"Another basic problem with MSRs is that the materials used to manufacture the various reactor components will be exposed to hot salts that are chemically corrosive, while being bombarded by radioactive particles. So far, there is no material that can perform satisfactorily in such an environment. A 2018 review from the Idaho National Laboratory could only recommended that “a systematic development program be initiated” to develop new alloys that might work better. There is, of course, no guarantee that the program will be successful."

https://theconversation.com/nuclear-power-why-molten-salt-re...

Molten salt reactors are designed to avoid meltdowns.

But most of the harm at Chernobyl was from the explosion. There is nothing in a molten salt reactor that makes them any safer than Chernobyl if the reactor containment is breached.

Massive amounts of highly radioactive particles will be ejected into the atmosphere in exactly the same way as happened at Chernobyl.

Molten salt advocates will say "yes, but what could possibly breach the reactor if there is no meltdown". Well we almost saw the answer to that today.

but also cannot realistically operate for very long becase structural components tend to deteriorate quickly from the combo of salt, high heat, and radiation.