Structural materials used in nuclear reactors are subjected to the simultaneous action of mechanical stress and irradiation. Under these combined effects, components such as cladding, springs of fuel assemblies and screws in reactor vessel internals undergo irreversible deformation due to a phenomenon known as irradiation creep, which is significantly more pronounced than thermal creep. 

Many models of irradiation creep have been proposed in the literature, leading to various dependencies on the applied stress and microstructural features (dislocations, dislocation loops, etc.). However, none of them could be validated at the microscopic scale, due to the lack of dedicated in-situ experiments and simulations involving dislocation climb and glide.

The objective of this internship is to identify possible climb and glide deformation mechanisms explaining creep in metals and metallic alloys under irradiation. To this end, we will use two simulation codes developed at CEA: STACCATO, an object kinetic Monte Carlo (OKMC) code that simulates the evolution of irradiation damage under the stress generated by microstructural features, and NUMODIS, a nodal dislocation dynamics (DD) code that accurately models dislocation glide and dislocation interactions. 

The two main steps of the work will be as follows:

• Validate and optimize the coupling of STACCATO and NUMODIS.
• Simulate the propagation of dislocations under steady production of self-interstitial atoms and vacancies within a population of obstacles (e.g., dislocation loops and/or precipitates), and compare the results with existing analytical models.

Master’s Degree (M2) or Engineering School specializing in Materials Science, Condensed Matter Physics.

Ability to code (Fortran, C++) is a plus.