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Understanding the 2 Billion-Year-Old Natural Nuclear Reactor In W Africa

samzenpus posted about 8 months ago | from the it's-getting-hot-in-here dept.

Science 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."

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I don't know but there for Aliens. (5, Funny)

Noishkel (3464121) | about 8 months ago | (#46887191)

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 (1)

Anonymous Coward | about 8 months ago | (#46887249)

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 (-1)

Anonymous Coward | about 8 months ago | (#46887705)

OH NOOOOz
Natural Thermonuclear Global Warming, THE SKY IS FALLING, THE SKY IS FALLING!!!
We should make a law! We should throw all the farty cows in a volcano!
Were all gonna die! We need a Democrat to save us!
Wheres Obamaman when you need him?
Its an Arab plot I tell you.

1.5 BILLION YEARS! (0)

Anonymous Coward | about 8 months ago | (#46887859)

3 x 10^9 years - 300 x 10^3 years is still roughly 3 x 10^9 years. Where did they get the 1.5 x 10^9 years? What am I missing here?
 
captcha: ancients

Mod parent up (0)

Anonymous Coward | about 8 months ago | (#46887907)

I, too, would like to know how this works!

Re:1.5 BILLION YEARS! (1)

Anonymous Coward | about 8 months ago | (#46889463)

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.

Re:More awesome than Autobots. Us, I mean (0)

Anonymous Coward | about 8 months ago | (#46887867)

Uranium hexafluoride. It's used in the enrichment process. They put it in ice cream, AC. CHILDREN'S ICE CREAM. How does THAT go for your commie Arab plot?

Re:More awesome than Autobots. Us, I mean (4, Funny)

K. S. Kyosuke (729550) | about 8 months ago | (#46887997)

Obviously, that uranium ice cream must good for the nuclear family.

Re:More awesome than Autobots. Us, I mean (1)

wirefarm (18470) | about 8 months ago | (#46888603)

And it goes great with Yellow Cake [wikipedia.org]

Re:I don't know but there for Aliens. (2)

KingOfBLASH (620432) | about 8 months ago | (#46887287)

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 would be cost prohibitive. In addition, any civilization THAT advanced would undoubtedly be able to get better efficiency out of their reactors before zipping away.

Unless maybe it's technology from Atlantis. Given no doubt by the same aliens who built the pyramids. When do Milla Jovovich and Bruce Willis come out to save the world?

*Cue conspiracy flame wars*

Re:I don't know but there for Aliens. (1)

Gareth Iwan Fairclough (2831535) | about 8 months ago | (#46887403)

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:I don't know but there for Aliens. (2)

tlambert (566799) | about 8 months ago | (#46887493)

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:I don't know but there for Aliens. (2)

angel'o'sphere (80593) | about 8 months ago | (#46887775)

France has no running breader reactors since decades.

Re:I don't know but there for Aliens. (2)

SJHillman (1966756) | about 8 months ago | (#46888049)

No breader reactors? What about baguette reactors?

Re:I don't know but there for Aliens. (0)

Anonymous Coward | about 8 months ago | (#46889585)

still bread. crusty, flaky, wonderful bread.

Also, why dump the waste on earth??? (0)

Anonymous Coward | about 8 months ago | (#46887429)

I mean they could dump it on the moon or anywhere as they come from space. However, maybe they needed to make plutonium for so they built some natural reactors. Manufactured and extracted the plutonium, dump the rest back in the pits and fueled up left this god forsaken rock. Possible after one of the made it with one the locals for fun....

Re:Also, why dump the waste on earth??? (2)

Chas (5144) | about 8 months ago | (#46887457)

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.

Re:Also, why dump the waste on earth??? (2)

mrbester (200927) | about 8 months ago | (#46887677)

"...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:Also, why dump the waste on earth??? (1)

flyingfsck (986395) | about 8 months ago | (#46887729)

Well, I hope you enjoy mowing the lawn of your elderly neighbour...

Re:Also, why dump the waste on earth??? (1)

angel'o'sphere (80593) | about 8 months ago | (#46887799)

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:Also, why dump the waste on earth??? (1, Informative)

BitZtream (692029) | about 8 months ago | (#46888217)

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:Also, why dump the waste on earth??? (1)

angel'o'sphere (80593) | about 8 months ago | (#46889615)

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.

