Looking out over the flat expanse of Arco, Idaho, it’s understandable why it’s been used for nuclear reactor experimentation.  Any slip ups would render uninhabitable a plain that is already devoid of trees or towns.  It’s pretty empty here still, with the 900 square mile Idaho National Energy Laboratory closed to the public.  A historical marker boasts, “Since 1949, more nuclear reactors, over 50 of them, h