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Nature’s Nuclear Reactors: The 2-Billion-Year-Old Natural Fission Reactors in Gabon, Western Africa

The views expressed are those of the author and are not necessarily those of Scientific American.


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Two billion years ago— eons before humans developed the first commercial nuclear power plants in the 1950s— seventeen natural nuclear fission reactors operated in what is today known as Gabon in Western Africa [Figures 1 and 2]. The energy produced by these natural nuclear reactors was modest. The average power output of the Gabon reactors was about 100 kilowatts, which would power about 1,000 lightbulbs. As a comparison, commercial pressurized boiling water reactor nuclear power plants produce about 1,000 megawatts, which would power about ten million lightbulbs.

Figure 1: The geology of the Franceville Basin. The natural nuclear reactors are located at Oklo and Bangombé. Other uranium deposits (which did not host natural nuclear reactors) are found at Boyindzi, Okélobondo,  and Mikouloungou. Figure taken from Mossman et al., 2008.

Despite their modest power output, the Gabon nuclear reactors are remarkable because they spontaneously began operating around two billion years ago, and they continued to operate in a stable manner for up to one million years. Further, at the Gabon reactors many of the radioactive products of the nuclear fission have been safely contained for two billion years, providing evidence that long-term geologic storage of nuclear waste is feasible.

The possibility that natural nuclear reactors may have operated on the ancient Earth was first hypothesized by scientists in the 1950s, when commercial nuclear reactors were first being developed and becoming popular. Notably, in a 1956 paper Paul Kuroda theorized the conditions under which nuclear fission could spontaneously develop and be sustained.

Figure 2: Geologic cross-section of the Oklo and Okélobondo uranium deposits, showing the locations of the nuclear reactors. The last reactor (#17) is located at Bangombé, ~30 km southeast of Oklo. The nuclear reactors are found in the FA sandstone layer. Figure taken from Mossman et al., 2008.

These conditions are very similar to the conditions under which nuclear reactions are sustained in manmade nuclear reactors.

In manmade nuclear reactors, power is generated when uranium (or sometimes plutonium) atoms fission or break into parts, releasing nuclear energy. As a result of this fission, fast neutrons are produced. If slowed down by a moderating substance (typically water or graphite), these neutrons may induce other atoms to undergo fission. When carefully controlled, a self-sustaining “critical” reaction of nuclear fission can generate power for a long time—until the nuclear fuel becomes depleted of fissionable atoms.  The energy produced by nuclear fission is generally used to heat water and produce steam, which turns large turbines that produce electricity.

Uranium is the most common fuel used in commercial nuclear power plants. Uranium has three isotopes: uranium-238, uranium-235, and uranium-234. Because of nuclear properties, uranium-235 is most likely to fission when bombarded with neutrons. However, on Earth today uranium-235 comprises only 0.720% of uranium while uranium-238 is the dominant isotope of uranium (99.275%) and uranium-234 is present only in trace amounts (0.006%). The isotopic distribution of uranium is remarkably uniform in Earth’s crust, so all uranium ore mined today contains about 0.720% uranium-235. In order to increase the efficiency of the nuclear chain reactions, uranium-235 is artificially enriched to approximately 3% before uranium is used as a fuel in nuclear power plants.

To control nuclear chain reactions in manmade reactors, water is used as both a moderator (something that slows down neutrons) and as a coolant. To control or shut down a nuclear chain reaction, control rods are used. These control rods consist of elements (such as silver, iridium, and cadmium) that are capable of absorbing neutrons without undergoing fission. Boron (another element very good at absorbing neutrons without undergoing fission) can also be added to water surrounding a nuclear reactor to moderate or shut down a nuclear reaction. 

Thus, in manmade nuclear reactors the concentration of uranium, the abundance of uranium-235, and the presence of neutron moderators and absorbers are all carefully controlled. These same factors play a role in natural nuclear reactors.

There are four conditions which must be met in order for a stable natural nuclear reactor to develop:

1.    The natural uranium ore must have a high uranium content and must have a thickness (at least ~2/3 of a meter) and geometry that increase the probability of spontaneous, natural fission in uranium-238 inducing a self-sustaining fission reaction in uranium-235.

2.    The uranium must contain significant amount of fissionable uranium-235.

3.    There must be a moderator, something that can slow down the neutrons produced when uranium fissions.

4.    There must not be significant amounts of neutron-absorbing elements (such as silver or boron), which would inhibit a self-sustaining nuclear reaction, in the vicinity of the uranium.

