Structure and corrosion mechanism of iron phosphate glass with strontium from electrochemical reprocessing

Strontium is a representative divalent radionuclide present in the salt wastes from the electrochemical reprocessing of spent fuel. Iron phosphate glass has demonstrated excellent properties as a vitrification matrix for halogen-containing high-level radioactive waste. In this paper, iron phosphate borate glass was used to vitrify simulated strontium fluoride waste in a series of concentrations. X-ray diffraction analysis showed that crystallisation began when the content of SrF2 reached 30 wt% in the raw materials. The results of long-term immersion experiments revealed good chemical stability of these glass samples. Scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to determine the elemental of the glass samples, strontium but no fluorine was detected in the glass composition. The depth profiles at the edge (1–2 µm) of one sample after the leaching experiment, and the existence of a layer of Fe2O3 was clearly found. Raman spectroscopic analysis further verified that the structure of this series of glass samples is mainly composed of orthophosphate groups.