"Through these holes in the south face of the Brookhaven reactor are introduced tons of pure uranium metal. Once in the graphite moderator of the reactor proper, uranium atoms fission, or split, in a chain reaction. The reaction releases atomic particles, known as neutrons, for use in experiments and for production of radioisotopes. The holes can also be used to insert certain types of metals and other substances to be irradiated by neutrons. Some of these materials emerge with radioactivies of thousands of curies of beta and gamma rays, fors of radiation now used in industry and agriculture. The tecnician in the photo is standing on an elevator which enables him to move to any level of charging holes. He is using a periscope to view the handling of these highly radioactive sources by remote control, by means of grappling tools and other equipment. A wall of heavy concrete five feet thick protects him from radiation given off by the reactor." Photo circa 1955-1963.