Thermal iodine release of surface-implanted iodine in zirconia and its affect on hull disposal

During the reactor processing fission products, among which iodine is one, are implanted by recoil inside the Zircaloy cladding tube, most of them being distributed within the first 2 μm. At the same time, oxidation of the cladding tubes occurs and therefore in the waste disposal phase zirconia will act as the first migration barrier. In order to analyse the mechanisms involved in iodine migration, stable and radioactive iodine atoms were introduced in oxidised zirconium samples by means of ion implantation at the near surface (mean range around 50 nm). Iodine thermal-release was measured either by Rutherford backscattering spectrometry (RBS) or γ-spectroscopy.