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Science

Reactor at Earth's Core? 69

Posted by michael from the light-up-my-life dept.
An anonymous submitter sent in this story suggesting that uranium in the Earth's core may be acting as a giant breeder reactor, generating a large amount of heat and perhaps being responsible for the Earth's magnetic field.
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Reactor at Earth's Core? More

Reactor at Earth's Core?

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  • Wow, this is crazy. Like something out of a 60's sci-fi flick.

    I guess now people are going to be fined for core dumping.
  • This is interesting stuff. I've always read that scientists thought that the core was made out of iron (Fe). If this new revelation is true then the density of the center of the core may be much higher than previously thought. What does that mean for the rest of the core? The density must be lower than previously thought???
  • In an article [sci-e-research.com] titled No second chance: can Earth explode as a result of Global Warming? by Dr Tom J. Chalko, MSc, PhD, Head of Geophysics Division, Scientific E Research P/L, Melbourne, Australia writes

    "It is a well established fact, verified by decades of seismic measurements, that the Earth's inner core is a nearly spherical solid of about 1220 km radius that occupies the central position of our planet. The generally accepted view today is that this solid grew slowly to its current size as a result of the "crystallization" of the surrounding liquid. The "latent heat" of this "crystallization" allegedly explains how the inner core generates heat.

    This article considers global hydro-gravitational equilibrium conditions for the Earth's inner core and presents a rigorous and compelling scientific proof that the solid core of our planet could never be smaller or lighter than a certain minimum, otherwise the core would not be able to remain in the center of the planet.

    Since the inner core could have only been larger and heavier in the past than it is today - it cannot be the result of any "crystallization". This simple conclusion has astonishing consequences.

    Imagine a gigantic object of 1220 km radius that slowly becomes smaller, lighter and gives off heat for millions of years. What could it be? It can only be an object that generates heat by nuclear decay.

    The main consequence of the above is that all heat generated inside Earth is of radionic origin. In other words, Earth in its entirety can be considered a nuclear reactor fuelled by spontaneous fission of various isotopes in the super-heavy inner core, as well as their daughter products of decay in the mantle and in the crust.

    Life on Earth is possible only because of the efficient cooling of this reactor - a process that is controlled primarily by the atmosphere. Currently this cooling is responsible for a fine thermal balance between the heat from the core reactor, the heat from the Sun and the radiation of heat into space, so that the average temperature on Earth is about 13 deg C.

    Since the radionic heat is generated in the entire volume of nuclear fuel (the entire Earth) and cooling can occur only at the surface, the hottest point of the planet should be in its very center.

    This article examines the possibility of the "meltdown" of the central part of the inner core due to the reduced cooling capacity of the atmosphere, which traps progressively more solar heat due to the so-called greenhouse effect. Factors that can accelerate the meltdown process, such as an increased solar activity coinciding with increased emissions of greenhouse gasses are discussed.

    The most serious consequence of such a "meltdown" could be a gravity-buoyancy based segregation of unstable isotopes in the molten inner core. Such a segregation can "enrich" the nuclear fuel in the core to the point of creating conditions for a chain reaction and a gigantic atomic explosion. Can Earth become another "asteroid belt" in the Solar system?

    It is a common knowledge (experiencing seasons) that solar heat is the dominant factor that determines temperatures on the surface of Earth. In the polar regions however, the contribution of solar heat is minimal and this is where the contribution of the heat from the inside of our planet can be seen best. Raising polar ocean temperatures and melting of polar caps should therefore be the first symptoms of overheating of the inner core reactor.

    While politicians and businessmen still debate the need for reducing greenhouse emissions and take pride to evade accepting any responsibility, the process of overheating of the inner core reactor has already begun - polar oceans have become warmer and polar caps have begun to melt. Do we have enough imagination, intelligence and integrity to comprehend the danger before the situation becomes irreversible?

