I should also point out that just about every reactor ever built has had problems with corrosion. Its it not just a matter of a material choice, it has to be something that works with the neutron economy as well. Also the corrosion that happens in a high radiation environment is quite different and typically faster and more aggressive than plain corrosion. Even many of the Dry casket storage systems are failing due to radiation driven corrosion and that is much lower activity radiation.
