Chick 1 says:

Because most spaceships have rickety walkways over their nuclear core.

Welcome back to Trope of the Week or as it shall henceforth be called, Troperiffic Tuesday! 

Ever seen a movie where the cap is knocked off a pipe joint with very little effort and blinding hot steam comes spraying out?  Or someone has to cross a narrow walkway high above some flesh-grinding machinery with no guardrails?  Or a character falls into an easily accessible vat of acid?  Then you, my friend, are familiar with this week’s trope, No OSHA Compliance.  As always, SPOILERS FOLLOW. Read more