Force a signal in the output of a logical gate: destructive?

Thank you very much for your help.

I'll have some reading for the next days then :p

I know it's not a good idea to have a port in the wrong direction, but the problem is that I can't have control over SEU (single event upset caused by charged particle in space). In the meanwhile, I've minimized as much as possible the weak spot of my design (I mean the place where a SEU can operate and the cause an electrical conflict).

Again, thanks a lot :)