Obligatory Nuke Snark (3)

Latent Heat (558884) | about 8 months ago | (#46888257)

Is this a geek thing, a Web thing, or our modern age that information is passed on in a scolding?

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:Obligatory Nuke Snark (0)

Anonymous Coward | about 8 months ago | (#46889249)

It's a geek thing. I suspect this is why a lot of geeks get beaten up at school. They simply aren't aware they're being arseholes.

Re:Obligatory Nuke Snark (1)

angel'o'sphere (80593) | about 8 months ago | (#46889479)

Usually the assholes beat the non assholes ...

problem, no one is doing it (0)

Anonymous Coward | about 8 months ago | (#46889747)

I found what he said to be the same old comment and argument about nuclear waste. And the industry rushed to make reactors that did a piss poor job of using all of the energy in the fuel. And during the time the 'perfected' one reactor, there were others that could have done a hell of a lot better. Their was a molten core reactor which should be able to use up the life, so it would create little waste so it would be safe in the decades.

For some reason and it is a combination, of public fear, government buy offs, and the industry {nuclear} dictating everything, as to why non of these ideas have come to pass. And it appears to be at a global scale with the industry, since no other country seems interested in developing or continuing research on previous reactors.

I understood the Chas's point, and his passion to see us stop wasting and using up resources.

Re:Also, why dump the waste on earth??? (1)

Chas (5144) | about 8 months ago | (#46888507)

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:Also, why dump the waste on earth??? (1)

angel'o'sphere (80593) | about 8 months ago | (#46889447)

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:Also, why dump the waste on earth??? (1)

SJHillman (1966756) | about 8 months ago | (#46888055)

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:Also, why dump the waste on earth??? (0)

Anonymous Coward | about 8 months ago | (#46889659)

Technically possible, however, imagine a Challenger-type disaster, with a payload of nuclear waste. That's why nuclear powered rockets are banned.

Re:Also, why dump the waste on earth??? (1)

CrimsonAvenger (580665) | about 8 months ago | (#46888941)

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.

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.

Re:Also, why dump the waste on earth??? (0)

Chas (5144) | about 8 months ago | (#46889553)

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 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).

Over time, you're dealing with an ever more compact and more radioactive mass.
Sooner or later it's really no longer suitable for reactor fuel, and, if we're lucky, has been converted to something that will quickly break down into something harmless.

Space 1999 (1)

p51d007 (656414) | about 8 months ago | (#46888473)

They can't! Didn't you ever watch the 70's sci-fi show "Space 1999"? ;)

Re:Space 1999 (0)

Anonymous Coward | about 8 months ago | (#46888733)

Of course I did. I was in love with Maya by the way. I liked their little "staple gun" energy weapons...

Re:Also, why dump the waste on earth??? (1)

Hamsterdan (815291) | about 8 months ago | (#46889155)

"I mean they could dump it on the moon"

I'm gonna miss the moon...

Re:I don't know but there for Aliens. (2, Interesting)

Anonymous Coward | about 8 months ago | (#46887515)

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:I don't know but there for Aliens. (0)

Anonymous Coward | about 8 months ago | (#46887589)

If you do have nuclear waste in space - why would you dump it on earth? Just send it towards the nearest star, you'll never hear from it again.

And yes, this has been suggested as a method to deal with our nuclear waste - but placing a few ton of nuclear material on top of a 100.000 liters of fuel and ignite the package somehow isn't very popular these days...

Re:I don't know but there for Aliens. (0)

Anonymous Coward | about 8 months ago | (#46888067)

You're assuming that a starship would use uranium as a fuel source. Uranium might be as useful for powering a starship as wood is for fuelling a modern car

cost prohibitive (0)

Anonymous Coward | about 8 months ago | (#46888115)

And why would an advanced civilization descend into a gravity well to dump their spent fuel? Compressing it into a sphere and chucking it into a gas giant, throwing it into a sun or stuffing it into a large asteroid would be far less costly in terms of energy and wouldn't threaten a biosphere.

Re:I don't know but there for Aliens. (1)

InvalidError (771317) | about 8 months ago | (#46889167)

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:I don't know but there for Aliens. (1)

ProzacPatient (915544) | about 8 months ago | (#46888765)

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" (4, Interesting)

SuperKendall (25149) | about 8 months ago | (#46887197)

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:"Have all been mined out" (2)

Sockatume (732728) | about 8 months ago | (#46887443)

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.

