Coupling Techniques for Multi-Physics Modelling of Molten Salt Reactors

Abstract

Molten Salt Reactors (MSR) have recently gained renewed attention due to potential advantages compared to conventional reactors, such as inherent safety and reduced costs. The circulating fuel in an MSR implies a strong coupling between neutronics and thermal hydraulics, in part due to the delayed neutron production being effected by the fuel velocity fields, thus requiring new modeling approaches for these reactors. In this article we investigate the operator-splitting and direct coupling schemes between neutronics and thermal hydraulics models applied to simple test geometry. We apply commercial software; ANSYS CFX for thermal hydraulics and MCNP for neutronics in the operator splitting technique, whereas direct coupling is performed by means of open source software. Static and dynamic properties of the circulating fuel are investigated with the two approaches, comparing accuracy, computational time and numerical stability. Finally we outline a procedure for material evolution calculations.