Impact of the Melt-Refining Process on the Performance of Sodium-Cooled Rotational Fuel-Shuffling Breed-and-Burn Reactors

This study assesses a Rotational Fuel-Shuffling Breed-and-Burn (RFBB) fast reactor that operates in breed-and-burn (B&B) mode with a rotational fuel-shuffling scheme and remains within the 200 displacements per atom (DPA) radiation damage constraint of currently verified cladding materials. The design is based on a commercial-scale fast burner reactor called the Super Power Reactor Innovative Small Module (S-PRISM) reactor. To reduce the high DPA values of discharged fuels, the melt-refining process developed in the Experimental Breeder Reactor-II (EBR-II) project is adopted in this study. The effects of the melt-refining process on the performance of the RFBB are investigated via five scenarios and compared with a core to which the melt-refining process is not applied: Scenario I, “Homogenization,” occurs without the removal of fission products (FPs) during the melt-refining process; Scenario II, “Homogenization and FP Removal,” occurs with the removal of FPs to a fraction similar to that in the melt-refining process developed in the EBR-II project; Scenario III, “Homogenization, FP Removal, and Make-Up,” is similar to Scenario II but makes up fuel losses with natural uranium; Scenario IV, “With 1% TRU [transuranics] Losses,” is similar to Scenario III but is evaluated with 1% of actinides not recovered; Scenario V, “With 10% TRU Losses,” is similar to Scenario III but is evaluated with 10% of actinides not recovered. The results show that it is neutronically and thermal hydraulically feasible to establish a B&B mode with the rotational fuel-shuffling scheme and by reconditioning the fuel whenever its cladding reaches its proven 200 DPA radiation damage limit. In Scenario V, the core is subcritical due to a large number of actinides not being recovered during the melt-refining process. The cores of the other scenarios are all critical. The cores of scenarios in which FPs are removed during the melt-refining process have higher excess reactivity than that of the core of Scenario I (“Homogenization”) and that of the core to which the melt-refining process is not applied. The numerical analyses also show that in scenarios that include making up fuel losses during melt refining, the core is fed with more natural uranium make-up fuel during operation and thus has lower burnup. Other characteristics, such as power density distributions, neutron flux profiles, and fertile and fissile nuclide density distributions, are all stable during operation.