Investigation of Fission Product Transport into Zeolite-A for Pyroprocessing Waste Minimization

Abstract

Methods to improve fission product salt sorption into zeolite-A have been investigated in an effort to reduce waste associated with the electrochemical treatment of spent nuclear fuel. It was demonstrated that individual fission product chloride salts were absorbed by zeolite-A in a solid-state process. As a result, recycling of LiCl-KCl appears feasible via adding a zone-freezing technique to the current treatment process. Ternary salt molten-state experiments showed the limiting kinetics of CsCl and SrCl₂ sorption into the zeolite. CsCl sorption occurred rapidly relative to SrCl₂ with no observed dependence on zeolite particle size, while SrCl₂ sorption was highly dependent on particle size. The application of experimental data to a developed reaction-diffusion-based sorption model yielded diffusivities of 8.04 × 10^-6 and 4.04 × 10^-7 cm²/s for CsCl and SrCl₂, respectively. Additionally, the chemical reaction term in the developed model was found to be insignificant compared to the diffusion term.