[AtlasBarfed]

5 years to construct a commercial fusion reactor after the demonstration? And it's nuclear, even if there isn't nasty fission products, there's still neutron degradation that needs to be shielded.

Again, I'd be happy if cheap fusion appeared, but it doesn't have a good track record.

[Sniffnoy]

Well, sure, like I said, it's ambitious; there's no guarantee this is going to actually work. But it's not like the people working on it haven't thought about the problem. They have an interesting approach to the neutron degradation problem, using a liquid blanket that can be circulated, so you don't have to deal with the problem of replacing solid shielding after it becomes too degraded.