Coupled Neutronics and Thermal-Hydraulics Simulations of Molten Salt Nuclear Reactors

Nuclear power offers sustainable, abundant and economically competitive energy production with carbon footprint close to zero. Within the spectrum of Generation IV nuclear power plant designs, the liquid-fuel Molten Salt Reactor (MSR) features several potential benefits in terms of enhanced safety, reduced proliferation risks and economical competitiveness. Furthermore, high outlet temperatures enable compatibility with process heat applications, and several designs for small modular MSR’s show significant promise. With respect to successful licensing and commercialization of MSRs, Modeling and Simulation (MS) techniques are required to demonstrate plant behavior under a wide range of operational and accidental scenarios. This is done throughout design development stages and for the safety assessment of the plant. However, the liquid fuel employed in MSRs introduces several key differences between these and other types of nuclear reactors based on solid fuel, that result in a fundamentally different approach to modelling and simulation.
This PhD thesis focuses on development of Multiphysics coupling techniques applied to Molten Salt Reactors. Specifically, Monte-Carlo particle transport software capable of modelling heat production from nuclear fission is coupled to high fidelity Computational Fluid Dynamics (CFD) software in order to accurately capture the impact of the fuel being liquid on the intrinsic operational and safety features of the plant. Alongside this method a different technique of deterministic neutron transport modeling is also explored. This thesis provides an overview of possible approaches for Multiphysics modeling of MSRs and discusses potential benefits and drawbacks of the techniques applied within this work. The methods developed can be used for design development and optimization of MSRs. In addition, the work holds merit for other areas of MS applications wherein coupling between different physical phenomena is required.