In reactor, the fuel is subjected to various loadings that can induce cracking and affects its mechanicals, physicochemical and transport properties. Thereafter, matter can diffuse inside the crack and clog it, which can restore the material’s rigidity. This phenomenon is commonly referred to as crack healing.Nuclear fuel for sodium fast reactor can be healed by diffusion welding (Salmon et al., 2026) or porosity migration (Barani et al., 2022).

This Ph.D. thesis aims at developing a multiphysics modeling of crack healing based on a coupling between fracture mechanics, matter transport in cracks and local physicochemical process which induce healing. Dedicated numerical method must be extended to couple damage gradient model, crack width and matter transport.

Model validation is a major challenge, notably because of the difficulty of distinguishing and characterizing the various mechanisms at play in irradiated nuclear fuel. To address this challenge, the project will also investigate cementitious materials, for which dedicated experiments on crack healing have been conducted.

This PhD project will be carried out within the MISTRAL Joint Laboratory, bringing together Aix-Marseille University, CNRS, Centrale Marseille and CEA, in collaboration between the IRESNE institute (CEA Cadarache site) and the ISAS institute (CEA Saclay site). The PhD student will be primarily based at Cadarache and will spend a period of 6 months to 1 year at the CEA Saclay site. The student will also benefit from the scientific environment of the Laboratoire de Mécanique et d’Acoustique (LMA). This collaboration aims to develop a generic model applicable to both nuclear fuels and cementitious materials.

The PhD student will showcase his results through publications and participation in conferences. He/she will have gained strong skills in multiphysics coupling, numerical method and numerical simulation, which will be a major asset in several fields, both in academic and industrial sectors.

(Barani et al., 2022) Barani T, Ramière I, Michel B (2022) Analysis of fabrication and crack-induced porosity migration in mixed oxide fuels for sodium fast reactors by the finite element method. J Nucl Mater 558:153341. https://doi.org/10.1016/j.jnucmat.2021.153341
(Salmon et al., 2026) Salmon, L., Blanc, V., Garajeu, M. et al. A thermo-mechanical cohesive zone model for damage and healing in brittle solids. Comput Mech 77, 501–520 (2026). https://doi.org/10.1007/s00466-025-02675-5