Fusion, Hah.

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And if you got that joke, you’re a huge nerd. Not necessarily the right kind of nerd to follow the rest of this post, but a giant nerd nonetheless.

But anyway.

Nuclear fusion is a dumb idea.

Or, to be more precise, any form of nuclear fusion that relies on deuterium-tritium fusion is a dumb idea, and functionally every form of nuclear fusion that is even in the perpetually “thirty years away” category relies on those particular fuels.

Because deuterium-tritium fusion doesn’t really solve any problems.

Just Googling the phrase “nuclear fusion” will probably show you a simplified image of the process, smashing deuterium and tritium (isotopes of hydrogen, the latter of which is radioactive) and producing helium, energy, and one little excess neutron.

That little excess neutron is the problem.

Because that little neutron is hauling ass on its way out of that particular collision, and high energy neutrons cause all kinds of problems.

I mean, what are the objectives of nuclear fusion as opposed to fission?  Elimination of nuclear waste, increased safety, readily available fuel, and nuclear nonproliferation, right?

Deuterium-tritium fusion solves maybe one of those issues, increased safety, but so do a variety of next generation fission reactor designs.  As for the rest?

Not so much.

Elimination of nuclear waste?  In the case of a fission reactor, that waste takes a variety of forms, the more dangerous of which is spent fuel, but with better reactor designs, that spent fuel can be reduced, recycled, and otherwise limited to a significant degree compared to current designs.

However.

A great deal of “nuclear waste” that comes out of fission reactors doesn’t have anything to do with actual nuclear fuel, it has to do with…. high energy neutron bombardment of materials near the reactor itself.

The same neutrons that come pouring out of every deuterium-tritium fusion reactor, only in the case of the fission reactor most of the things being bombarded by neutrons are… mechanically simple in comparison to the sort of apparatus that encompass functionally every proposed fusion reactor design.

Neutron embrittlement means that the materials surrounding the reactor will grow progressively weaker, not to mention radioactive, and need to be periodically replaced.  D-T fusion will suffer from this exact same problem, only carrying much greater cost regarding the components that need replacing.

On the up side, of course, that neutron bombardment would allow a D-T reactor to breed its own tritium, as the isotope is not available to any significant degree in nature, and while this may sound like a good thing (a reactor that makes its own fuel!), the problem is that you can put other things in the path of that neutron stream.

Like uranium.

And when we subject uranium to neutron bombardment we get… plutonium!

Which means that nuclear nonproliferation is off the table with these D-T reactor designs, because they can easily be used to produce what is probably the easiest material from which to construct a nuclear weapon.  The simplest nuclear weapon design, in fact; the kind of weapon that you could build in the average machine shop.

So with reduced nuclear waste being negligible, readily available fuel and nuclear nonproliferation effectively cancelling each other out, we’re left with increased safety as the only potential advantage offered by D-T fusion, and even that is… somewhat sketchy.

It’s true that such a reactor couldn’t melt down, and that while a catastrophic failure in containment might result in a really, really bad day for the guys working at the plant, it wouldn’t scatter much in the way of radioactive waste around, the fact remains that there are much more attainable fission reactor designs that are similarly resistant to runaway reactions. And won’t be thirty years away for the next century.

I’m not by any means opposed to carrying out research into fusion energy.  There’s always a chance that the pursuit of such will reveal some way to move beyond the current limitations of the technology, or even some more fundamental understanding of the universe.

But I’m also realistic about the chances that such research will result in anything practical.  And those chances are not good.  As you progress towards lighter isotopes of hydrogen in the fusion process, the difficulty goes up enormously, and I’m not entirely convinced that straight hydrogen-hydrogen fusion is possible for humanity, even in the long term.

Personally I’d rather see the bulk of the money currently going into fusion research temporarily redirected towards next-gen fission reactor designs, and then in five years or so we could put it back towards fusion, since it would still be 30 years away.

Probably forever.