Understanding the 2 Billion-Year-Old Natural Nuclear Reactor In W Africa 152
KentuckyFC (1144503) writes "In June 1972, nuclear scientists at the Pierrelatte uranium enrichment plant in south-east France noticed a strange deficit in the amount of uranium-235 they were processing. That's a serious problem in a uranium enrichment plant where every gram of fissionable material has to be carefully accounted for. The ensuing investigation found that the anomaly originated in the ore from the Oklo uranium mine in Gabon, which contained only 0.600% uranium-235 compared to 0.7202% for all other ore on the planet. It turned out that this ore was depleted because it had gone critical some 2 billion years earlier, creating a self-sustaining nuclear reaction that lasted for 300,000 years and using up the missing uranium-235 in the process. Since then, scientists have studied this natural reactor to better understand how buried nuclear waste spreads through the environment and also to discover whether the laws of physics that govern nuclear reactions may have changed in the 1.5 billion years since the reactor switched off. Now a review of the science that has come out of Oklo shows how important this work has become but also reveals that there is limited potential to gather more data. After an initial flurry of interest in Oklo, mining continued and the natural reactors--surely among the most extraordinary natural phenomena on the planet-- have all been mined out."
I don't know but there for Aliens. (Score:5, Funny)
Come on... who here doesn't think that this isn't the remains of a eons own star cruiser out there?
Well okay, it probably isn't... but it would be cool if it was!
More awesome than Autobots. Us, I mean (Score:1)
Seeing things fly made us dream of the skies and eventually led to flight.
Spider webs led to modern ballistic fibers.
But this time, there was no such natural inspiration. We dreamed and created something we could not have conceived of have been standing on without ever noticing (well, not for long before an 'invisible curse' killed everyone anyways) not even two centuries ago. Only with functional, if crude, reactors operational did we come across their ancient burnt out forms.
We made the atom ours, friend.
Re:More awesome than Autobots. Us, I mean (Score:5, Funny)
Re: (Score:2)
And it goes great with Yellow Cake [wikipedia.org]
Re: (Score:1)
The natural reactor operated for a total of 300,000 years but it was not continuous operation. The water that passed over the formation was the neutron moderator which allowed the U-235 (percent at that time about 3%) to go critical. The water also cooled the reaction but as heat was generated the water would boil off and the reactor would go subcritical. The duration of time the reactor would be critical was due to how much water was available during the different seasons and throughout a long duration of
Re: (Score:3)
Were that true, there should be other evidence of the starship. Unless they were just disposing of spent fuel? Cool idea, right, since uranium is found naturally in nature and we could just dispose of it by making it as diluted in rock as it is in nature?
Although that's an interesting idea for the disposal of nuclear (fission) waste for an advanced civilization, I tend to believe that the energy required to melt rock and integrate melted fuel rods to a dilute enough concentration not to harm natural life
Re: (Score:2)
In addition, any civilization THAT advanced would undoubtedly be able to get better efficiency out of their reactors before zipping away.
My guess is they'd also be running reactors that could use the fuel up more or less completely, resulting in far less spent fuel being produced, if any.
Re: (Score:3)
In addition, any civilization THAT advanced would undoubtedly be able to get better efficiency out of their reactors before zipping away.
My guess is they'd also be running reactors that could use the fuel up more or less completely, resulting in far less spent fuel being produced, if any.
You know, kind of like France does, with their spent fuel reprocessing and use of breeder reactors...
Re: (Score:3)
France has no running breader reactors since decades.
Re: (Score:3)
No breader reactors? What about baguette reactors?
Re: (Score:2, Interesting)
The host rock for the Oklo reactors is fairly ordinary Proterozoic-aged sandstone and shales, so if some ancient civilization did abandon waste products, they basically left it on the surface on a beach or river bank about 1.7 billion years ago. It wasn't molten rock. Interestingly enough, there's also a lot of bitumen (solid oil) in the deposit, so there was plenty of organic material associated that was probably involved in trapping the uranium. Maybe a gigantic landfill? :-)
Re: (Score:2)
As usual, the guy saying "cost prohibitive" has absolutely no idea what he's talking about. Typical financier.
