Two billion-year-old nuclear reactor

Prehistoric civilizations have always been a topic of fascination, and no wonder, after all, humans have been on Earth for so short a time in its history that if the history of the planet were compressed into a single day, humans would have appeared in the last two minutes of that day. In the past, there have been frequent claims of the discovery of suspected prehistoric civilizations, the most notable of which would be a two-billion-year-old nuclear reactor.

The story begins in 1972, when the uranium enrichment plant in Pierrelatte, France, collected uranium-containing samples from several mines, and physicist Francis Perrin, using a mass spectrometer to analyze a sample of uranium hexafluoride from the Oklo mine in Gabon, Africa, found that the ratio of uranium-235 to uranium-238 in this sample was significantly low, in other words, the uranium-235 in this sample was much less than the normal value.

I believe we are all familiar with what uranium-235 can do, so this discovery quickly drew strong attention from interested parties, and it didn't take long for a team of researchers consisting of several scientists in related fields to arrive at the Oklo mine site to investigate. The researchers extracted additional mineral samples from several areas of the site, and after analysis, found that the uranium-bearing minerals here did contain much less uranium-235 than normal, but that this was not the work of modern humans.

Further research showed that a significant proportion of nuclear fission products (including five xenon isotopes, neodymium-143, ruthenium-99, and some transuranic elements) were also present in these low uranium-235 samples, which, according to dating, are about two billion years old, and the researchers then came to the startling conclusion that there were multiple nuclear reactors at the Oklo mine The researchers then came to the surprising conclusion that multiple nuclear reactors existed at the Oklo site and that these reactors ceased to operate 2 billion years ago.

(Summary of geological composition, where "1" is the location of the nuclear reactors; "2" is the sandstone deposit; "3" is the uranium-bearing mineral layer; "4 ("4" is a granite-based bedrock)

So how should these 2 billion-year-old nuclear reactors be explained? Is it true that Earth's civilization is constantly reincarnating? In this regard, prehistoric civilization enthusiasts certainly hold a positive attitude, and the reasons they give are mainly the following three points.

1. A sufficiently high concentration of uranium-235 is a necessary condition for a nuclear reactor.

2. Generally speaking, when a U-235 nucleus fissions, it produces very fast "fast neutrons" with an average energy of 2 Mev, while other U-235 nuclei cannot effectively capture the "fast neutrons", which will, Therefore, the nuclear reactor must be equipped with a neutron moderator to ensure the normal operation of the nuclear reactor.

3. Nuclear reactors need to be in a controlled state, otherwise, uncontrollable chain reactions will occur.

Prehistoric civilization enthusiasts believe that all three of these points require manual operation, so these 2 billion-year-old nuclear reactors should prove that civilization existed on Earth long before humans.

Of course, the scientific community does not easily agree with the idea that "Earth's civilization is constantly reincarnating", and after more in-depth research, scientists have provided an explanation based on natural phenomena.

First of all, the problem with uranium-235 concentration, uranium-235 is a radioactive isotope, its half-life is about 704 million years, that is, for uranium-containing minerals in uranium-235, every 704 million years, its quantity will be reduced by half.

According to scientists' estimates, 2 billion years ago, the proportion of uranium-235 in uranium-bearing minerals at the Okoro site could reach 3.7% of the uranium content, which is already more than the minimum value (3%) required for a nuclear reactor, and with the help of oxygen, water, and bacteria, this uranium-235 could be enriched to start a nuclear fission reaction.

Then there is the issue of neutron moderators. Scientists believe that the low terrain where these reactors are located makes it easy for water to collect here, and it is this water that acts as the "role" of the neutron moderator.

As for the controlled problem of nuclear reactors, scientists explain it this way: when the nuclear fission reaction occurs, the water here will continue to evaporate because of the high temperature, and less and less water means that the neutron moderator in these nuclear reactors is also less and less when the water is evaporated, the uranium-235 here will not be able to effectively capture the "fast neutron When the water is evaporated, the uranium-235 here cannot effectively capture the "fast neutrons," so the reactor gradually stops operating.

When the reactor cools down, the water collects here again (because of the lower terrain), and the fission reaction continues until the water is evaporated again. It should be noted that the actual situation confirms this statement, and subsequent studies have shown that these nuclear reactors have been in intermittent operation, and this has continued for hundreds of thousands to millions of years.

As you can see, the explanation given by scientists is reasonable, that is, the nuclear reactors of 2 billion years ago do not prove that civilization existed on Earth long before humans.

On the other hand, if Earth's civilizations were reincarnating and some of them had reached the technological level of being able to build nuclear reactors, then they would certainly have left a lot of artificial traces in the Earth's strata, but we have never found anything definite in this regard, so we can also speculate that prehistoric civilizations should not exist, and human civilization should be the only civilization on Earth The only civilization that has existed so far.