Wait.... (1)

sycodon (149926) | about 8 months ago | (#46888505)

"...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:Wait.... (0)

Anonymous Coward | about 8 months ago | (#46888971)

Certain of the constants might not be.

Re:Wait.... (2)

MightyYar (622222) | about 8 months ago | (#46889069)

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:Wait.... (0)

Anonymous Coward | about 8 months ago | (#46889129)

Yes, it's science not religion.

The laws of physics have been amended many times in light of new information. The behavior of contemporary nuclear reactions is well understood, but if for example the speed of light in a vacuum used to be higher, the efficiency of an ancient reactor would have been grater (as per E=Mc^2).

Physics has a ton of "constants" like c that we've never observed change but since we haven't been observing them for all of time we can't say with certanty that they have never changed. An ancient nuclear reactor provides opportunities to compare the results of an event from long before we began taking measurements to out models to see if they line up (they probably do, but science is about trying things to find out what happens)

Non-Tablet-Friendly Version Please (1)

Anonymous Coward | about 8 months ago | (#46887241)

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:Non-Tablet-Friendly Version Please (2)

rvw (755107) | about 8 months ago | (#46887407)

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:Non-Tablet-Friendly Version Please (0)

Anonymous Coward | about 8 months ago | (#46887525)

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

What happened to CTRL-C?

Re:Non-Tablet-Friendly Version Please (0)

Anonymous Coward | about 8 months ago | (#46887639)

Have you not heard? Clever people don't need Ctrl-C, with their unconstructive magnificence it just happens while they are being deafened by the whooshing noise of the point that they entirely missed.

And Ctrl-numpad_minus is easier.

Re:Non-Tablet-Friendly Version Please (0)

Anonymous Coward | about 8 months ago | (#46887741)

CTRL+INS, SHIFT+INS, that's what I've been using for 20 years, and that's why I hate when keyboards shuffle up the area above the cursor.

Re:Non-Tablet-Friendly Version Please (1)

gmclapp (2834681) | about 8 months ago | (#46887787)

TIL CTRL+INS, SHIFT+INS works the same way as CTRL+C, CTRL+V. Who knew!

Re:Non-Tablet-Friendly Version Please (1)

MightyYar (622222) | about 8 months ago | (#46889087)

I only know this because I use a terminal program too much. Don't want to be hitting control codes in that situation :)

Re:Non-Tablet-Friendly Version Please (1)

Noah Haders (3621429) | about 8 months ago | (#46889551)

i remapped copy to be ctrl-a. so for me the flow is mouse highlight the entire article, ctrl-a, ctrl-v. but ctrl-v i mapped to the application switcher, so one at notepad I have to go to the edit menu and choose paste.

Re:Non-Tablet-Friendly Version Please (1)

pisces22 (819606) | about 8 months ago | (#46888711)

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:Non-Tablet-Friendly Version Please (0)

Anonymous Coward | about 8 months ago | (#46888807)

In Firefox: View -> Page Style -> No Style

Thank You!
Simple, informative, helpful.
Have some upvotes :)

bottom pop up ads on slashdot? (5, Insightful)

Anonymous Coward | about 8 months ago | (#46887265)

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:bottom pop up ads on slashdot? (0)

Anonymous Coward | about 8 months ago | (#46887487)

I don't know. But I hate them. Slashdot is one of the few sites on my whitelist when it comes to ads, because I want to support the site. I'm fine with the banner ad along the top and on the right. But those pop-up/slide-up ads at the bottom are something new, and obviously they don't respect my browser settings to prevent regular pop-up windows. They're something else. If I can't find an easy way to target those, I guess I'll have to kill off all the ads.

The "beta" was bad enough, yes, but it's solved with "http://slashdot.org/?nobeta=1", which is now the only way I browse. It must make for an interesting informal poll in the sever logs if they count up how many people use that URL.

If someone has a targetted way to take out those bottom pop-up ads, I'd appreciate it.

Re:bottom pop up ads on slashdot? (1)

ljhiller (40044) | about 8 months ago | (#46887545)

Many years ago I uninstalled and boycotted NoScript because the author started pushing out pointless updates to get advertising hits on his post-upgrade splash screen. Two weeks ago I reinstalled it, because ads that block the content they are supposed to be supporting are unconscionable and obnoxious. Now I don't see any ads.

