Many people think that nuclear power is an invention of mankind, and some even believe that it violates the laws of nature. But nuclear power is actually a natural phenomenon, and life could not exist without it. This is because our Sun (and every other star) is itself a giant powerhouse, lighting up the solar system through a process known as nuclear fusion.
Humans, however, use a different process to generate this force called nuclear fission, in which energy is released by splitting atoms rather than by combining them, as in the process of welding. No matter how inventive humanity may seem, nature has already used this method as well. In a single but well-documented site, scientists have found evidence that natural fission reactors were created in three uranium deposits in the western African nation of Gabon.
Two billion years ago, uranium-rich mineral deposits began flooding with groundwater, causing a self-sustaining nuclear chain reaction. By looking at the levels of certain isotopes of xenon (a by-product of the fission process of uranium) in the surrounding rock, the scientists determined that the natural reaction took place over several hundred thousand years at intervals of about two and a half hours.
Thus, the natural nuclear reactor at Oklo operated for hundreds of thousands of years until most of the fissile uranium was exhausted. While most of the uranium in Oklo is the non-fissile isotope U238, only 3% of the fissile isotope U235 is needed to start a chain reaction. Today, the percentage of fissile uranium in the deposits is about 0.7%, which indicates that nuclear processes took place in them for a relatively long period of time. But it was precisely the exact characterization of the rocks from Oklo that first puzzled scientists.
Low levels of U235 were first observed in 1972 by employees at the Pierrelate uranium enrichment plant in France. During routine mass spectrometric analysis of samples from the Oklo mine, it was found that the concentration of the fissile uranium isotope differed by 0.003% from the expected value. This seemingly small difference was significant enough to alert authorities, who were concerned that the missing uranium could be used to build nuclear weapons. But later, in the same year, scientists found the answer to this riddle - it was the first natural nuclear reactor in the world.
In 1972, an ancient nuclear reactor was discovered in Africa on the territory of the Republic of Gabon. At first, scientists found rich deposits of uranium ore. When its composition was checked, it turned out that this ore had already been used.
Given the age of the ancient reactor at 2 billion years, who could have created it to generate energy in those distant times? The most reliable answer is that one of the past civilizations of people on Earth did this.
Huge reserves of uranium ore were used
The source of uranium ore discovered in Gabon (Oklo area) is the largest source of uranium ore in the world. Therefore, he aroused the interest of scientists in many countries after the message of French geologists. They began to investigate the composition of uranium ore. It turned out that the rock contains a lot of uranium-238 and very little uranium-235, which is of interest to people.Uranium-238 is essentially spent nuclear fuel.
Samples of uranium ore from Oklo (Gabon).
Who built the most complex nuclear reactor 2 billion years ago? The complex design of the reactor in Africa with its 16 power units speaks of the high technological level of its creators in those distant times.
For millions of years, the structures of the buildings of a nuclear reactor could crumble to dust. However, radioactive isotopes continue to emit energy after thousands of years. Spent uranium-238 speaks of thousands of years of operation of a giant nuclear reactor. Small remnants of uranium-235, which is used in energy production, point to the sites of fuel storage for the reactor of an ancient civilization.
There are facts, but science is silent about the ancient nuclear reactor
This is where the usual story begins, when modern science does not want to recognize the facts, passing them off as a mistake. If it cannot be recognized as a mistake, then these facts are simply hushed up. What happened to the ancient nuclear reactor of the past civilization in Gabon.
Versions of the origin of the ancient nuclear reactor
natural nuclear reactor
The most common version of scientists is that a natural nuclear reactor was found in Oklo. Allegedly rich uranium ores were flooded with water, which caused a nuclear reaction. There were no intelligible explanations of how “nature” managed to start the reactor and maintain its operation for thousands of years.
There are deposits of uranium-235 in different parts of the world, but there has not been a natural nuclear reactor reproducing the operation of at least one power unit. Recall that in Gabon found 16 pockets of spent nuclear fuel!
Nowhere else in the world have such huge reserves of spent uranium-238 been found. Physicists doubt that it is possible to produce this element in natural conditions in such quantities. Until now, uranium fission has been carried out only in an artificial environment with the help of a person.
