Nah, we pretty much accept everyone who has a basic idea of how to use Industrialcraft and all that stuff. (To prevent catastrophic failures when someone new to Tekkit start building.)
The reactor overloading is very bad yes... A friend and I where on his server... and we blew up 50 nukes for fun just to test the destruction. (I would never do this on another server). That hole was HUGE!
Nukes are cool, yeah, but we disabled spawning and crafting of them on the server. Because there will always be someone who can't withold his/her excitement.