Several empirical equations were available in the literature for density equation for tri-n-butyl phosphate (TBP)–bearing mixed organic solutions used in the PUREX/UREX process; however, all most all of the equations were found to have a limited range and a limited number of solutes to be handled. In this work, a robust density equation is proposed in a dimensionally consistent manner. In the proposed equation, TBP is also considered as a solute, rendering the proposed equation valid over a full range of TBP concentrations. The highlights of this technical note include

1. Density equation for mixed organic solutions, containing TBP, n-dodecane, and nitrates of heavy metals, is proposed in a dimensionally consistent manner.

2. TBP is also considered as a solute, rendering proposed equation valid over 0% to 100% of TBP concentrations.

3. The proposed equation is valid for uranium concentrations 0 to 120 g/L in organic phase.

4. With a small loss of precision, the same can be used for PUREX solvent loaded with Pu(IV).