Which material reflects the most light transparent, translucent, or opaque?

There's no rule like that.  A glass mirror is opaque but reflects
more light than a clean transparent glass window does. 

On the other hand, a material that's transparent but shiny may
reflect more light than an opaque material that's painted black. 

You can't give any general rule.

For me a person with a phd and who knows what there talking about.i know the chances of a radiation leak is low but if it does the area within a 96.3 mile radius would be unusable because of contamination