My understanding is that only 1 inmate is allowed out of a cell at any given time and that 2 guns are trained on that inmate at all times. They even put a court room and medical facilities in the prison so you are never transported out.
All furniture (including bed) is made of concrete and there are no metal objects anywhere in a cell, not even in the concrete.
Its a roach motel...they check in but they don't check out.