Re: Fusion and nuclear Power

From: Iain Strachan (iain.strachan2@ntlworld.com)
Date: Thu Sep 12 2002 - 13:07:21 EDT

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    Hi Lawrence,
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    I would ask Glenn or other energy people what the world supply of=20
    available Uranium and=20
    Thorium is. My impression is that there is enuf in proven lodes to=20
    keep the world in energy=20
    for many decades. And just as we have to mine the water supply and=20
    use a lot of energy to=20
    get a teeny amount of Deuterium, we may be able in a pinch to mine=20
    the oceans for the dissolved=20
    Uranium. This should give us a big reprieve until the world's=20
    scientists can develop an even=20
    better energy source, perhaps fusion.=20

    I've not worked in the nuclear industry for many years now (the =
    government privatized us and forced us down the route of exploiting =
    spin-off technologies), but I can offer a few thoughts.

    As I said in an earlier post, the considered opinion of those working in =
    Fusion is that we are not going to have a demonstration Fusion reactor =
    putting electricity on the grid till 2050 at the earliest. It takes a =
    huge amount of energy and time to build such a plant, so the =
    availability of vast amounts of fusion power to synthesise carbon =
    chains, or hydrogen etc is not going to be for decades after that. One =
    real problem in construction of a fusion power station is that the =
    magnetic coils are so huge they cannot be transported; they would have =
    to be manufactured in situ. It is thus a major undertaking, and =
    economically an extremely expensive option. It would take years before =
    the energy generated was equal to the energy put in to build the thing =
    in the first place.

    Mining the water supply for Deuterium is not a big problem compared to =
    geneating the Tritium required for fusion from a Lithium blanket. =
    However, Lithium is plentiful, so it's still potentially a vast =
    resource.

    But I don't think we have to have fusion at the next stage. There are =
    indeed (as I understand it) huge supplies of Uranium for thermal =
    reactors, but also there are even huger amounts of Plutonium obtainable =
    by processing the spent fuel from thermal reactors, that could be put to =
    profitable use in fast reactors. This is also a vast resource, which =
    would more than cover the length of time needed to develop Fusion (I =
    believe hundreds of years). However, one of the problems in the =
    propaganda battle for Fast reactors is the horrible misnomer FAST =
    BREEDER REACTOR, which gives the impression that the Breeding is fast, =
    and that huge amounts of Plutonium are generated for nasty people to =
    make bombs with. Hence the anti-Nuke's battle cry "The only safe fast =
    breeder is a rabbit". But it doesn't work like that. The "Fast" refers =
    to the energy of the neutrons generated (fast neutrons rather than =
    "thermal" neutrons), and NOT to the breeding rate. In fact, I seem to =
    remember that a thermal reactor "breeds" plutonium (from U238) faster =
    than a Fast reactor would. Furthermore, it is possible to adjust the =
    breeding ratio in a Fast reactor (which is done from blankets of U238), =
    so that the Fast reactor can be made to be a net consumer of Plutonium =
    rather than a net producer. This is what would happen initially, as we =
    are overstocked with Plutonium.

    Of course, the downside is the safety aspect. We can't ignore the fact =
    that if Nuclear power goes wrong it goes horribly wrong; witness all the =
    cancers and deformities in Kiev etc in the wake of Chernobyl. One can =
    protest that the Russians were absolutely terrible at safety, and it =
    wouldn't happen over here, but the spectre of such a problem hangs over =
    NP (and Three Mile Island was an uncomfortably near miss). And then =
    there is the worry of terrorist threats. I guess someone somewhere has =
    almost certainly done the calculations as to what happens if you crash =
    an airoplane into a Nuclear Power station, but I don't know what the =
    results of such a study would be.

    But I guess in the end, it's going to have to be fission, with all the =
    safety risks, in the medium term, before Fusion can be practicable.

    Iain.



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