Numerical Simulation of Extraction Behavior of Americium and Nitric Acid in the TRUEX Process

A numerical simulation code for the transuranium extraction (TRUEX) process was developed to determine the optimum operational conditions for the separation and recovery of transuranium (TRU) elements, such as americium. Equilibrium constants for the americium extraction by octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) were determined by the least-squares method using experimental data. The activity coefficients for nitric acid and water were calculated with equations derived from experimental data. The calculated concentration profiles of americium, by using the best available equations, did not agree well with the experimental data in the extraction section. The stage efficiency was added in this code as a parameter to correct the differences between the calculated and the experimental profiles. The calculated concentration profiles using the modified code were in good agreement with the experimental data when 0.9 was used for the stage efficiency.