Fission Piles provide heat AND electricity. Doesn't get more green than that.
I heard South Texas Nuclear lost at least one unit due to the freeze. I did not hear exactly why.
Not sure how they do it at the nuke plant, but everyone gets complacent down here on the Gulf Coast since we rarely see temps more than 5 degrees below freezing. Once you drop below that, things that don't normally freeze start freezing. Damaged insulation doesn't get repairs, lines that would be insulated further north are not insulated here. I can think of at least one water line we did not insulate a few years ago (we argued about it) froze and cracked. I also hear plants further north enclose critical areas in buildings and such. In our case, we just don't put enough effort into maintaining robust freeze protection. That might change since global warming is obviously causing all this and it will get worse.