During the past few years, the Neutronics Methods and Codes group in the Nuclear Engineering Division has researched and developed high performance neutronics tools that take advantage of massively parallel systems such as Argonne’s Leadership Computing Facility (ALCF). The resulting toolset includes the second order discrete ordinates code, PROTEUS-SN, which has been used to analyze several problems. In this talk, Emily will introduce the supercomputing resources for which the high performance neutronics codes were tailored, introduce the PROTEUS-SN code, and show an analysis example performed with PROTEUS-SN on the ALCF supercomputer.