In this 1964 “Science Reporter” program we take a tour of the nuclear reactor at the U.S. Army Materials Research Agency in Watertown, MA, and learn how it is being used as a scientific research tool to detect and fingerprint infinitesimal impurities in metals. Homer Priest (director of the Watertown Research Laboratory) traces how knowledge of molecular structures has grown over time, and discusses the implications of nuclear reactor research for industries such as semi-conductors. Also interviewed by MIT reporter John Fitch '52 are Jack O'Connor, Chief of the Nuclear Reactor Division, and research physicist John Antal. Produced by MIT and WGBH. Film to HD transfer courtesy of MIT 150. MIT Museum Collections. [[T6024]