In the context of developing innovative sodium-cooled fast reactors (SFR), this PhD aims to explore the use of a phase change material (PCM) to remove residual power. The PCM studied in this project is Zamak, a metallic alloy that presents advantageous properties for such thermal applications. Some SFR designs incorporate passive safety systems intended to ensure the removal of residual power, which refers to the heat generated by delayed fission and radioactive decay of fuel isotopes after reactor shutdown. The use of PCM is a promising option, as they can absorb and store heat through a melting process and subsequently release it gradually during a solidification process.
The core of this PhD focuses on Computational Fluid Dynamics (CFD) modeling of the Zamak melting process and the scaling of this model for use in a system-size calculation tool. The main challenge lies in predicting the behavior of the melting front, its stability, and its impact on the kinetics of residual power removal. This melting front is influenced by numerous factors such as the wetting angle and the physico-chemical properties of the PCM-wall or PCM-surrounding gas interface, which will be examined throughout the thesis. The research will thus involve developing a CFD model that integrates these aspects, using a porous enthalpy approach, allowing predictive simulations of the PCM's behavior in the residual power removal system. A scaling analysis will then be conducted.
The PhD candidate will be part of a research team on innovative reactors at the IRESNE institute located at the CEA Cadarache site. Career opportunities after the thesis include academic research, R&D, and the nuclear industry, as well as sectors utilizing PCM technologies.