Radiation enhanced solubility of calcite: implications for actinide retention

To investigate possible solubility changes induced by α-dccay in actinide-containing carbonates, partially masked polished sections of calcite have been bombarded with various doses ot 1.8 MeV He ions and 200 keV Ph ions which respectively simulate the radiation effects of α-particles and of α-recoils. A marked increase in solubility occurs above a dose of 1014 ions/cm2, reflected by the formation of a step-height between irradiated and unirradiated areas following leaching. XPS analyses allow to ascribe this change in solubility to the decomposition of carbonate into oxide. The consequences of this new phenomenon for the disposal of high-level radioactive waste in a geological repository are discussed.