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Understanding the 2 Billion-Year-Old Natural Nuclear Reactor In W Africa
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."
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!
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.
"There is more worth loving than we have strength to love." - Brian Jay Stanley
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...
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.
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?
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.
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 sit out in what's essentially a parking lot in the back.
At the end of it all, you wind up with a relatively tiny amount of waste, compared to what we output today. Easier to store, easier to manage, easier to transport when a site finally completely decommissions and is returned to nature.
Dumping it into space is 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.
Chas - The one, the only.
THANK GOD!!!
"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.
Clearly it's the Cradle of Life.
"...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.
"Wait. Something's happening. It's opening up! My God, it's full of apricots!"
Well, I hope you enjoy mowing the lawn of your elderly neighbour...
Excuse me, but please get off my Pennisetum Clandestinum, eh!
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?
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
We're just some alien's toilet.
rewriting history since 2109
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?
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.
Persistent Volume manager for Kubernetes - https://github.com/dwimsey/openshift-pvmanager
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?
"...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?
When Fascism comes to America, it will call itself Anti-Fascism, and tell you to give up your guns.
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?
Chas - The one, the only.
THANK GOD!!!
"to discover whether the laws of physics...may have changed"
No.
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 means there's a lot of energy being released, which can be converted into something useful.
The long half-life stuff is what you want to leave behind. Like U-238, which has a half-life in the billions of years range.
In short, making nuclear waste "not radioactive" is a matter of getting rid of the SHORT half-life stuff. The longer the half-life, the less radioactive something is.
"I do not agree with what you say, but I will defend to the death your right to say it"
"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."
That this story is 42 years late?
Donald Trump, on a crusade to make Nixon look respectable
It says the reactor powered on two billion years ago, that is 2,000 million years ago, then it says that it ran for 300,000 years, that is 0.3 million years. Then it says that it has been powered off for 1,5 billion years ago (1,500 million years ago). If it was powered for less than a million years, why do the numbers disagree by 500 million years?
"I mean they could dump it on the moon"
I'm gonna miss the moon...
I've got better things to do tonight than die.
How much heat could such a natural reactor generate? Would it be enough to affect local climate? Ocean currents and/or temperatures?
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'?
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
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 time. Eventually the fission process and natural decay of U-235 lowered the concentrations to a point where criticality could no longer be sustained.
Don't let the hippies hear you suggest that fission is a naturally occurring process. They might...
...go nuclear.
*sunglasses*
"You will pay for your lack of vision..." - Emperor Palpatine to Ray Charles
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 transport and needs cooling and finally a safe deposite (in safe containers).
So again: reprocessing does not solve any waste problem, it creates more waste in an order of one or more magnitudes. Exactly that is the reason why only bomb nations reprocess ... they need to do it to get the plutonium. For non bomb nations it only makes the problem worse.
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
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.
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 regardless what you do with same later, they are completely useless in a nuclear reactor except for continuing to decay (depending on isotope) and adding some difficult to control extra heat to the reactor.
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
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.
"Think about how stupid the average person is. Now, realise that half of them are dumber than that." - George Carlin
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.
"Think about how stupid the average person is. Now, realise that half of them are dumber than that." - George Carlin
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.
Chas - The one, the only.
THANK GOD!!!
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 considered expensive is because it's still easier to dig it out of the ground right now and process it from raw ore or buy and then down-blend material from soviet warheads..
The problem with this approach is that we're putting out "spent" fuel that has the potential to fire reactors for an extended period of time, but instead of reprocessing them, they're going into containment casks and expected to just sit there for the next few million years?
Insanity.
Chas - The one, the only.
THANK GOD!!!
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.
-><- no
You are missing the age of the deposit. It has little to do with the age of the earth which is gotten from U/Pb ratios in zircons. The U in the deposit was concentrated in an open system which became closed in the formation of the deposit. It then evolved so that a natural reactor could form, as a closed system for some 300.000 years. The age of 1.5 BYA has to come from field relations and probably some absolute dating. It would be enough for concordant U/Pb ages to come from rocks surrounding the deposit to bracket the date of its formation, even though the natural reactor caused its U-235/U-238 ratio to be altered. Possibly, there is independent U/Pb dating, but it needn't have concordance within the deposit, and the system needn't remain closed to geochemistry since its formation, only that surrounding rocks give concordant ages and constrain its relative age stratigraphically.
Understand that absolute dates give the date a system was closed. Different isotopes can be used to date different parts of the history of a system. U/Pb can date the prolith of a grainite, for example. Zircons survve the metasomatic process that metamorphoses sediments into granite or gneiss. K/Ar dates might reveal a younger age from the same rock dating when the system was open to introduction of alkali metals in the later metamorphic process. Further studying field relations can justify dates of subsequent dates of metamorphism when the clock for different pairs of isotopes are reset giving different ages, such as Sr/Rb and K/Ar dates but reveal when prograde and retrograde metamorphic events occurred that must match up with field relations. This has been extensively done for the batholithic rocks of California and the West Coast and the geochemical and thermal history of these rocks is now well known and related to plate tectonics history.
Nevertheless the only thing you can 'burn' is the remaining uranium AFTER you have enriched it again.
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
This is contradicted by the geology of the deposit.
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"