Re: Fusion Reactors

From: george murphy (
Date: Sun Sep 08 2002 - 07:11:13 EDT

  • Next message: Iain Strachan: "Re: Fusion Reactors"

    Iain Strachan wrote:

    > Hi, George, You wrote: Of course we can build a fusion reactor.
    > But there is no guarantee that this is possible. Of course
    > controlled
    > fusion is possible - the sun does it all the time. But short of
    > building a
    > star, it may be that plasma instabilities and all the other problems
    > that
    > beset controlled fusion research will mean that fusion as a source of
    > power
    > for everyday use just isn't viable. I think this is perhaps too
    > pessimistic. I'm sure most physicists working on Fusion really
    > believe that it is possible; we are not relying on developing "warp
    > drives" or other as yet unknown bits of physics to solve the
    > technology problems. It is just that they will take far more time
    > than we appear to have, if Glenn is correct about oil running out. As
    > it happens, I spoke to a plasma physicist who works on the JET
    > experiment this morning after church. This is what happens next in
    > the programme. (1) The next big experiment is called ETA, and its
    > purpose will be to demonstrate continuous generation of power by
    > controlled nuclear fusion. However, there will be no attempt to
    > convert this power into electricity. The purpose of the experiment is
    > largely to determine the correct plasma parameters for a fusion
    > reactor. The plasma instabilities are not an insurmountable problem,
    > but one does need to build very large experiments costing billions, in
    > order to get them right. At present, several sites in Europe, Japan
    > and Canada are being considered and assessed for feasibility for
    > building the experiment. Countries involved are Russia, Europe, Japan,
    > Canada. Not America at present. Once the site is agreed on, it will
    > take 12 years to build the experiment and get plasmas into it, and a
    > further 12 for the experimental programme. (2) The reusults from ETA
    > are then supposed to feed into DEMO, a demonstration Fusion power
    > station, which will supply electricity to the grid. This will also
    > take 12 years to build and 12 to run. By which time the feasibility
    > will have been established. Hence the current estimate for when we get
    > fusion in practice is 2050. I asked about Glenn's suggested 20 year
    > time span. The response was as I expected; no-one working in Fusion
    > research would consider 20 years as anything other than a
    > "pipe-dream" (his words). Throwing extra money at it might reduce
    > the timescales somewhat, but would never reduce it by anything like a
    > half. I also asked about the other technology problems that had to be
    > solved. He was of the opinion that the Tritium breeding was not the
    > most difficult problem (though still hard). There will be a lithium
    > blanket in the ETA experiment. In his opinion the hardest problem was
    > the design of the materials for the vacuum vessel. (To withstand
    > corrosion, radiation, etc). I can add here that I started my career at
    > the UKAEA Culham labs particularly because I believed that Fusion was
    > the future solution to our energy needs. That was in 1981. The very
    > day I joined, the Conservative government axed the large experiment I
    > was recruited to work on (RFX), which eventually got built on a
    > reduced scale in Italy. The government continued its destructive
    > course by turning the UKAEA into a Trading Fund, where we were obliged
    > to make money by exploiting some of the technology that had been
    > developed in the fusion programme. For example, much laser technology
    > had been developed for plasma diagnostics (measuring the plasma
    > temperature by Thompson scattering). The laser expertise we had
    > developed was then diverted into more immediately lucrative projects,
    > such as developing a machine for cutting a pattern in the security
    > thread for the 50 pound note. That's what governments do to long term
    > programmes that won't get them any votes when they come to get
    > re-elected. Needless to say this is all pretty depressing, but it has
    > to be said that the naive idealism with which I started my career has
    > been replaced by a more realistic, if less hopeful attitude. So it
    > would appear to me that if its true that we're all going back to the
    > middle ages if we don't get Fusion power stations being churned out by
    > the dozen in 20 years, then that is precisely what will happen, and
    > we'd better get used to the idea.

             Let me clarify. I was not saying controlled fusion _is_
    impossible, that it's in the same category as interstellar travel, or
    that there should not be intensive work on it. My point was simply that
    a technology is not necessarily achievable just because we need it in
    order to maintain a certain standard of living. & I'd add that the
    technological optimism I referred to can be self-deluding & dangerous if
    it enables people to say that we don't need to be concerned about
    reducing petroleum use &c because fusion energy will be available when
    we need it.



    George L. Murphy
    "The Science-Theology Interface"

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