John Wheeler was a theoretical physicist who joined the Manhattan Project in 1942. During the early stages of the project, Wheeler worked under Arthur H. Compton at the Metallurgical Laboratory, where he helped examine potential problems that could arise during the startup of the world’s first nuclear reactor. Wheeler later became the lead physicist at the Hanford Site, where he solved the riddle of the B Reactor going dead a few hours after it started, an event that threatened to delay seriously the first production of plutonium. In this interview, Wheeler discusses his early collaboration with Niels Bohr on the liquid drop model of nuclear fission. He also discusses his involvement in designing the B Reactor and solving the problem of xenon poisoning that occurred during startup.