Could the Earth's Core be a Fission Reactor?

In summary: Not sure if that's still true or not though.In summary, fusion reactions require special conditions to start and keep going, and they can only occur in the cores of brown dwarfs.
  • #1
Merlin
32
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Could the center of the Earth's core be a critical mass of U-235 or other heavy metals, sustaining a fission reaction. (or might fusion be possible with the presures and magentic fields there? ). If not Earth what about Jupiter or larger exra solar planet?

Merlin
 
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  • #2
Originally posted by Merlin
Could the center of the Earth's core be a critical mass of U-235 or other heavy metals, sustaining a fission reaction. (or might fusion be possible with the presures and magentic fields there? ). If not Earth what about Jupiter or larger exra solar planet?

Merlin

Nuclear fission is what keeps the Earth's core warm. There's another thread here on the subject. But it is not a critical mass of U-235. I believe some fusion occurs in Jupiter, although not a lot.
 
  • #3
No fusion in Jupiter

Originally posted by Chemicalsuperfreak
Nuclear fission is what keeps the Earth's core warm. There's another thread here on the subject. But it is not a critical mass of U-235. I believe some fusion occurs in Jupiter, although not a lot.
Fusion reactions require certain minimum conditions to start, and keep going; Jupiter's core is quite a long way from having these.

The coolest/least-dense conditions under which fusion can occur (special cases aside) are those found in the cores of brown-dwarf mass objects under-going gravitational contraction. In these conditions deuterium fusion can occur; however, that's a thin gruel, soon exhausted, leaving the brown dwarf alone to cool, and look pretty much like Jupiter (albeit considerably more massive).
 
  • #4
hmmm reply to reply Mass = Fusion?

Fusion reactions require certain minimum conditions to start, and keep going; Jupiter's core is quite a long way from having these.

The coolest/least-dense conditions under which fusion can occur (special cases aside) are those found in the cores of brown-dwarf mass objects under-going gravitational contraction. In these conditions deuterium fusion can occur; however, that's a thin gruel, soon exhausted, leaving the brown dwarf alone to cool, and look pretty much like Jupiter (albeit considerably more massive).

hmmm' so it would be impossible for fusion ot occur at any form in the core of a Jupiter size mass, save for special conditions? What about fission or just below critical mass at the Earth's core (or larger rocky planets)?

And special conditions would be? (mag. fields, shear or tidal forces , "other elements than H in the core etc?). Merlin
 
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  • #5
Caveat (there are always caveats)

clarification (a.k.a. caveat): fusion and fission here = self-sustaining processes, as in 'fusion reactor', 'nuclear power plant' or Oklo.
so it would be impossible for fusion ot occur at any form in the core of a Jupiter size mass, save for special conditions?
yes
What about fission or just below critical mass at the Earth's core (or larger rocky planets)?
not while the cores are composed of iron, nickel etc
And special conditions would be? (mag. fields, shear or tidal forces , "other elements than H in the core etc?).
collision with a white dwarf or neutron star, as two examples.
 
  • #6
clarification (a.k.a. caveat): fusion and fission here = self-sustaining processes, as in 'fusion reactor', 'nuclear power plant' or Oklo.

Im calling fusion like what may happen in a first generation nuke power plant as follows, for example a D-T fusion reaction. Nuclei of two isotopes of hydrogen, deuterium (D) and tritium (T) react to produce a helium (He) nucleus and a neutron (n). In each reaction, 17.6 MeV of energy (2.8 pJ) is liberated: D + T 4He (3.5 MeV) + n (14.1 MeV).

Fission is the term that I use to describe the process that powers today's nukes (or yesterdays Hiroshima bomb). It seems to me that U235, and even the isotope uranium 238 along other naturally occurring radioactive metals would be in the core of rocky planets in copious amounts. I would suspect that some heat generation exist at the Earth's core (from nuclear process ,maybe even fission!) Some factors such as purity , pressure, etc needed to start and sustain a fission reacation might not be present. But there is enough to produce heat.
MERLIN
 
  • #7


Originally posted by Nereid
Fusion reactions require certain minimum conditions to start, and keep going; Jupiter's core is quite a long way from having these.

The coolest/least-dense conditions under which fusion can occur (special cases aside) are those found in the cores of brown-dwarf mass objects under-going gravitational contraction. In these conditions deuterium fusion can occur; however, that's a thin gruel, soon exhausted, leaving the brown dwarf alone to cool, and look pretty much like Jupiter (albeit considerably more massive).

