CFD Analysis of Scaled Wire-wrapped rod Bundle Cooled by LBE

Abstract

Lead bismuth eutectic (LBE) is one of the most potential materials for coolant for Lead based reactor and Accelerator Driven Systems (ADS). Thermal-hydraulic behaviour of LBE in fuel assembly is a key issue for development of the systems. To get a deeper understanding on the complex thermal-hydraulic features of wire-wrapped rod bundle cooled by upward LBE, CFD calculation based on RANS methodologies were also performed to support the experimental results analysis. The results concluded that LBE has the similar flow resistance characteristics with traditional fluids. Both the Rehme correlation and CFD showed a good agreement with the experimental results. As for the entrance characteristics, during the fully heating length (exceeding 140 times the hydraulic diameter), the thermal field did not reach a fully developed and stable condition which is contrary to the ducted flows. Based on the experimental results and CFD investigation of heat transfer coefficient showed that the hexagonal shell has a great influence on the heat transfer coefficient in rod bundle geometry. For this reason, the application of empirical correlation should be kept cautious in rod bundle analysis.