    Those crazy Aussies ahead of their time!
    • Concerns about global warming aside, the Earth's external temperature has fluctuated *wildly* during the 4 or 5 billion years our planet has been around. At times, such as when the atmosphere wasn't made primarily of oxygen for example, it has been much colder or hotter. Assuming that our planet's core does indeed act like a breeder reactor, something so slight as global warming is not going to significantly affect it.
      • I agree. I am not a cosmologist, but I think Venus can be our control group in this case. It is roughly the same size, probably roughly the same (internal) composition, but has a surface temperature hundreds of degrees higher than Earth's. And it's still there.

        • Re:What if that Reator Blew Up! (Score:1, Funny)

          by Anonymous Coward
          yeah, the planet is still there, but the increased atmospheric pressure and higher temperatures forced all of the women to move here.
    • of unstable isotopes in the molten inner core

      Molten inner core?

      Last time I talked to a geophysicist (today) the inner core was solid. Go to my web page and ask me how I know.

      No science is worse than the science FOX NEWS reports on...

  • When did the Earth's magnetic field suddenly become such a "big mystery"?
    Also, when did natural radioactive decay become a definition of a reactor?

    Next thing ya know, we'll be discussing who invented the telephone!
      • I knew I should have mentioned Oklo. In the Earth's crust I can see uranium occuring in concentrations high enough for this to occur, but I don't think it's likely in the molten portions of the Earch due to high diffusivities and continuous convection.
      • The site linked to in your sig shows a remarkable lack of geopolitical history, as well as an inability to see rational distinctions between situations. It so simplifies a handful of cases that the analogies fail.

        You could as easily say that the 1840's Texans were Palestinian; only their allies (USA vs. Jordan/Syria/Egypt/Etc... for the Palestinians) actually won the first war, and conquered out a chunk of Mexico for the Texans to live in.
        • Cruelty is creulty. The distinction is simple, thanks for pointing that out for everyone.
          • The least cruel thing that could be done is to euthanize everyone in the world as simultaneously as possible. If you let them live, they will suffer at some point in their life.

            The distinction is not simple, because that's not what I was making my point on, not did that seem to be the point of said cartoons in your sig link. Sometimes you are stuck between a rock and a hard place. With Hamas refusing to make any deals whatsoever, the Israelis, and hence the Palestinians, are in that horrid middle place.

            It would have been better if the expulsion had been permanent, ala the legal expulsion and seizure of property of the loyalists who chose to side with the British in the US Revolutionary war. (Most of said loyalists went to Canada during and following the war and made a new life) This probably would have been the best situation, but the other nations around Israel refused asylum/refuge to many of said Palestinians.
            • and a PS.

              Hopefully, the fence will stop most of this, and the Israelis will be smart enough to withdraw from the settlements.
              • and another.

                The Palestinians aren't the only ones being cruelly done to. So are the Israelis (unless you don't consider the deliberate murder and maiming of children to be cruel). This type of violence can only end when the VAST majority of BOTH sides SIMULTANEOUSLY decide they would rather have peace than conflict. Or when (as in the Cold War) both sides are so evenly matched and strong that an attack would be mutually destructive (though in this type of fight, if one side was willing to self-destruct in an Arthur-Modred type suicide attack, the stand-off will not last).

                The majority Palestinian support for Hamas, et al., no matter how necessary in their eyes (due to Israeli actions), makes peace impossible barring the extinction of one side.
              • Yes! I hope that the fence will help.

                It's silly that both the settlers and the Arabs hate it. The settlers hate it for seperating their stupid neighborhoods from Israel, and the Arabs hate it because it makes it harder for them to infiltrate Israel (usually for doing illegal work and stealing cars, but also for their dedicated shahid service).
          • The artist, Latuff, who made the thing linked in your sig supports terrorism. Look at this [indymedia.org] thing.

            Many of the things written (with bad grammar) in that drawings are true, unfortunately, but the reasons for all those are not mentioned. The reasons houses get destroyed and people gets killed is that the PA encourages the terrorists organizations. The PA is powered by hatred, and the children are educated to hate [edume.org] Israel and Jewish people, even in times of peace.

            Btw: Are you a girl?
            • Not a girl.

