Re: OT: New Climate Pact!

In article <1h0gp2k.838lz5q49lu3N%peter@xxxxxxxxxxxxxxxx>,
Peter Ceresole <peter@xxxxxxxxxxxxxxxx> wrote:
>Chris Brown <cpbrown@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
>> >Fusion reactors do not exist yet,
>>
>> *Commercial* reactors don't exist. However, These guys may beg to differ
>> with the suggestion that fusion reactors don't exist full-stop:
>>
>> http://www.jet.efda.org/
>
>'Reactors' yes, as in 'reaction in a test tube for a vanishingly small
>time' and test tube as in 'sodding great machine'.

Vanishingly small? JET, as far back as 1991 managed plasma confinement for
one minute. In 1997, they were able to produce a steady output of 4
megawatts for 4 seconds. Further experiments have allowed them to make
significant advances in confinement, to the point where it is now believed
that the ITER machine should be able to manage continuous running.

This is all on their website - you just need to go and look.

>Mike Pentz joined a team working on fusion reaction not long after the
>war. He told me that they planned to do the job in the basement
>lavatories of the Royal School of Mines, because their walls were thick
>enough to shield from the relatively mild radiation they were expecting.
>He told me 'the theory was fine, it was going to be quite easy'. Then,
>as he said 'we discovered plasma instability'. It wasn't the fundamental
>physics that were the problem. It was the engineering. It still is.

It would appear that the twin benefits of actually having a small scale
reactor (i.e. JET) to test this on, as well as nice powerful supercomputers
to model the plasma, and react to changes in confinement in real time, is
allowing significant progress to be made on this issue. Indeed, if the
developments from the JET machine scale to ITER, it would appear that it's
pretty much a solved problem.

>And
>as Jack says, the radioactivity problem is just about as great as with
>fission, because you have to dispose of the kit after a quite short
>time.

Hardly. Fission produces waste that remains dangerous for thousands of
years. In the case of fusion, the radioactive material you do get (inner
walls of decomissioned reaction vessels) is vastly shorter lived. It is
disingenious to suggest that the problem is remotely comparable to that with
fission reactors, in either scale or longevity.

Indeed, JET first fired up their reactor 22 years ago, and it has been used
pretty much continuously for fusion experiments since. The reactor vessel
still appears to be safe enough for people to work inside it with moderately
little protection. I wouldn't want to do that inside a fission reactor -
even one that's only been used for experimental runs for 22 years.
.

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