Book Idea, need good title however

My story is more adult science fiction, but here is the gist of what it is about. Basically a worldwide catastrophic event has destroyed everything, and any left over humans are forced to band together too survive. The group of known survivors consists of 56 people ranging from men to women to children and two dogs.  They use whatever they can find to create huts and shelters and must start over, as they enable historic methods of surviving. The books main focus is on the hardships, as little as they may seem now too us because we have amenties that we take for granted now. But it also focuses on what the event has done to Earth. One of the survivors is a scientist who notices large areas of what appear to be nuclear waste deposits, leading him to believe it was a nuclear accident. As the weeks progress they find out the waste product has created creatures that were once unknown, and in addition to this, it is changing the survivors too.