              I don't believe in "terrorism". I believe in revolutionary social, and geopolitical change accompanied by isolated outbursts of violence by a repressed populace. Massive violence is out of the question look at India/Pakistan, and in a few months or years an arab state or organization will point a nuke or W.O.M.D. at Israel and say beg for forgiveness or "BANG". I don't support any violence (I'm pro-life and proud), but I don't hide the reality or nessecity of it away because I'm too swilled on reality tv and budweiser. I was expecting a sept 11th scale attack on the US for years, and I suspect a nuclear attack (dirty most likely) very soon. I wouldn't worry about israeli policy if you like me live in the united states I would worry about american policy.

    • The "self-excited dynamo" theory of geomagnetism has always been shakey and based on a lot of unwarrented assumptions; but, until now, has been the best explanation.

      Natural radioactive decay is not the same as a fission reaction.
    • Come on, did you read the article?

      The existing Dynamo theory doesn't properly explain why the Earth's magnetic field has varying power levels and periodically shuts down.

      This theory properly explains for that, as well as answers some questions about why helium-3 and helium4 isotopes are being found in deep-source volcanic lava rock.

      The theory for why it periodically shuts down is quite interesting. I wonder if this theory of how this reactor works couldn't help produce better artificial reactors. Nature/evolution seems to have (if all the data pans out) created a very efficient (over-efficient if it's really a breeder) reactor.

      -malakai
      • Probably even more interesting and strange are the polar switches. The article implies that switches are infrequent, but from my geology classes I seem to recall that there is a polar swap every time the field drops to zero, which seems to be going to be happening again soon (within a few millenia). I would realy like to know whether the reactor theory can handle the polar switches as well as the on again, off again pattern.

        • There have actually been hundreds of switches in the past couple several tens of million years. We know this because we can examine the orientation of the magnetic field of minerals in oceanic basalts on either side of spreading centers (ie mid-Atlantic ridge) in the ocean. When field orientation is plotted on a map of the seafloor, bands of alternating magnetic fields show up very nicely. The bands will just about exactly parallel the spreading center quite well. That's pretty damn cool if you ask me.

  • Let me just get this out of the way... (Score:3, Funny)

    by tswinzig ( 210999 ) on Tuesday June 18, 2002 @11:40AM (#3722725) Journal
    So the earth is sort of like a giant shed in your mother's backyard?
  • Combine that with the exploded planet hypothesis [metaresearch.org] and you got yourself a great book.

  • it's not quite as bizarre as it may seem (Score:3, Informative)

    by g4dget ( 579145 ) on Tuesday June 18, 2002 @11:57AM (#3722843)
    People have thought for a long time that radioactive decay contributes to warming of the earth's core. That was also considered to be the source of the He3 that still can be found in volcanic vents.

    The question is just how much of a chain reaction there is. I guess traditionally, the assumption was "not much". But it seems quite plausible that uranium might concentrate and actually start a significant chain reaction.

  • Now what? (Score:3, Funny)

    by Sentry21 ( 8183 ) on Tuesday June 18, 2002 @12:17PM (#3722981) Journal
    Anyone want to take bets on how long until some boy scout tries to make a planet in his mother's potting shed?

    --Dan
  • We all know what is REALLY under the earth [scifi.com]'s surface. Why do you think fossils are coming from underground? Duh.

  • Man, is this article bad. (Score:5, Interesting)

    by Christopher Thomas ( 11717 ) on Tuesday June 18, 2002 @12:23PM (#3723021)
    Man, is this article bad.

    The article proposes a 5-mile sphere of uranium at the Earth's core as the source of Earth's geothermal energy.

    Now, the idea of radioactive decay powering the Earth's geothermal heat generation isn't a new one - in fact, it's one of the more plausible models, as it works quite well over a very long time frame and explains the presence of helium in the mantle. However, the uranium, thorium, and other elements involved would be diffused through the core material (i.e. in solution in the liquid outer core, or as dopants in the iron crystal of the inner core). The absolute concentration of uranium in the Earth is very, very low. Without a really strong mechanism operating to separate it out and concentrate it, it's going to remain a trace impurity in other ores, and not a ball at the center of the Earth.

