In order to obtain the exact information of atomic number density in the ternary system of HNO3−UO2(NO3)2−H2O, the densities were measured with an Anton-Paar DMA60/602 digital density meter thermostated at 298.15±0.01 K. The apparent
molal volumes for the systems were calculated from the experimental data. The present measured apparent molar volumes have
been fitted to the Pitzer ion-interaction model, which provides an adequate representation of the experimental data for mixed
aqueous electrolyte solutions up to 6.2 mol/kg ionic strength. This fit yields θV, and ψV, which are the first derivatives with respect to pressure of the mixing interaction parameters for the excess free energy.
With the mixing parameters θV, and ψV, the densities and apparent molar volumes of the ternary system studied in this work can be calculated with good accuracy,
as shown by the standard deviations.