Alien nuclear burial ground
This version is supported by the convenient location of uranium deposits. The Oklo area is characterized by a stable surface of the Earth. Reserves of uranium rest in the bowels of a thick basalt slab. There are no earthquakes and other natural disasters.
Aliens hypothetically could use this area to bury the remains of nuclear production. But did it make sense to do it on Earth? Doubts are added by the presence of uranium-235, as well as 16 foci, reminiscent of the design of a giant, once operating, reactor.
Folk legends
The legends and oral beliefs of the people inhabiting this area speak of an ancient race of demi-gods. In ancient times, according to legend, a developed powerful civilization lived in the province of Oklo, which was looking for treasure in the rocks in order to become invincible. Aborigines consider the place where the ancient nuclear reactor is located mysterious and mystical.
Perhaps scientists should have listened more seriously to the stories of local residents. Folk wisdom does not arise from scratch, but can serve as a source of knowledge for revealing the secrets of science and life.
Lessons from Past Civilizations
Today there are scientists and historians who understand that this Earth was inhabited by more than one of our civilizations. It is enough to recall the unique finds confirming that there was , , Mayan civilization, , humanity - how many mysterious ancient civilizations has our planet seen?
Many proofs of phenomena that are beyond the scope of modern science have already been found. , superpowers, ancient civilizations - all this could help people realize the meaning of their stay on Earth and prevent the sad end of our humanity.
Walking along the path of rejecting the divine principle of the world, scientists drive themselves into a corner with the narrow framework of scientific dogmas. The Creator's intention is difficult to understand for those living in a world of constant competition and struggle. If you choose the path of returning to your traditions, handed down by the Creator to people, you may be able to survive, unlike many other previous civilizations on Earth.
In West Africa, not far from the equator, in an area located on the territory of the state of Gabon, scientists made an amazing find. This happened at the very beginning of the 70s of the last century, but so far representatives of the scientific community have not come to a consensus - what was found?
Deposits of uranium ore are a common phenomenon, although quite rare. However, the uranium mine discovered in Gabon turned out to be not just a deposit of a valuable mineral, it worked like ... a real nuclear reactor! Six uranium zones were discovered, in which a real uranium fission reaction took place!
Studies have shown that the reactor was launched about 1900 million years ago and worked in the mode of slow boiling for several hundred thousand years.
The opinions of representatives of science about the phenomenon were divided. The majority of pundits took the side of the theory, according to which, the nuclear reactor in Gabon started up spontaneously due to an accidental coincidence of the conditions necessary for such a start.
However, not everyone was satisfied with this assumption. And there were good reasons for that. Many things said that the reactor in Gabon, although it does not have parts outwardly similar to the creations of thinking beings, is still a product of intelligent beings.
Let's take a look at some facts. Tectonic activity in the area in which the reactor was found was unusually high for the period of its operation. However, studies have shown that the slightest shift in the soil layers would necessarily lead to a shutdown of the reactor. But since the reactor has worked for more than one hundred millennia, this did not happen. Who or what froze the tectonics for the period of the reactor operation? Maybe it was done by those who launched it? Further. As already mentioned, groundwater was used as a moderator. To ensure the constant operation of the reactor, someone had to regulate the power given out by it, since if it was in excess, the water would boil away and the reactor would stop. These and some other points suggest that the reactor in Gabon is a thing of artificial origin. But who on earth possessed such technology two billion years ago?
Like it or not, the answer is simple, although somewhat banal. Only aliens from outer space could do this. It is quite possible that they came to us from the central region of the Galaxy, where the stars are much older than the Sun, and their planets are older. In those worlds, life had the opportunity to originate much earlier, at a time when the Earth was not yet a very comfortable world.
Why did the aliens need to create a stationary high-power nuclear reactor? Who knows... Maybe they have equipped a "space recharging station" on Earth, or maybe...
There is a hypothesis that highly developed civilizations at a certain stage of their development "take patronage" of life emerging on other planets. And they even have a hand in turning lifeless worlds into habitable ones. Maybe those who built the African miracle belonged to just such? Maybe they used the energy of the reactor for terraforming? Scientists are still arguing how the earth's atmosphere, so rich in oxygen, arose. One of the assumptions is the hypothesis of the electrolysis of the waters of the oceans. And electrolysis, as you know, requires a lot of electricity. So maybe the aliens created the Gabon reactor for this? If so, then it is apparently not the only one. It is very possible that someday others like him will be found.
