Well, I suspect where there is smoke there is fire, in this case. It is probably a much worse problem in some facilities than in others. Rape is primarily a power issue. Many people who feel powerless tend to turn their anger into sexual aggression against someone else. Who would be much more inclined to feel powerless than someone who has been incarcerated by society and locked up in a cell? Such a person will often seek whatever vicarious power he thinks he can find...and that will rebound on those he has the easiest access to.