I am not a structural engineer, but based on what I know of our from the UFSAR, with the cracking problems they have, I don't see how it could be reparable. Replaceable? Like someone above said, they'd have to see if that makes sense economically. I doubt it would. I could only imagine that cost being sky high. I mean, is it even possible? So long as there is fuel in that building, among other things, I don't see how you could just take it down and put another back up.
I think Mike is right, it's done for.