Posted on 04/10/2006 7:50:32 PM PDT by blam
Researchers Describe How Natural Nuclear Reactor Worked In Gabon
The Oklo natural nuclear-reactor site in Gabon.
St Louis MO (SPX) Nov 01, 2004
To operate a nuclear power plant like Three Mile Island, hundreds of highly trained employees must work in concert to generate power from safe fission, all the while containing dangerous nuclear wastes.
On the other hand, it's been known for 30 years that Mother Nature once did nuclear chain reactions by her lonesome. Now, Researchers at Washington University in St. Louis have analyzed the isotopic structure of noble gases produced in fission in a sample from the only known natural nuclear chain reaction site in the world in Gabon, West Africa, and have found how she does the trick. Picture Old Faithful.
Analyzing a tiny fragment of rock, less than one-eight of an inch, taken from the Gabon site, Alexander Meshik, Ph.D., Washington University senior research scientist in physics, has calculated that the precise isotopic structure of xenon in the sample reveals an operation that worked like a geyser.
The reactor, active two billion years ago, worked on a 30-minute reaction cycle, accompanied by a two-and-a-half hour dormant period, or cool down.
In the Oct. 29, 2004 issue of Physical Review Letters, Meshik and his Washington University collaborators write: "This similarity (to a geyser) suggests that a half an hour after the onset of the chain reaction, unbounded water was converted to steam, decreasing the thermal neutron flux and making the reactor sub-critical."
"It took at least two-and-a-half hours for the reactor to cool down until fission Xe (xenon) began to retain. Then the water returned to the reactor zone, providing neutron moderation and once again establishing a self-sustaining chain."
Prior to this calculation, it was known that the natural nuclear reactor operated two billion years ago for 150 million years at an average power of 100 kilowatts. The Washington University team solved the mystery of how the reactor worked and why it didn't blow up.
Meshik and his collaborators, Charles Hohenberg, Ph.D., Washington University professor of physics, and Olga Pravdivtseva, Ph.D., senior research scientist in physics, used a selective laser combined with sensitive, ion-counting mass spectrometry to concentrate on the sample's moderator, a uranium-free mineral assembly of lanthanum, cerium, strontium and calcium called alumophosphate.
The xenon found and analyzed provides the story of this ancient natural nuclear reactor. Meshik and his colleagues inferred from the xenon analysis the mode of operation and also the method of safely storing nuclear wastes, particularly fission xenon and krypton.
"This is very impressive, to think this natural system not only went critical, it also safely stored the waste," said Meshik.
"Nature is much smarter than we are. Nature is the first genius. We have all kinds of problems with modern-day nuclear reactors. This reactor is so independent, with no electronics, no models. Just using the fact that water boiled at the reactor site might give contemporary nuclear reactor researchers ideas on how to operate more safely and efficiently."
In 1952, the late Paul Kuroda predicted that if the right conditions existed, a natural nuclear reactor system could go critical. Twenty years later, noticing that uranium ore from the Oklo mine was depleted in 235 Uranium , it was discovered that the site had once been a natural nuclear reaction system.
"The big question we addressed was: When it reached criticality, why didn't it blow up?" Meshik said. "We found the answer in the xenon."
Critical means that a fissionable material has enough mass to sustain a reaction. There were two major theories on how the reactor operated.
One held that the system burned up highly neutron-absorbing impurities such as rare earth isotopes or boron, and because of that the system shut down regularly, and different parts of the reactor might have operated at different times. The other involved the role of water acting as a neutron moderator.
As the temperature of the reactor went up, water was converted to steam, reducing the neutron thermalisation and shutting down the chain reaction. The chain reaction re-started only when the reactor cooled down and the water increased again.
Analysis of the xenon, the largest concentration of xenon ever found in any natural material, confirmed the water method. It also revealed the role of alumophosphate as the system's waste absorber.
Xenon is extremely rare on earth and very characteristic of the fission process. Chemically inert, the element has nine isotopes and is abundant in many nuclear processes.
"You get a big diagnostic fingerprint with xenon, and it's easy to purify," said Hohenberg, who noted the importance of alumophosphate in the natural nuclear reactor.
"More krypton 85, a major waste from modern nuclear reactors, is getting piped into the atmosphere each year," he said. "Maybe this natural mode can suggest a safer solution."
Can there be a natural nuclear reactor in actual operation today?
"Today even the largest and richest uranium deposit cannot become a reactor because the present concentration of 235 U is too low – only about 0.72 percent," said Meshik.
"However, because 235 U decays much faster than 238 U, in the past, 235 U was more abundant. For example, two billion years ago 235 U was five times higher, about three percent, approximately the concentration of enriched uranium used in modern commercial reactors."
Another vital condition for self-sustaining nuclear reaction is the high content of a moderator to slow the neutrons, Meshik said.
Water, carbon, most organic compounds, silicon dioxide, calcium oxide and magnesium oxide all are natural neutron moderators. Also, the concentrations of neutron absorbents – iron, potassium, beryllium, and especially gadolinium, samarium, europium, cadmium and boron – should be low.
"Only when all of these requirements are met can a self-sustaining chain reaction occur," Meshik said.
I was looking for answers and I found this, lol.
Maybe in the middle of the earth?
"I was looking for answers and I found this, lol."
I'm not sure I want to know the question, LOL. :-D
I think these guys are full of s#!t...whadda you think blam?
There is an isotope of Xenon (Xenon 135) that is a HUGE neutron absorber, so much so that it can shut down reactors on its own. It is made naturally as a fission by product or the beta decay of another fission by produce (Iodine 135.) Since Xe 135 has a half life of 9.5 hours it will go away on its own allowing the reaction to happen again. That might have been cause of natural shutdowns too.
