Validation of RANS simulations on a 61-pin wire-wrapped fast-reactor fuel assembly under the presence of localized blockages

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 of the Nuclear Power Plant. Accumulation of debris or cladding deformation may generate a partial or total flow blockage of coolant channels at different locations. In this paper, Unsteady Reynolds-Averaged Navier-Stokes (URANS) is applied using different turbulence models to predict the axial friction factor under the presence of blockages, placed at different positions on the bundle cross section. The simulated Reynolds number was 17,000. Results are compared with experimental friction factor data produced at the Texas A&M experimental facility. The sensitivity analysis of the RANS turbulence models concluded that the k-∊ Realizable model is the recommended one for this Reynolds number because it presented the minimum relative error with respect to the experimental data that was found below 5%.