Be that as it may, the Gabonese miracle makes us think. Think and look for answers.
Korol A.Yu. - student of class 121 SNIEiP (Sevastopol National Institute of Nuclear Energy and Industry.)
Head - Ph.D. , Associate Professor of the Department of YaPPU SNYaEiP Vah I.V., st. Repina 14 sq. fifty
In Oklo (a uranium mine in the state of Gabon, near the equator, West Africa), a natural nuclear reactor operated 1900 million years ago. Six "reactor" zones were identified, in each of which signs of a fission reaction were found. Remains of actinide decays indicate that the reactor has operated in a slow boil mode for hundreds of thousands of years.
In May - June 1972, during routine measurements of the physical parameters of a batch of natural uranium that arrived at the enrichment plant in the French city of Pierrelate from the African Oklo deposit (a uranium mine in Gabon, a state located near the equator in West Africa), it was found that the isotope U - 235 in the incoming natural uranium is less than standard. It was found that uranium contains 0.7171% U - 235. The normal value for natural uranium is 0.7202%
U - 235. In all uranium minerals, in all rocks and natural waters of the Earth, as well as in lunar samples, this ratio is fulfilled. The Oklo deposit is so far the only case recorded in nature when this constancy was violated. The difference was insignificant - only 0.003%, but nevertheless it attracted the attention of technologists. There was a suspicion that there had been sabotage or theft of fissile material, i.e. U - 235. However, it turned out that the deviation in the content of U-235 was traced all the way to the source of uranium ore. There, some samples showed less than 0.44% U-235. Samples were taken throughout the mine and showed systematic decreases in U-235 across some veins. These ore veins were over 0.5 meters thick.
The suggestion that U-235 "burned out", as happens in the furnaces of nuclear power plants, at first sounded like a joke, although there were good reasons for this. Calculations have shown that if the mass fraction of groundwater in the reservoir is about 6% and if natural uranium is enriched to 3% U-235, then under these conditions a natural nuclear reactor can start working.
Since the mine is located in a tropical zone and quite close to the surface, the existence of a sufficient amount of groundwater is very likely. The ratio of uranium isotopes in the ore was unusual. U-235 and U-238 are radioactive isotopes with different half-lives. U-235 has a half-life of 700 million years, and U-238 decays with a half-life of 4.5 billion. The isotopic abundance of U-235 is in nature in the process of slowly changing. For example, 400 million years ago natural uranium should have contained 1% U-235, 1900 million years ago it was 3%, i.e. the required amount for the "criticality" of the vein of uranium ore. It is believed that this was when the Oklo reactor was in a state of operation. Six "reactor" zones were identified, in each of which signs of a fission reaction were found. For example, thorium from the decay of U-236 and bismuth from the decay of U-237 have only been found in the reactor zones in the Oklo field. Residues from the decay of actinides indicate that the reactor has been operating in a slow boiling mode for hundreds of thousands of years. The reactors were self-regulating, since too much power would lead to the complete boiling off of the water and to the shutdown of the reactor.
