PEMANFAATAN ABU LAYANG SEBAGAI BAHAN PEMBENTUK GELAS PADA VITRIFIKASI LIMBAH CAIR TINGKAT TINGGI

UTILIZATION OF FLY ASH AS A GLASS FRITS ON HIGH LEVEL LIQUID WASTE VITRIFICATION. High level liquid waste (HLLW) is a waste generated from reprocessing of spent nuclear fuel. This waste contains many fission products and a few actinides. The waste is vitrification with borosilicate glass. The important factors influencing the characteristics of the waste-glass among others waste content and glass frits composition. Fly ash is the ash generated from coal firing. The ash composed of SiO2, Al2O3, CaO and Fe2O3, which is similar to that of glass frits. It was assumed that fly ash is possible to be used as substitute for glass frits. The aims of this research was to study the utilization of glass frits for HLLW vitrification. Some waste-glass were studied, namely waste-glasses A, B, C that contain waste loading of 23.21; 36.75 and 50.133 wt % respectively, and waste-glass D that was vitrified whith fly ash without addition of SiO2 oxide. A standard glass from JAEA was used as reference. The characteristics to be observed were density. leaching rate and devitrification. The higher the density and waste loading of the waste-glass, made the leaching rate higher. The waste-glass with the highest density was the waste-glass C; while the highest leaching rate was the waste-glass D. Devitrification occured on the waste glass A under temperature of 700 0C for 5 hours heating. The devitrification was identified by the formation of crystal dominated by SiO2. It was concluded that the fly ash can be used as glass frits on vitrification of HLLW with addition of SiO2 for improvement of waste-glass characteristics, in order to meet the requirement.
Keywords: High-level liquid waste , vitrification , glass frits , fly ash.