Characterizing the United States Nuclear Used Fuel Inventory Using the Cyclus Fuel Cycle Simulator

The used fuel inventory of the United States commercial nuclear fleet has been accumulating since the inception of nuclear reactors. In order to understand the mass and composition of the used fuel inventory, a nuclear fuel cycle simulation package (Cyclus) is used with a reactor modeling tool (Bright-lite). The parameters for the simulation are obtained as historical operation and burnup data for every reactor in the US fleet, taken from the U.S. Energy Information Administration. The historical burnup data is used to calculate the fuel enrichment of every reactor at every refueling. Discharged uranium inventories calculated by the software are shown to closely match the reference data. The total mass of three major actinide groups are presented as they build up over time. In addition, the evolution of the plutonium composition in discharged fuel is also presented, illustrating Cyclus’ ability to track the composition of material flowing through a large, evolving reactor fleet over decades.