One of the things that I don't get is that there a lot of cool fission designs that are arguably only hampered by the state of the art in molten-salt plumbing, but the only fusion design with mainstream support requires molten lithium plumbing for breeding tritium and heat exchange, along with a few other things that are still a touch experimental. Hash out the molten salt plumbing for the fission reactors since it appears strictly a subset of the fusion problems.