How did nature manage to create the conditions for a nuclear chain reaction? First, in the delta of the ancient river, a layer of sandstone rich in uranium ore was formed, which rested on a strong basalt bed. After another earthquake, common at that violent time, the basalt foundation of the future reactor sank several kilometers, pulling the uranium vein with it. The vein cracked, groundwater penetrated into the cracks. Then another cataclysm raised the entire "installation" to the current level. In nuclear furnaces of nuclear power plants, fuel is located in compact masses inside the moderator - a heterogeneous reactor. This is what happened in Oklo. Water served as a moderator. Clay "lenses" appeared in the ore, where the concentration of natural uranium increased from the usual 0.5% to 40%. How these compact lumps of uranium were formed is not precisely established. Perhaps they were created by seepage waters that carried away clay and rallied uranium into a single mass. As soon as the mass and thickness of the layers enriched with uranium reached critical dimensions, a chain reaction arose in them, and the installation began to work. As a result of the operation of the reactor, about 6 tons of fission products and 2.5 tons of plutonium were formed. Most of the radioactive waste remains inside the crystalline structure of the uranite mineral, which is found in the body of the Oklo ores. Elements that could not penetrate the uranite lattice due to too large or too small ionic radius diffuse or leach out. In the 1900 million years since the Oklo reactors, at least half of the more than 30 fission products have been bound in the ore, despite the abundance of groundwater in this deposit. Associated fission products include the elements: La, Ce, Pr, Nd, Eu, Sm, Gd, Y, Zr, Ru, Rh, Pd, Ni, Ag. Some partial Pb migration was detected and Pu migration was limited to less than 10 meters. Only metals with valency 1 or 2, i.e. those with high water solubility were carried away. As expected, almost no Pb, Cs, Ba, and Cd remained in place. The isotopes of these elements have relatively short half-lives of tens of years or less, so that they decay to a non-radioactive state before they can migrate far in the soil. Of greatest interest from the point of view of long-term problems of environmental protection are the issues of plutonium migration. This nuclide is effectively bound for almost 2 million years. Since plutonium by now almost completely decays to U-235, its stability is evidenced by the absence of excess U-235 not only outside the reactor zone, but also outside the uranite grains, where plutonium was formed during the operation of the reactor.
This unique nature existed for about 600 thousand years and produced approximately 13,000,000 kW. hour of energy. Its average power is only 25 kW: 200 times less than that of the world's first nuclear power plant, which in 1954 provided electricity to the city of Obninsk near Moscow. But the energy of the natural reactor was not wasted: according to some hypotheses, it was the decay of radioactive elements that supplied energy to the warming Earth.
Perhaps the energy of similar nuclear reactors was added here. How many are hidden underground? And the reactor at that Oklo in that ancient time was certainly no exception. There are hypotheses that the work of such reactors "spurred" the development of living beings on earth, that the origin of life is associated with the influence of radioactivity. The data indicate a higher degree of evolution of organic matter as we approach the Oklo reactor. It could well have influenced the frequency of mutations of unicellular organisms that fell into the zone of increased radiation levels, which led to the appearance of human ancestors. In any case, life on Earth arose and went a long way of evolution at the level of the natural radiation background, which became a necessary element in the development of biological systems.
The creation of a nuclear reactor is an innovation that people are proud of. It turns out its creation has long been recorded in the patents of nature. Having designed a nuclear reactor, a masterpiece of scientific and technical thought, a person, in fact, turned out to be an imitator of nature, which created installations of this kind many millions of years ago.
During routine analysis of uranium ore samples, a very strange fact came to light - the percentage of uranium-235 was below normal. Natural uranium contains three isotopes that differ in atomic masses. The most common is uranium-238, the rarest is uranium-234, and the most interesting is uranium-235, which supports a nuclear chain reaction. Everywhere - in the earth's crust, on the moon, and even in meteorites - uranium-235 atoms make up 0.720% of the total amount of uranium. But samples from the Oklo deposit in Gabon contained only 0.717% uranium-235. This tiny discrepancy was enough to alert the French scientists. Further research showed that about 200 kg of ore was missing - enough to make half a dozen nuclear bombs.
A uranium open pit in Oklo, Gabon, has unearthed more than a dozen zones where nuclear reactions once took place.
The specialists of the French Atomic Energy Commission were puzzled. The answer was a 19-year-old article in which George W. Wetherill of the University of California, Los Angeles and Mark G. Inghram of the University of Chicago suggested the existence of natural nuclear reactors in the distant past. Soon, Paul K. Kuroda, a chemist at the University of Arkansas, identified the “necessary and sufficient” conditions for a self-sustaining fission process to spontaneously occur in the body of a uranium deposit.
According to his calculations, the size of the deposit should exceed the mean path length of neutrons that cause splitting (about 2/3 meters). Then the neutrons emitted by one fissile nucleus will be absorbed by another nucleus before they leave the uranium vein.
The concentration of uranium-235 must be high enough. Today, even a large deposit cannot become a nuclear reactor, since it contains less than 1% uranium-235. This isotope decays about six times faster than uranium-238, which implies that in the distant past, for example, 2 billion years ago, the amount of uranium-235 was about 3% - about the same as in enriched uranium used as fuel in most nuclear power plants. It is also necessary to have a substance capable of moderating the neutrons emitted during the fission of uranium nuclei so that they more effectively cause the fission of other uranium nuclei. Finally, the mass of ore must not contain appreciable amounts of boron, lithium, or other so-called nuclear poisons that actively absorb neutrons and would cause a quick stop to any nuclear reaction.
