Economic Assessment of Recycling High Assay Low Enriched Uranium Sodium Cooled Fast Reactor Used Nuclear Fuels

Sodium-cooled fast reactors (SFRs) are being developed with various fuel cycle strategies, including once-through and recycling options. Initial U.S. deployments are expected to use compact SFR cores fueled with high-assay low-enriched uranium (HALEU). As SFR technology advances, higher fuel burnups and lower enrichments are anticipated. This study provides an economic assessment of utilizing HALEU in SFRs with a once-through fuel cycle (OTC) compared to recycling used nuclear fuel (UNF) across a range of advanced fuel and reactor designs. As an alternative to current once-through options (FC #1), three recycling alternatives are evaluated: (FC #2) recovered uranium (RU) downblended for pressurized water reactor (PWR) fuel, (FC #3) RU re-enriched for SFR fuel, and (FC #4) RU co-recycled with transuranics (RU/TRU) for SFR fuel. Results indicate that recycling RU from SFR UNF in both fresh PWR and SFR fuel can be economically advantageous compared to the OTC approach, provided the U-235 content remains sufficiently high—a condition met by current and near-term SFR designs. Increased burnup and in situ plutonium production in SFRs reduce overall OTC costs and natural uranium requirements. However, the economic viability of recycling SFR RU depends strongly on the specific UNF composition and the recycling pathway chosen. Recycling both RU and TRU consistently offers the lowest fuel cycle costs across all scenarios, even as fuel and reactor designs advance. These findings provide a framework for identifying when recycling offers economic benefits over direct disposal, informing future fuel cycle decisions for advanced reactors.