Re: (Score:2)
Yeeees. Nothing particularly abnormal about the host rock.
Noooo. Part of the point of the paper linked to (you did read TFP, didn't you? That's why the authors wrote it and posted it to Arxiv, for people to read.) was to describe a lutetium excite state thermometer wh
Re: (Score:2)
If your civilization is advanced enough to have inter-stellar starships, the simplest way of dumping a few tons of nuclear waste without having to worry about environmental impact would be to load the material in a rocket/torpedo and fire it at the most convenient star you come across.
Re: (Score:2)
I agree that they would have better things to do with the waste but they could bury it in a s
Re: (Score:3)
Why "dump" anything?
Reprocess. Instead of polluting the environment with stuff that has a half-life measured in thousands of years, keep reprocessing it, and burn the stuff down into something that could be used in next-gen reactors and keep going until you've extracted as much energy from it as possible and the remaining waste has a half-life measured in decades or a few short centuries.
Done right it can be reprocessed on-site and almost in-situ.
This way there's no need for large containment vessels to si
Re: (Score:2)
"...the equivalent of shitting on your elderly neighbor's lawn. You may not have to deal with it right away, but it's eventually going to come back and haunt you."
I'm pretty sure I'll outlive my elderly neighbour. In fact, I think I'll *make* sure I do, brb.
Re: (Score:2)
Re: (Score:2)
When you reprocess fuel you get two things: new fuel and waste.
If you repeat that, by burning the new gained fuel again, you get more and more waste, not less.
Should be a no brainer.
Perhaps you should read up what kind of waste a normal nuclear plant 'produces' and what kimd of waste a reprocessing plant 'produces' to get an idea?
Re: (Score:2, Informative)
Nuclear reactors turn matter into energy. If you can continue to reprocess the waste without adding more matter, you will end up with less waste over time. Better still is that the new waste, while more dangerous in the short term, is much much less dangerous in the long term.
Even if it is released, it's going to cause less of an effect on the planet.
Re: (Score:2)
Waste after reprocessing consists usually out of many really poisonous acids, and the 'non fuel' part of the original waste. The original waste might have been a cubic yard, containing 10% reprocessable fuel.
After reprocessing it is the original one cubic yard - 10% plusall the stuff that got addedduring reprocessing, that ends up in about ten to twenty times as more waste as it was before.
On top of that the new waste is poisonous, mostly acid, still highly radioactive, difficult to store difficult to trans
Obligatory Nuke Snark (Score:4)
A post offers reprocessing as a solution to the reactor waste problem, and a proper counter to that argument is that reprocessing has a waste problem all its own. The total amount of long-lived waste may be reduced, but the "hot" shorter lived waste get spread around into corrosive liquid effluents?
Could a a person remind Slashdot readers of this tradeoff without suggesting that the original post was made by an untutored fool? Or is it important to label someone suggesting reprocessing as a foolish person, to offer a (mild) public scolding of their idea because reprocessing is a bad enough policy that shaming is merited?
Re: (Score:2)
Usually the assholes beat the non assholes ...
Re: (Score:1)
Jocks, having a strong core and a tight ass get their pelvis pushed forward. These are the dicks. Dicks like to fuck everybody over.
But since recorded history in greece, the dicks always like to beat on the assholes.
The sooner you accept you're an asshole, the sooner you can turn it around.
Re: (Score:2)
What produces a larger, longer-lived waste stream in the end?
Burning the fuel once and then putting it into storage for the next half million years while you grab more pristine fuel and put it through the same single cycle?
Or reprocessing several times and putting the waste into storage for the next couple centuries?
Re: (Score:2)
The later, that is why most countries don't reprocess.
Or do you really believe all nuclear nations don't reprocess because the solution is 'so easy'?
Re: (Score:2)
You'd be wrong.
I'd also accuse you of not reading the question either.
Why do we want to deal with waste that has a potential lifespan measured in hundreds of thousands or millions of years?
We can use it and eventually cook it down to byproducts that remain dangerous for far FAR less time.