Re:bottom pop up ads on slashdot? (0)

Anonymous Coward | about 8 months ago | (#46888409)

There has been a box to not show that for a while
Options-notifications-display the release notes on updates

Re:bottom pop up ads on slashdot? (0)

Anonymous Coward | about 8 months ago | (#46888573)

The noscript default whitelist is ridiculous. If you install it thinking you won't run scripts, you are sadly mistaken.
Thats the problem I have with "HTML 5". You can use stuff like flashblock to keep it from happening. The flyup ads are part of the content of the page and you can't block parts of "HTML 5", otherwise nothing works, which I think is sadly the point.

Re:bottom pop up ads on slashdot? (1)

Charliemopps (1157495) | about 8 months ago | (#46887893)

You need to familiarize yourself with browser plug-ins...

take your time (0)

Anonymous Coward | about 8 months ago | (#46887417)

Wow, these guys really didn't waste any time, did they?
They found out in '72 and now they publish that the mine is practically gone. So someone actually beat them to it?

No wounder dinosaurs died out (0)

Anonymous Coward | about 8 months ago | (#46887433)

No wounder dinosaurs died out, they all worked at nuclear power plant

Re:No wounder dinosaurs died out (1)

nospam007 (722110) | about 8 months ago | (#46887555)

"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:No wounder dinosaurs died out (1)

RivenAleem (1590553) | about 8 months ago | (#46887653)

Clearly it's the Cradle of Life.

Not cradle of life - it isn't old enough. (0)

Anonymous Coward | about 8 months ago | (#46887845)

It would have to have been about 3.5 billion years ago for that, not 2 billion years ago.

http://en.wikipedia.org/wiki/Timeline_of_evolutionary_history_of_life

But it could have added a higher mutation rate to the bacteria/algae that did exist and lead to the rest of us eventually.

How low can you go?(power density) (3, Interesting)

tinkerton (199273) | about 8 months ago | (#46887451)

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.

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:How low can you go?(power density) (1)

ssam (2723487) | about 8 months ago | (#46887745)

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) (5, Interesting)

silentcoder (1241496) | about 8 months ago | (#46887757)

>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:How low can you go?(power density) (1)

tinkerton (199273) | about 8 months ago | (#46888029)

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:How low can you go?(power density) (1)

Sockatume (732728) | about 8 months ago | (#46888397)

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:How low can you go?(power density) (1)

tinkerton (199273) | about 8 months ago | (#46889679)

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 short leash because it's speculation. And often its untestable speculation , and it's best to stay out of that territory. And when you do experiments and they don't come out right, the hypothesis that 'maybe current scientific understanding is wrong' should be considered a very expensive claim that should be postponed until all other options have been exhausted. Instead, and partly because of popular media, it's become a very cheap claim that is easily made.
In the OPERA experiment they came up with the explanation that maybe neutrinos go faster than light. If you want to claim that maybe all of our scientific understanding is wrong then you need an awful lot of evidence to back it up, or you shouldn't make the claim. The guy should just have shut up and kept searching rather than hoping for a scoop.

People should not start trotting out a 'variable constant' hypothesis because some ratio of elements is wrong in ore.

Re:How low can you go?(power density) (1)

Sockatume (732728) | about 8 months ago | (#46888407)

...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:How low can you go?(power density) (1)

ceoyoyo (59147) | about 8 months ago | (#46888431)

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:How low can you go?(power density) (0)

Anonymous Coward | about 8 months ago | (#46888201)

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..

Exactly, for instance during the initial big bang the universe expanded faster than the speed of light (according to the current theory). This in itself suggests that there have been changes to the "constants" that we claim. The problem that makes most people (myself included) uneasy is that we dont know of any good way to really determine what changed. The problem is that that branch of science has to work backwards looking at the "effect" and estimate the most probable "cause". If the laws changed over time then that would make it very very difficult to do.

Re:How low can you go?(power density) (2)

AlecC (512609) | about 8 months ago | (#46888353)

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 which we will never see, because light cannot cross the ever-expanding gulf between us.

Re:How low can you go?(power density) (1)

Noah Haders (3621429) | about 8 months ago | (#46889695)

maybe it's a technology limitation and we'll be able to see them with bigger telescopes.