    Secondly, I'm pretty sure that a 5-mile ball would be over the critical mass/volume envelope for an uncontrolled chain reaction of the U-235 and U-233 present in uranium ore. The fact that the Earth hasn't exploded suggests that uranium is not concentrated into a ball. Anyone with the fast-neutron cross section data care to work this out?

    Now, on to other questionables.

    The Earth's magnetic field is created by movement of the conducting material in the Earth's outer core. The polarity changes in the field are adequately explained by the idea that turbulence destabilizes the dynamo fluid currents every so often. A fascinating article was published about this a while back, but the citation escapes me.

    Turbulence happens; it's a known and expected phenomenon. However, the article authours propose no mechanism for their magical solid-state fission reactor to turn on and off every so often to reset the dynamo currents. Thus, I consider the turbulence conjecture the more plausible.

    Now, on to Jupiter. While Jupiter undoubtedly also has heavy element fission contributing to its heat, the majority of its heat is expected to come from it essentially continuing to slowly compact itself. The idea is that as hydrogen progresses from gas to liquid to metallic liquid to metallic solid state, it undergoes several exothermic phase transitions (analagous to the heat of condensation for more common substances). This provides a feedback loop that limits the rate of conversion - for example, if a lot of liquid hydrogen starts converting to liquid metallic hydrogen, the boundary layer heats up, which makes it less favourable for the conversion to continue. The rate of conversion for some of these phases is expected to be slow enough for Jupiter not to have reached its final equilibrium composition. If the conversion is still going on, then as it's exothermic, it could indeed explain heat generation in Jupiter.

    A similar mechanism involving crystallization of iron was proposed as a source of Earth's geothermal energy, though this is less convincing as the amounts of matter involved are small enough that Earth should have reached equilibrium long ago.

    In summary, the "mysteries" that the article attempts to invoke compact reactors to solve are already adequately explained without the need for such an implausible mechanism.
    • However, the article authours propose no mechanism for their magical solid-state fission reactor to turn on and off every so often to reset the dynamo currents.

      The article DID say how the reactor turns on and off.

      The elements that would soak up the neutrons to stop the chain reaction are concentrated differently over time, allowing the process to turn on and off over time.

      Re-read the article.

    • Only if you don't read it carefully (Score:5, Informative)

      by texchanchan ( 471739 ) <ccrowleyNO@SPAMgmail.com> on Tuesday June 18, 2002 @12:38PM (#3723131)
      Re, ...the article authours propose no mechanism for their magical solid-state fission reactor to turn on and off...

      Yes, they do:
      "One might imagine instances in which the rate of production of [neutron-absorbing] fission products exceeds their rate of removal by gravitationally driven diffusion," Herndon wrote in a recent paper on the subject. If so, he explained, "the power output of the geo-reactor would decrease and the reactor might eventually shut down, thereby diminishing and ultimately shutting down the Earth's magnetic field."


      Over time, as the lighter elements moved away from the uranium core, the reactor would restart.
      Also, re Without a really strong mechanism operating to separate it out and concentrate it, it's going to remain a trace impurity in other ores, and not a ball at the center of the Earth.

      There is such a mechanism. Everyone agrees that the core is iron. How did that happen, when the Earth coalesced from random rocky materials? The same way. If iron, why not uranium? From the article:
      ...over time, solid uranium particles would rain out from Earth's fluid core at high temperatures. Because of their high density, they could collect at the very center of the Earth.

      • Re:Only if you don't read it carefully (Score:4, Interesting)

        by CheshireCatCO ( 185193 ) on Tuesday June 18, 2002 @01:07PM (#3723340) Homepage
        But how do you get the fission products out of a solid chunk of uranium? Solids neither convect nor differntiate.

        This theory also doesn't explain why the Sun's magnetic field chances orientation in a 22-year cycle.

        I'm not sure about the second point, either. Uranium, as far as I know, chemically reacts with other elements and doesn't necessarily differentiate out of the Earth. If you sliced open Earth, you wouldn't find it layered like an onion, one layer per element. Many of them are chemcially mixed in with the major constituents, like iron.

