Computational Fluid Dynamics in the Safety Analysis and Design of Sodium-Cooled Fast Reactors

The Sodium-Cooled Fast Reactor (SFR) stands as a cornerstone of the Generation-IV initiative, offering a strategic solution to the dual challenges of nuclear waste management and long-term energy sustainability. Its reliance on liquid sodium as a coolant, however, introduces a unique and complex set of thermal-hydraulic phenomena that must be thoroughly understood to ensure operational reliability and to build a robust safety case for licensing. This report provides an exhaustive technical assessment of the critical role that advanced Computational Fluid Dynamics (CFD) simulation plays in the design, analysis, and safety substantiation of SFR technology. The analysis reveals that CFD has become an indispensable tool, moving beyond simple verification to become a primary means of design optimization and fundamental physical discovery. The unique properties of liquid sodium—in particular its high thermal conductivity and low viscosity, which result in a very low Prandtl number—invalidate the foundational assumptions of many standard engineering turbulence models.