Kuroda pointed out that the conditions necessary for a natural nuclear reactor to develop could have been present in ancient uranium deposits. Today, there are many concentrated uranium deposits, but—as you might be relieved to hear— it is impossible for nuclear fission to spontaneously develop. This is because the concentration of uranium-235 is too small (only 0.720% of uranium, as I mentioned above) for a self-sustaining fission reaction to be sustained. However, the relative proportions of uranium-238 and uranium-235 have been changing over the history of the Earth.

When the Earth was first formed, uranium-235 comprised more than 30% of uranium [Figure 3]. The proportion of uranium-235 relative to uranium-238 has been changing because isotopes of uranium are radioactive and decay to other elements over time. However, uranium-238 decays at a much slower rate than uranium-235, so uranium-235 has become more and more depleted (relative to uranium-238) over the Earth’s 4.54 billion year history. Billions of years ago, the abundance of uranium-235 in uranium ore was high enough for a self-sustaining fission reaction to develop. Two billion years ago, there would have been about 3.6% uranium-235 present in uranium ore— about the proportion of uranium-235 used in pressurized boiling water reactor nuclear power plants.  So, in theory, an ancient (billions of years old) uranium deposit could have spontaneously developed a self-sustaining nuclear fission, assuming the uranium was concentrated enough, there was a substance (probably water) to act as a moderator, and there were not significant amounts of neutron-absorbing elements nearby.

Figure 3: Uranium-235 / uranium-238 in the Earth’s crust over time. The x-axis is in units of millions of years. When the Gabon natural nuclear reactors operated about 2 billion years ago, the Earth’s crust contained approximately 3.68% uranium-235. Figure taken from Gauthier-Lafaye and Weber, 2003.

Sixteen years later, in 1972, just such a natural nuclear reactor was discovered in Gabon. The French had been mining uranium in Gabon—their former colony— for use in nuclear power plants. During a routine isotopic measurement of uranium ore from Gabon, the French noticed something very strange: the uranium ore did not have a uranium-235 content of 0.720%. Rather, the uranium ore was anomalously depleted in uranium-235, containing only 0.717%. This may sound like a tiny variation, but this discrepancy was very alarming for the French nuclear officials. You see, uranium-235 in Earth’s crust (and even in moon rocks and in meteorites) varies very little from the average value of 0.720%. Since uranium-235 can be used to make nuclear bombs, it was very important to account for this “missing” uranium-235.

Fortunately, the nuclear officials and scientists eventually remembered the old publications of Kuroda and others, and they soon realized that the anomalous uranium from Gabon provided evidence of something extraordinary—the first natural nuclear reactor ever discovered. The uranium ore was depleted in uranium-235 because two billion years ago some of that uranium-235 had been used up in a natural nuclear reactor. Eventually, sixteen natural nuclear reactors were discovered in uranium mines at Oklo [Figure 1]. An additional seventeenth natural nuclear reactor was also discovered at Bangombé, located about 30 km to the southeast of Oklo.

The natural nuclear fission reactors in Gabon are unique— to date, no additional natural nuclear reactors have been discovered. Unfortunately for science, the sixteen natural nuclear reactors at Oklo have been destroyed, completely mined out for their rich uranium ore. Scientists only have limited uranium samples (often with sparse field notes) on which to conduct their study of these extraordinary nuclear reactors. In the late 1990s, there was danger that the last natural nuclear reactor at Bangombé would be mined as well. In 1997 scientist Francois Gauthier-Lafaye (and co-authors) wrote a plea to the journal Nature advocating that mining of the Bangombé uranium be stopped. They wrote,

The last known natural fission reactor on Earth is likely to be mined this year. Because these natural reactors are unique, at least one should be preserved for present and future research programs… All the reactors except one are located in the most important uranium deposit of Gabon’s Franceville basin, at Oklo… This deposit will be completely mined out soon, in 1998. Future work on these reactors will therefore have to rely on previously collected samples, many of which are poorly documented and are out of their geological context… Work is still possible, however, in a reactor located in the very small uranium deposit of Bangombe 30 km from Oklo. We propose that this unique, scientifically important deposit be preserved for present and future research. This deposit is no less unique, and certainly more irreplaceable, than the most valued specimens from the Moon and Mars.

