Dissolution of plasma treated non-radioactive surrogate cemented concentrates and ion exchange resins in KOH solution at 40 °C

In Belgium, plasma incineration is a possible option to (re-)condition low and intermediate level short-lived waste streams in order to obtain end products which can fulfill the criteria developed for a near surface disposal facility. In this study, the chemical durability of lasma treated non-radioactive surrogate cemented concentrates and ion exchange resins (or plasma slags) was investigated by performing MCC-1 leach tests in a KOH solution at pH 13.5 and 40 °C. Results showed that initial dissolution rates of plasma slags were similar to that of SON68-I glass, and final dissolution rates around one order of magnitude lower. SEM analysis revealed the presence of alteration layers rich in K, Ca and Fe, which probably act as diffusion barriers and, associated with the increase of Si and Al concentration in solution, lead to the decrease of the plasma slag dissolution rates.