Fusion-Fission Hybrid Reactor: The answer to our problems?

Discussion in 'General Science & Technology' started by ElectricFetus, Feb 12, 2009.

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  1. ElectricFetus Sanity going, going, gone Valued Senior Member

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    Nuclear reactors produce nuclear waste which is the most cited reasons for public disapproval of nuclear power (so claimed). Nuclear waste requires high energy neutrons to release energy and transmuted it into less harmful elements and isotopes . By its nature as waste it is usually incapable of producing enough neutrons to sustain nuclear fission criticality in a convention nuclear reactor.

    Nuclear fusions is seen as some kind of dream power source by some, but at present it is not energy positive (can't produce more energy than consumed) and gives off huge amounts of high energy neutrons which cause a variety of problems, as well as required rare fuels (tritium) which must be breed via nuclear reactions.

    Obviously the solutions is spelled out here: Use existing fusions reactor technology as a neutron sources to transmute nuclear waste. The transmutation of nuclear waste would act as a energy and neutron multiplier making the fusion reactor energy positive while still producing enough neutrons to breed nuclear fusion fuel. Unlike most convention nuclear reactors these hybrid reactor would be melt down proof as it is sub-critical and cannot sustain a chain reaction that could run away and melt down. Most of all the reactor would consume more nuclear waste than is produced flipping the nuclear waste argument against nuclear power upside down: now we need these reactors to clean up decades of built up nuclear waste, while at the same time provide clean(ing up) energy for cheaper then existing nuclear power (assuming the fuel being nuclear waste in cheap)

    http://www.smartbrief.com/news/asce...E&copyid=90DBD4DA-34E4-4ACC-95C9-D7B0CCCF8A49
    http://www.eponline.com/articles/70697/
    http://www.futurepundit.com/archives/005926.html
     
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  3. PieAreSquared Woo is resistant to reason Registered Senior Member

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  5. ElectricFetus Sanity going, going, gone Valued Senior Member

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    I hate the tokamak: they stick to it because they know so much about it, but what they do know is that to achieve energy positive fusion it will have the be titanic, and use the easiest of neutratic fusion (D+T). I rather more money be spent on radical designs like Bussards fusor and Dense plasma focus which if they work (be it unlikely) could provide much cheaper fusion sources using much cheaper fuel and not spitting out ungodly amounts of neutrons. It simple prove or disprove the radical designs for a few hundred million dollars verse 50 billion for ITER a reactor we know for the get go will be uneconomical.

    As for funding more fusions research that were a hybrid reactor could bridge the gap.
     
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  7. PieAreSquared Woo is resistant to reason Registered Senior Member

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    I like the Pinch , in fact it was what i worked on when I was at Los Alamos... Where I met Tuck. Nice man btw

    Last time I was there they had a sort of wagon wheel concept in mind, plasma translation to larger chambers to allow for expansion. Don't know if anything came about on it. many many years ago. Then my buddy up there died, so no more insider tours

    Guess I should go up the hill and visit the Bradbury Museum
     
  8. fedr808 1100101 Valued Senior Member

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    Nuclear fusion does not produce high energy neutrons. High energy neutrons come from fission, since the atom is split, there are a few extra neutrons that break off and leave which become the high energy neutrons.

    In nuclear fusion, two hydrogen atoms fuze together to form helium, each hydrogen atom has 1 neutron, and one protons. And helium has 2 neutrons, and 2 protons.

    And since we all know that energy and matter are not created, or destroyed, just switched from one form to another. We can all assume that nuclear fusion by its fundamental mathmatics cannot produce high energy neutrons.
     
  9. PieAreSquared Woo is resistant to reason Registered Senior Member

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    Titanium alloys have been considered for structural materials in fusion energy devices since the 1970's.

    Austenitic stainless steels were historically selected because they could be fabricated at a lower system acquisition cost. Nickel alloys allowed higher operating temperatures and provided higher electrical resistivity for reactor performance [1].

    Today, a greater emphasis has been placed on total system life cycle cost to include not only system acquisition costs but also operational life, decommissioning, and irradiated materials storage.

    The stainless steels and nickel alloys become irradiated after neutron bombardment and have radioactive species that must be stored for centuries before radioactivity dissipates to human safe handling levels.

    Titanium and specifically Ti-6Al-4V have radioactive species that would allow safe hands-on maintenance during initial operation and then eases decommissioning. This paper discusses the issues related to the use of Ti-6Al-4V for the Tokamak Physics Experiment (TPX) to be built at Princeton Plasma Physics Laboratory
     
  10. ElectricFetus Sanity going, going, gone Valued Senior Member

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    Incorrect:
    D+T -> n(14.1Mev) +He4(3.5Mev)
     
  11. PieAreSquared Woo is resistant to reason Registered Senior Member

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  12. leopold Valued Senior Member

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    why all the fuss over fusion reactors anyway?
    hasn't anyone ever heard of breeder reactors that produce more radioactive material than they consume?

    fusion is the combining of two light atoms into a heavier one, they don't necessarily need to be hydrogen.
     
  13. ElectricFetus Sanity going, going, gone Valued Senior Member

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    The idea is this would be cheaper than breeders and consume more nuclear waste then breeders ever could. Since A hybrid reactor does not need complex fuel recycle (in theory) in forgoes most of the problems with reprocessing an breeding. For example a conventional nuclear economy with hyrbid burners would go like this

    Uranium 235/238 -> LWR -> Waste (transuranics, plutonium, radioisotopes) -> Hybrid waste destroying reactor -> minimal Waste (short half-life radioisotopes)

    While a Plutonium economy breeding cycle would be far more complex and thus expensive:

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    Note this diagram has a sub-critical reactor step on the bottom, basically a hybrid reactor economy would be like this diagram except everything on the top left would be skipped and we would go from "waste disposal" on the top right to (fusion driven) sub-critical reactor on the bottom with minimalism reprocessing.
     
  14. cosmictraveler Be kind to yourself always. Valued Senior Member

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    Today it takes more power to make this "fusion" happen than it outs out therefore making the process not worth doing.
     
  15. ElectricFetus Sanity going, going, gone Valued Senior Member

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    no shit sherlock! Hence why adding a fissionable/fertile breeder layer in a hybrid reactor fixes the problems of the need for net postive energy: the fusion reactors only acts as a neutron sources, most the the energy comes from the neutron induces fission of the heavy actinides in the nuclear waste: hence the term "energy amplifier" or "energy multiplier" in theoretical subcritical reactor designs powered by proton accelerator splatation and other neutron sources (like fusions). A hybrid reactor allow for present energy negative fusion reactor technology to become energy positive: roughly 300-400% increase in energy yields over existing "pure" fusion reactor designs is claimed.
     
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