Everything I've seen shows that, so far, typical lifetimes of offshore wind turbines are in the 10—12 year range. That should improve a bit once the experience is a bit better digested. We've seen foundation scour, a whole lot of stress-corrosion problems and just physical damage due to the sea-air interface, very rapid blade erosion due to spray, and of course the usual cyclic loading effects.
Nuclear plants belong near load centers, to supply heat plus power.