Numerical Study on the Thermal Hydraulic Characteristics in a Wire-Wrapped Assembly of LFRs

Abstract

The concept of wire-wrapped assembly has been widely adopted in liquid metal-cooled reactors to enhance the capability of flow and heat transfer. The detailed 3D thermal hydraulic behaviors of liquid metal in the wire-wrapped assembly directly affect the safety of the reactor. In the present work, a numerical study on a 19-pin wire-wrapped assembly cooled by a lead-bismuth eutectic was carried out using the CFD method. The geometrical model is referred to in the test section in KIT’s 19-pin experiments, which is a scaled test assembly based on the MYRRHA reactor. The established CFD model was validated against experimental data and results showed that the SST k-ω model accompanied with the modified Prt was appropriate for the current problem. Then the numerical models were extensively used in the modeling of the blocked assembly flow with a cylindrical blockage. Also, the influences of blockage longitude, position, and porosity on the thermal hydraulic characteristics in the assembly were evaluated in detail. This work is meaningful for the deep understanding of safety features under the condition of assembly blockage operation in LFRs.

Liquid metal cooled fast reactor thermal hydraulic research development: A review

“…Additionally, the impact of Inter-Wrapper Flow (IWF) on fuel assemblies with liquid metal cooling was investigated experimentally [ 62 , 63 ]. Furthermore, the CFD approach on a 19-pin wire-spaced fuel assembly using LBE was scaled to test the MYRRHA reactor’s fuel assembly [ 64 ]. The numerical model created was heavily utilized to simulate the obstructed assembly flow with a cylindrical blockage and was validated against experimental data.…”

Study on the turbulent Prandtl number model for liquid metal flow and heat transfer in a narrow rectangular channel

“…Feng et al (2020) carried out the numerical simulation of liquid metal natural circulation heat transfer by CFX. Li et al (2020) adopted the SST k-omega model with the modified turbulent Prandtl model to simulate the thermal-hydraulic behaviors of liquid metal in the wire-wrapped assembly. When predicting the turbulent heat transfer of low Prandtl number fluid, the turbulent Prandtl number model needs to be introduced.…”

CFD analysis of a wire-wrapped infinite sub-channel using temperature-dependent LBE properties

“…One of the most distinguishing engineering features of LMFR is the employment of wire-wrapped fuel assemblies, which consist in metal wires revolved around the fuel rods, making it a compact and stiff assembly. However, due to the large amount of contact points and tight gaps, wire-wrapped fuel assemblies are considered to be complex in geometry, which makes analytical predictions practically impossible and highlights the importance of a consistent Computational Fluid Dynamics (CFD) modeling approach, such as developed in recent years by [4][5][6][7].…”

“…Given that most works on CFD simulations of MYRRHA's infinite wire-wrapped sub-channels [5][6][7] were only done using fixed thermal-physical coolant properties (density, dynamic viscosity, thermal conductivity and specific heat), this work's main goal is to bring a brief evaluation of whether the implementation of variable coolant properties leads to different results on the velocity, temperature and turbulent kinetic energy fields, when compared to the use of static properties.…”