Pressure drop and flow characteristics in partially blocked wire wrapped rod bundles

Abstract

One of the fuel assembly designs considered for liquid metal-cooled fast reactors (LMFR) uses wires helically wrapped around fuel pins as spacers. The understanding of the coolant behavior in LMFR fuels under the influence of a partially blocked flow area is required for a correct safety assessment. Accumulation of debris or cladding deformation may generate a partial or total flow blockage of coolant channels at different locations. Unsteady Reynolds-Averaged Navier-Stokes (URANS) is applied using different turbulence models to predict the axial friction factor under the presence of blockages. Results are compared with experiments. The different turbulence models presented a variable performance for the blockage scenarios under study, finding k-∊ Realizable the recommended model for turbulent regime and k-ω SST the recommended model at transition regime. A Large Eddy Simulation was also implemented to simulate the case with the largest blocked area finding its results in reasonable agreement with the experiments.