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Comment by seanmcdirmid | Hacker News Reader

If we could figure out economical nuclear fusion, we wouldn't be arguing right now. We are always 20 years from figuring it out also.

Once we have fusion, producing hydrogen liquid fuel should be cake.

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Or about 80bn EUR away from figuring it out.. would be a more useful scale imho (that's at least the number that the local plasma physics institute estimated iirc), as the ETA will keep changing if you change the yearly budget.

The problem with fusion is that in the form accessible to us here on Earth (deuterium-tritium), it still creates radioactive waste. It is not the sort of long lived waste you would see from Uranium based nuclear fission, it is more comparable to Thorium based fission reactors. In other words we already have a pretty decent alternative.

The real holy grail would be Hellium 3 fusion, but first we have to figure out how to import the fuel back to Earth from places like the surface of the Moon or from Jupiter.

Interesting. The moon has Helium 3, but the Earth doesn't?

It does, but only in rather small quantities. In fact it seems that most He-3 that's used is produced in Tritium decay reactions rather than extracted.

> first we have to figure out how to import the fuel back to Earth from places like the surface of the Moon

All we need is a psycho korean holding company and Sam Rockwell and we should be good.

(See "Moon" if you haven't. It's amazingly excellent.)

There are no working reactors (not even tested designs) that harness the potential of thorium. Experimental plants have had serious problems (edit:)and low power generation from thorium (see for example THTR-300 in germany; beware of the english wikipedia page, it is incomplete). So... come up with a safe design for a thorium reactor? (Edit2:) Until then, you might as well say fusion. Anyway, none of this is a reason to keep classic LWRs going.

What about the liquid fluoride thorium reactors? There's been some hype about these recently: http://www.youtube.com/watch?v=bbyr7jZOllI

This is just molten salt reactors all over again. They have disastrous security problems. Basically the salt eats away metal parts of the reactor, the graphite moderators are flammable and large parts of the reactor become radioactive because they catch neutrons which makes repair, maintenance and deconstruction almost impossible.

(edit:) I forgot about loss of fuel solubility events and the unsolved problem of tritium retention.

(edit:) It's interesting how the english wikipedia pages miss all the details on the failed projects in this field.

Strange, Kirk Sorensen (the guy in the video) seems very sure that these are much safer then any other alternatives. They don't have to be pressurised and water-cooled. Instead there's passive security with a frozen plug and a drain tank. Here's a longer documentary with lots of details (about 2 hours) http://www.youtube.com/watch?v=31HEijtqF5I

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