Since the discovery of the Gabon natural nuclear reactors in 1972, scientists have been puzzling over why these reactors developed in Gabon two billion years ago and—seemingly— have developed at no other place or time on Earth.  Scientists are still working to understand the Gabon reactors, but over the past forty years, they have managed to tease out some of the details of how these nuclear reactors operated and were preserved in the geologic record.

You might be wondering why natural nuclear reactors developed in uranium deposits only two billion years ago, when uranium-235 had already been depleted to less than 4% of uranium. Wouldn’t fission reactors have been even more likely to develop earlier in Earth’s history, when the uranium-235 levels were even higher? Remember that a high isotopic abundance of uranium-235 is just one of four conditions required for a natural nuclear reactor to develop. Another important condition is that uranium be concentrated.  It turns out, no significant concentrations of uranium developed on Earth prior to about two billion years ago. The reason for this is simple: oxygen. 

In most rocks on Earth, uranium is present only in trace quantities (parts per million or parts per billion). Uranium is generally concentrated by hydrothermal circulation, which picks up uranium and concentrates it in a new hydrothermal deposit. In order for this hydrothermal circulation to concentrate uranium, that uranium must be soluble (able to be picked up in water). However, uranium solubility is a little tricky. When uranium is in its reduced form (U4+), uranium tends to form very stable compounds that are not easily brought into solution. However, when uranium is in its oxidized form (U6+), uranium easily forms soluble complexes.  There was very little oxygen in Earth’s very early atmosphere. So, it would have been very difficult to concentrate a significant amount of uranium since there was no oxygen to transform uranium into its soluble forms.

However, starting around 2.4 billion years ago, there was an event called the “Great Oxidation Event” during which the levels of oxygen in the atmosphere rose significantly, from <1% to ≥15%. This significant rise in atmospheric oxygen was a result of photosynthetic cyanobacteria producing oxygen. For awhile, the oxygen produced by these bacteria was taken up by minerals which became oxidized. However, when these minerals became saturated in oxygen, this oxygen began to accumulate in the atmosphere. This increase of atmospheric oxygen allowed uranium to become mobile and to be concentrated through hydrothermal circulation.

In Gabon rich uranium deposits formed about two billion years ago in a marine sandstone layer in the Franceville Basin [Figure 2]. The lower part of this sandstone layer originally contained many small bits of uranium-bearing minerals (monazite, thorite, probably uraninite). These minerals were dispersed until the sandstone became infiltrated with oxidizing waters around two billion years ago. These oxidizing waters dissolved the uranium-bearing minerals and concentrated the uranium in several deposits towards the top of the sandstone layer. The uranium actually became extraordinarily well-concentrated. Fission of uranium could have begun when the uranium concentration reached 10%; the Gabon uranium deposits in which natural nuclear reactors developed contained about 25% to 60% uranium.

Thus, two billion years ago in Gabon two of the four conditions for the development of a natural nuclear fission reactor were met: there were significant concentrations of uranium, and this uranium still contained a significant amount of highly-fissionable uranium-235. The other two conditions were also met. Water was able to percolate into the permeable sandstone containing the uranium deposits, and this water acted as the neutron moderator. There were also no significant quantities of neutron-absorbing elements to inhibit the self-sustaining fission reaction. All of this provided the perfect recipe for a natural nuclear fission reactor.

The Gabon natural nuclear reactors operated for several hundred thousand years.The reactors likely switched on and off at regular intervals. The nuclear fission began, moderated by water, and continued until all available water boiled away as a result of nuclear heat. The reactions could not begin again until new water infiltrated the reactor. This on-and-off behavior of the reactors probably operated over a timescale of a few hours, analogous to the way in which geysers erupt periodically as a result of groundwater recharge. Possibly because of this periodic on-and-off behavior, the Gabon natural nuclear reactors were extremely stable. There was not a single melt-down; the reactors operated in a stable fashion for up to 1 million years.  Eventually, the fissionable uranium-235 was depleted, and the Gabon natural nuclear reactors shut down.

The long-term preservation of the Gabon natural nuclear reactors is perhaps even more remarkable than the reactors themselves. These nuclear reactors have survived two billion years of geologic time. The preservation of the Gabon reactors is a result of two factors: the long-term stability of the African craton, and the isolation of the uranium deposits from oxidizing groundwater. The natural nuclear reactors in Gabon seem to have been largely protected by enveloping carbonaceous substances and clay, which created and maintained reducing (low oxygen) conditions which largely inhibited the movement of uranium and other radioactive products of nuclear fission.