Natural fission reactors have only been found in the heart of Africa, in Gabon, at Oklo and the neighboring uranium mines at Okelobondo, and at the Bangombe site, some 35 km away.
The researchers determined that the conditions created 2 billion years ago at 16 separate sites both within Oklo and at neighboring uranium mines in Okelobondo were very close to what Kuroda described (see "Divine Reactor", "In the World of Science ", No. 1, 2004). Although all these zones were discovered decades ago, it was only recently that we were finally able to figure out what was going on inside one of these ancient reactors.
Checking with light elements
Soon physicists confirmed the assumption that the decrease in the content of uranium-235 in Oklo was caused by fission reactions. An indisputable proof appeared in the study of the elements arising from the splitting of a heavy nucleus. The concentration of decomposition products turned out to be so high that such a conclusion was the only true one. 2 billion years ago, a nuclear chain reaction took place here, similar to the one that Enrico Fermi and his colleagues brilliantly demonstrated in 1942.
Physicists around the world have been studying evidence for the existence of natural nuclear reactors. Scientists presented the results of their work on the Oklo phenomenon at a special conference in the capital of Gabon, Libreville, in 1975. The following year, George A. Cowan, representing the United States at this meeting, wrote an article for Scientific American (see "A Natural Fission Reactor“, by George A. Cowan, July 1976).
Cowan summarized the information and described the concept of what was happening in this amazing place: some of the neutrons emitted from the fission of uranium-235 are captured by nuclei of the more common uranium-238, which turns into uranium-239, and after the emission of two electrons turns into plutonium-239. So in Oklo more than two tons of this isotope were formed. Then part of the plutonium underwent fission, as evidenced by the presence of characteristic fission products, which led the researchers to conclude that these reactions must have continued for hundreds of thousands of years. Based on the amount of uranium-235 used, they calculated the amount of energy released - about 15 thousand MW-years. According to this and other evidence, the average power of the reactor turned out to be less than 100 kW, that is, it would be enough to operate several dozen toasters.
How did more than a dozen natural reactors come about? What ensured their constant power for several hundred millennia? Why didn't they self-destruct immediately after the nuclear chain reactions began? What mechanism provided the necessary self-regulation? Were the reactors operated continuously or intermittently? The answers to these questions did not appear immediately. And the last question was shed light quite recently, when my colleagues and I began to study samples of the mysterious African ore at Washington University in St. Louis.
Splitting in detail
Nuclear chain reactions begin when a single free neutron hits the nucleus of a fissile atom, such as uranium-235 (top left). The nucleus splits, producing two smaller atoms and emitting other neutrons, which fly off at high speed and must be slowed down before they can cause other nuclei to split. In the Oklo deposit, just as in today's light water nuclear reactors, ordinary water was the moderating agent. The difference is in the control system: nuclear power plants use neutron-absorbing rods, while the reactors at Oklo simply heat up until the water boils away.
What was the noble gas hiding?
Our work on one of the reactors at Oklo was devoted to the analysis of xenon, a heavy inert gas that can remain trapped in minerals for billions of years. Xenon has nine stable isotopes that occur in varying amounts depending on the nature of the nuclear processes. As a noble gas, it does not react chemically with other elements and is therefore easy to purify for isotopic analysis. Xenon is extremely rare, which makes it possible to use it to detect and track nuclear reactions, even if they occurred before the birth of the solar system.
Uranium-235 atoms make up about 0.720% of natural uranium. So when workers discovered that Oklo's uranium contained just over 0.717%, they were surprised. This figure is indeed significantly different from other uranium ore samples (above). Apparently, the ratio of uranium-235 to uranium-238 was much higher in the past, since the half-life of uranium-235 is much shorter. Under such conditions, a cleavage reaction becomes possible. When the uranium deposits at Oklo formed 1.8 billion years ago, the natural abundance of uranium-235 was about 3%, the same as in nuclear reactor fuel. When the Earth formed about 4.6 billion years ago, the ratio was in excess of 20%, the level at which uranium is today considered "weapons grade".
