Modeling and validation of a water-cooled reactor Cavity cooling system (RCCS)

Abstract

High Temperature Gas-cooled Reactors (HTGRs) have garnered interest for use in commercial energy production and for providing high temperature process heat for industrial applications. One of the passive safety systems suggested for decay heat removal in accident conditions is known as the Reactor Cavity Cooling System (RCCS). Two steady-state experimental data sets with varying Reynolds numbers (Re = 2490, 10279) conducted with the TAMU RCCS experimental facility were modeled and simulated using the computational fluid dynamics code STAR-CCM + and the TRACE system thermal hydraulics code for code validation. It was found that both the CFD and system code models showed good agreement with respect to the global conditions of the internal flow within the RCCS. Comparisons of the local temperature measurements showed that the TRACE code tended to overpredict temperatures toward the bottom of the RCCS cooling panel but showed good agreement above the midpoint of the RCCS risers. The CFD model found significant thermal stratification and recirculation in the Low Reynolds case due to the asymmetric heating profile applied to the riser panel. The bottom and lower manifold geometries of the RCCS design were also found to produce asymmetrical flow conditions which led to differences in local riser temperatures.