        To add a point: the authors really don't understand energy production or planets (possibly both). Jupiter has to generate about as much energy as it takes in from that Sun. That's or order 10 Watts per square meter, according to my quick calculation. Now, Jupiter's core, IF it has a core at all, is mainly ices. The rocky/metal bit is probably not larger than Earth. So it shouldn't be generating more power than Earth's core. Earth's outward heat flux due to internal heat is 0.01 Watts per square meter. Consider that Jupiter has over 100 times the surface area, and now your core has to be generating 100,000 times the energy that Earth's is, despite being the same size.
        Does this sound reasonable?
        • You don't seem to grasp the size of Jupiter by suggesting it doesn't have a core or that its core is mainly ices. Jupiter is a gigantic ball of Hydrogen surrounding a "rocky" core of heavy elements. Jupiter's surface a and below for a couple Earth diameters is liquid hydrogen, it is liquid not due low temperatures but to the high pressure of the planet's gravity. Then below that is a layer of hydrogen another couple Earth diameters thick composed of liquid metallic hydrogen. The hydrogen becomes so compressed that the electrons spring forth and it all becomes a super efficient conductor. That sort of compression causes immense heat from the condensation of hydrogen. The weight of the hydrogen just increases the deeper down you go. For the size of Jupiter's liquid metallic core it doesn't produce orders of magnitude more heat than the Earth's core, it is just a couple orders of magnitude larger.

          There was nothing mentioned about uranium diffenciating in the parent post, uranium would most likely be held either in solutions or suspended in the material of the core. It might form some kind of uranium-iron alloy but it is still going to decay radioactively.

          The Sun's magnetic field has nothing to do with the Earth's magnetic field. Well they follow the same princibles but they are generated a bit differently. The ionized gases that make up convective zone in the Sun move all around (because of the heat convection) generating a powerful magnetic field. The reason it shifts polarity regularly is the gases around the equator move a lot faster than the gases at the poles. The magnetic fields being produced by this gas end up twisting because of the difference in gases' velocity. After about 11 years the orientation has reached its maximum twistiness and has begun to procede in the opposite direction causing the magnetic fields to have an opposite polarization from when they started. Two cycles of this and you've got your 22 year solar magnetic polarization cycle.

          The center of the Earth is by no means a solid, the temperature and pressure prohibit the formation of solids. I think what the parent post meant was that the center of the Earth would be fairly uniform, not a solid chunk of something. Fission byproducts would easily diffenciate out of the core of the Earth, sometimes rapidly due to the severe weight difference between the fission byproducts and the surrounding material.
          • Actually, I'm going to have to say that YOU don't understand Jupiter. Jupiter's core, by current measurements, is 0 to 10 Earth masses. This is based on the gravitational moments measured by Voyagers I and II and Galileo. Now, only around 10% of that is rocky, the rest are hydrogen compounds (water, methane and ammonia ices, mainly). This is based on the composition of comets and the massive abundance of hydrogen. So now you're left with a rocky/metallic bit that is AT MOST the size of Earth. Unless you assume there was a lot more uranium at 5.2 AU than at 1.0 (and all evidence, dynamical and cosmochemical are to the contrary), that uranium core CANNOT be much larger than Earth's. And, yet, it's putting out way more power according to their speculations. Highly unlikely.

            So, no, Jupiter's metallic core is NOT larger. Unless you'd like to point me to some papers to the contrary. (For reference: Most of what I know has come from attending the Jupiter Meeting a year ago, assorted DPS talks and my graduate classes in planet formation.)

            And, yes THERE WAS mention of differentiation. Implict, perhaps, but it's there. You need to study you're nuclear physics. Uruaniam mixed in with iron won't start a reactor. That's the whole point behind purifying the stuff out of ores (and then isolating U-235) in the first place, when you think about it. The idea that there is radioactive decay in the Earth generating heat is EXACTLY what most geologists believe is going on. If these guys got up and said this, no one would notice since it's an old idea.

            The Sun's field isn't the exactly same as Earths, but the dynamo models have a unifying effect on ALL magnetic fields in astronomy. If you suddenly decieded Earth's field is different, you either are demanding two or more models or need to explain how the Sun fits in to your model. Either way, you're going to get a lot of resistence because you're making the theory messier with no obvious evidence to support it needing the complication.

