Numerical analysis of density wave instability and heat transfer deterioration in a supercritical water reactor

The present study numerically investigates Density wave oscillations (DWOs), a dynamic instability and captures Heat transfer deterioration (HTD) phenomenon for a Supercritical water reactor (SCWR) of the U. S. reference design. A Thermal-hydraulic (TH) model is employed to solve the nonlinearly coupled mass, axial momentum and energy conservation equations in a time domain using characteristics based implicit finite difference scheme accounting for the compressible flow dynamics of supercritical water. The analysis of DWOs is carried out to obtain the marginal stability thresholds. Next, the steady as well as transient safety analyses are carried out to determine the occurrence of HTD, access its severity and identify the safe operating conditions. Finally, the common operating conditions are predicted where the U. S. SCWR will be stable as well as safe.