More Fusion Thoughts

Obviously I have net access here in Madison, though it’s excruciatingly slow.

Rand’s post below reminds me of an idea I had a while back, and which has a little bit of traction in the fusion community (though I think it’s had multiple independent inventors). The basic idea is to make a virtue of the neutrons produced in D-T or D-D fusion by using them to transmute nuclear waste into short lived (high radioactivity) isotopes. The isotopes could then be stored while they decay into something (relatively) stable. The benefits are many. First of all it deals with fission waste, helping to remove one of the obstacles to widespread deployment of fission power. Secondly, it doesn’t require break-even from the fusion reactor, which makes everything a heck of a lot easier. The net transmutation plant power balance is now the sum of the fusion power and the power produced by the decay of the transmuted isotopes. A transmutation plant might plausibly be fully self sustaining. Once fusion reactors are in the hands of capitalist captains of industry, they will get better, cheaper, and more reliable.

A more exciting option is a mature fission-fusion hybrid cycle in which there are multiple passes of fission fuel through the reactor wall, to generate power using a set of reactions which spits out very low activity waste, cutting the initial fission reactor part entirely out of the cycle. This, it seems to me, is the logical long-term consequence of getting the evolutionary driving force of the markeplace to bear on the problem of commercial fusion. In the very long term, of course, we will likely see pure fusion power plants, but the path there must be along a sequence of evolvable reactor designs, each of which is at least marginally profitable.

More tomorrow, when the conference proper starts.