To analyze the isotopic composition of xenon, you need a mass spectrometer, a device that can sort atoms by their weight. We were lucky to have access to an extremely accurate xenon mass spectrometer built by Charles M. Hohenberg. But first we had to extract the xenon from our sample. Typically, a xenon-containing mineral is heated above its melting point, causing the crystal structure to break down and no longer be able to hold the gas it contains. But in order to collect more information, we used a more subtle method - laser extraction, which allows you to get to the xenon in certain grains and leaves the areas adjacent to them untouched.
We have machined many tiny sections of the only rock sample we have from Oklo, just 1mm thick and 4mm wide. To accurately target the laser beam, we used a detailed x-ray map of the object, built by Olga Pradivtseva, who also identified the minerals that made up the object. After extraction, we purified the released xenon and analyzed it in a Hohenberg mass spectrometer, which gave us the number of atoms of each isotope.
Several surprises awaited us here: firstly, there was no gas in the uranium-rich grains of minerals. Most of it was captured by minerals containing aluminum phosphate - they were found to have the highest concentration of xenon ever found in nature. Secondly, the extracted gas differed significantly in isotopic composition from that normally formed in nuclear reactors. It practically lacked xenon-136 and xenon-134, while the content of lighter isotopes of the element remained the same.
The xenon extracted from the aluminum phosphate grains in the Oklo sample turned out to have a curious isotopic composition (left) that does not match that produced by the fission of uranium-235 (center) and does not resemble the isotopic composition of atmospheric xenon (right). Notably, the amounts of xenon-131 and -132 are higher and the amounts of -134 and -136 are lower than would be expected from uranium-235 fission. Although these observations puzzled the author at first, he later realized that they held the key to understanding the operation of this ancient nuclear reactor.
What is the reason for such changes? Perhaps this is the result of nuclear reactions? Careful analysis allowed my colleagues and I to dismiss this possibility. We also looked at the physical sorting of different isotopes, which sometimes happens because heavier atoms move a little slower than their lighter counterparts. This property is used in uranium enrichment plants to produce reactor fuel. But even if nature could realize such a process on a microscopic scale, the composition of the mixture of xenon isotopes in aluminum phosphate grains would be different from what we found. For example, measured relative to xenon-132, the decrease in xenon-136 (heavier by 4 atomic mass units) would be twice as much as for xenon-134 (heavier by 2 atomic mass units) if physical sorting worked. However, we have not seen anything like it.
After analyzing the conditions for the formation of xenon, we noticed that none of its isotopes was a direct result of the fission of uranium; they were all products of the decay of radioactive isotopes of iodine, which, in turn, were formed from radioactive tellurium, etc., according to the known sequence of nuclear reactions. In this case, different xenon isotopes in our sample from Oklo appeared at different times. The longer a specific radioactive precursor lives, the more delayed the formation of xenon from it. For example, the formation of xenon-136 began only a minute after the start of self-sustaining fission. An hour later, the next lighter stable isotope, xenon-134, appears. Then, a few days later, xenon-132 and xenon-131 appear on the scene. Finally, after millions of years, and much later than the cessation of nuclear chain reactions, xenon-129 is formed.
If the uranium deposits in Oklo had remained a closed system, the xenon accumulated during the operation of its natural reactors would have retained a normal isotopic composition. But the system was not closed, as evidenced by the fact that the Oklo reactors somehow regulated themselves. The most probable mechanism involves the participation in this process of groundwater, which boiled away after the temperature reached a certain critical level. When the water that acted as a neutron moderator evaporated, nuclear chain reactions temporarily stopped, and after everything cooled down and a sufficient amount of groundwater again penetrated into the reaction zone, fission could resume.
This picture makes two important points clear: the reactors could operate intermittently (on and off); large quantities of water must have flowed through this rock, sufficient to wash out some of the xenon precursors, namely tellurium and iodine. The presence of water also helps explain why much of the xenon is now found in aluminum phosphate grains rather than in uranium-rich rocks. The aluminum phosphate grains were probably formed by the action of the water heated by the nuclear reactor after it had cooled to about 300°C.