            And, yes, the center of the Earth is solid. I can see you also need to study your geology. We know this from seismic data. The inner core is solid. Since the authors of this work would have us believe that the uranium is differentiating out of the iron because it is denser, they MUST have the uranium in the inner core. So it is solid. And therefore you won't get differnetiation of fission products.
            • What the fuck are you talking about? Jupiter is 310 Earth masses, about a third of that is the rocky core mass as well as the metallic hydrogen mass. Most of the condensation heat is generated not by the rocky inner core but the several thousand miles worth of metallic hydrogen moving about in its highly conductive way. Heat transfer through a metallic liquid is very efficient due to the sheer density of the material. Any compression on that material is going to generate a bit of heat that is efficiently transfered. The inner rocky mass according to all models is not a solid rocky core but a liquid one about the size of the Earth. Please recall that the liquid rock core is the size of the Earth, not the size of the Earth's core.

              Uranium mixed with iron will not start a reactor but that is not what I suggested was happening. Uranium mixed with iron will will radiate and generate heat and decay byproducts like say...helium-4. Fission reactions in the Earth's core would produce far more genergy than the pressures of gravitation could contain and the planet would explode. I wasn't defending nor suggesting the idea that fission is taking place in the core.

              No the Earth's core is not solid. It is very dense but seismic data does not suggest it is fully solid. It is more of a hyper plastic, there is elastic motion in the material of the core but the resistance is very high due to the density of the material which is believed to be mostly unoxidized iron. The differenciation begins at the upper surfaces of the core where the extremely hot yet lighter material separates from the dense iron in inner core.

              I said the dynamo effect of the Sun's magnetic field followed the same princibles as the Earth's; did you miss that part? The dynamics are the same but the generation source is very different in terms of relative position in the sphere. The core of the Earth is responsible for generating our magnetic field making the magnetic twisting of the fast moving equitorial material a much slower process because the radial velocity differences are much lower than of the Sun's convective zone. The Sun's convective zone which is generating the magnetic field is much larger is preportion than the metallic core of the Earth causing a much faster magnetic field flipping effect. As seen in glacial core samples as well as some deep rock cores the Earth's magnetic field changes polarity MUCH slower than the Sun's and is much less active.
              • I told you very clearly what I was talking about. Where, pray tell, do you get your "facts"? Because they disagree with what I see in published papers and texts.

                Jupiter's core: Check out Protostars and Planet IV, page 1087. You'll clearly see that size of Jupiter's core, from measurments. It is nowhere NEAR 100 Earth masses. I've never heard of anyone suggesting that, especially now that we've been there and that's many times outside of the error bars. It's 0-10 Earth masses. If you're arguing against that, the burden of proof is on you, since you're arguing with a MEASURED QUANTITY. (Admittedly, it's an *indirect* measurement. But I am confident they can tell the difference between 10 and 100 Earth masses in the core.)

                Your statments about the heat flow and generation don't seem to make sense if you are arguing with me. You're arguing for what pretty much everyone in the planetary community beleives, not what this no theory suggests. Namely that Jupiter's heat comes from a fission reactor in the core. As I've said, there isnt' enough uranium there to do it. (See above.)

                I've already addressed the point you repeat in your second paragraph: you're arguing for the status quo theory, in *agreement* with me. This issue here is what these guys are suggesting: an actual fission reaction at the core, not slow radioactive decay.

                Yes, the inner core is solid. Unless you can point me to a kosher source claiming otherwise, I'll trust my geology textbooks and my geophysics faculty on this point. Or at least explain how you get differential from the middle of the inner core (you only claim you get it at the outer edge of the core, which is liquid and not important here, since the uranium is going to be in the ceter of the inner core). Both my texts and my faculty have claimed that the inner core is "solid." (Sorces: _Physical Geology_, by Monroe and Wicander, page 264 and _Moons and Planets_ by Wm. K. Hartmann (planetary geologists, for the record), page 211. And statments made in graduate classes by geology faculty.)

