On the Dissolution of (U,Pu)O₂ Solid Solutions with Different Plutonium Contents in Boiling Nitric Acid

(U,Pu)O₂ solid solutions are completely soluble in boiling 5 and 10 M nitric acid up to plutonium concentrations of 55 and 65 wt% of PuO₂, respectively. The dissolution of the solid solutions decreases drastically at plutonium concentrations above 35 and 40 wt% of PuO₂ in 5 and 10 M nitric acid, respectively, with a total metal content of 1 mol/ℓ. This is attributed to a saturation of the solution.