Nobody said the reprocessing is easy. Or cheap.
But nobody said filtering exhaust from coal and oil plants was easy or cheap either.
And there ARE nuclear nations that DO reprocess. France being one of them.
The reason it's
Re: (Score:2)
A better question is, if you're going to dump it at all, why do it on a planet with life and go through the trouble of diluting it? Why not choose a dead rock, deep space, or, ya know, a star?
Re: (Score:2)
If they're aliens with a giant star cruiser that presumably came from space (or maybe the fifth dimension? I dunno), I don't think this would be a major issue.... especially because of the "already in space" part.
Re: (Score:2)
No, nuclear rockets are banned because of short-sighted politicians signing treaties they don't understand about technologies they have no comprehension of. There is no reason that a nuclear rocket couldn't be made as safe as an RTG.
Re: (Score:2)
Hmm, you seem to be unaware that the stuff with a half life "measured in decades or a few short centuries" is quite useful still - the short half-life
Re: (Score:1)
Uhm. No.
The longer a half-life it is, the longer it hangs around in the environment, posing a threat to the local ecology.
Ideally, we could burn stuff down and reuse it long enough that the byproducts are inert, radiologically speaking.
Realistically though, we can burn things down so that fuel that's been reprocessed enough goes from something that breaks down (goes inert) over tens or hundreds of thousands of years to something that breaks down in a few hundred.
As people say, at the end of the fission pow
Re: (Score:2)
As people say, at the end of the fission power process, you wind up with a very compact amount of waste that's highly radioactive (and not always suitable as fuel for the reactor it came from, though second, or third generation reactors might be able to burn it).
Where does this idiotic idea come from that a reactor can burn waste?
Uranium (92 protons) is split in a reactor into something like Ba(56) and Kr(36). Both neither can be 'split' again nor can they be breeded to something that can be split again.
So
Re: (Score:2)
When I say "burn", it's not becasue we're actually, y'know, burning it.
It's because it's a simple concept that jumps over all the physics and allows luddites a grasp of the process of fuel consumption in a familiar package.
Re: (Score:2)
Nevertheless the only thing you can 'burn' is the remaining uranium AFTER you have enriched it again.
Re: (Score:2)
"I mean they could dump it on the moon"
I'm gonna miss the moon...
Re: (Score:2)
If the advanced civilization arose in a gas giant they might think chucking it at a "useless" rocky planet a more reasonable solution. And if they stuffed it in an asteroid that rock may have crashed into Africa at some point.
Re: (Score:2)
Re: (Score:2)
Come on... who here doesn't think that this isn't the remains of a eons own star cruiser out there?
Well okay, it probably isn't... but it would be cool if it was!
If I recall correctly Commander Adama set the fleet for a collision course with the sun, not the earth.
"Have all been mined out" (Score:5, Interesting)
Except for the shallow one mentioned at the end of the article that still remains, just mostly washed out...
It seems like the other aspects they wanted to study (like the spread of byproducts) is still feasible, since those would have spread beyond the mining site if they spread at all.
Re: (Score:3)
One of the useful early findings was that the reaction products hadn't appreciably migrated away from the original uranium seam, which is important for understanding waste disposal. Unfortunately that probably means that most of the useful information left with the uranium.
Re: (Score:2)
One of the useful early findings was that the reaction products hadn't appreciably migrated away from the original uranium seam
Exactly, that's the primary interest on that front. Now they know that even over billions of years dangerous elements can stay put given the right geologic conditions.
Unfortunately that probably means that most of the useful information left with the uranium.
But some of it still remains in the shallow reactor, so they can find it if they think there's anything more of value to lear
Re: (Score:2)
...
Also now that they know is possible, they can probably find other areas where the same effect occurs. I think it's really unlikely that's the only place on earth the effect happened when it occurred naturally across several sites in the area.
Such rich ore in thick veins is very rare - the uranium content of the ore was the highest in the world, 20-60% uranium, the average ore concentration current mined is around 1%, and many mines operate with ores containing a few tenths of a percent. Some Canadian mines have ore grades up to 20%, so there is a possibility it another might be found there.
