Melting-solidified waste form is expected to act as an engineered barrier due to the stabilization of radionuclides and hazardous elements. Solidified products are categorized to metal and slag, which originate from metallic and non-metallic components, respectively. Static leach tests were performed for SiO2-CaO-Al2O3 slag specimens in the presence of cement at 90°C to investigate the dissolution behavior of the slag under repository conditions. The dissolution rate of slag was constant during the leaching up to 144 days. Dissolution of slag was followed by precipitation of calcium silicate hydrates, which is expected to depress the concentration of Si dissolved silica in solution and to maintain the solution conditions far from the saturation with the slag. The far-from-saturation state is likely to be a cause of the constant dissolution rate.
