Study of Zircaloy-4 fuel cladding corrosion using ion beams - Application to long term disposal of nuclear wastes

AC

Radiation endurance in Al2O3nanoceramics

The lack of suitable materials solutions stands as a major challenge for the development of advanced nuclear systems. Most issues are related to the simultaneous action of high temperatures, corrosive environments and radiation damage. Oxide nanoceramics are a promising class of materials which may benefit from the radiation tolerance of nanomaterials and the chemical compatibility of ceramics with many highly corrosive environments. Here, using thin films as a model system, we provide new insights into the radiation tolerance of oxide nanoceramics exposed to increasing damage levels at 600 °C-namely 20, 40 and 150 displacements per atom. Specifically, we investigate the evolution of the structural features, the mechanical properties, and the response to impact loading of Al2O3 thin films. Initially, the thin films contain a homogeneous dispersion of nanocrystals in an amorphous matrix. Irradiation induces crystallization of the amorphous phase, followed by grain growth. Crystallization brings along an enhancement of hardness, while grain growth induces softening according to the Hall-Petch effect. During grain growth, the excess mechanical energy is dissipated by twinning. The main energy dissipation mechanisms available upon impact loading are lattice plasticity and localized amorphization. These mechanisms are available in the irradiated material, but not in the as-deposited films

IBA and SIMS coupling to study glass alteration mechanisms

International audienceAlkali-alumin o-boro silicate glasses have been synthesized by melting the stoichiometric corresponding powder mixtures and heating at 1100 degrees C in a platinum crucible. Electron microprobe analyses were then carried out in order to determine their initial composition. Glass samples were submitted to static aqueous leaching tests in deionized water during 1 month (surface/ratio = 0. 3 cm(-1)) at temperature of 96 degrees C. The leachates were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The leached samples were then characterized by ion beam analytical (IBA) methods: Rutherford backscattering and elastic recoil spectrometries (RBS and ERDA), proton-induced X-ray or gamma ray emission (PIXE and PIGE) and secondary ion mass spectrometry (SIMS). The role of the presence of one or several contained transition elements (Fe, Mo, and Nd) and the effect of their respective contents on the chemical durability of alkali-borosilicate glasses were investigated. This work outlines the fact that a competition may occur between congruent and selective dissolution. Both surface hydration thickness and mobile element depletion amplitude cannot be considered as the unique reliable glass durability indicators. (c) 2007 Published by Elsevier B.V