There are a lot of post-apocalyptic stories out there ranging from zombie attacks (The Walking Dead) to diseases (12 Monkeys). While the end of the world is a fascinating story setting, the reality would be more depressing than practically any of us could remember -that's because nuclear disasters, fire, floods, disease, malnutrition and more would actually leave everyone dead within a short span of time. Survivor stories aren't exactly all that interesting when there aren't any survivors and this TopTenz article explains why there's a good chance that any disaster on this scale would wipe out all humans -not just most of them.
Why would there be explosions did the workers place extremity sophisticated explosive devices in the reactors and change the uranium type?