The original question: In 1940-41 the Germans captured all the heavy water in the world from the Norwegians and it was used in the German atom bomb program.
What were the Norwegians doing with the heavy water at that time?
Huh, wha… More anthropomorphizing from a college professor!
I’m sure Mother Nature has had a few of these so-called reactors go “China Syndrome” and blow up some fault line or volcanic region in the history of the Earth, too. We just haven’t found them yet.
Let me guess: The 1883 Krakatoa explosion was Mother Nature just running a series of experiments on Shock Wave Theory and Global Cooling.
Jeez.
Nope. But as sort of an ironic twist, the core of the earth is composed of the most stable element produced in nuclear fusion reactions: iron. The center of the earth due to its composition would be the least likely place to find a nuclear fusion reactor. Any nuclear reaction with a stable isotope of iron is endothermic (vice exothermic which produces heat).
OK - so now we know the question, don't keep us in suspense - what's the answer?
(man, am I in trouble now. I promised myself I'd finish my taxes tonight, buy just one peek at FR won't hurt anything, right? I mean, I can quit anytime I want, right? It's not like it's gonna disappear, right? But, then I just had to ask - & I STILL haven't got my taxes done - got to get that answer 1st - ANYTHING to put off doing that stupid 1040, LOL)
Will any of you come visit me when the IRS or the guys in the white coats come take me away?
The Norwegians were selling it to scientists all over the world for experiments; it was used as neutron source, in medical experiments, etc.
They weren't trying to build a bomb or anything.
See post #14, that's the first answer I've gotten.
1. Enter your taxable income from Form 1040, line 43 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.
2. Enter your qualified dividends from Form 1040, line 9b . . . . . 2.
3. Enter the amount from Form 4952, line 4g 3.
4. Enter the amount from Form 4952, line 4e* 4.
5. Subtract line 4 from line 3. If zero or less, enter -0- . . . . . . . . 5.
6. Subtract line 5 from line 2. If zero or less, enter -0- . . . . . . . . . . . . . . . . . . . . . . 6.
7. Enter the smaller of line 15 or line 16 of Schedule D . . . . . . . 7.
8. Enter the smaller of line 3 or line 4 . . . . . . . . . . . . . . . . . . 8.
9. Subtract line 8 from line 7. If zero or less, enter -0- . . . . . . . . . . . . . . . . . . . . . . 9.
10. Add lines 6 and 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.
11. Add lines 18 and 19 of Schedule D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.
12. Enter the smaller of line 9 or line 11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.
13. Subtract line 12 from line 10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.
14. Subtract line 13 from line 1. If zero or less, enter -0- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.
15. Enter the smaller of:
•• T$h2e9 ,a7m00o uifn ts ionng llein oer 1m oarrried filing separately; }
. . . . . . . . 15.
$59,400 if married filing jointly or qualifying widow(er); or
$39,800 if head of household
16. Enter the smaller of line 14 or line 15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.
17. Subtract line 10 from line 1. If zero or less, enter -0- . . . . . . . 17.
18. Enter the larger of line 16 or line 17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18.
If lines 15 and 16 are the same, skip lines 19 and 20 and go to line 21. Otherwise, go to line 19.
19. Subtract line 16 from line 15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.
20. Multiply line 19 by 5% (.05) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20.
If lines 1 and 15 are the same, skip lines 21 through 33 and go to line 34. Otherwise, go to line 21.
21. Enter the smaller of line 1 or line 13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.
22. Enter the amount from line 19 (if line 19 is blank, enter -0-) . . . . . . . . . . . . . . . . 22.
23. Subtract line 22 from line 21. If zero or less, enter -0- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.
24. Multiply line 23 by 15% (.15) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24.
If Schedule D, line 19, is zero or blank, skip lines 25 through 30 and go to line 31. Otherwise, go to line 25.
25. Enter the smaller of line 9 above or Schedule D, line 19 . . . . . . . . . . . . . . . . . . . 25.
26. Add lines 10 and 18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26.
27. Enter the amount from line 1 above . . . . . . . . . . . . . . . . . . 27.
28. Subtract line 27 from line 26. If zero or less, enter -0- . . . . . . . . . . . . . . . . . . . . 28.
29. Subtract line 28 from line 25. If zero or less, enter -0- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29.
30. Multiply line 29 by 25% (.25) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30.
If Schedule D, line 18, is zero or blank, skip lines 31 through 33 and go to line 34. Otherwise, go to line 31.
31. Add lines 18, 19, 23, and 29 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.
32. Subtract line 31 from line 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.
33. Multiply line 32 by 28% (.28) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.
34. Figure the tax on the amount on line 18. Use the Tax Table or Tax Computation Worksheet, whichever applies . . . . . . . . . . 34.
35. Add lines 20, 24, 30, 33, and 34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35.
36. Figure the tax on the amount on line 1. Use the Tax Table or Tax Computation Worksheet, whichever applies . . . . . . . . . . . 36.
37. Tax on all taxable income (including capital gains and qualified dividends). Enter the smaller of line 35 or line 36. Also
include this amount on Form 1040, line 44 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37.
*If applicable, enter instead the smaller amount you entered on the dotted line next to line 4e of Form 4952.
It probably involved lutefisk.
It's amazing that these people get paid. Even worse, some people believe this drivel.
But what I really want to know is, what were those clever little Paleoproterozoic stromatolites doing with 100 kilowatts of power?
I guess that really screws the carbon dating model too....
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.