Homepage Forums Dense Plasma Focus (DPF) Science and Applications Could pB11 focus fusion device be modified to use thorium?

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  • #4340
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    joachimqui
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    I am really interested in this. I work beside a cyclotron, and that is used to produce radioactive isotopes for the treatment of cancers. So I’m wondering if fusion could be used as a better, cheaper source of these isotopes, in the future. It’s a fascinating thought, considering that the production facilities for these isotopes are relatively non abundant! It seems to me, if fusion could be used to produce much more radioactive material, then that could be used instead of the setup we have now, a cyclotron, for these isotopes. This would effectively work around the isotope shortage the world is currently experiencing (at least, the cancer treatment world).

    Tasmodevil44 wrote: Here’s a crazy idea. Don’t know if it would work. instead of focus fusion, could it be modified to focus fission if boron was substituted for thorium? It would produce considerably more radioactive material, but still not as much as coventional reactors. In a dense, hot plasma is it possible for the hydrogen proton (or even alpha particles of helium) to be absorbed by a thorium nucleus? And would it cause it to undergo transmutation into something else like U-233 or U-235 and then fission?

    It may even be possible to hybridize the dense focus reactor in such a way that you have both boron fuel and thorium fuel used simmultaneously. But it’s probably just another one of those longshot ideas not very likely to work-out.

    But then again, the two reactions might even aid each other and enhance reactions. The heavy atom fission reactions might dump more energy into the plasma to aid the boron reactions. Conversely, the boron reactions might supply more energy to aid transmutation of thorium into something that’s more fissinable.

    If the energetic fission products of a heavy atom like U-233 also exit the reaction site as a unidirectional beam…… just like alpha particles…… then the conversion of thorium to electric power might also be far more efficient than a conventional fission reactor. The heavy fission products could also be tapped by direct induction the same way. This would equate into far less radioactive material produced for the same amount of electricity generated. But I admit this is just an idea that may not work.

    #4343
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    Tasmodevil44
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    The more I got to thinking about this ” outside – the – box ” idea, the more I began to realize how correct belbear is in the major technical and nuclear physics obstacles to trying to ” burn ” thorium, uranium, etc. in the DPF. Belbear said it takes about 6 hours for protactinium to decay into U233. But it gets even worse than that. After reading more on thorium nuclear power, I found that it can take as long as a month and a half for the transmutation to occur ! ! ! Far too long for only a 6 picosecond time window.

    I also looked at other possibilities. For example, you might be able to leapfrog over the lengthy protactinium step if a thorium nucleus absorbs an energetic enough alpha particle and goes directly to becoming uranium. But this would be working against the binding energy curve and would actually tend to absorb energy from the plasma rather than heat it. Not to mention the enormous X – ray loss from an atom with such a large atomic number. I also checked – out on the internet an exotic new type of thorium fisssion discvered by researchers in Ohio back during the 1990’s. ( Read my other post) . But alas, this produces no energy at all, even though it’s a nuclear reaction !

    #4355
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    jeg3
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    Thorium has a lot of potential for electrical generation using a Liquid Fluoride Thorium Reactor (LFTR) because it is a lot more efficient than uranium, and can also with deal with the stockpiles of long lived transuranic waste.

    See video below, this video and the one with Bussard are interesting with regard to the history and Gov’t (non) actions.

    http://www.youtube.com/watch?v=AZR0UKxNPh8&eurl=http://thoriumenergy.blogspot.com/&feature=player_embedded

    I think both technologies have potential and the future may include both, it all depends on timing of development, cost for electricity generation, etc.
    So even if Focusfusion becomes the dominant electrical generator, LFTR is still useful for dealing with the transuranic waste already generated (and long lived) and producing useful fission materials.

    #4666
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    Tasmodevil44
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    You are indeed correct, jeg3. The LFTR is specifically designed for the use of thorium. I can see where BOTH focus fusion and thorium reactors can have their special niche they fit into best. Just as solid-stste transistors did not make all applications of the vacuum tube obsolete overnight. Focus fusion may eventually beat the LFTR in economics of electric generation, but the LFTR may be better suited to destruction of long-lived transuranic actinides that remain highly radio-toxic for so long.

