[Dallas59]

A natural nuclear fission reactor is a uranium deposit where analysis of isotope ratios has shown that self-sustaining nuclear chain reactions have occurred. The existence of this phenomenon was discovered in 1972 at Oklo in Gabon, Africa by French physicist Francis Perrin. The conditions under which a natural nuclear reactor could exist had been predicted in 1956 by P. Kuroda. The conditions found were very similar to what was predicted.

The natural nuclear reactor formed when a uranium-rich mineral deposit became inundated with groundwater that acted as a neutron moderator, and a nuclear chain reaction took place. The heat generated from the nuclear fission caused the groundwater to boil away, which slowed or stopped the reaction. After cooling of the mineral deposit, short-lived fission product poisons decayed, the water returned and the reaction started again. These fission reactions were sustained for hundreds of thousands of years, until a chain reaction could no longer be supported.
Fission of uranium normally produces five known isotopes of the fission-product gas xenon; all five have been found trapped in the remnants of the natural reactor, in varying concentrations. The concentrations of xenon isotopes, found trapped in mineral formations 2 billion years later, make it possible to calculate the specific time intervals of reactor operation: approximately 2 hours and 30 minutes.

A key factor that made the reaction possible was that, at the time the reactor went critical, the fissile isotope 235U made up about 3% of the natural uranium, which is comparable to the amount used in some of today's reactors. (The remaining 97% was non-fissile 238U.) Because 235U has a shorter half life than 238U, and thus decays more rapidly, the current abundance of 235U in natural uranium is about 0.7%. A natural nuclear reactor is therefore no longer possible on Earth without heavy water.
The Oklo uranium ore deposits are the only known sites in which natural nuclear reactors existed. Other rich uranium ore bodies would also have had sufficient uranium to support nuclear reactions at that time, but the combination of uranium, water and physical conditions needed to support the chain reaction was unique to the Oklo ore bodies.
Another factor which probably contributed to the start of the Oklo natural nuclear reactor at 2 billion years, rather than earlier, was the increasing oxygen content in the Earth's atmosphere. Uranium is naturally present in the rocks of the earth, and the abundance of fissionable 235U was at least 3% or higher at all times prior to reactor startup. However, uranium is soluble in water only in the presence of oxygen. Therefore, the rising oxygen levels during the aging of earth may have allowed uranium to be dissolved and transported with groundwater to places where a high enough concentration could accumulate to form rich uranium ore bodies. Without the new aerobic environment available on earth at the time, these concentrations probably couldn't have taken place.

It is estimated that nuclear reactions in the uranium in centimeter- to meter-sized veins consumed about five tons of 235U and elevated temperatures to a few hundred degrees Celsius. Remarkably, most of the non-volatile fission products and actinides have only moved centimeters in the veins during the last 2 billion years. This offers a case study of how radioactive isotopes migrate through the Earth's crust—a significant area of controversy as opponents of geologic nuclear waste disposal fear that releases from stored waste could end up in water supplies or be carried into the environment.
Oklo is the only known location for this in the world and consists of sixteen sites at which self-sustaining nuclear fission reactions took place approximately 2 billion years ago, and ran for a few hundred thousand years, averaging 100 kW of energy output during that time.

[Vaquero]

The Explanation

“It all began 75 million years ago with a galactic federation of planets ruled by the evil Lord Xenu, Fearing overcrowding, Xenu rounded up countless aliens from all those planets and had those aliens frozen. The frozen alien bodies were loaded onto Xenu's galactic cruisers, which looked like DC-8s, except with rocket engines. They were sent to earth and dumped into the volcanoes of Hawaii and other volcanoes. They were no longer frozen. They were dead. "The souls of the aliens floated toward the sky," the president continued, explaining that Xenu had built giant "soul catchers" to collect them all and unload them into a brainwashing facility he had built on earth. "The souls were forced to watch days of brainwashing material that tricked them into believing a false reality," the president revealed. "Xenu then released the alien souls that roamed the earth aimlessly in a fog of confusion. At the dawn of man the aliens found bodies they could grab onto. They attached themselves to all mankind, which still to this day causes all our fears, confusions and problems."

[a fool in paradise]

Sounds like nuclear energy is just as natural as solar or wind then.

[edcoil]

So the heat from the naturally occurring plant caused the plants to die and the sand to take its place?

“Oklo is the only known location for this in the world and consists of sixteen sites at which self-sustaining nuclear fission reactions took place approximately 2 billion years ago, and ran for a few hundred thousand years, averaging 100 kW of energy output during that time.”

Clearly did not power toasters... Wonder what the energy output did.

[hellbender]

Remarkably, most of the non-volatile fission products and actinides have only moved centimeters in the veins during the last 2 billion years. This offers a case study of how radioactive isotopes migrate through the Earth's crust—a significant area of controversy as opponents of geologic nuclear waste disposal fear that releases from stored waste could end up in water supplies or be carried into the environment.

[JoeProBono]

[lunarville]

So I’m confused..

I have lived/worked near the (3) Indian Point (NY) reactors all my life and know for a fact that they produce electricity by converting the heat from the reactor into super-heated STEAM to power the turbine generator.

Can someone please explain where the 100kw comes from in this article? Some parts are missing...

[UnbelievingScumOnTheOtherSide]

They might have mentioned that a large part of earth’s internal heat comes from nuclear reactions occuring after most uranium and thorium concentrated in the core. (and not primordial compression)

[meyer]

I suppose they shut those down after 3 mile island too! ‘

/s :-)

[RichInOC]

OG: WHAT HAPPEN?

[RichInOC]

OG: WHAT HAPPEN?

[SunkenCiv]

· GGG managers are SunkenCiv, StayAt HomeMother, and Ernest_at_the_Beach · · join list or digest · view topics · view or post blog · bookmark · post a topic · subscribe ·
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[SunkenCiv]

thanks KoRn! Thanks Dallas59 for the topic. J. Marvin Herndon ping.

• Scientific maverick's theory on Earth's core up for a test [2004]

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[Straight Vermonter]

Ping

[Lonesome in Massachussets]

I sorta surprised the black nationalists types haven’t appropriated this as evidence of the superiority of African technology.

[Tijeras_Slim]

Didn’t the Soviets try this inadvertently at Chelyabinsk-40? ;)

[redgolum]

Interesting.