That's a good question. The short answer is that the only molten salt reactor in the US used Hastalloy-N (a Ni alloy), and it failed. See also: https://art.i

That's a good question. The short answer is that the only molten salt reactor in the US used Hastalloy-N (a Ni alloy), and it failed. See also: https://art.inl.gov/ART%20Document%20Library/High%20Temperature%20Materials/45171%20Status%20of%20Metallic%20Structural.pdf https://art.inl.gov/ART%20Document%20Library/High%20Temperat...