Perhaps natural nuclear reactors operated in several other places on Earth two billion years ago. Perhaps we haven’t yet found evidence of other natural nuclear reactors, or perhaps the radioactive remains of other natural nuclear reactors have long since been eroded or oxidized and dissolved. As of today, however, the Gabon natural nuclear reactors remain “unique, and certainly more irreplaceable, than the most valued specimens from the Moon and Mars.” Since the Gabon reactors were so stable, operated over such a long time, and have been preserved for two billion years, scientific study of these unique natural reactors provides important insights relevant to anthropogenic nuclear power and nuclear waste storage. Mother Nature, it seems, knows how to operate a nuclear reactor.

References:

Bourdon et al, 2003. Introduction to U-series Geochemistry. In: Uranium-Series Geochemistry. Reviews in Mineralogy and Geochemistry, vol. 52: 1-22.

Gauthier-Lafaye, 2006. Time constraint for the occurrence of uranium deposits and natural nuclear fission reactors in the Paleoproterozoic Franceville Basin (Gabon). Geological Society of America Memoirs, vol. 198: 157-167.

Gauthier-Lafaye et al., 1997. The last natural nuclear fission reactor. Nature, vol. 387: 337.

Gauthier-Lafaye and Weber, 2003. Natural nuclear fission reactors: Time constraints for occurrence and their relation to uranium and manganese deposits and to the evolution of the atmosphere. Precambrian Research, vol. 120, no. 1-2: 81-101.

Hollinger and Devillers, 1981. Contribution à l’étude de la température dans les réacteurs fossils d’Oklo par la mesure du rapport isotopique du lutétium. Earth and Planetary Science Letters, vol. 52: 76-84.

Kuroda, 1956. On the nuclear physical stability of uranium minerals. Journal of Chemical Physics, vol. 25: 781-782.

Meshik, A. 2005. The Workings of an Ancient Nuclear Reactor. Scientific American, vol. 293, no. 5: 82-91.

Mossman et al., 2008. Carbonaceous substances in Oklo reactors—Anologue for permanent deep geologic disposal of anthropogenic nuclear waste. Reviews in Engineering Geology, vol. 19: 1-13.

Porcelli and Swarzenski, 2003. The Behavior of U- and Th- series Nuclides in Groundwater. In: Uranium-Series Geochemistry. Reviews in Mineralogy and Geochemistry, vol. 52: 317-362.

 *

About the Author: Evelyn Mervine is currently pursuing her PhD in Marine Geology & Geophysics in the joint program between MIT and Woods Hole Oceanographic Institution. She writes a geology blog named Georneys, which recently joined the AGU blog network. In March and April of 2011, Evelyn regularly interviewed her father, a nuclear engineer, about the ongoing Fukushima Daiichi nuclear power plant disaster in Japan. Her interviews with her father became extremely popular and were distributed far and wide on the internet. She is currently compiling a book of all of the nuclear interviews and plans to interview her father again as the Fukushima disaster approaches the four-month mark. She can be found on Twitter as @GeoEvelyn.

The views expressed are those of the author and are not necessarily those of Scientific American.

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Ed. note: thanks to readers for pointing two errors, now fixed: it is ten million, not one million lightbulbs that a manmade reactor can power, and it is nuclear, not chemical energy that is released in it.






Comments 33 Comments

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  1. 1. lamorpa 8:17 am 07/13/2011

    "100 kilowatts, which would power about 1,000 lightbulbs."

    100,000 watts = 1,000 lightbulbs (100 watts per bulb)

    ("boiling water reactor nuclear power plant"s)
    "1,000 megawatts, which would power about one million lightbulbs."

    1,000,000,000 watts = 1,000,000 lightbulbs (1,000 watts per bulb)

    Why so bright for the man-made reactors?

    Link to this
  2. 2. candide 8:39 am 07/13/2011

    Bad math, even here. Doesn’t say much for our schools.

    Of course it should be: "1,000 megawatts, which would power about TEN million lightbulbs."

