Natural Nuclear Reactors

bungeejumper writes "The Astronomy Picture of the day has a picture of a natural nuclear reactor discovered in an uranium ore mine in Africa. This link has much more detailed information on this subject. Does this tie in with this wacky story about a HUGE PLUTONIUM FAST BREEDER REACTOR at the centre of the earth ?"

Re:No it doesn't

[WeaponOfChoice]

I think it's interesting how long the story has persisted (and the many forms it has taken over the years). I remember reading (in one of those amusing crackpot pseudoscience books) about Oklo being proof that ET's had visited earth in eaons past (and presumably built primitive reactors to boot)...

funny world...

Re:No it doesn't

[macdaddy357]

The hippies have always hated manmade nuclear reactors, but they might approve of natural ones.

Re:No it doesn't

[budgenator]

All of those Flower-Children could be in charge of growing spiderwort at the site. see radiation detector [gdr.org] if you don't understand the joke. Seriously I've never heard of a nuclear power plant that didn't grow lots of spiderwort, they believe in back-up systems

The story is only 26 years old, a new record

[HotNeedleOfInquiry]

The story was originally covered in Scientific American, July 1976. It was a great read then and now. Highly recommended. There has also been talk about a second natural reactor (not in the center of the earth), but I can't put my finger on a source right now.

Re:The story is only 26 years old, a new record

[Observer]

I recall a short story in - I think - a SciFi anthology published a few years after the Scientific American article, which related that a similar concentration of uranium ore had been found very near the surface, but where conditions had not been sufficient to sustain even a slow chain reaction. Until, that is, the ore was uncovered, and then either through natural rainfall or because of water pumped through the site as part of its exploitation, enough of the fast neutrons were moderated down to slower energies that the the deposit as a whole crossed the criticality threshold, and... Fwoom.

--
When Dinosaurs Ruled the Earth - a book of recollections of the days of the mainframes, by one who was there.

Magnetic field

[u19925]

You don't need nuclear reactor to explain magnetic field. Whereever in nature, there are ionized particles and systematic rotation, magnetic field is found. Stars, neutron stars, galaxies (spiral galaxies have more magnetic field because they have systematic rotation while elliptical galaxies have less magnetic, since the star motion in them is random). Earth interior is at very high temperature, so, ionized particles are expected. Couple that with systematic rotation, and you have a magnetic field. Heavy objects in general produce more ionized in the interior than lighter object. Thus moon which has very small rotation and smaller in mass has no detectable magnetic field. Why would a nuclear reactor exist in earth's core but not on moon? Why would magnetic field exist on jupiter, saturn?

The heat in lava can be explained by the heat transfer from the core. Earth's thermal conductivity is so small, that the heat trapped in the interior needs billions of years to come out and it is stil coming out. Additionally, earth contains some radio active material too, which generates additional heat. There are some theories in which relative importance of these two effects is different.

RTFA

[HotNeedleOfInquiry]

The article said that the reactor explains why the poles flip every 200k years, not why they exist.

Re:RTFA

[Christopher Thomas]

The article said that the reactor explains why the poles flip every 200k years, not why they exist.

There are turbulence models that explain this too, without a concentrated core of uranium and thorium needing to be postulated.

See my post in the previous article for a more detailed critique.

Re:RTFA

[u19925]

Quote from the article:

"Herndon and his collaborator, Daniel Hollenback, say the theory explains mysteries that have baffled experts. One is the way Earth's magnetic field is generated."

Re:Magnetic field

[fluffy666]

Remember that for depths greated then 50-200km, depending where you are, the mantle is in vigorous convection (well, over decent timescales). Conduction is only a factor in the crust and lithosphere.

The Nuclear reactor hypothesis also explains the excess heat production of Jupiter and Saturn.

Discover Magazine

[LudditeMind]

Discover had an article on the reactor at center of planet.

http://www.discover.com/aug_02/featplanet.html

No connection

[f97tosc]

There is little connection between the two topics.

The 'reactors' are of different types, and the center of earth one is something that is only predicted by a controversial model.

The surface reactors in Africa are extremely interesting and have been known for quite some time now.

They are also a powerful argument for nuclear power plants.

