Yeah, unfortunately we still cant get a self sufficient biodome to work let alone a spaceship. Youre no better off than in a bunker. In fact we'd probably live longer than you if its a SpaceX ship. Lol
I think a better question would be, why would you want to survive a nuclear war? Get your delusions out, its NOT going to be like playing Fallout. Lmao!!!
I mean seriously, lets just say that there is still enough air and enough ice and water sublimate to keep it breathable, immediately afterward you have acid rain with a ph low enough to melt your face, radioactive dust storms, nuclear fallout and radiation hotzones (which by the time you realize youre in one its already too late), continent wide wildfires (which are emitting radioactive smoke and ash) and thats all in the 6 to 8 months leading up to the nuclear winter which will last for most of a decade and drop worldwide temps to that of the last ice age. And any food or water you find will be too contaminated to consume, meaning the only thing you will have to eat is non-irradiated people...
Yeah, yall have fun.