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  3. 3. lamorpa 8:49 am 07/13/2011

    I wouldn’t even say bad math just in terms of computation. I was pretty sure the latter number of lightbulbs was off by an order of magnitude as I read it. A check with fingertip decade counting told me it was wrong in less than 5 seconds. How does something like this slip through in proof reading? (I say this because I respect SA and expect high quality from them)

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  4. 4. jtdwyer 9:38 am 07/13/2011

    The article states:
    "Further, at the Gabon reactors many of the radioactive products of the nuclear fission have been safely contained for two billion years, providing evidence that long-term geologic storage of nuclear waste is feasible."

    Sorry, but the evidence does not support the idea that successful geologic storage constructed by humans is feasible, only that it may be possible in some favorable conditions.

    Conditions may not be favorable for radioactive waste stored in North American salt deposits if the Arctic ice sheet quickly melted, for example.

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  5. 5. 04rearo 9:56 am 07/13/2011

    "In manmade nuclear reactors, power is generated when uranium (or sometimes plutonium) atoms fission or break into parts, releasing chemical energy."

    chemical energy?

    Is this energy not due to nuclear forces?

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  6. 6. Evelyn_Mervine 10:37 am 07/13/2011

    Thanks, lampora, candide, and 04rearo. I’ve asked the editor to fix those errors. Thanks for being my proofreaders/math-checkers. I apologize for the errors.

    jtdlawyer– certainly, anthropogenic nuclear waste storage is very challenging. We are nowhere close to making such storage possible. However, taking a scientific look at how much of the Gabon nuclear waste was contained (and not all of it was!) could be helpful as we humans try to figure out what to do with
    our own nuclear waste.

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  7. 7. lamorpa 11:13 am 07/13/2011

    Evelyn: I’m sure you are an infinitely better geologist than I am.

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  8. 8. Evelyn_Mervine 11:18 am 07/13/2011

    Thanks! And I really do appreciate you catching my math error :-) .

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  9. 9. jtdwyer 12:18 pm 07/13/2011

    Thanks for your reply. These fascinating natural laboratories certainly do provide some very real very long term observational data for study. I hope we can use it to develop reliable nuclear waste storage technology. It’s certainly too late to ignore long term storage demands.

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  10. 10. skiphuffman 12:55 pm 07/13/2011

    Was the Gabon uranium deposit formed in a unique manner? Or are there other veins of uranium ore that fulfilled two or three of the necessary conditions for criticality?

    Also, how deep were these deposits at the time they were fissioning? And were they sub oceanic or terrestrial?

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  11. 11. sonoran 1:39 pm 07/13/2011

    That was a very interesting article! One thing that struck me was that it seemed in the natural reactor the reaction was effectively shut down when water (the neutron moderator and coolant) was removed. That doesn’t seem to be the case in the enriched uranium reactors of human design. Is that because of the remaining lighter radioactive isotopes? Did the intermittent natural process not allow these isotopes to build up sufficiently to cause enough heat to meld the deposit after the coolant was removed?

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  12. 12. Evelyn_Mervine 3:02 pm 07/13/2011

    Does anyone know if the last natural nuclear reactor was ever mined? I’d really like to know, but I had trouble finding out much information.

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  13. 13. uli 3:22 pm 07/13/2011

    Sonoran:

    There is no difference in the shutdown of natural or man-made reactors. In both cases the fission chain reaction stops when insuficient moderation is available to sustain the chain reaction. And in both cases, the fission products still generate heat after the chain reaction stops.

    However in a natural reactor, the heat from the decay of the fission products was probably so low that it was carried away by conduction through the soil materials.

    In the case of the man-made reactor the heat generated by fission products is still sufficiently significant (even years after the chain reaction stops)that it requires cooling. This need for cooling decreases over time, and eventually is low enough so that spent fuel can be air cooled in dry storage casks.

    Ulrich Decher Phd Nuclear Engineering

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  14. 14. Evelyn_Mervine 3:40 pm 07/13/2011

    Thanks, Ulrich!

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  15. 15. Oliver K. Manuel 3:49 pm 07/13/2011

    Thank you, Evelyn, for this interesting report.

    I started research on the origin of the Solar System and its elements with the late Professor Paul Kazuo Kuroda in 1960.

    In 1945, when a faculty member at the Imperial University of Tokyo, Kuroda had been sent to Hiroshima to discover the mysterious weapon that vaporized that city on August 6, 1945.

    He first reported natural nuclear reactors ["On the nuclear physical stability of the uranium minerals", Journal Chem. Phys. 25 (1956) 781; "On the infinite multiplication constant and the age of the uranium minerals", Journal Chem. Phys. 25 (1956) 1295].

