3:30–4:30 pm Maria Goeppert-Mayer Lecture Hall
Nuclear Archaeology: New Insights Into the First Reactor
Carl Willis, University of New Mexico
The first human-made nuclear reactor, Chicago Pile-1, operated under the west stands of old Stagg Field between December 7, 1942, and February 28, 1943, under the supervision of Enrico Fermi, Herbert Anderson, and others. Inspired by the gift of a fuel-containing "live block" of this pile from Mrs. Anderson, I took an interest in what modern measurements and models could reveal about this seminal reactor eight decades later. Originally, my focus was establishing a timeline for that artifact based on its fission product inventory and uranium isotopics, but this pursuit drove the development of a detailed neutronics model of CP-1 for the MCNP code, incorporating new measurements from the artifact materials. This model has been tested against 1942-43 measurements, including the assembly approach to critical, final approach to critical, excess reactivity, regulating rod worth, air pressure, and various temperature coefficients of reactivity, and it is shared here for the first time and freely available to download. As nuclear reactor technology has advanced, CP-1 has become relatively rare as an example of an ambient-air, natural-uranium graphite reactor, with few comparable modern benchmarks. However, such reactors remain of interest from proliferation as well as historical standpoints