I used an emoji but it doesn't look right. I meant to write "asshat" :D slashdot is great this was my first comment ever and I was called an asshat straight away :D

"Asshat" ðY£ when you say "thorium reactors" I guess you are referring to molten salt reactor designs where the thorium (and yes, also definitely uranium) is dissolved in the liquid molten salt. For sure there are some safety advantages w that. But as always, there are some very serious tradeoffs as well. This is why none have been built for more than 50 years and very few have ever been built. Now china has built one so it will be interesting to see what is the operating experience once that comes online.

A thorium reactor is still a uranium reactor. Thorium has no fissile isotopes, it is there to breed a fissile uranium isotope that will go on to fission and produce most of the reactor power.

Ceramics like SiC can withstand higher temperatures than metals without melting, but they are brittle, and thus can be harder to work with and might be more subject to cracking. So when switching to a ceramic cladding from a metal cladding this is a major tradeoff that engineers have to consider. Perhaps you gain some margin for an accident scenario, but the cladding might be harder to manufacture, and thus cost more, and it might introduce other problems like cracking. Also SiC probably absorbs more neutrons than the zirconium alloys predominantly used in nuclear reactors today.