I'm not saying there's a self sustained fusion reaction going on in Jupiter like you'd find in a star, but I do remember reading that at least some fusion is occurring. What's the lower mass limit for a brown dwarf?
 
  • #8
Originally posted by Merlin
clarification (a.k.a. caveat): fusion and fission here = self-sustaining processes, as in 'fusion reactor', 'nuclear power plant' or Oklo.

Im calling fusion like what may happen in a first generation nuke power plant as follows, for example a D-T fusion reaction. Nuclei of two isotopes of hydrogen, deuterium (D) and tritium (T) react to produce a helium (He) nucleus and a neutron (n). In each reaction, 17.6 MeV of energy (2.8 pJ) is liberated: D + T 4He (3.5 MeV) + n (14.1 MeV).

Fission is the term that I use to describe the process that powers today's nukes (or yesterdays Hiroshima bomb). It seems to me that U235, and even the isotope uranium 238 along other naturally occurring radioactive metals would be in the core of rocky planets in copious amounts. I would suspect that some heat generation exist at the Earth's core (from nuclear process ,maybe even fission!) Some factors such as purity , pressure, etc needed to start and sustain a fission reacation might not be present. But there is enough to produce heat.
MERLIN

Fusion is not what happens in first generation power plants. It's all fission, fusion has only occurred in hydrogen bombs and test facilities. Nobody's generated power from fusion.

Uranium certainly exists in the Earth's interior, but most of the hearing is produced by radioactive potassium.
 
  • #9
Superfreak,...Either we must agree to disagree or, "What we have here is a failure to communicate!" (Jackie Gleason.) I am at a loss when putting my thoughts clearly into words. I should have said the first generation fusion reactors (yet to be). I thought you would make the connection without elaboration. My bad.

I did say fission is for A bombs like those dropped on Japan. And today's nuke plants. Power plants sustain a critical reaction with u 235 at about 2 or 3%. Bombs require a 90% or more enrichment. Most H bombs, of course use fission as a trigger for the Main event,... fusion...hiss bang pop.. to occur. Outside of the said bomb controlled fusion has yet to fulfill its potential for power production etc.

I don't agree that the decay of potassium to argon (or the trace amounts of thorium, etc)., would generate the required heat energy. Also the properties of the potassium mixing with the Fe in the core must be right on, sulfur and a few other elements in the correct amounts and purity would allow it to mix with the cores massive Fe reserves. The simple (and correct, I know, because I've been at the core myself... heh) theory is, ignoring tidal and rotational forces, convection,(anyone got a super computer for sale cheap?) the heavy metals would migrate to the center first. Hmmm, at about .9 to 2.3%,the last more than enough to sustain heat production. No?...
...MERLIN
 
  • #10
No, it's also a question of abundance. Iron is by far the most abundant of the heavier elements. Moreover, by measurements of all possible seismic properties, it seems possible to test hypotheses based on an iron inner core.

About nuclear fission. For a sustained fission reaction, the critical mass property is exactly that, "critical". The margin of the number of fissable atoms per volume is rather narrow. A few too liitle and the reaction dies. A few too much and you have the nuclair inferno.

Another problem for the heavy fissable molecules to get together is that thermodynamic motions are much stronger than gravity in the core. So it's is impossible for them to clog together, when the tea keeps being stirred (assuming a fully liquid core).

And now, for some humor only:

warning crackpot inside
 
  • #11
No fusion in Jupiter

Originally posted by Chemicalsuperfreak
I'm not saying there's a self sustained fusion reaction going on in Jupiter like you'd find in a star, but I do remember reading that at least some fusion is occurring. What's the lower mass limit for a brown dwarf?
From the site below:
-> above 8% of the mass of the Sun, red dwarf
-> between 1% and 8%, brown dwarf
-> below 1%, no fusion.

All numbers are approximate, and Jupiter has a mass ~0.1% of the Sun's, so a brown dwarf will have at least 10 times the mass that Jupiter has.

http://chandra.harvard.edu/xray_sources/browndwarf_fg.html
 
  • #12
fission, fusion; confusion?

There seems to be some confusion of terms here, and I may have contributed to it.

