[fuzzthatwuz]

Very interesting post. Thank you.

[Billthedrill]

And you can, of course, extract energy from steam as well. Interesting story. Thanks for posting.

[konaice]

The energy generated by the nuclear reaction boiled the groundwater around the deposit. Water is a natural neutron moderator, so as it was converted into steam, it stopped absorbing neutrons and shut down the chain reaction. As the rocks cooled down, the steam condensed, and the presence of water once again slowed the neutrons down and restarted the chain reaction. Meschik calculates that the reactor operated for about half an hour at a time, then shut down for two and a half hours.

Does this sound backwards to you as it does to me?

If it stopped absorbing Neutrons as water was deminished that would SPEED UP the reaction.

[AreaMan]

In a nuclear reactor, it takes large numbers of specialists and serious application of high technology to prevent reactions from running away. 'The big question we addressed was: when the uranium reached criticality, why didn't it blow up?' says Alexander Meschik of Washington University in St Louis, Missouri.

In water moderated reactors, like this one. Water temperature has an inverse coefficient of reactivity.

at least that is how it was explained to me in school. Which is why nuke boats run a little better with cold primary coolant.

[Robert357]

Now how far away from the area in Africa where some scientists claim human life evolved was this massive source of radiation and what was that Darwin said about evolutionary mutations?

[fuente]

What a bunch of crap! I safely stored the waste products for 2 BILLION years! Guess that was enough time for them to decay to NOTHING! We in the nucular (spelling intentional) have alway said that the Romans had nuclear power because they solidified their waste (mostly Co-60) in concrete drums (like we do today), then the drums rusted away. Now we call them columns. (and yes, I'm kidding)

[winodog]

Wow!! The Creator is amazing. Theres nothing new under the sun. Everything man does God has already done.

[brutuss]

Interesting article, however, not new information. This mode of operation, to my knowledge, has been assumed since the discovery of the site.

With regard to commercial applications, the measure of the effect of water density on criticality is called Alpha T. A negative Alpha T implies that a decrease in water density promotes shutdown (as described here). A positive Alpha T implies the opposite. All US and Western commercial reactors have always, by law, been required to have a negative Alpha T. The Soviet RBMK reactor (think Chernobyl) OTOH had a positive Alpha T.

The principle described therefore has always been a bedrock of Western commercial reactor design.

[nightdriver]

There was an article about this in Scientific American about 20 years ago.

[sionnsar]

The world's only known natural nuclear reactor, which decommissioned itself over two billion years ago,

Guess this one qualifies for the geezer geeks... it is old technology!

Geezer Geek ping.
FReepmail me if you want on or off this list.

[nightdriver]

"The site, in Gabon, West Africa, ran for 150million years without blowing up, and storing its own waste in a safe manner."

So, in only 150 million years, the waste of our modern reactors should be safe too, so noone should be concerned. (/sarc.)

[Flightdeck]

"natural uranium will not undergo nuclear reactions, because it contains too little of the fissionable isotope, uranium-235 (U235)."

U-238 is also fissionable. U-235 is fissile, however, which means a neutron with no additional velocity will cause it to fission.

[NicknamedBob]

Question for Robert A. Cook, P.E. = Since, “hydrogen-containing material like water, or light metals like carbon, Al, polyethylene, plastic, and other light metals and liquids literally "slow down" the neutron better than heavier material.”, a rocket ship with a nuclear engine could use solid Carbon Dioxide very efficiently as a reaction fuel, by extruding a cylinder of dry ice into a nuclear chamber where it would incandesce like a candle to produce an exhaust gas at high speed. Theoretically a simple design, but would it be better to use dry ice, or simply pressurized CO₂?

Question for Sionnsar = Was this the “Valley of the Shadow of Death”? (For this accretion of material, it had to be a valley.)

Question for Wonder Warthog = Does this mean I have to use Heavy Metals for my basement cold fusion plant? I really hate that kind of music.