible for the Earth itself to create a natural nuclear reactor and to sustain its reactions. Given that humans had only discovered nuclear fission was possible in 1939 and then managed to design the very first nuclear reactor in 1942 that claim must have seemed downright outrageous. How could the earth manage the required conditions to make a running nuclear reactor? Well, surprisingly it did. A French physicist Francis Perrin in 1972 found 17 sites at the Oklo mines in Gabon, West Africa where the earth made its own nuclear reactor. It happened 1.7 billion years ago and the reactor ran for 300,000 years. Mind-blowing isn’t it?
In order to have the conditions for a nuclear reactor to take place you need a concentration of uranium U235 of more than 3%. The average amount of this isotope found today in the environment is usually 0.72% so those conditions are very rare. But 1.7 billion years ago, the perfect conditions were found in Oklo, West Africa to produce a concentration of 3.1%. A moderator to slow down neutrons produced was required and fortunately there was a water source present. If there had been boron or lithium they would have stopped the reaction but fortunately they were both absent from this particular geographical area. It is thought that oxygen, which was required, was contributed by aerobic oxygen from bacteria. There needed to be a uranium layer 1 metre thick, which Oklo had and as the fission reaction took place it generated heat. This heat gradually boiled away the available water which stopped the reaction. Then after cooling, water would return and the reaction started again. In three hours, one whole cycle would be completed but imagine this cycle successfully repeating itself for 300,000 years! Eventually with time the fissile material concentration was reduced so that it could no longer sustain a chain reaction.
All of this is pretty amazing and Paul Kazuo’s predictions turned out to be completely verified. It helps to understand a bit of the chemistry and physics behind this world we live in. The periodic table contains all the elements or atoms that exist. From the lightest Hydrogen which has just one proton and one electron to very heavy atoms like one of the heaviest uranium with 92 protons, 92 electrons and 143 neutrons. As you go up the periodic table the atoms get fatter! They gain neutrons and protons deep inside the nucleus. The neutrons have no charge but they do add weight. Radioactive decay comes from deep inside the nucleus and involves a change in the number of neutrons or protons due to instability in their neutron/proton ratio. This instability means they will decay. All elements with atomic numbers greater than 83 have unstable nuclei and are radioactive. As a radioactive element tries to stabilize, it may transform into a new element in a process called transmutation. I just want to emphasis here that nuclear reactions involve changing the fundamental nature of the element you started with. This transformation happens right at the heart of the atom and when you have nuclear fission you divide the atom nucleus creating two smaller lighter nuclei along with a lot of neutrons, alpha particles, gamma radiation and electrons from deep inside the nucleus.
The story could end there but this planet is more mysterious than we suspected. It keeps surprising scientists regularly. It has now been proposed that georeactors could (earth’s natural reactors) exist deep beneath us where the earth’s mantle meets its metalcore. It is thought such reactors burn uranium and produce plutonium with other products such as helium and xenon. This would explain the confusing ratios of such gases found in volcanic magma.
Radioactive decay of unstable isotopes of heavy metals such as uranium contribute to the heat of the earth’s mantle and help to create convection currents in the mantle rock that power the drift of the tectonic plates at the surface of the earth causing mountain ranges and earthquakes. Nuclear fission reactors deep below us could release an immense amount of heat and it is thought that radioactive decay provides over 50% of the earth's total heat. It has long been known that the earth is radiating much more heat than it should (45TW, where a TW is unit of power equal to one million million (1012) watts).
But how do we find out if this proposed explanation is true? Well, fortunately when nuclear reactions take place neutrinos and antineutrinos are released. These particles pass right through the earth easily. In Japan there is Kamioka Liquid Scintillator Antineutrino Detector (KamLAND). It is an underground neutrino detection facility situated in a drift mine shaft in the Japanese Alps. Kamland is surrounded by Japanese commercial nuclear reactors and is, therefore, able to measure antineutrinos from these reactors. When The Kashiwazaki-Kariwa Nuclear Power Plant, the largest single nuclear power station in the world, was completely shut down for 21 months following an earthquake in 2007 it allowed the KamLAND to monitor antineutrinos that might be coming from deep beneath the earth’s mantle. It did find evidence of antineutrinos from deep in the earth’s mantle.
The jury is still out on exactly what is going on but this earth is an amazing place that we need to have so much respect for. It somehow strikes me as an important metaphor that transmutation (the change in the nucleus of the atom) powers the earth's tectonic plates producing earthquakes and volcanoes that shape our physical world. Perhaps our inner spiritual transmutation should achieve changes in our world’s society of equally epic dimensions.
“..every atom in the universe possesses or reflects all the virtues of life”
Abdu’l Bahá