    A book, in progress, will report this surprising introduction to our findings about the origin of the Solar System and nuclear energy:

    "The forces that cause centers of atoms, stars and galaxies:

    a.) To explode violently on some occasion, and
    b.) To release streams of continuous energy at other times.

    The atomic bomb that destroyed Hiroshima in 1945 and the stellar explosion that gave birth to the Solar System five billion years (5 Gyr) earlier will turn out to be powered by the same nuclear force that generates the continuous flow of energy from nuclear reactors and the flow of energy from the Sun that sustains life.

    This is also an expression of amazement that the products of Genesis of the atomic forms of matter that comprise us are capable of comprehending that the Dissolution of compact, nuclear forms of matter is also the process that now sustains our lives and maintains the entire cosmos as a dynamic, vibrant system."

    A very grateful former student
    of Professor Paul Kazuo Kuroda,
    Oliver K. Manuel,
    Former NASA P. I.
    for Apollo Samples

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  16. 16. Evelyn_Mervine 4:03 pm 07/13/2011

    Oliver: Thank you so much for posting a comment! How wonderful that you knew Paul Kuroda. I look forward to reading the book you mentioned!

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  17. 17. Oliver K. Manuel 4:26 pm 07/13/2011

    Thanks, Evelyn, for your kindness.

    The dogma of our Sun as a giant ball of Hydrogen is starting to crumble faster than a cookie in hot coffee!

    That was apparently part of a 1972 decision by world leaders to use "Global Climate Change" as a common enemy that would unite nations, end nationalism, and end the threat of mutual nuclear annihilation.

    See the NASA news story by NASA’s Dr. Tony Phillips on "Dark fireworks on the sun" and comments from readers.

    http://www.physorg.com/news/2011-07-dark-fireworks-sun.html

    Again, thanks for your kindness.

    All is well,
    Oliver

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  18. 18. Harvey_J_Goldberg 5:19 pm 07/13/2011

    Today’s natural uranium can sustain a nuclear reaction. It needs to be enriched when it is moderated with natural water. The USA’s production reactors were moderated with ultra pure carbon as were (are?) the USSR’s (Russian) production reactors, e.g. Chernoble. Also, the Canadians use a heavy water moderator and can "burn" natural uranium.

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  19. 19. Evelyn_Mervine 5:27 pm 07/13/2011

    Thanks for the clarification/comment, Harvey. You are correct about some nuclear reactors using un-enriched uranium. I think there’s still no risk of a natural nuclear reactor developing today since it’s unlikely that pure carbon or heavy water will be available to act as a moderator in nature.

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  20. 20. robert schmidt 6:29 pm 07/13/2011

    @jtdwyer, "Sorry, but the evidence does not support the idea that successful geologic storage constructed by humans is feasible…may be possible in some favourable conditions" do you not understand the word feasible? You just contradicted yourself. If nature is able to do it then it is feasible for us to do it. That doesn’t mean it is easy or highly probable, just possible. Unless you are implying that nature has some special magic powers humans don’t possess.

    "Conditions may not be favorable for radioactive waste stored in North American salt deposits if the Arctic ice sheet quickly melted, for example." don’t think that was what the author was implying or that that is the definition of feasible. You are in such a rush to show everyone how wrong they are that you don’t stop to check how wrong you might be.

    I thought it was a well written and interesting article.

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  21. 21. Oliver K. Manuel 9:46 am 07/14/2011

    RE: Energy from 1. reactors, 2. bombs, and 3. the Sun:

    1. Radioactive waste – concentrated energy – can be contained and used to generate power (e.g., steam for turbines). Nuclear industry must do that instead of reaping profits from easy energy and storing waste products for the next generation.

    2. Neutron repulsion powers A-bombs, reactors, 65% of solar energy [J. Fusion Energy 20, 197 (2003)].

    3. Book: "A Journey to the Core of the Sun," by O. K. Manuel, in progress (Connor Court Publishing Pty Ltd)

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  22. 22. Dr. Strangelove 9:49 pm 07/14/2011

    Evelyn,

    I believe we can safely store nuclear waste deep underground. France has one right? The geologic rock in that underground storage has not moved in a million years and geologists say will not move for another million years.

    Btw, why don’t we drop nuclear waste in the Mariana trench? If a few feet of water can contain the radiation in nuclear plants, certainly 35,000 feet can do a better job.

