🚀 go-pugleaf

In article <24270@wraxall.inmos.co.uk> des@frogland.inmos.co.uk (David Shepherd) writes:

>however, are all these claims of a limitless energy supply being
>overplayed? at the (excellent) open day at JET in the summer one
>of the leaflets/films said that the power would be produced by sheathing
>a fusion reactor in lithium, which would itself fuse with high energy
>deuterium (?) nuclei flying out of the reaction and that the heat
>from this would be used to generate electricity. in then went on to
>say that currently known reserves of lithium would be enough to 
>satisfy the worlds energy demands for 100 years ..... but what
>happens after that?


The claims certainly are overplayed.  And, if the reactor is too hot to go
into for 4 months after a 2 megajoule pulse, what's going to happen if
a commercial reactor producing 3000 MW (th) continuously should break
down?  I have this image of ITER becoming a major embarassment.

Known reserves of lithium are a small subset of the amount of lithium
in the crust (average crustal abundance is about 20 ppm).  Also, the
amount of lithium consumed by a fusion reactor per unit energy
produced is so small that the price of lithium could be much higher
and still have little effect on the cost of energy.  Lithium can also
be extracted from seawater; the Japanese have an ion-exchange
technology for doing this at a price not too much above the current
price.

The lithium is transmuted by neutrons, btw.  The (n,t) reaction on 6Li does
produce some additional heat, but most the energy is from d+t fusion reactions
in the plasma, carried to the blanket by the neutrons.

I wonder why JET didn't do a D + 3He experiment (or did they?).

	Paul F. Dietz
	dietz@cs.rochester.edu