Fuel cladding in pressurized water reactors (PWR) is subjected to a very soliciting and extremely complex environment, liquid water under pressure containing boron and lithium under neutron flux in very severe thermohydraulic conditions. Under these conditions, the zirconium alloy cladding degrade chemically by covering themselves, in particular, with an oxide layer on the external face and by absorbing hydrogen which, beyond a certain content, will precipitate under form of embrittling hydrides. These two coupled degradation phenomena, oxidation and hydriding, are currently only partially modeled. On the other hand, the components of the metal/oxide system are subjected to continuous irradiation causing damage to the materials. The creation of irradiation defects in the oxide or in the metal results in significant changes in corrosion mechanisms and oxidation kinetics in particular. As it stands, two driving forces are likely to play a role in the kinetic control of the oxidation of zirconium alloys: (i) the effect of the electric field in the layer and/or (ii) the effect of stresses or more generally of the mechanical state of the components of the metal/oxide system, on the rate of oxidation. The objective of this work is to investigate the influence of the second driving force and to provide elements of understanding on the effect of residual stresses on the diffusion speed of the species involved in the corrosion process and on the impact of the mechanical state of the metal, such as hardening under irradiation or creep, on diffusion and oxidation kinetics.
This subject covers many areas ranging from fine characterization at the microstructure scale, to more macroscopic characterization, via a wide range of mechanical tests. It will allow the candidate to acquire solid training in materials and more particularly in the field of microstructural characterization of materials. We are looking for a candidate with a Master 2 or an engineering school diploma with good knowledge of materials sciences and mechanics and who has a penchant for experimentation.