A preliminary feasibility study is performed for a sodium-cooled breed-and-burn (B&B) fast reactor core for achieving high uranium utilization without solid fission product separation that could fit within a reactor vessel of the dimensions of SuperPRISM (S-PRISM). This 1000-MW(thermal) B&B core is to be fueled with depleted uranium with the exception of the fissile loading required for achieving initial criticality. When the fuel reaches its radiation damage limit, it is reconditioned using the melt-refining process and reloaded into the core until it runs out of reactivity.

It is found that the maximum burnup at which the S-PRISM-sized B&B core can be designed to discharge its fuel is 43% fissions per initial metal atom. The corresponding uranium utilization is nearly 90 times higher than that of a light water reactor. The achievable burnup strongly depends on the fuel volume fraction but is almost insensitive to the core power density, fuel-reconditioning frequency, and duration of the fuel-reconditioning process.