The media is always seeming to portray it like http://tvtropes.org/pmwiki/pmwiki.php/Main/NuclearPhysicsGoof" [Broken] waiting to go off. Now I've done a fair amount of research into nuclear power and it's readily apparent to me that this is not the case. I was wondering what, if any circumstances would cause a major explosion in a nuclear reactor. Is there any set of circumstances that would cause an actual nuclear bomb type explosion in the reactor? What reactors would be most prone to disasters? Are there statistics on the safety of reactors verses conventional power?