When a uranium nucleus splits, the two fission fragments race through the fuel material at nearly 15,000 km/s, releasing all their energy in just a few picoseconds. The crystal lattice is shaken violently before almost returning to its initial state—except for one crucial detail: hundreds of thousands of atoms remain displaced from their sites. These irradiation defects are not just microscopic curiosities; they have a profound impact on the material’s properties. Most importantly, they disrupt the propagation of phonons, the vibrations that carry heat, thereby altering thermal conductivity.

The goal of this internship is to quantify the impact of irradiation defects on the thermal conductivity of UO₂, the standard fuel used in nuclear reactors.

Your work will involve several key steps:

• Quantify irradiation defects: Using a cluster dynamics code (Skorek thesis), you will simulate the evolution of defect populations under different irradiation conditions.
• Linking defects to heat transport: You will combine the simulated defect concentrations with conductivity variation coefficients, some of which are being calculated as part of an ongoing PhD project using classical and ab initio molecular dynamics. You will also extend this dataset by performing similar simulations for missing defect types.
• Developing physical insight: Beyond raw calculations, you will contribute to a theoretical understanding of how defects interact with phonons and reduce heat transport.
• Predicting fuel behavior: Finally, you will simulate how thermal conductivity evolves in real fuel under various temperature and flux histories.

This project is part of a long-term, multi-scale physics program that brings together atomic-scale simulations, mesoscale models, and fuel rod-level studies. The ultimate aim is to develop predictive tools that can guide both research and industrial applications in nuclear energy.

By the end of this internship, you will not only have deepened your expertise in materials science, irradiation physics, and heat transport, but also gained first-hand experience in how different modeling techniques and experiments come together to solve real-world challenges in nuclear technology.

• You follow a Master 2 cursus in solid state physics, materials physics, computational physics
• You have a taste for and skills in theory (statistical, quantum and solid state physics) and simulation.
• You are motivated by upstream research applications and would like to work in a rich, multidisciplinary environment (theory, simulation, software, experiments).