We do know that similar reactors have existed in the past. The isotopic concentration of U-235 in natural samples exhibits an unusual variation in concentra
Wait.... (Score:2)
"...to discover whether the laws of physics that govern nuclear reactions may have changed in the 1.5 billion years..."
Laws of physics changed?
What?
Re: (Score:3)
It's conceivable that some constants and such have a slight drift. Hell, space itself appears to be expanding so anything is fair game IMHO!
Re: (Score:2)
Re: (Score:2)
To be more precise, by comparing the various decay product chains, they constrain the amount of change that could have happened in parameters such as the fine structure constant. Which is an effort the astronomers are making too, at the other end of the periodic table.
Non-Tablet-Friendly Version Please (Score:1)
Is there a non-tablet-friendly version of the article? One that's non-blinding on a normal screen?
Sorry for trying to read it...
Re: (Score:3)
Is there a non-tablet-friendly version of the article? One that's non-blinding on a normal screen?
Sorry for trying to read it...
CTRL-A, open your text editor, CTRL-V
Re: (Score:1)
Re: (Score:2)
Re: (Score:2)
I only know this because I use a terminal program too much. Don't want to be hitting control codes in that situation :)
Re: (Score:2)
Re: (Score:1)
Is there a non-tablet-friendly version of the article? One that's non-blinding on a normal screen? Sorry for trying to read it...
In Firefox: View -> Page Style -> No Style
Re: (Score:2)
The paper cited is a standard PDF written to "Letter" size or "B4" (I can't tell the difference at a glance). Nothing blinding. I didn't waste time looking at the linked "science journalism" - why would you if you've got the paper to read?
bottom pop up ads on slashdot? (Score:5, Insightful)
What's the deal with these ads that pop up from the bottom on slashdot?
Wasn't the "beta" experiment enough to piss people off with?
They need to find new ways?
Re: (Score:2)
You need to familiarize yourself with browser plug-ins...
Re: (Score:2)
Re: (Score:2)
How low can you go?(power density) (Score:4, Interesting)
What bollocks. I think the actual question to ask is how it's possible to create the conditions for an very large (the size of the mine)and extremely low density (the concentration of natural ore) nuclear reactor.
In the days the preference for civilian reactors was to develop further along the design of the compact high density submarine reactors. The nuclear industry never got over that. There are prototypes of large reactors with much lower power density. It's a natural question to ask how low enrichment and low density one can go.
Re: (Score:2)
Some people believe that rates of radioactive decay have changed with time, to allow the isotopic abundances that we see to be consistent with a 6000 year old universe and in order to be able to discount any archaeological or palaeontological result they don't like. Showing that nuclear physics was the same 2 billion years ago is unlikely to change their minds.
Re:How low can you go?(power density) (Score:5, Interesting)
>What bollocks. I think the actual question to ask is how it's possible to create the conditions for an very large (the size of the mine)and extremely low density (the concentration of natural ore) nuclear reactor.
No bollocks involved - those laws depend on the fundamental constants. Scientists have speculated for decades about the possibility that these may have been slightly different in the distant past - and thus the laws of physics would not be exactly the same.
This is quite controversial, mavericky science because it's very hard to test - but it's actually become less so in the past 20 years or so because some evidence from astronomy (in particular the cosmic background radiation) is suggesting that they may have been slightly different in the very early days of the universe.
Oklo offers a chance to look more recently (on a universal scale) but still a long time ago - 2 billion years, about half the lifetime of the planet.
If there had been subtle and slight changes over the years - then 2 billion years ago should be enough to detect some - much smaller even than what cosmic radiation data has hinted at, but on the same line (that said there are other theories that could explain the radiation data - the question is unanswered at the moment since none of them have any other supporting evidence yet either).
Now there's no proof the fundamental constants have changed at all since the big bang, but there's no proof they haven't. For most physics it's perfectly adequate to assume they have always been constant, but if they weren't and we could determine that, it would change a lot of our understanding of physics - particularly the physics of the early universe.
By factoring in those different values we could possibly explain a lot of the other things which currently remain open questions.
