Development of an Iodine Immobilization Technique by Low Temperature Vitrification With BiPbO2I

This paper describes low temperature vitrification process with BiPbO2I (BPI) as a promising immobilization technique in which Iodine-129 reacts with BiPbO2NO3 (BPN) to form BPI, which is then solidified into a lead-boron-zinc glass matrix (PbO-B2O3-ZnO) using a low temperature vitrification process. Studies with EPMA, STEM-EDS and XRD found that iodine, lead and zinc were homogeneously dispersed in the waste form, and that there were no residual crystalline minerals in the amorphous glass matrix. Leaching tests conducted under typical geological disposal conditions show that iodine dissolves congruently with the BPI glass matrix in simulated seawater, whereas it dissolves incongruently in alkaline Ca(OH)2 solutions. This is due to retention within an altered surface layer.