Mesoscale to multiphysics : insoluble material behavior, transport, and interaction in molten salt reactors

Abstract

Molten salt reactors (MSRs) are a type of advanced nuclear reactor that utilize liquid fuel dissolved in a high temperature liquid ionic salt. This distinctive liquid fuel feature gives rise to many advantages over both traditional and advanced solid fuel reactors, but it also complicates the design and analysis of the reactor due to complex multiphysics phenomena that arise in such a dynamic system. Specifically, insoluble material (IM) behavior, transport, and interaction, can directly interfere with the thermal-hydraulics and neutronics of the reactor. This work focuses on developing the methodology and integrating the computational models that are necessary to inform a system level chemical species analysis of an MSR. Interfacial sink and source term models for IMs are developed based upon various physical and electrochemical interactions that occur on surfaces in the reactor. The suite of coupled IM interaction models housed in a chemical species transport framework are then applied in analyzing the Molten Salt Reactor Experiment (MSRE) and a proposed Versatile Experimental Salt Irradiation Loop (VESIL). Further parametric studies are also carried out to determine the most sensitive parameters in the various interaction models, and how even small amounts of insoluble chemical species can affect the reactor’s overall behavior. The conclusion of this work directly informs the state of the art in system level analysis of MSRs, particularly in modeling the IM induced multiphysics effects that up until this point were not previously addressed. Specifically, the drastically different multiphysics behaviors of the 233U vs. the 235U MSRE runs due to IM interactions are successfully replicated. Lastly, this work will guide future experimental research to better understand the intersection of these complicated processes, advise IM mitigation strategies deployed in future reactor designs, and advance the technological readiness of MSRs for near term deployment.