So while it's unlikely - it's nevertheless and most decidedly NOT bollocks. It's maverick science for sure - but it's still science and still done according to the scientific method. If it yields results those results will be greatly valuable.
Just because there's a 99.999% chance your theory is a dead end, doesn't mean it's not proper science to damn well test it and make sure.
Re: (Score:2)
I'm not saying researching the possibility that universal constants are not constant is bollocks, though I'd consider it too speculative for science. But once one starts taking an open environment 'dirty' testcase where the ratio 235/238 is different from the sample nextdoor as a clue for variable universal constants, then one is really in the middle of bollocks territory.
Re: (Score:2)
It really isn't. I'm no nuclear physicist but it seems that the reaction cross-sections change so dramatically with respect to the fine structure constant, that seeing these fission reactions at all puts a very strong bound on how the fine structure constant could have varied.
Re: (Score:2)
Well I asked for that. I should have said it differently. Another try: there is a lot of experimental evidence to show that the fine structure constant is constant. If it hadn't been constant we would have known. With the claim that the fine structure constant is a real constant one is on solid ground.
Then the possibility that outside of the solid experimental proof the constant could still vary "maybe the constant was not always the same" - should be handled very sparingly. It's an idea to be kept on a sho
Re: (Score:2)
People should not start trotting out a 'variable constant' hypothesis because some ratio of elements is wrong in ore.
The wrongness in the ore did not challange them to consider some old constants in fact may vary (you seem not to believe that this in deed a long open question in physics. However: it is!). The wrongness lead them to that particular mine and with test data going back roughly 2billion years, they figured that could be a good hunting ground. Thats all.
Re: (Score:2)
People should not start trotting out a 'variable constant' hypothesis because some ratio of elements is wrong in ore.
Nonetheless:
-- Isaac Asimov
Re: (Score:2)
No, the OPERA group was right. They said, "We have this result, which makes no sense. We've looked at A, B, C, D and E, and still get the same results. We've recalibrated F, G and H multiple times and it makes no difference. We've replaced I and J, but the equipment seems fine. Anyone got any ideas?" When you think you've done everything right and still get surprising results it's time to let others know, not time to hide the evidence. Do that and every piece of research you do in the future is taint
Re: (Score:2)
The ratio wasn't wrong. The research was provoked as a way of quantifying the possible variability given that it appears constant.
Re: (Score:2)
...and for that it's worth, the research takes into account site-to-site variability in the composition and the subsequent behaviour of the reactor.
Re: (Score:2)
As opposed to one of the best available alternate methods for determining universal constants, astronomy?
Physicists and chemists are aware of how to use statistics to make good estimates in the presence of heterogeneity.
Re: (Score:2)
its not about the sample next door, its about every single sample from the giant cloud of debris from which our solar system formed. The fact that its all the same throughout the world (when it hasn't undergone spontaneous fission is part of the reason we know how old the rock we are standing on is.
Re: (Score:2)
I'd suggest that you read the Arxiv paper, and find out what the actual researchers are saying, not what "science journalists" are saying.
Re: (Score:2)
There was a really great science fiction book I read that dealt with that. I thought it was by Alastair Reynolds, but looking over his bibliography I didn't see anything that fit the description. Essentially it's one of those "we've found ancient alien shit, scientists go explore it and discover THE TERRIBLE SECRET OF SPACE!" books. In it, a rogue planet is discovered in interstellar space with an ancient alien city/mechanism. None of the technology works right, or makes any sense from our understanding of
Re: (Score:2)
Re: (Score:2)
Scientists have speculated for decades about the possibility that these may have been slightly different in the distant past - and thus the laws of physics would not be exactly the same.
This is quite controversial, mavericky science because it's very hard to test -
If it's not testable, then by definition it is not science.
Now there's no proof the fundamental constants have changed at all since the big bang, but there's no proof they haven't... By factoring in those different values we could possibly explain a lot of the other things which currently remain open questions.
So while it's unlikely - it's nevertheless and most decidedly NOT bollocks.
Then it's not science.
It's maverick science for sure
"Maverick Science". Made up definitions still don't get you to a testable theory.
