Modeling Material Requirements of the Transition to HALEU Fueled Reactors

Current nuclear reactors employed in the United States use Low Enriched Uranium (LEU) fuel enriched to no more than 5%. New reactor designs, such as the Ultra Safe Nuclear Company (USNC) Micro Modular Reactor (MMR) TM, will require High Assay Low Enriched Uranium (HALEU) fuel enriched between 5-20%. To meet HALEU fuel requirements, the U.S. Department of Energy is considering recovery and down blending of High Enriched Uranium (HEU) fuel and enriching natural uranium to the required levels, with each of these methods containing their own limitations. The existing physical supply of HEU and down blending capacity limits the recovery and down blending method. Centrifuge capacity limits the enrichment of natural uranium method. This work aims to quantify the resource requirements of the current U.S. reactor fleet and of the transition to different reactors that require HALEU fuel. The fuel cycle scenarios are modeled using Cyclus, an agent-based fuel cycle simulator. The scenarios model the current U.S. fuel cycle with each reactor unit modeled as a separate agent, from 1965 to 2090. The International Atomic Energy Agency (IAEA) Power Reactor Information System (PRIS) database provided information about each Light Water Reactor (LWR) in the simulation. The first scenario modeled does not include the transition to an advanced reactor; is used to provide a baseline of resources required. The next scenarios modeled include the transition to either the USNC MMRTM or the X-energy Xe-100TM reactor and model either a no-growth or 1% growth scenario. This creates five different scenarios. The advanced reactors were selected to provide a comparison between an advanced reactor with small cores and long cycle times and an advanced reactor with a large core that employs online refueling. The results of this work includes the rate of reactor deployment, the mass of enriched uranium, and the Separative Work Unit (SWU) capacity required for each scenario. These metrics inform the material requirements and provide insight into the best method to meet fuel requirements for these transition scenarios. Preliminary results show that for the no-growth transition, 5962 MMR reactors and 795 Xe-100 reactors are required to meet the energy demand, and MMR transition requires a greater mass of enriched uranium than the Xe-100 transition but requires less SWU capacity. (authors)