    But I have abandoned the idea of any fission / fusion hybrid in which heavy atom fission might aid pB11 in the DPF. There would be too much X-ray losses caused by such heavy atoms. Not to mention the difficulty in getting them to fission in the first place. Belbear is definitely correct about the difficulty in applying this approach. Plutonium fission might trigger an H – Bomb, but employing fission to trigger fusion in the DPF is far more problematic. Plus the same costly radioactive problems reactors have now.

    Although skeptics like Jimmy T argue against the idea of lithium…… that pB11 is still the so – called ” Holy Grail ” of fusion…… I still think that lithium may still have the best potential chance for a ” kick – starter ” to help get pB11 going. It has only three neutrons, which means less X – ray energy loss. It also has a lower ignition temperature. Which means it may ignite first before the boron does, dumping more energy into the plasma to pre – heat it more than the power supply alone can. And it might even help to extend the reaction time window beyond only 6 picoseconds so that more reaction events can occur. Forget large atom fission. I still think lithium has the best possibilities.

    Hydroboranes like decaborane and pentaborane have only two chemical elements: boron and hydrogen. But there’s another class, or family, of chemical compounds which contain all three: hydrogen, lithium and boron. I wonder…… has Lerner thought about these as possible fuel candidates yet ?

    #4667
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    Tasmodevil44
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    This is getting a little off the subject, but believe me jeg3, you don’t have to tell me about our lovely Gov’t non (action) of good ‘ol Uncle Sam…… and how good research money of taxpayers at work is poured down the drain. Everybody already knows about all the mismanagement and waste (Heck, doesn’t everybody these days ?). There’s just no continuity or consistency to NASA, the Pentagon, or anything else these days. Build an Apollo Saturn 5 rocket, then scrap it. Finance a renewable space shuttle only ” half – assed “, by going with dangerous external tank and solid – fuel boosters…… instead of riding ” piggy – back ” on larger rocket plane…… then scrap all invested in the shuttle, too. Finance the Bussard nuclear fusion device, then cancel all funding as soon as it begins to look very promising…… what a way to run a government ! ! !

    And the very sad thing about it is not only that we were so close (but still so far thanks to gov’t dropping the ball), but also the fact that all the knowlege and expertise for this may be permanently lost and unrecoverable. Bussard is now deceased R.I.P. , as well as a lot of these other old – timers. Many of the younger physicists are specialized in things like solid – state electronics and robotics and the like, but lacking much of the plasma and vacuum physical know – how of many of these old guys. And although many people don’t believe in conspiracy theories (and consider them all to be nuts), how much specially intrenched vested interests like oil companies, coal mining and the like may have been involved in killing it ?

    #4688
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    belbear42
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    Tasmodevil44 wrote: …Although skeptics like Jimmy T argue against the idea of lithium…… that pB11 is still the so – called ” Holy Grail ” of fusion…… I still think that lithium may still have the best potential chance for a ” kick – starter ” to help get pB11 going. It has only three neutrons, which means less X – ray energy loss. It also has a lower ignition temperature. Which means it may ignite first before the boron does, dumping more energy into the plasma to pre – heat it more than the power supply alone can. And it might even help to extend the reaction time window beyond only 6 picoseconds so that more reaction events can occur. Forget large atom fission. I still think lithium has the best possibilities.

    Hydroboranes like decaborane and pentaborane have only two chemical elements: boron and hydrogen. But there’s another class, or family, of chemical compounds which contain all three: hydrogen, lithium and boron. I wonder…… has Lerner thought about these as possible fuel candidates yet ?

    Are you sure about that ignition temperature being lower for p-Li6 ?
    I took a look at the “nuclear fusion” wiki and found several interesting fusion reactions compared.
    Just assuming here these values are correct:
    p-Li6 fusion has a lower optimal burn temperature (66keV) than p-B11 fusion, (123keV), but achieving practical ignition is a whole different story.
    The power density of p-Li6 appears to be appallingly low, so it also appears to have an even higher ignition temperature (Ti=800KeV) than p-B11 (Ti=300KeV) These values take into account the bremsshtrahlung losses in a thermalized plasma.

    Remarkably, I was surprised by the very high value (Ti=500keV) for the “mainstream” D-D reaction. Although it burns at a marginally higher temperature than D-T, D-D break-even is even harder to achieve than p_B11! That’s why all tokamak research focuses on D-T and its 50keV Ti, with the next (and for a tokamak only) possible upgrade being D-3He (Ti=100KeV). That’s why they dream of mining it from the moon!