                And on your final paragraph: then we agree. If we want a radically new paradigm on the Earth's field behavior, it'll be at odds with the theories used on other bodies. Hence the general sense of dissatification with the new theory, espeically seeing as there is a lack of evidence that implies a shift is in order.

                So what case are you arguing? For the authors or against them? Three of your paragraphs have turned around and *agreed* with the status quo theory (and with what I'm saying, here). Could you please clearly state your views here, relative to the new theory?
                • From the beginning I agreed with status quo planetary formation theories. I was pointing out missing pieces of information in your original post. You were originally trying to point out flaws in some other theory but you didn't answer your own questions. Posing questions to another poster without defining any answers yourself suggested you didn't know what the fuck you were saying and thus I answered your questions.

                  As for Jupiter's core I said the core was Earth massed and the heat was from condensation, not fission. You're so convinced of your own superiority you're automatically thinking I said something contrary to the accepted belief. I was pointing out that the non-rocky core of Jupiter, the hundred of Earth masses worth of metallic hydrogen was the culprit in the massive heat production.

                  Neither is Earth's core powered by nuclear fission, as I said. I don't know where you're finding suggestions that I thought nuclear fission was powering anything. I was pointing out that uranium does not differenciate in the Earth's core because the concentration would be such that the uranium WOULD become fissal and blow up the planet. Since we're able to discuss this point I think it is safe to assume the Earth has not exploded and there is no measurable amounts of nuclear fission in the core. The theory of nuclear fission in the Earth's core is a bit far fetched and uses absurb leaps in logic to conclude its findings.
      • Without a really strong mechanism operating to separate it out and concentrate it, it's going to remain a trace impurity in other ores, and not a ball at the center of the Earth.

        There is such a mechanism. Everyone agrees that the core is iron. How did that happen, when the Earth coalesced from random rocky materials? The same way. If iron, why not uranium?

        Iron is plentiful. Enough of it was present for gross gravitational effects to be enough to separate it from lighter ores within solution.

        Uranium is far, far less plentiful, and so would tend to remain dissolved.

        There are no "grains" to migrate, as you suggest - uranium would be mixed in as impurities on an atomic level, literally dissolved in other metals and metal oxides.
    • Man, is this article bad.
      Agreed. See the primary literature at PNAS web site:http://www.pnas.org/cgi/content/full/98/20/11 085 [pnas.org]
      Secondly, I'm pretty sure that a 5-mile ball would be over the critical mass/volume envelope for an uncontrolled chain reaction of the U-235 and U-233 present in uranium ore. The fact that the Earth hasn't exploded suggests that uranium is not concentrated into a ball. Anyone with the fast-neutron cross section data care to work this out?

      Not likely. See the Oklo data. The thermal fissionable isotopes would be diluted by the shear volume of U-238. Fast neutrons from U-238 spontaneous fission cannot induce fission in U-235 without thermalization by a moderator. There would be no adequate moderator in the molten core.
      • Not likely. See the Oklo data. The thermal fissionable isotopes would be diluted by the shear volume of U-238. Fast neutrons from U-238 spontaneous fission cannot induce fission in U-235 without thermalization by a moderator. There would be no adequate moderator in the molten core.

        What you're implying is that injection of a large enough moderator into the earth's core could drive it critical.

        Wow. I think we've just discovered a new Doomsday device. Fortunately I don't think we have the tech to send burrowing missles filled with deuterium to the planet's core, yet.
        • I've always favored Greg Bear's 100ktons of neutronium and anti-neutronium method of planetary doomsday devices. If that isn't very plausible for you though, when I become an official super-villain, I have a much more evil way to destroy Earth.

          Yes, I will broadcast 1980's sitcoms 24/7 on every frequency from my death satellites. The plague of suicides should be enough to cause humanity's extinction in a matter of days.

  • Primary Literature (Score:5, Informative)

    by Wayne Hoxsie ( 224012 ) on Tuesday June 18, 2002 @12:23PM (#3723026)
    As usual, the pop science publications do this little justice. The primary literature is published by the Proceedings of the National Academy of Sciences and is published online at: http://www.pnas.org/cgi/content/full/98/20/11085 [pnas.org] and certainly makes the case sound more convincing.

