The problem is that the nuclear reactions produce many random materials which in turn might be corrowive to the reactor veasel. Dont forget that the vessel has to last decades, so even minor corrosion is a big deal.

No, steel doesn't work, the salt is too corrosive. It's a very challenging problem, imagine you have half the periodic table floating around in a very radioactive salt at high temperature.

Early molten salt reactor experiments used Hastelloy N (nickel: 71 wt%, molybdenum:16 wt%, chromium: 7 wt%, iron: 5 wt%, others:1 wt%), which apparently works. But as others have noted, there is ongoing research to further improve it.

Metals melt at lower temperatures than salt.

Also think of how saltwater effects metal. That's just a bit of salt dissolved in water. Molten salt is like that, but way more concentrated, and hotter. Corrosive reactions go faster when you add heat. Molten salt is like metal's worst nightmare.

That's before you even add the radioactivity into the mix, I believe that makes this problem an order of magnitude harder than just trying to contain molten salt, which is already kinda pretty hard.

Stone, maybe, something like a specialized ceramic could work?

You'd still need a heat exchanger at some point, and you want a lot of surface area and thin walls for that.

Random thought experiment -- why not just drop it in the middle of a lifeless desert, forget about heat exchangers, and just let it slowly melt its way down through the crust of the earth? Assuming it went straight down and into the mantle, it would probably not impact the ecosystem.

Even in a desert, you'll cross the water table before reaching the mantle. And people prefer to consume electricity in hospitable locations.

"probably" being the key word here; Chernobyl was in a fairly remote area but the fallout spewed over a big part of Europe.

If you go to the desert to make use of the space, might as well build a solar array instead.

Wouldn’t be particularly helpful for power generation since the salt needs to be cooled by water to create the steam to make the power.

That's more or less what terrapower plans to build: dig a hole fill it with nuclear stuff and let it burn for decades.

Like an uncontained nuclear reaction spewing radioactive materials over a large area?

brb inventing teleportation