Overview of PhD students, Postdocs and MSc students and their research topics within the SAMOSAFER project
Bouke KAAKS – TU Delft
Ph.D. thesis title: “Melting and Solidification Phenomena of Salt in a Molten Salt Nuclear Reactor”
Short description of the activity: A good understanding of the melting and solidification phenomena of the LiF-ThF4-UF4 fuel in the Molten Salt Fast Reactor is required for the design of the freeze plug, a key safety component, and for the analysis of accident scenarios where solidification of the fuel might pose a risk. As such, the goal of this PhD thesis is to improve the melting and the solidification modelling capabilities. To this end, the effects of phase change will be included in a computational fluid dynamics (CFD) model based on the discontinuous Galerkin (DG) approach through the so-called enthalpy method, where the melting/solidification front is tracked implicitly. The coupling of the enthalpy method with the DG approach is new and is expected to lead to a higher accuracy of the predicted melting/solidification front, as compared to more diffusive discretization schemes such as the finite volume method (FVM). Experimental validation of the applied numerical models will be performed using a cylindrical vessel containing a phase-change material with a melting point close to room temperature and a Prandtl number matching the LiF-ThF4-UF4 salt (ESPRESSO), where the lid rotates at speeds capable of establishing both laminar and turbulent flows.
Thomas DUMAIRE – TU Delft
Ph.D. thesis title: “Thermochemistry and evaluation of the thermo-physical properties of key fission products and corrosion products in Molten Salt Reactor”
Short description of the activity: The goal of this PhD will be to improve the understanding of the behaviour of key fission products and corrosion products in MSR fuel. We will develop a thermochemical model to describe the chemistry of the fuel and the most important volatile fission products, noble metals and their fluoride phases, and corrosion products. The required structural and thermodynamic data for relevant sub-systems will be assessed coupling experimental measurements by calorimetry, X-ray absorption spectroscopy, atomistic simulations, and CALPHAD thermodynamic modelling. In addition, the retention capacity of the fuel salt for volatile fission products will be investigated as a measure to reduce the source term.
Thibault LE MEUTE – CNRS
Ph.D. thesis title: “Modeling of a reactivity insertion scenario in a Generation IV molten salt reactor”
Short description of the activity: The objective of this PhD is to study an accidental scenario likely to induce mechanical effects on the containment of a molten salt reactor and to characterize these effects. In a first phase of the PhD, the reactivity effects possibly involved in the different accident scenario families will be systematically studied. Their dynamics and respective influence on the power transient will be evaluated with a systematic dimensional analysis.
In a second step, taking into account effects that may be involved and their dynamics, studies will be carried out to insert reactivity ramps in order to study the natural behaviour of the reactor in the presence of these ramps. For these reactivity ramps, the consequences will be evaluated by performing, as part of this PhD, a modeling coupling neutronic effects to thermohydraulic effects in order to evaluate the calorific energy deposited in the salt. Given this energy, the phases formed when the salt is heated up to high temperature will have to be determined. Then, an adaptation of the vapour and gas expansion model developed at CEA will be carried out in order to evaluate the mechanical effects of expansion.
Finally, the capacity of the various mitigation measures (salt discharge system, depressurization devices, ect.) of the accident to reduce its consequences will be assessed for a preliminary design of the reactor. Depending on the main parameters driving the effectiveness of these provisions, design improvements in terms of mitigation will be proposed.”