The leaching behavior of borate waste glass SL-1

Vitrification is an attractive approach for treatment of the borate waste from nuclear power plants. SL-1 glass is a suitable borosilicate glass form to solidify the borate waste containing relatively high quantities of B and Na. The leaching behavior of SL-1 glass in deionized water has been investigated. Compared to the HLW-glass, the network structure of SL-1 glass is weak. It was found that the ion-exchange reactions dominated the glass corrosion process with water in low temperature leaching conditions ( 70°C). The ion-exchange and network hydrolysis reactions together controlled the glass dissolution in high temperature leaching conditions (>70°C). There was a peak in leach rate at about 70°C and a valley at about 110°C. The surface layer thickness was about 25 μm (MCC-1, 90°C for 28 days in deionized water). Na was almost totally depleted in the surface layer. At low temperature, the glass corrosion increases with leaching time. The glass corrosion remains about constant with leaching time at 90°C. The surface layer formed at 90°C is protective, which is less porous than the surface layer formed at 40 and 70°C.