    I think the danger in Fukushima plant was exaggerated. Has anybody died there due to radiation? Ask your father, is it true that you will get more radiation from chemotherapy than standing on the blown Fukushima reactor for one hour?

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  23. 23. tblakeslee 2:38 pm 07/15/2011

    There are many other natural nuclear reactions in nature. For example, lightning strikes transmuted many of the elements found on earth today. By using these natural reactions nuclear power can be created without dangerous waste products. Focus Fusion is testing a reactor based on these principles. Also Brillouin Energy and Defkalion are testing smaller clean reactors for distributed power generation.
    http://www.renewableenergyworld.com/rea/blog/post/2011/07/renewables-generate-more-than-nuclear-eia-first-quarter-report

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  24. 24. Meisam 2:37 pm 07/18/2011

    I studying on igneous uranium deposits as a part of my thesis. I liked your article very much.

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  25. 25. Evelyn_Mervine 12:29 am 07/19/2011

    Thanks!

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  26. 26. Meisam 2:32 am 07/20/2011

    Unfortunately uranium can easily disperse in water and contaminate it. Uranium has two oxidation states, U4+ and U6+. U6+ is highly soluble in water, in contrast to U4+. If we bury the radioactive waste, uranium can become oxidized and dissolve in the water. So it will contaminate the whole body of water nearby.

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  27. 27. Dr. Strangelove 9:58 pm 07/24/2011

    I don’t mean exposed uranium waste. Put the nuclear waste in concrete and lead container, and store the container deep underground or deep undersea. Eventually the container would degrade and leak radiation but that would take many years and the earth and seawater will be the radiation shield. I think that’s safer than current practice of storing the waste in nuclear plants.

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  28. 28. dmbeaster 8:57 pm 08/3/2011

    There is nothing unique about the formation of these uranium deposits. Uranium ores are typically located in these types of sedimentary formations (here, sandstone) – a layer that for various different reasons allows water-borne uranium solution to precipitate in the host rock (usually along an oxidation/reduction zone that brings the uranium out of solution). The uranium is not necessarily deposited when the sedimentation for the host rock is first deposited, but subsequently as water percolates through the existing rock. For this deposit, I have read that geologists believe the deposition of the sandstone host rock and the uranium was fairly close in time. It is likely that in the 2 – 2.5 billion years ago time frame, other such veins were formed that could have allowed a nuclear reaction to occur (there are 16 reactor locations discovered in this rock formation), but extremely unlikely that those were preserved from 2 billion years ago when the necessary ratio of U235 existed to cause the reaction.

    It is probably impossible to know how deep the deposits were when fissioning, or whether they were located in an ocean or continental terrane. You can usually tell the environment existing when the host rock was created, which in this case are believed to be a fluviodeltaic deposit (water borne sediment from erosion settling out in any of a number of different types of environments). But the environment at the time of the subsequent deposit of the uranium compounds and then fissioning to my knowledge cannot be determined. If as believed by some the formation of the host rock, the uranium deposits, and the fissioning occurred relatively close together in time, that would suggest a shallow deposit in a continental terrane (sediment basin). It is indeed incredible that relatively undisturbed rocks of that age can be found at all. Rocks of that age can be found, but they are almost always significantly metamorphosed or otherwise disturbed so that the evidence of earlier fissioning would have been hopelessly obscured.

    It cannot be stressed strongly enough how remarkable it is that this formation was still relatively intact and accessible by surface mining 2 billion years later (my recollection is that the reactors were less than 500 feet below the surface- there are pictures of the mining site showing the location of the reactors in relation to the cut in the ground for the mine).

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  29. 29. dmbeaster 8:59 pm 08/3/2011

    Uh, 28 was supposed to show as a response to 10.

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  30. 30. Reddie 3:01 pm 04/8/2012

    this is not possible since earth wasn’t cool enough to be in a liquid form

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  31. 31. daosipc 11:33 pm 10/19/2012

