Short communication : the dissolution of UK simulant vitrified high-level-waste in groundwater solutions

Dissolution of a simulant UK nuclear waste glass containing Mg, Ca and Zn was investigated over 35 d at 50 °C in water and simulant groundwater solutions. The dissolution rates were influenced subtly by the groundwater composition, following the trend, from least to most durable: clay > water > granite ≈ saline. Solutions were rapidly silica saturated but boron dissolution rates continued to increase. This is hypothesised to be due to the formation of secondary Mg-silicate precipitates, preventing the formation of a passivating silica gel layer and allowing glass dissolution to proceed at close to the maximum rate.