Retention capacities of zirconia and apatites towards iodine and technetium fission products

This paper is devoted to the study of apatites and zirconia used as conditioning materials of nuclear wastes. Among the long-lived fission products 129I and 99Tc release has to be evaluated. First, the stable isotopes 187Re and 98Mo considered as chemical homologous of Tc were implanted in hydroxyapatite. Then, cladding tube pieces (hulls) present a thin superficial zirconia layer in which most of the radioactivity is concentrated. Stable 127I release due to diffusion or to corrosion process was investigated in order to model its long term behaviour. Diffusion studies were performed by successive air annealings (300-900 C). The distribution evolution characterised by RBS allowed to identify the migration mechanisms. XPS and XANES methods were used to follow the chemical evolution of the compounds as function of temperature. (author)