Nuclear reactors, man-made machines designed to generate energy from nuclear fission, have been around since 1942. However, some may be surprised to learn that although man-made nuclear reactors were created nearly 80 years ago, natural nuclear reactors existed before that. In fact, natural nuclear reactors have existed for billions of years before man-made reactors in various regions of the world. Central Africa, in particular, is a country with 16 natural nuclear reactors. The Gabonese nuclear reactor is capable of producing about 100 kilowatts of energy, enough to light about 1,000 light bulbs at the same time.
Many people want to know how gabonese nuclear reactors were formed, and how likely it is that future natural nuclear reactors will form elsewhere on earth. Scientists and researchers were able to piece together some information about these reactors to give us a better understanding of their function. By looking at how these natural nuclear reactors are formed, we can analyze the potential for more nuclear reactors in the future, and even learn one or two lessons about energy production from Mother Nature.
Ludovic Ferrière, director of the Rock Collection, owns the Oklo reactor at the Natural History Museum in Vienna
Raw all-natural energy source
Gabon is short for the Gabonese Republic and is located on the west coast of Central Africa. It has a population of nearly 2.2 million and originated in French territory in the 1800s. Therefore, the main language spoken in Gabon is French. Gabon gained independence from France in 1960, along with several other African countries that had previously been part of the French Community.
Geologically, the interesting thing about Gabon is that it is mainly composed of Paleoproterozoic igneous and metamorphic rocks from nearly 2 billion years ago. This ancient crust contains precious natural resources, including magnesium, iron, uranium, gold and oil. Throughout the landscape, explorers and researchers alike can find ancient formations, such as the rift valley basin formed during the separation of Pangea 175 million years ago. The Gabonese natural nuclear reactor is another ancient structure discovered by chance nearly 50 years ago.
Miners discovered the 16 reactors in Oklo, in southeastern Gabon, in the 1970s, when they were looking for uranium to power the French nuclear power plant. Uranium is the main element used to generate energy through nuclear fission. In man-made nuclear power plants, uranium is made into granules that are used as fuel in nuclear reactors. These uranium core blocks are then placed into rods bundled together to form fuel assemblies. The fuel assembly is packed in a reactor vessel, which is immersed in water as a coolant.
Samples were donated to the Natural History Museum in Vienna
In nuclear fission, the first uranium atoms are split, releasing a neutron. This neutron then hits the other uranium atoms, which in turn splits them. As more neurons split out more uranium atoms, these chemical reactions generate heat, which is then used to turn water into steam. This steam is then used to rotate steam turbines to produce environmentally friendly renewable energy. The water submerged in the reactor vessel acts as a cooling element and slowing down the neutrons so that the reaction does not occur too quickly.
Uranium is highly sought after by nuclear power plants because of its ability to easily split into smaller atoms compared to other elements. When French miners found natural uranium in Oaklow, they called the area. The researchers noticed that the concentration of 235 U was lower. They also found evidence of cesium, americium, curium and plutonium, elements often thought of as waste from uranium decay in nuclear reactors. This is the first discovery to suggest that nuclear fission can occur naturally within Earth.
Oklo's natural nuclear fission reactor: (1) Nuclear reactor area. (2) Sandstone. (3) Uranium ore layers. (4) Granite
The basic elements of a natural nuclear power plant
As researchers began to delve deeper into the nuclear fission that occurred in the Gabonese nuclear reactor, they began to wonder how nuclear fission could occur so haphazardly. In man-made nuclear reactors, coolants such as water are needed to slow down chemical reactions by slowing down the speed at which neutrons move. Reducing neutron motion reduces the splitting of uranium atoms, resulting in easier-to-control heat and steam. Without coolants like water, nuclear fission would occur so quickly that reactor vessels would become hot enough to melt, burn, or even explode.
A classic example of uncontrolled nuclear fission is the Chernobyl disaster, which melted the reactor's core and triggered several explosions, resulting in several casualties and severe radioactive contamination in the area. Several more deaths followed due to radiation exposure, leading to various cancers and diseases in the affected.
Simple nuclear fission diagram
When analyzing the Gabonese nuclear reactor, scientists first realized that for natural nuclear fission to occur, a significantly higher concentration of 235 U must exist at some point to initiate a chain reaction. Given the extremely high half-life of uranium (700 million years), this concentration existed nearly 2 billion years before the discovery of uranium ore. At such high concentrations, atoms naturally collide and split, leading to further reactions. The researchers believe that this high concentration of uranium is likely caused by a combination of weathering and high bacterial activity in ancient igneous rocks.
