Technology development of industrial liquid radioactive waste treatment: The immobilization of high level radioactive liquid wastes using matrix material of SYNROC titanate

The research of immobilization of high level radioactive liquid wastes (HLLW) using matrix material of titanate SYNROC have been carried out. The research aim to immobilization of the HLLW by solidification using matrix material of titanate SYNROC through sintering process at high temperature as development of hot isostatic pressing process. Immobilization process was carried-out by mix the HLLW simulation with precursor oxide, then drying the mixture, calcination at 750 °C, then it was pressed in the moulder. Further process are sintering at the temperature of 1000-1300 °C with the time 1-4 hours to form the SYNROC of solid multiphase ceramic. The composition of precursor oxide (in % weight) i.e : Al₂O₃ (5,4); BaO (5,6); CaO (11,0); TiO₂ (71,4) and ZrO₂ (6,6). Waste loading in the waste SYNROC block are 10 - 60 % weight. The quality of the SYNROC block was determinated by testing of density, pressing strength, and leaching-rate. The testing results showed that the best quality of waste SYNROC block was obtained at the waste loading 20 % weight, sintering process at 1200 °C for 3 hours with values of density 3,35 g/cm³, pressing strength 14,18 kN/cm², total leaching-rate 2,5.10^-3 g.cm^-2.day^-1 , and leaching-rate of Cs, Sr, and U are 4,1x10^-4 g.cm^-2.day^-1, 2,3x10^-6 g.cm^-2.day^-1 and 6,3x10^-7 g.cm^-2.day^-1 respectively. The quality of the waste SYNROC block produced by the sintering process conform to the hot isostatic pressing process. (author)