Yes it is completely safe, they where building one in west Texas but got abour 3\4s done and lost funding. the worst that could go wrong is an underground nuclear explosion, but that is unlikely. They run tests evryday to similate all the posible out comes, like half are good then about a fourth of the outcomes where a miss, then the rest was that it would not reach full power.
I also think that the have to wait 6 weeks before each fire, so that they do not disrupte normal life in the area.
with the amounts of energy a device like that could produce, I would think that if it were to explode..... it could destroy half the universe.
maybe that kind of explosion would only happen if the circumstances were "just right", and maybe the odds of those "just right" circumstances are inconcievable, but murhpys law states that whatever can go wrong, will go wrong.
and we all know that murphy is more powerful than even god.
but it is simply amazing at what humans can create...scientists found a way to break down DNA and now this...and did they already dissect the particles in a nucleus...probably...wow, that is some heavy stuff to read....
Thats crazy. Its amazing what all engineering and resources goes into something like that. I've read many things about the Tevatron but I guess this is even bigger. Wow.