Of course, rats survived. That's how mole rats came to be in the first place. Most likely radiations merged moles and rats and voila a new species. The other rats who survived were the ones living in caves. Cave rats from FO1 especially,
Yeah, nope:
"On the "Pentagon Library Terminal" in the Citadel, it can be discovered that the mole rats in the Capital Wasteland (and possibly the other mutated rats in Fallout 1 and 2) are the result of a government program to develop an invasive organism that could be planted in China, where its aggression and fast breeding would help undermine the Chinese war effort. It is noted that a genetic 'kill switch' was included to help the US Army clean up the rats after the theoretical fall of China. (This may be the mechanism stumbled onto by Moira in the Repellent Stick.) Additionally, it is revealed that the researchers attempted to use FEV to further augment their creation, but dismissed this course of action as the result proved sterile. "
Considering that Vaults have the meanings to survive in defiantly underground (barring equipment failure), why wouldn't a space station have similar water chips and food/clothes dispensers? Maybe that could be a back story for a new FO game. A crew of astronauts living in space are forced to land because of malfunctioning equipment.