    I could be wrong, but it could as well be the other way around, p-B11 fusion serving as a kickstart for p-Li6 🙂
    And besides that, I think using three reactants introduces two more useless collisions (Li-Li and Li-B), draining more energy.

    Also interesting is the Pfusion / Pbremsshtrahlung ratio. For p-Li6 this is only 0.21, less than half of the 0.57 for p-B11
    Both values are below 1, which means less fusion power than X-ray losses.
    But Dr Lerner appears to have just found a solution for that little problem…

    #4689
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    Brian H
    Member

    belbear42 wrote:

    Also interesting is the Pfusion / Pbremsshtrahlung ratio. For p-Li6 this is only 0.21, less than half of the 0.57 for p-B11
    Both values are below 1, which means less fusion power than X-ray losses.
    But Dr Lerner appears to have just found a solution for that little problem…

    Yes, it appears that the quantum tuning more or less reverses that ratio, I think.
    P.S.
    AFAIK, Eric is not a PhD, hence is not Dr. Lerner.

    #5054
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    Axil
    Member

    Brian H wrote:

    Believe me: DPF’s and fission are compatible. It’s a fusion device and fusion is done with light elements. And DPF’s are all about an attempt to “make watts, not rads”

    I think you meant “incompatible”. DPFs are vastly more efficient than any possible fission rig.

    It all depends on what you mean by the word efficient!

    Here is how the fusion/fission hybrid neutron economy breads down.

    I will address the thorium fuel cycle since it is highly proliferation resistant (I think proliferation proof) when coupled with fusion in preference to the uranium fuel cycle and its plutonium (a proliferation risk) byproduct.

    An aneutronic boron reaction nets about 8 MeV of power and that’s it. On the other hand a d-d fusion reaction that breeds thorium nets about 200 MeV per initial thorium fission and that in turm will breed with 3 other secondary thorium atoms to net 800 MeV per each fusion/fission reaction.

    In other words, each D-D fusion produces one neutron that breeds 4 U233 atoms.

    An ideal thorium breeder reactor design will have a breeding ratio of 1.07. But due to neutron losses from the accumulation of isotopes of various kinds that poison the fission reaction, a thorium breeder will be lucky to break even. Let us assume a real world worse case breeding ratio in the range between .95 and .99.

    So in round numbers, for every fusion neutron produced, about 400 thorium fissions can result. At 200MEv per fission that is (200Mev) (400) = 80000MeV per fusion neutron; as opposed to just 8Mev for boron fusion. That is an increased energy density factor of 10,000.

    However, if not supplied with a small number of supplemental fusion produced neutrons, the thorium breeding nuclear reaction will eventually stop because the thorium breeding ratio is just a little less than one.

    Without an occasional dose of fusion neutrons, the thorium fuel cycle will wind down to a stop.

    It is not an overstatement to say that for the lack of an occasional neutron, the thorium fuel cycle is lost.

    Those occasional neutrons can come from U235 and even Pu239 but fusion neutrons are clean and pure. It enables a pure thorium fuel cycle that leaves no long-lived nuclear wastes about.

    #5062
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    Brian H
    Member

    Tasmodevil44 wrote:

    But then again, like transmute said, these neutrons could also be harnessed to remediate existing stockpiles of the most wicked and nasty legacy of the Cold War and Arms Race.

    Focusing neutrons is inherently difficult or impossible, since they are uncharged. They radiate in a statistical sphere. So now you have a shell of nasty-legacy isotopes.

    The complications really multiply exponentially, don’t they? 😆

    #5187
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    Axil
    Member

    Brian H wrote:

    But then again, like transmute said, these neutrons could also be harnessed to remediate existing stockpiles of the most wicked and nasty legacy of the Cold War and Arms Race.

    Focusing neutrons is inherently difficult or impossible, since they are uncharged. They radiate in a statistical sphere. So now you have a shell of nasty-legacy isotopes.

    The complications really multiply exponentially, don’t they? 😆

    There is a neutron reflector used is many fission reactors called a “neutron reflector”. It is made of graphite whose crystal structure is specially designed and manufactured to reflect neutrons to a high degree of efficiency.

    Certain types of fusion/fission combo hybrid reactors(thorium) does not produce any long lived nasty-legacy isotopes. Sorry!

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