Multiphysical modeling of a dual-frequency induction-heated metallothermic reactor

The recycling of uranium extracted from spent fuel (reprocessed uranium or URT) is of major strategic interest as regards both closure and economics of the cycle as well as for national sovereignty. France has initiated the development of a reprocessing route for this URT, involving an entire production chain relying on SILVA laser enrichment technology.
In this context, the CEA is in charge of developing all the processes in this chain, in particular the steps involved in the conversion of uranium oxide into uranium metal required for laser enrichment. For this purpose, the “Laboratoire d'étude des technologies Numériques et des Procédés Avancés” (LNPA) is studying the transposition of the historical metallothermy process to a cold crucible type reactor. This dual-frequency inductive furnace is designed to melt a two-phase charge consisting of a fluorinated slag and a metal produced in situ by the metallothermic reaction.
Alongside a multi-year technology development program on reduced-scale inactive pilot plants, numerical modeling studies of the reactor are undertaken in order to consolidate the change in working scale and enable system parameters to be optimized before deployment of the technology in active operation on depleted uranium for validation tests. The aim of the proposed thesis work is to develop the magneto-thermo-hydraulic (MTH) multiphysical model of the cold crucible metallothermic furnace.

Design of electrically small antennas for connected object applications

This doctoral project focuses on the design of innovative antennas suited for Internet of Things (IoT) applications, addressing major challenges related to size, performance, and integration. The scientific context is based on the growing demand for electrically small and efficient antennas, capable of seamlessly integrating with IoT devices while maintaining high radiation efficiency. The proposed work involves the creation of electrically small antennas, optimized for performance, tunability, and compatibility with electronic and metallic environments. The designs will explore various types of antennas, such as loops, F-type antennas, top-loaded monopoles, and metallic cage structures, incorporating state-of-the-art tunable components.

The main objectives include benchmarking the performance of these antennas against theoretical physical limits (e.g., Chu/Gustafsson), analyzing dielectric and metallic losses, and achieving dual-band reconfigurability tailored to communication standards. The candidate will use electromagnetic simulation tools, develop behavioral models, and create prototypes, as well as conduct performance tests in anechoic chambers. The expected outcomes are highly efficient, frequency-agile miniature antennas that will advance the understanding of electromagnetic radiation phenomena for compact antennas and meet the requirements of tomorrow's connected objects.