    The article at EV world doesn't didn't, to my dismay, discuss the electro-magnetic implications at all. It sounded like a stretch to me to conflate geomagnetism with a nuclear process.
  • Here's a bit of wild speculation, but wouldn't it be interesting if the radiation generated by a giant breeder reactor contributed to the amount of genetic variation in life on Earth? Wouldn't it be more interesting still, if such a radiation source were in fact needed to get life going as well as it has on our planet.

    That would kind of put a new variable into the Drake equation.
  • 75% of the Earth's surface is covered in water, we all know this from grade school science class. Now, if you were to submerge, maybe 30 to 40 meters anywhere on the globe, including the world's hottest places, you'd find plentiful amounts of cool water, untouched by the scorching greenhouse effect. The idea that because the Earth is getting a little warmer on the surface could overheat the core is seemingly ridiculous to me. IMHO, the only thing a faulty o-zone is going to do is create more ocean - see Waterworld or A.I. - and simply give the reactor more water to cool off its exhaust. But I could easily be wrong.
  • We don't want the terrorist to get their hands on these seemingly unlimited U235 supply.

    Although, they may have to dig deep; I'd say, let them stay busy digging (keeps them out of circulation)
  • So does this mean that Greenpeace will be protesting against God for using nuclear power as part of the Earth's energy system?
  • Reactor at Earth's Core

    To power the PC that we are, you know... Um. It's past 2000, WHERE'S THE QUESTION TO THE ANSWER OF LIFE??!! :-P

    --pi

    42+3.1415926535897932384626433832795028841971... ..

  • Gravity effect wrong? (Score:2, Informative)

    by katarn ( 110199 )
    I'm sure it's my misunderstanding, but it seems they may not be correctly accounting for the effect of gravity in their theory. In their scientific article published at: http://www.pnas.org/cgi/content/full/98/20/11085 [pnas.org] Their conclusion states in part:

    "In a reactor deep inside the Earth, one would expect fission products, having an average density about 60% that of actinides, to diffuse radially outward as the fuel reconcentrates radially inward because of gravity."

    But at the center of the earth gravity is a much weaker force. I would guess that at the center of the earth, there would be no gravity, and the area around the center of the earth would have negligible gravity; sort of like how we see astronauts and satellites "floating" in orbit, but in reality most are in a slowly decaying orbit. The formula for calculating gravity & acceleration inside the earth is given at: http://www.syvum.com/physics/gravitation/gravitati on2.html [syvum.com], though even with these formulas my math skills are not sufficient for me to answer my one last question:

    Is there a point just outside the center of the earth where gravity would actually pull you *UP*, since the bulk of the earth's mass lays above you? If so, then the denser fuel elements in this reactor would be pulled outward forming a layer enclosing it's byproducts in the center, rather then the opposite as they state in their theory.

    • But at the center of the earth gravity is a much weaker force.

      True, but the pressure of the material above the center, which is attracted towards the core, is very strong. That's what causes the earth's core to be dense - gravity creates pressure.

      Is there a point just outside the center of the earth where gravity would actually pull you *UP*, since the bulk of the earth's mass lays above you?

      No. The Earth is roughly spheroid, remember? The "center" of the Earth for the purposes of this discussion is the center of gravity, which is the net gravitational effect of all of Earth's atoms at any point. At the center of gravity, those forces cancel out. But anywhere other than that, the net force is towards the center of gravity.

    • Correct. In theory at the center of the Earth there is no gravity, but you do have extremes of pressure.
      So the density of the materials you are considering will determine whether they flow inwards or outwards.

      Not my field, but I have put some thought into it several years ago.
  • A number of years ago, when I was in grad school, several uranium deposits in southern Africa were discovered to have been "critical" during the Precambrian after they formed. Geochemists knew this because they contained daughter products that could only have been produced by a nuclear reaction, not just normal breakdown of radioactive isotopes. So the idea of a natural reactor is not that far fetched.

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