    This link explains this subject very clearly: http://falundafa.org/book/eng/lecture1.html#4
    ———————————-
    To give another example of a more remote age, the Gabon Republic in Africa has uranium ore. This country is relatively underdeveloped. It cannot make uranium on its own and exports the ore to developed countries. In 1972, a French manufacturer imported its uranium ore. After lab tests, the uranium ore was found to have been extracted and utilized. They found this quite unusual and sent out scientists to study it. Scientists from many other countries all went there to investigate. In the end, this uranium mine was verified as a large-scale nuclear reactor with a very rational layout. Even our modern people cannot possibly create this, so when was it built then? It was constructed 2 billion years ago and was in operation for 500 thousand years. Those are simply astronomical figures, and they cannot be explained at all with Darwin’s theory of evolution. There are many such examples. What today’s scientific and technological community has discovered is sufficient to change our present textbooks. Once humankind’s conventional mentalities form a systematic way of working and thinking, new ideas are very difficult to accept. When the truth emerges, people do not dare to accept it and instinctively reject it. Due to the influence of traditional conventions, no one today has systematically compiled such findings. Thus, human concepts always lag behind developments. Once you speak of these things, there will be people who call them superstitious and reject them—despite their already having been discovered. They are just not yet publicized widely.

    Link to this
  32. 32. katesisco 1:23 pm 02/14/2013

    I, like the rest of your commentators thank you, and am astonished by this effect. The closest our science has come is the Tokaimura criticality in Japan 1999.
    Excerpt: The accident

    On 30 September three workers were preparing a small batch of fuel for the JOYO experimental fast breeder reactor, using uranium enriched to 18.8% U-235. It was JCO’s first batch of fuel for that reactor in three years, and no proper qualification and training requirements had been established to prepare those workers for the job. They had previously used this procedure many times with much lower-enriched uranium – less than 5%, and had no understanding of the criticality implications of 18.8% enrichment. At around 10:35, when the volume of solution in the precipitation tank reached about 40 litres, containing about 16 kg U, a critical mass was reached.

    At the point of criticality, the nuclear fission chain reaction became self-sustaining and began to emit intense gamma and neutron radiation, triggering alarms. There was no explosion, though fission products were progressively released inside the building. The significance of it being a wet process was that the water in the solution provided neutron moderation, expediting the reaction. (Most fuel preparation plants use dry processes.)

    The criticality continued intermittently for about 20 hours. It appears that as the solution boiled vigorously, voids formed and criticality ceased, but as it cooled and voids disappeared, the reaction resumed. The reaction was stopped when cooling water surrounding the precipitation tank was drained away, since this water provided a neutron reflector. Boric acid solution (neutron absorber) was finally was added to the tank to ensure that the contents remained subcritical. These operations exposed 27 workers to some radioactivity. The next task was to install shielding to protect people outside the building from gamma radiation from the fission products in the tank. Neutron radiation had ceased.

    Indeed amazing that this rock basin still survives.

    Link to this
  33. 33. raomap 8:29 am 07/17/2013

    LATEST RESEARCH PAPER RELATED TO THE CURRENT TOPIC:

    M.A. Padmanabha Rao, Discovery of Self-Sustained 235-U Fission Causing Sunlight by Padmanabha Rao Effect,
    IOSR Journal of Applied Physics (IOSR-JAP), Volume 4, Issue 2 (Jul. – Aug. 2013), PP 06-24, http://www.iosrjournals.org/iosr-jap/papers/Vol4-issue2/B0420624.pdf

    EXCERPTS OF THE PAPER: Sunlight phenomenon being one of the most complex phenomena in science evaded from previous researchers. Understanding the phenomenon needed advanced knowledge in the fields of nuclear physics, X-ray physics, and atomic spectroscopy. A surprise finding, optical emission detected from Rb XRF source in 1988 led to the discovery of a previously unknown atomic phenomenon causing Bharat radiation emission followed by optical emission from radioisotopes and XRF sources reported in 2010 [10]. The same phenomenon was found causing the Sunlight. However, it took nearly 25 years of research to reach the current level of understanding the Sunlight
    phenomenon reported here.

    BREAKTHROUGHS:
    (1) On the basis of fusion, many solar lines could not be identified previously and what causes these lines remained puzzling. Though 11 solar lines could be identified by other researchers, they became questionable. The significant breakthrough has come when it became possible now to identify as many as 153 lines on the basis of uranium fission taking place on Sun’s core surface. Surprisingly, the fission products released in Chernobyl reactor accident in 1986 also seem to be present in solar flares.
    (2) Explained what are Sun’s dark spots and their cause.
    (3) For the first time, it is shown what constitutes Dark Matter and showed existence of Dark Matter in Sun.
    (4) It is explained with unprecedented detail how Bharat Radiation from fission products (radioisotopes) causes Sunlight by an atomic phenomenon known as Padmanabha Rao Effect.

    Link to this

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