# "Natural" Fission Reactors? **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [May 28, 2000, 3:07am UTC](https://boards.straightdope.com/t/natural-fission-reactors/20716 "2000-05-28T03:07:26Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Demo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/demo/32/8472_2.png) [@Demo](https://boards.straightdope.com/u/Demo)\ **Post date:** [May 28, 2000, 3:07am UTC](https://boards.straightdope.com/t/natural-fission-reactors/20716/1 "2000-05-28T03:07:26Z")
Just bumming around on the net and found this: [Natural Fossil Fission Reactors](http://energyindustry.about.com/industry/energyindustry/gi/dynamic/offsite.htm?site=http://www.curtin.edu.au/curtin/centre/waisrc/OKLO/) > [@](#): > > In 1972 the very well preserved remains of several ancient natural nuclear reactors were discovered in the middle of the Oklo Uranium ore deposit. Has anyone else heard of this? I guess, around 2000 million years ago, some big ass Uranium deposits just started fissioning. I believe they have found 17 sites, all in Africa. The reactions went on as long as 1 million years and were true breeder reactors, in that they produced enough fuel to continue the reaction, sometimes even more. I hadn’t ever heard about this, but it is _fascinating_ to think of sustained fission going on underground for a million years! Unfortunately, the site doesn’t have many details, but there are some other links in the page which I will research. Just thought I’d share. 😉 ---
**Author:** ![pluto](https://avatars.discourse-cdn.com/v4/letter/p/f08c70/32.png) [@pluto](https://boards.straightdope.com/u/pluto)\ **Post date:** [May 28, 2000, 6:37am UTC](https://boards.straightdope.com/t/natural-fission-reactors/20716/2 "2000-05-28T06:37:10Z")
I read about this a long time ago in _Scientific American_ and was fascinated by it. My recollection is fuzzy but I seem to recall that one factor in the formation of the natural reactors was the conversion of the earth’s original reducting atmosphere to its current oxidizing atmosphere, which affected solubility, concentrating the uranium ore where it precipitated out of streams or rivers. This geologic concentration process, combined with the higher fraction of U-235 present hundreds of millions of years ago allowed the fission process to proceed slowly for millions of years. Cool, huh? ---
**Author:** ![KP](https://avatars.discourse-cdn.com/v4/letter/k/a9adbd/32.png) [@KP](https://boards.straightdope.com/u/KP)\ **Post date:** [May 28, 2000, 6:55am UTC](https://boards.straightdope.com/t/natural-fission-reactors/20716/3 "2000-05-28T06:55:51Z")
It’s been 10-15 years since I read up on this, but back then they were also suggesting it as a driving force for the ‘hotspots’ that leave chains of islands as the Pacific Ocean plates move over them. However that could be a very different type of reactor in terms of structure and origin than the one democritus described so nicely. Where’s our resident geophysicist, [Beatle](http://boards.straightdope.com/sdmb/showthread.php?threadid=25613), when we need him? ---
**Author:** ![KP](https://avatars.discourse-cdn.com/v4/letter/k/a9adbd/32.png) [@KP](https://boards.straightdope.com/u/KP)\ **Post date:** [May 28, 2000, 7:22am UTC](https://boards.straightdope.com/t/natural-fission-reactors/20716/4 "2000-05-28T07:22:02Z")
I couldn’t find the Scientific American article I was looking for, but I did find something on [hot spots](http://www.sciam.com/0497issue/0497scicit1.html) which reminded me that a few days ago scientists got to watch a hot spot island break surface for the first time. (not covered in the article, obviously) I also found a [Phillip Morrison essay](http://www.sciam.com/1998/0698issue/0698wonders.html) that mentions the natural reactors, if you like his writing style