Re:How low can you go?(power density) (0)

Anonymous Coward | about 8 months ago | (#46888213)

I don't think it is even that maverick-y. Although it sounds like a neat label.

Two glaring questions we have about the early universe is the idea that inflation may have broken the speed of light limit for a short period and that we exist due to the non-equal distribution or creation of antimatter and matter.

Re:How low can you go?(power density) (1)

meta-monkey (321000) | about 8 months ago | (#46888403)

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 physics. It turns out the mechanism is billions of years old and helped the aliens escape in to a new universe, because their technology (and biology?) was based on dark energy, and the universal constants that allowed their tech to work were changing. So they created a new universe and went there.

I wish I could remember the name of the book...

Re:How low can you go?(power density) (1)

Grizzley9 (1407005) | about 8 months ago | (#46888453)

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:How low can you go?(power density) (1)

Tyler Durden (136036) | about 8 months ago | (#46888777)

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.

hard to test != untestable

Re:How low can you go?(power density) (1)

Chris Mattern (191822) | about 8 months ago | (#46888887)

Now there's no proof the fundamental constants have changed at all since the big bang, but there's no proof they haven't.

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:How low can you go?(power density) (0)

Anonymous Coward | about 8 months ago | (#46889265)

Well, except that:

1. Astronomy's estimates of how far back they're seeing are based on the speed of light in avaccume being constant, and
2. Astronomy is where the idea that some constants might have changed comes from as it could explain observed oddities in cosmic background radiation and the rate of the universe's expansion.

Re:How low can you go?(power density) (1)

Sockatume (732728) | about 8 months ago | (#46887835)

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:How low can you go?(power density) (1)

Noah Haders (3621429) | about 8 months ago | (#46889749)

i don't know what fine structure constant means. my office has solar panels and we produce 30kw, so I don't think 100kw is a lot. also, any miner will tell you that it is hot underground, indicating these reactions are more common than you think (when the nuclear reaction happens it creates lots of heat).

Re:How low can you go?(power density) (2)

Zorpheus (857617) | about 8 months ago | (#46887849)

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: How low can you go?(power density) (0)

Anonymous Coward | about 8 months ago | (#46888221)

When the reactor was critical, the U-235 enrichment was much higher than it is today. U-255 decays faster than U-238. Today the U-235 enrichment is about 0.72%, but it would have been higher. With a higher enrichment, it is easier to get a critical mass

Face it. (1)

JustOK (667959) | about 8 months ago | (#46887803)

We're just some alien's toilet.

Ah Africa (-1)

Anonymous Coward | about 8 months ago | (#46887853)

A natural reactor was found there, because with there level of intelligence it sure wouldnt be artificial

Quaid (0)

Anonymous Coward | about 8 months ago | (#46888041)

Start the reactor....

really? (1)

slashmydots (2189826) | about 8 months ago | (#46888627)

"to discover whether the laws of physics...may have changed"
No.

Re:really? (1)

GodfatherofSoul (174979) | about 8 months ago | (#46889547)

That's a legit question over great lengths of space and time.

So does this mean: (1)

pslytely psycho (1699190) | about 8 months ago | (#46888989)

"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?

300,000 years (1)

Xeno-Root (2914175) | about 8 months ago | (#46889117)

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?

Heat output? (1)

digsbo (1292334) | about 8 months ago | (#46889247)

How much heat could such a natural reactor generate? Would it be enough to affect local climate? Ocean currents and/or temperatures?

Re:Heat output? (1)

Bob the Super Hamste (1152367) | about 8 months ago | (#46889741)

Depends on how local you are referring to. A poster further up mentioned that it probably put out about about 100kw or about the same power as a small car. While cool I would probably put it in the same category as the natural laser on Mars [harvard.edu] as just an interesting natural phenomenon that won't affect me.

Careful... (4, Funny)

Mayhem178 (920970) | about 8 months ago | (#46889467)

Don't let the hippies hear you suggest that fission is a naturally occurring process. They might...

*sunglasses*

...go nuclear.

data? burn it, fast! (0)

Anonymous Coward | about 8 months ago | (#46889697)

> mining continued and the natural
> reactors ... have all been mined out.

Ya know where you could have found an astonishingly detailed fossil record of life on Earth over deep time?

Coal beds.

If we hadn't burned them.

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