Fusion-Fission Hybrid... A break-even fusor?

It may be difficult to separate "theory" from "application," but let''s see if this helps facilitate the discussion.
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Andrew Huot
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Fusion-Fission Hybrid... A break-even fusor?

Post by Andrew Huot » Thu Jul 26, 2012 5:06 pm

Recently, I have done a great deal of research on the "energy amplifier". (designed by Dr. Rubbia, former director of CERN) It's a sub-critical fission reactor driven by neutrons from a particle accelerator. Yes, SUB-CRITICAL: so it cannot meltdown. The primary fuels are Thorium and depleted Uranium, so it could burn the majority of waste produced in conventional nuclear reactors.

According to Rubbia, this implies "An essentially unlimited power supply". A baseball sized piece of Thorium would satisfy an individuals lifetime power consumption. Wow! Yet, the reason this concept has failed to become a reality is due to the fact that particle accelerators are just too damn expensive.

Now for the million dollar question: Could a Fusor be used as the neutron source? While we all know that Fusors fail miserably at producing energy (1 billionth of energy input is produced), they are a prolific neutron source. Is this the future of nuclear energy? Or a mating against nature?

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Richard Hull
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Re: Fusion-Fission Hybrid... A break-even fusor?

Post by Richard Hull » Thu Jul 26, 2012 5:34 pm

The fusor would not be a particularly potent enough neutron source for the fission reactor in question.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Chris Bradley
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Re: Fusion-Fission Hybrid... A break-even fusor?

Post by Chris Bradley » Thu Jul 26, 2012 5:41 pm

Andrew Huot wrote:
> Now for the million dollar question: Could a Fusor be used as the neutron source?

You've actually overcomplicated this, because a Thorium energy amplifier uses protons to create neutrons by spallation with a lead coolant, to activate the fertile thorium. Proton neutral beam injectors of several MW are used routinely in magnetic fusion research and achieve eye-wateringly good efficiencies, because most of the energy is in the accelerating of the protons, so the power spent in ion formation (which is the 'inefficient' stage) is trivial.

This can also not be argued to be a subject limited by deliberately restricted investment. There are a number of companies right now trying to commercialise this, such as Aker ( http://www.akersolutions.com/en/Global- ... r-station/ ) who are bank-rolled by their sub-sea oil facility business, and even the Indian Government has recently announced they are going to commit to thorium reactors (not sure if it will be the proton 'energy amplifier' type yet) because they have, literally, tonnes of the stuff lying around their beaches.

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Carl Willis
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Re: Fusion-Fission Hybrid... A break-even fusor?

Post by Carl Willis » Thu Jul 26, 2012 5:59 pm

The thermal power developed in a nuclear reactor is proportional to the neutron population, and to have a high neutron population in a subcritical reactor you have to continuously flood the core with an intense source of neutrons. That's the technical challenge for accelerator-driven subcritical reactors. It's not so much a problem of mere budget as it is a problem of research and development being necessary: the intense, reliable, practical accelerator sources that would be used in a power-plant-scale realization of this concept are not in the technological repertoire yet. It's true that some notable innovators like George Miley have suggested fusors as neutron generators for subcritical systems, but the technological readiness level of IEC as an intense neutron source is nowhere near that of, say, current spallation sources. (These are the only kinds of sources that can achieve power-reactor-like fluxes today.) Advantages existing in principle or hypothesized to exist in the IEC devices may not extend to reality.

Sub-critical doesn't mean a reactor is impervious to meltdown. Although immune from some kinds of reactivity and power-excursion accidents, you can still fail to properly cool the fuel and have it melt with all the same unfortunate repercussions. You still have decay heat to remove. Probably most reactors that have melted down have been subcritical during the process: TMI and the Fukushima units for instance.

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Re: Fusion-Fission Hybrid... A break-even fusor?

Post by David Geer » Fri Jul 27, 2012 3:26 am

Sub-critical fusion means it won't go nuclear but still runs the risk of meltdown and creating a gaint hole in the ground.
- David Geer

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