Thorium, the Green Nuke

By Miss Cellania in Science & Tech on Dec 22, 2009 at 12:00 pm

Aerospace engineer Kirk Sorensen became interested in nuclear energy by reading records of experiments done by Alvin Weinberg and his team after World War II at the Oak Ridge Nuclear Plant. What really captured Sorenson’s attention was the promise of thorium, which has advantages over uranium as a nuclear fuel. Uranium worked best for nuclear weapons, but it is rare, dangerous, and produces lots of nuclear waste.

When he took over as head of Oak Ridge in 1955, Alvin Weinberg realized that thorium by itself could start to solve these problems. It’s abundant β€” the US has at least 175,000 tons of the stuff β€” and doesn’t require costly processing. It is also extraordinarily efficient as a nuclear fuel. As it decays in a reactor core, its byproducts produce more neutrons per collision than conventional fuel. The more neutrons per collision, the more energy generated, the less total fuel consumed, and the less radioactive nastiness left behind.

Even better, Weinberg realized that you could use thorium in an entirely new kind of reactor, one that would have zero risk of meltdown. The design is based on the lab’s finding that thorium dissolves in hot liquid fluoride salts. This fission soup is poured into tubes in the core of the reactor, where the nuclear chain reaction β€” the billiard balls colliding β€” happens. The system makes the reactor self-regulating: When the soup gets too hot it expands and flows out of the tubes β€” slowing fission and eliminating the possibility of another Chernobyl. Any actinide can work in this method, but thorium is particularly well suited because it is so efficient at the high temperatures at which fission occurs in the soup.

Sorenson is leading a campaign to revive thorium as a nuclear fuel by bringing scientists and engineers together on his blog called Energy From Thorium. A bill is now before congress to provide funds for thorium research. At least one commercial company is already using thorium. Could this be the element that saves nuclear power? Link -via reddit

(image credit: Thomas Hannich)


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  1. larryv
    Dec 22nd, 2009 at 12:12 pm

    This isn’t the only one out there. Toshiba has a small reactor that uses lithium-6
    “The 200 kilowatt Toshiba designed reactor is engineered to be fail-safe and totally automatic and will not overheat. Unlike traditional nuclear reactors the new micro reactor uses no control rods to initiate the reaction. The new revolutionary technology uses reservoirs of liquid lithium-6, an isotope that is effective at absorbing neutrons. The Lithium-6 reservoirs are connected to a vertical tube that fits into the reactor core. The whole whole process is self sustaining and can last for up to 40 years, producing electricity for only 5 cents per kilowatt hour, about half the cost of grid energy.”

  2. Mitch
    Dec 22nd, 2009 at 12:20 pm

    It’s probably not accident proof but it’s definitely an idea worth exploring. “The atomic boy scout” made a homemade reactor using thorium from mantles bombarded with radium from luminous clock faces.

  3. Gauldar
    Dec 22nd, 2009 at 12:29 pm

    If this is proven to be as efficient as they say it is, I hope the bill passes. Uranium is nasty shiz.

  4. Hum
    Dec 22nd, 2009 at 1:11 pm

    Hmmm, Thorium reactors are not a new concept, but are technically very difficult to engineer:
    - de nuclear decay of Thorium produces some isotopes by-products that impede the initial nuclear reaction. You must get rid of them during the reaction if you want to make it run continuously.
    - that’s why there is this idea of dissolving the Thorium in hot fluoride salts: in the liquid state, it is much easier to filtrate the “bad” isotopes. However this process is complex.
    - finally, there is the good old engineering problem: which material to use to make the reactor ? Sadly, no one knows, at the moment. Forget the idea of the “magic alloy”, “unknown-yet-but-soon” wonder ceramic or metal or anything mystically working because you have “nano” in the name. Materials science doesn’t work like this, especially in heavy industries with strong security issues.

    Thorium reactors are a good candidate for the future. But more for the years 2050′s. At that time, we will know if fusion reactors are feasible (that means: ready for production in the years 2100′s).

    Of course, if there is still a humanity…

  5. Gauldar
    Dec 22nd, 2009 at 1:51 pm

    @Hum

    Heh, unobtainium huh? :D

  6. Alex
    Dec 22nd, 2009 at 1:52 pm

    From the article: Weinberg and his men proved the efficacy of thorium reactors in hundreds of tests at Oak Ridge from the ’50s through the early ’70s. But thorium hit a dead end. Locked in a struggle with a nuclear- armed Soviet Union, the US government in the ’60s chose to build uranium-fueled reactors β€” in part because they produce plutonium that can be refined into weapons-grade material.

    Wow – that’s the military industrial complex at work, folks.

  7. SlappyMcDoodle
    Dec 22nd, 2009 at 2:45 pm

    Pebble bed reactors, no risk of melt down and uses already viable technology. Done.

  8. Johnny Cat
    Dec 22nd, 2009 at 2:57 pm

    Maybe if they can refine it enough to where it becomes viable and superior to uranium, we could offer to build awesome, efficient reactors that can create an abundance of energy for, oh, say, Iran. Cause they are really into nuclear energy I hear.

  9. Xinavera
    Dec 22nd, 2009 at 3:33 pm

    What Slappy said: Medium-sized pebble bed reactors. Next problem.

  10. Cluck
    Dec 22nd, 2009 at 4:26 pm

    As Hum hinted at and the article completely bypasses the process is EXTREMELY corrosive. We just do not currently have a material that we could build the reactor with that could withstand long term use.

  11. Larfin Jackarse
    Dec 23rd, 2009 at 5:16 am

    Hoomans has green nukla bom now?

  12. Robolasse
    Dec 23rd, 2009 at 5:31 pm

    Or, we could build a lot of windmills.


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