This question already has an answer here:
As clearly defined in Life After People Nuclear Power plants would melt down days to weeks after people disappeared. Now, I seriously doubt that anybody would stick around to even try to operate the reactors when the crap hit the fan......so since America alone has over 100 reactors so in theory the good old USA should be a desolate, radioactive death-zone ass well as filled with the undead. Also why didn't the huge chemical spills that would have occurred after and during the panic effect the survivors at all?
My question is this: Why didn't the world become totally inhospitable after the mass outbreaks.