Oh, yeah, I agree with previous posters. I can't see any practical way that you'd have a "normal" Uboat used as an icebreaker or capable of surfacing through the ice. They were built to be strong but light, the pressure hulls were like "monocoque" structures. If you could build something like an ice breaking prow or a curved hump up to a "smoothed out" conning tower that was strong enough for the use you describe, there wouldn't be anything strong enough to attach these structres to. Also, that kind of Arctic ice has pressure ridges and thicker chunks of ice extending down into the water -- it's not nice and smooth just ready to be broken through.
But if you're happy with the "fiction" part of sci-fi, it's up to you. But this kind of use would be way over in the fiction part of a story.