Since the concentration of 235 U is so high, some type of coolant is needed to control the reaction and prevent them from causing an explosion inside the mine. It is believed that Oaklow previously had large amounts of water that could have been used as a natural coolant for mines 2 billion years ago. This will prevent any uncontrollable reactions within the mine over time.
For some scientists, the most appealing thing about Gabonese nuclear reactors is not that they once produced nuclear energy. The most interesting fact is that the test did not show evidence of high radioactivity in the area. Once poisonous cesium and plutonium, they have now decayed into barium that is harmless to humans. Wildlife in the area also shows no signs of radiation exposure, which naturally occurs around 16 natural nuclear reactors. The discovery of the Gabonese nuclear reactor suggests that over time nature has found a way to naturally eliminate the remarkable radioactivity of the region, and scientists are quickly trying to learn from it.
The topography surrounding the Ocroy natural nuclear reactor suggests that groundwater, located above a layer of bedrock, may be a necessary ingredient for uranium-rich ores capable of spontaneous fission
A series of unfortunate nuclear incidents
Researchers believe that the Gabonese nuclear reactor has been in operation for more than 1 million years after it was formed nearly 2 billion years ago. Reactors could have operated properly underwater until the water eventually evaporated due to the high heat generated by the nuclear reaction. This is the same reaction that occurs in man-made reactors, except that the water is recycled rather than completely evaporated.
After about a million years, the previously high concentration of 235 U will be significantly depleted. At this point, the reactor is likely to stop actively producing energy. Although natural reactors have been shut down, they have miraculously been preserved for millions of years due to the protection of the surrounding clay and carbonaceous material. These substances protect the reactor from nitrox sources that corrode or dissolve all traces of nuclear reactions over the past millions of years.
Regarding the future of Gabon's natural nuclear reactors, French miners continue to extract the remaining uranium for use in man-made nuclear reactors. Today, most of the available uranium in these mines has been depleted, which eliminates any chance that the reactor will produce more energy one day in the future. Scientists now call these areas "fossilized" natural nuclear fission reactors because they no longer function, but still contain evidence of their previous ability to produce energy.
Professor Francois Gautier-Lafaye showed a group of Swiss journalists the contact zone of natural nuclear reactor 10 at the Oklo uranium mine (Gabon) in 1997
Can natural energy make a comeback?
Although the Gabonese nuclear reactor has now mined all available uranium, miners have taken steps to reclaim the mine. Mine reclamation minimizes human behavior on the environmental impact of mining by restoring the mine to its original state. Reclamation may involve reducing erosion, stabilizing slopes and restoring any impact on local wildlife. Over time, it was believed that mine reclamation could lead the planet to replenish its own resources, although some of the effects of mine reclamation will not be seen in our lifetime. Many minefields have been turned into wildlife habitats or farmland.
For O'Kerr's fossilized natural nuclear reactor, mine reclamation is still ongoing. Given the region's history as a natural nuclear reactor site, plans for the region are not entirely clear, but scientists are actively working in the area to implement the best possible plan. The reclamation plans have led some to question whether the mines will one day start generating electricity again. Given the very low concentration of uranium in the mines at the moment, the likelihood of any chain reaction occurring in the near future is slim. Since uranium is a limited resource on Earth and cannot be manufactured, the concentration of uranium in mines is unlikely to increase over time.
While the future of Gabon's nuclear reactors looks bleak, scientists acknowledge that there must be other natural nuclear reactors elsewhere on Earth. While no discovery has been made yet, future explorations by miners and researchers in various regions could lead to the discovery of another natural nuclear reactor. Due to the high concentration of uranium in the ocean (estimated at about "four billion tons"), some scientists speculate that there may be some natural nuclear reactors in the ocean crust on the ocean floor.
Seawater will act as a natural coolant to prevent uncontrolled uranium splitting, similar to the Gabonese reactor 2 billion years ago. Given that about 80 percent of the ocean remains unmapped and explored, natural nuclear reactors are certainly likely to lurk somewhere in the deep ocean.
With further research and implementation of renewable energy, uranium will continue to be mined for use in man-made nuclear reactors. Nuclear scientists are still analyzing the long-term effects of nuclear energy, such as the need to dispose of nuclear waste without radioactive contamination of the planet. Using information gathered from the Gabonese nuclear reactor, scientists may be able to develop an effective and safe way to dispose of this waste in the future. With any luck, the Gabonese nuclear reactor will one day become an achievable example of how nuclear energy can be produced in an environmentally safe manner.