ABCC, Hiroshima These buildings were constructed by U.S. occupation forces five years after the end of World War II. The center was called the Atomic Bomb Casualty Commission (ABCC). Its mandate : to study the irradiated populations of Hiroshima and Nagasaki. Its method : to diagnose radiation illness but not to treat it. Eighty thousand people were chosen to be studied and are being followed until their deaths.