Empirical and Computational Pressure Drop Correlations for Pressurized Water Reactor Fuel Spacer Grids

Empirical and computational pressure drop correlations were developed to accurately estimate the pressure drop at the fuel spacer grid in a pressurized water reactor. The empirical correlation uses the balance of hydraulic forces acting on the spacer grid. The amount of pressure drop is assumed to depend largely on the reduction of the flow cross section, the flow constriction in the spacer region, and the frictional loss. The grid form drag due to the relative plugging and the flow constriction by the grid components were found to be the primary factors of the total pressure drop. The computational correlation combines the pressure drop due to flow blockage by the spacer grid and the pressure drop calculated by dynamics analysis. The pressure loss coefficients from the empirical correlation agree well with the measured ones for the spacer grids with and without the mixing vane. The computational correlation overpredicts the pressure loss coefficients for the spacer grid with the mixing vane.