Molten-salt-fuel reactors, as described in this article, are so lame... "It's already melted, so you can't have a meltdown." lol. More seriously, molten-salt-cooled reactors have some promise. They use solid fuel, usually TRISO particles, and are cooled by molten salts, which we now have lots of experience with from solar salt power systems. If you are interested in molten-salt-cooled reactors outside of this lame press release - check out Kairos Power. Their website sucks butt. But they are the main player in molten salt-cooled reactors - funded by Henry Laufer of Renaissance Technologies. They actually have the engineering and financing to get one built, and are reportedly doing very well with NRC (unlike OKLO - lolz).
Not an expert but I believe the problem with molten salt cooling for reactor designs is that nuclear reactors are supposed to just run for decades without replacing major parts that are really really radioactive. We just can't make parts that will resist corrosion for that long, unlike those towers in the solar arrays, which are really simple to replace. That's leaving aside the high level waste recovery, disposal, and storage issues.
