Influence of chloride ions on actinide chemistry. Effects of radiolysis and temperature

This research thesis addresses the chemistry of radionuclides in natural waters, an issue which is related to the management of long life radioactive wastes. Chloride ions are the most concentrated ions but their weak complexing power explains the fact that they are often neglected in speciation calculations. The objective of this research is to identify the influence of chloride ions on transuranium elements (Np, Pu and Am). Their influence is investigated with respect to chemical conditions close to that of underground waters and for concentrated media related to storage conditions in saline media. The author discusses media-related corrections applied to thermodynamic functions, reports a bibliographic study on the stability of actinide chloride complexes, reports a spectrophotometric investigation of complexation by chlorides, and reports the study of the influence of chlorides in a carbonate medium (solubility of americium at different temperatures, and notably at room temperature)