The liquid fluoride salt reactors got a lot of attention starting in the 00's but the more I look at it the more I see that liquid chloride fast reactors solve the problems of the fluoride salt reactor (graphite and its discontents, marginal neutronics for breeding, etc.) and of the fast reactor (fuel fabrication, fuel fabrication, fuel fabrication)

That kind of reactor can generate so many excess neutrons it can spend some breaking down the worst of the fission products -- it looks like something out of science fiction, it's maybe better than a fusion reactor.