Solidification of radioactive spent liquid scintillator wastes: Effect of additives on the leaching of radionuclides

Abstract

Along with the widespread application of liquid scintillation counting technology in terms of detecting low-energy β nuclides, the liquid scintillator wastes generated during the process has become a kind of radioactive organic waste liquids which was widely concerned and urgently needed for treatment. In this study, sulfoaluminate cement (SAC) was used to solidify the liquid scintillator wastes. Zeolite and nano-SiO2 were introduced as additives, and the effect of two additives on the leaching rate of Sr and Cs in cement solidified forms was studied. The increase in zeolite content from 0 to 2 wt% led to a decrease in the leaching rate of Cs, while further increase in zeolite content lead to an increase in the leaching rate of Cs. The lowest leaching rate of Sr was obtained in the formula of 5 wt% zeolite. The sample with 2% nano-SiO2 added led to the highest leaching rate of Sr and Cs, and reducing or increasing nano-SiO2 resulted in a decrease in leaching rate. SAC was suitable for cementation of liquid scintillator wastes, and the 42-day leaching rate of Sr and Cs in samples without or with zeolite and nano-SiO2 had met the requirements in GB 14569.1-2011.