Totally missing the point everyone!
So accepting the fact that Shera did for some reason survive the startup, which is not that problematic in my humble opinion, since there are more then one phase during startup of a rocket blah blah... (and how can a fuel tank explode anyway, there is no fire or spark in it unless there is a serious design flaw there ^^)
But my question is: How the hell did she survive the actual start of the rocket later in the game? She was apparently in a room next to the fuel tanks, wouldn't she get fried this time?
Also - if everyone kept the rocket ready to go and Shinra lost all interest - what kept them from just firing up the damn thing in all those years?