Fusion: like what happens in the core of the Sun, an H-bomb, etc. Main fusion reactions are, in summary, conversion of protons (and deuterons) to 4He and 3He. This only happens in a sustained way (power out > power in, in bulk, over more than ~1s) in gravitationally confined objects ('stars'), tho' many believe it will be possible in something like ITER. On Earth, the only natural fusion which takes place is (maybe) in cosmic ray collisions with atoms in the atmosphere or oceans.

Fission: the splitting of a heavy nucleus into two (or more?) lighter nuclei (alpha decay excepted). We usually also mean 'with a net production of kinetic energy'. This happens in A-bombs, in nuclear reactors (both man-made and natural*), and in some isotopes ('spontaneous fission').

Spontaneous fission, along with other forms of radioactive decay, generates heat if it occurs in atoms within rocks (and elsewhere). Radioactive decay (including spontaneous fission) is the primary source of the heat which results in the Earth's core being much hotter than its crust; the primary nuclides are 40K, 238U and 232Th.

It doesn't matter in what physical form a radionuclide is - pure element, chemically-bound, alloyed; concentrated (e.g. crystalline salt), impurity - it generates the same amount of heat when it decays.

*in the early days of the Earth, 235U was a more common isotope than it is today. There were some deposits of uranium - in the form of oxides? - in which sustained fission reactions took place, very similar to man-made reactors. Oklo is the best-known example:
http://antwrp.gsfc.nasa.gov/apod/ap021016.html

Such natural reactors are highly unlikely on, or in, the Earth today.

Finally, iron (and nearby elements in the periodic table) cannot undergo exothermic fission or fusion; they are the most stable nuclei.

Andre, that link is just sooo incredible
 
  • #13
Originally posted by Merlin
Superfreak,...Either we must agree to disagree or, "What we have here is a failure to communicate!" (Jackie Gleason.) I am at a loss when putting my thoughts clearly into words. I should have said the first generation fusion reactors (yet to be). I thought you would make the connection without elaboration. My bad.

I did say fission is for A bombs like those dropped on Japan. And today's nuke plants. Power plants sustain a critical reaction with u 235 at about 2 or 3%. Bombs require a 90% or more enrichment. Most H bombs, of course use fission as a trigger for the Main event,... fusion...hiss bang pop.. to occur. Outside of the said bomb controlled fusion has yet to fulfill its potential for power production etc.

I don't agree that the decay of potassium to argon (or the trace amounts of thorium, etc)., would generate the required heat energy. Also the properties of the potassium mixing with the Fe in the core must be right on, sulfur and a few other elements in the correct amounts and purity would allow it to mix with the cores massive Fe reserves. The simple (and correct, I know, because I've been at the core myself... heh) theory is, ignoring tidal and rotational forces, convection,(anyone got a super computer for sale cheap?) the heavy metals would migrate to the center first. Hmmm, at about .9 to 2.3%,the last more than enough to sustain heat production. No?...
...MERLIN

http://www.nature.com/nsu/030505/030505-5.html
 
  • #14
  • #15
APOD

It's a remarkable site, isn't it!?

I try to get to it every day, and often spend several minutes clicking on the links ... it's amazing that the two guys who run it can find so much material, and keep it up for some many years now.
 
  • #17
some of the Venus links were no longer any good.

APODs of the world, unite!
 

1. Could the Earth's Core be a Fission Reactor?

This is a highly debated topic among scientists. Some believe that the Earth's core could potentially be a fission reactor, while others argue that there is not enough evidence to support this claim.

2. What evidence supports the theory of the Earth's Core being a Fission Reactor?

One piece of evidence that supports this theory is the Earth's magnetic field. The core's movement, along with the presence of radioactive elements such as uranium and thorium, could potentially generate enough heat and energy to power a fission reaction.

3. What are the major objections to the theory of the Earth's Core being a Fission Reactor?

One major objection is the lack of detection of certain fission products in the Earth's mantle. Additionally, the Earth's core may not have the necessary conditions, such as high enough pressures and temperatures, to sustain a fission reaction.

4. How would a Fission Reactor at the Earth's Core impact our planet?

If the Earth's core was indeed a fission reactor, it would likely have a significant impact on the planet's overall heat and energy budget. This could potentially affect plate tectonics, volcanic activity, and the Earth's climate.

5. Is there any ongoing research or studies being conducted on the possibility of the Earth's Core being a Fission Reactor?

Yes, there are ongoing studies and research being conducted on this topic. Scientists are using advanced techniques, such as seismic imaging and computer simulations, to gather more evidence and better understand the Earth's core and its potential as a fission reactor.

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