I don't understand a lot about these fusion plans, so this might be a dumb question, but if it were to be used at scale, aside from the energy stuff, would it be a viable source of substantial quantities of helium?
It also produces huge amounts of activating radiation. The reactor walls will be highly radioactive, as will everything from the fuel supply to the helium itself. In principle you can split that off, but I wouldn't want to try. Fission reactors are a lot more tractable.