During each active period of the Oklo reactor, and for some time thereafter, while the temperature remained high, most of the xenon (including xenon-136 and -134, which are generated relatively quickly) was removed from the reactor. As the reactor cooled down, the longer lived xenon precursors (those that would later give rise to xenon-132, -131 and -129, which we found in greater numbers) became incorporated into the growing aluminum phosphate grains. Then, as more water returned to the reaction zone, the neutrons slowed down to the right degree and the fission reaction began again, forcing the cycle of heating and cooling to repeat. The result was a specific distribution of xenon isotopes.
It is not entirely clear what forces kept this xenon in the aluminum phosphate minerals for nearly half the life of the planet. In particular, why did the xenon that appeared in a given cycle of reactor operation not be expelled during the next cycle? Presumably, the structure of aluminum phosphate was able to retain the xenon formed inside it, even at high temperatures.
Attempts to explain the unusual isotopic composition of xenon at Oklo required consideration of other elements as well. Particular attention was drawn to iodine, from which xenon is formed during radioactive decay. Modeling the process of the formation of fission products and their radioactive decay showed that the specific isotopic composition of xenon is a consequence of the cyclic action of the reactor. This cycle is depicted in the three diagrams above.
nature work schedule
After the theory of the origin of xenon in aluminum phosphate grains was developed, we tried to implement this process in a mathematical model. Our calculations have clarified a lot in the operation of the reactor, and the obtained data on xenon isotopes led to the expected results. The reactor at Oklo was "turned on" for 30 minutes and "off" for at least 2.5 hours. Some geysers function in a similar way: they slowly heat up, boil, throwing out a portion of groundwater, repeating this cycle day after day, year after year. Thus, groundwater passing through the Oklo deposit could not only act as a neutron moderator, but also “regulate” the operation of the reactor. It was an extremely efficient mechanism that kept the structure from melting or exploding for hundreds of thousands of years.
Nuclear engineers have a lot to learn from Oklo. For example, how to deal with nuclear waste. Oklo is an example of a long-term geological repository. Therefore, scientists study in detail the processes of migration over time of fission products from natural reactors. They also carefully studied the same ancient fission zone at the Bangombe site, about 35 km from Oklo. The Bangombe reactor is of particular interest because it is shallower than Oklo and Okelobondo and, until recently, more water has passed through it. Such amazing objects support the hypothesis that many types of hazardous nuclear waste can be successfully isolated in underground storage facilities.
Oklo's example also demonstrates how some of the most dangerous types of nuclear waste are stored. Since the beginning of the industrial use of nuclear energy, huge amounts of radioactive inert gases (xenon-135, krypton-85, etc.) formed in nuclear installations have been thrown into the atmosphere. In natural reactors, these waste products are captured and held for billions of years by minerals containing aluminum phosphate.
Ancient Oklo-type reactors can also influence the understanding of fundamental physical quantities, for example, the physical constant, denoted by the letter α (alpha), associated with such universal quantities as the speed of light (see "Non-constant Constants", "In the World of Science", No. 9, 2005). For three decades, the Oklo phenomenon (2 billion years old) has been used as an argument against changes in α. But last year, Steven K. Lamoreaux and Justin R. Torgerson of Los Alamos National Laboratory found that this "constant" varied considerably.
Are these ancient reactors in Gabon the only ones ever formed on Earth? Two billion years ago, the conditions necessary for self-sustaining fission were not too rare, so perhaps other natural reactors will be discovered one day. And the results of the analysis of xenon from the samples could be very helpful in this search.
“The Oklo phenomenon brings to mind the statement of E. Fermi, who built the first nuclear reactor, and P.L. Kapitsa, who independently argued that only a person is capable of creating something like this. However, the ancient natural reactor refutes this point of view, confirming the idea of A. Einstein that God is more sophisticated…”
S.P. Kapitsa
About the author:
Alex Meshik(Alex P. Meshik) graduated from the Faculty of Physics of the Leningrad State University. In 1988 he defended his Ph.D. thesis at the Institute of Geochemistry and Analytical Chemistry. IN AND. Vernadsky. His dissertation was on the geochemistry, geochronology and nuclear chemistry of the noble gases xenon and krypton. In 1996, Meshik joined the Space Research Laboratory at Washington University in St. Louis, where he is currently studying solar wind noble gases collected and brought back to Earth by the Genesis spacecraft.
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