Re: (Score:2)
hard to test != untestable
Re: (Score:2)
>If it's not testable, then by definition it is not science.
I said it's HARD to test, I didn't say it's impossible.
The REASON it's hard to test is because it's a theory about what may have happened billions of years ago - and billion year old samples are kind of rare. The big bang theory was hard to test for the same reasons and took decades to become accepted - back in the 1960's it was laughed of as glorified creationism.
The whole point is to test the theory because this IS a 2 billion year old sample.
Re: (Score:2)
Yes, there is. Astronomers are peering into the past every time they look through their telescopes--often the very distant past. They don't see anything that indicates that the laws of physics are changing.
Re: (Score:1)
Yes! Finally, people are talking about this!
I have considered this before and it threw me for a loop, if you will.
Our understanding of everything about the past (i.e. big bang, evolution, etc) are hinged upon the idea that these constants are just that. Constants.
Now, if they aren't, then what happens to our measurements (i.e. age verification on fossils via radioactive decay and measuring the cosmic background) is these constants are not constants? Simple, they become wrong.
If, say, the constants changed c
Re: (Score:2)
Why does inflation making space expand faster than the speed of light change the constants? No particle or energy travelled faster than light. Just space expanded smoothly such that, over a sufficient distance, the rate of change of that distance exceeded C. Nothing to trouble relativity in that fact: geometry changed, but nothing moved to fast. In fact, it is still the case: if the Hubble expansion is uniform, as it appears to be, at some distance the rate of recession must exceed C; there are objects whic
Re: (Score:1)
Re: (Score:2)
No, the galaxies on the far side of the universe are receding from us (and us from them) at a speed exceeding c, so we'll never see them because at 300000 kilometers/second the light will never catch up with us. Well, I suppose it could be considered a technical limitation in a way, since we currently can't carry telescopes far enough that direction to ever run into their light.
Re: (Score:2)
No, it's not bollocks, it's actually a nice demonstration that the fine structure constant is actually constant. It's worth emphasising that even given the size of the mine, its power output was only about 100kW.
Re: (Score:1)
Re: (Score:1)
It's mostly cold there, which is why cheap geothermal can work.
Re: (Score:3)
What bollocks. I think the actual question to ask is how it's possible to create the conditions for an very large (the size of the mine)and extremely low density (the concentration of natural ore) nuclear reactor.
In the days the preference for civilian reactors was to develop further along the design of the compact high density submarine reactors. The nuclear industry never got over that. There are prototypes of large reactors with much lower power density. It's a natural question to ask how low enrichment and low density one can go.
2 billion years ago the concentration of U-235 was still 3% of the uranium. It decreased due to the shorter half-lifes of U-235.
A pressurized heave water reactor runs with today's unenriched uranium, so we are better than that already.
Re: (Score:2)
The actual reactor zones are much smaller than the mine. Only a few tens of metres across for some of them. The mine as a whole contained 14 to 17 reactor zones (counts vary) at different levels in the mine from near-surface to deep underground. Now that the mine has been mined out, there's just the one un-mined example at a mine 30-odd kilometres away. And that mine has been shut down for a coup
Face it. (Score:2)
really? (Score:1)
No.
Re: (Score:2)
That's a legit question over great lengths of space and time.
Re: (Score:1)
If you want absolutes, religion is on the left.
So does this mean: (Score:1)
That this story is 42 years late?
300,000 years (Score:1)
Heat output? (Score:2)
Re: (Score:2)
Careful... (Score:5, Funny)
*sunglasses*
" 300,000 years " or "300 million years"? (Score:2)
Given TFS later tells of "1.5 billion years since switching off", and the impossibility of measuring 300.000 years accurately in this context, I suppose the reactor was active for 300 million years, not 300 thousand years. Is ee the "300000" number is in TFA, but it looks suspect.
Re: (Score:2)
"No wounder dinosaurs died out, they all worked at nuclear power plant"
Perhaps not, but the mutations caused by the radiation made the development of humans possible, according to a few SF authors.
Re: (Score:2)
Clearly it's the Cradle of Life.