Application of Metakaolin-slag Binders to Solidify Rad-waste Glass Sharps: Leaching of 137Cs and 152+154Eu Radionuclides

Abstract

METAKAOLIN (MK) and blast furnace slag (BFS) were utilized to design alkali activated binders suitable for solidification of waste glass (WG sharps contaminated with 137Cs and 152+154Eu radionuclides). Two forms of WG, powdered and fused, were utilized. Effects of WG forms and BFS addition on the ability of formulations to withstand compression were preliminary studied. When cold powdered WG was solidified the corresponding compressive strength (MPa) values were decreased by increasing the loading percentages. While fused forms were positively affected MPa values till 10.0% loading. Positive relations between BFS addition and MPa values were also detected. Leaching of 137Cs and 152+154Eu from MK-based formulations was followed as affected by WG forms, BFS addition and early age (2hr) curing temperatures. Both studied radionuclides were cumulatively leached in larger fractions from solidified powdered WG than from fused one. The obtained results reflected the ability of the designed formulations to retain 137Cs in greater extents than 152+154Eu. The lowest diffusion coefficient values (2.01×10-11 and 3.92×10-10cm2/s) were recorded when fused forms of WG containing 137Cs and 152+154Eu, respectively, were solidified into slag seeded MK-based formulations, early aged cured at 40°C. Slope values of log(CLF) vs. log(time) plots were < 0.35 indicating that the controlling leaching mechanisms for all studied leaching systems were predicted to be wash-off.