Adsorption characteristics of boric acid on strong-base anion exchange resin

Abstract

The Boron Thermal Regeneration System (BTRS) is capable of controlling boron concentration in primary coolant and reducing the amount of liquid waste at the end of fuel cycle in a pressurized water reactor, but the system has not been in effective operation yet because of the lack of detailed information regarding the boron adsorption characteristics of the ion exchange resin packed in the demineralizers of BTRS. In this study, the adsorption characteristics of boric acid on a strong-base anion exchange resin, an Amberlite IRN-78LC resin in $OH^-$ form, were investigated at temperature from 10 $^\ciec$Cto 60 $^\circ$C in the concentrations of boron up to 1500 ppm covering the BTRS operational conditions. A computer code was developed to calculate the composition of borate ions in solution as a function of boron concentration, temperature and pH. From the calculated composition of borate ions and experimental data of adsorption equilibrium, the model was proposed for the adsorption isotherm of boric acid on the resin. The diffusion coefficient of the boric acid in the resin was calculated by the particle diffusion model and found that the temperature dependency of the coefficient follows an Arrhenius equation. The results in this study can be applied for the optimum operation of BTRS.