Col. Mark Bowen, commandant of the Defense Threat Reduction Agency’s Defense Nuclear Weapons School, discusses the intricacies of the control panel for the historic, first-of-its-kind, SM-1 nuclear reactor at Fort Belvoir during a site visit Tuesday September 19, 2017. Bowen was one of several military leaders that participated in a site visit with the retired Lt. Gen. Ernest Graves, who oversaw the completion and initial operations of the long-closed facility, to learn more about its history and the military’s history with nuclear power.