Study of iodine ceramization in an apatite matrix: experimental aspects of sintering and study of sensitivity to impurities

In the framework of the works carried out on the specific conditioning of long-lived radionuclides, a composite material of lead vanadates has been developed for iodine 129. Its preparation includes a reactive sintering under an uniaxial load which induces the formation of a iodine apatite. In order to minimize the ended volume of pellets required to absorb the wastes flux, it is important to obtain a dense ceramics. The study of the reactivity has revealed the baneful role of the presence of lead hydroxy-iodine as impurity. This compound creates a physical barrier during sintering which limits the relative density being able to be reached. Thus, its elimination has allowed to improve the densification rate of the apatite, of 50 to 88% of the theoretical density. A most homogeneous microstructure has also been obtained with a co-milling of the reagents by attrition. (O.M.)