In nitric acid solutions, zirconium exists only as Zr(IV), albeit in many chemical forms depending primarily on acidity, Zr concentration, and tem­perature. Hydrolysis and polymerization both increase with increasing tem­perature and decreasing acidity and change the Zr(IV) speciation in solution. Increasing nitric acid concentration and/or temperature increase the extraction of Zr. The ever-present radiolytic and hydrolytic degradation products of TBP and diluent in the solvent are yet another principal reason for the extraction of Zr. Though these degradation products cannot be eliminated, their concentration can be minimized by reducing the radiation exposure to the solvent and consequently the radiolytic degradation products.