After all, here is an example of how the radiocative by-products of fission have been stored safely for millions of years - without any sophisitcated protection technology.

Tor

Yes, but

[T.Hobbes]

The reaction ended two billion years ago.

Mr. Burns - "Hello. We want to bury our nuclear waste in your backyard. I will compensate you generously for your acceptance."
Homer - "Sounds dangerous..."
B. - "Hardly! In but the blink of an eye all the radioactivity will be down to the most natural of levels!"
H. - "Sounds great! We move out for two weeks and I'll be living like Duff-Man"
Smithers - "Well, more like two billi-"
B. - "[Hush, Smithers!] Exactly."
H. - "Sign me up"
B. - "Exxcelent. Oh, your check should arrive in three weeks or so..."
H. - "Woo-hoo!"

Sci Fi

[WeaponOfChoice]

If I remember rightly the idea had a recent ressurgence in the Stephen Baxter book Time (Manifold series, interesting read). The 'reactor' (read: large pile of fissile material maintained by people suffering terminal radiation poisoning) was used to power a small teleport system. Nice mix of the primative and super high tech.

Re:Sci Fi

[jtriska]

That was manifold: Space, not manifold: Time. All very fascinating books though. :)

Radioactive Decay?

[Gerry Gleason]

I thought the conventional thought about the Earths core involved radioactive decay slowing the general cooling trend. I didn't see any reference to this. What about all the individual things the theory claims to have a better explaination for? I guess I'm asking how solid is the conventional model? Regardless of the merits of this theory, is it possible that there are concentrations deep in the Earth?

Re:Conventional model.

[fluffy666]

Not rock solid (sorry for the pun..)

The mantle, and especially the crust, contain virtually all of the radioactive heat generating Isotopes (K-40, Thorium, Uranium + other minor ones). Hence the problem - how is heat generated in the core itself? Without a heat generation source, there would be no outer core convection and hence no magnetic field.

Current theory is core crystallisation; it does have problems. If mantle convection is single layer (a matter of heavy debate in the earth sciences), then the earth, and especially the core, should be frozen solid by now. Additionally, the presence of Helium-3 in the mantle is confusing, as it should outgas pretty quickly.

A core nuclear reactor solves both the heat and helium 3 problems.

Re:Conventional model.

[hoxa]

More detail availiable at http://www.pnas.org/cgi/reprint/98/20/11085.pdf

in Halliday's book (not modded yet, 0 karma)

[Gamasta]

Good and simple information can be found on page 1102 in 6th edition of Halliday's 'fundamentals of physics'.
Oklo, located in the Republic of Gabon, was discovered about 30 years after the first artificial nuclear reactor was built by Fermi et al.

This site [isu.edu] also contains rich information.

Harnessing power

[DRnetman86]

Would there be any way possible to harness the power of the fast breeder in the center of the earth. That could shut Dubya up and keep Cheney alive for at least 5 more years before we can't afford to pay his power bill.

Re:Harnessing power

[f97tosc]

The fact that Earth is generating some heat is hardly any news - and yes this geothermal energy can be harnessed in certain areas (for example Iceland).

The new model is an alternative explanation for the energy - not a discovery that it is there.

Digging to the center of the earth seems extremely unlikely, the deepest mines today are only a few km deep. On the other hand, we can build nuclear power plants that work exactly the same way.

Tor

Re:Harnessing power

[DRnetman86]

While we can build power plants that work in the same way, what it may not be able to do is work with the same ammount of power output. If it can generate more power, is incredibly well insulated, and is possible to safely extract, it may provide a power souce that is greater than many breeder reactors.

"Natural Power Source"

[bill_mcgonigle]

This is great. There's a class of people who will consume anything if it's 'all-natural'. The intersection with the set of people who have 'No Nukes' bumper stickers is fairly large.

Re:"Natural Power Source"

[Snafoo]

We can set up a generator on top and sell batteries at a steep markup at the Body Shop. :)

Re:"Natural Power Source"

[Snafoo]

I should add that I mean charged rechargeables.

Obviously, alkaline batteries would be simply manufactured.

Whoa

[baldass_newbie]

I thought it said 'Huge Plutonium BREAST FEEDER Reactor'