Studies on the Radiochemical Degradation of Tetraethylhexyl Diglycolamide and Ethylhexylphosphoric Acid in n -Dodecane Solution

The organic solvent phase composed of N,N,N’,N’-tetra-2-ethylhexyl diglycolamide (TEHDGA) and bis(2-ethylhexyl)phosphoric acid (HDEHP) in n-dodecane (n-DD) is regarded as a promising candidate for single-cycle separation of americium (III) from high-level liquid waste. The radiochemical degradation of a solution of TEHDGA + HDEHP/n-DD was investigated by irradiating the solvent to various absorbed dose levels of γ-radiation. The neat extractants or a solution of extractants in n-dodecane were irradiated in the presence and absence of nitric acid. The degree of degradation was assessed by measuring the variation in the extraction behavior of Am(III), Eu(III) and other metal ions in irradiated solvent systems. The distribution ratio of americium and europium decreased with increase of absorbed dose. The presence of n-dodecane enhanced the radiolytic degradation of the solvent; however, the role of nitric acid during degradation was insignificant. The recovery of Am(III) and Eu(III) from the irradiated solvent system was studied. The recovery of Am(III) was quantitative in 3 contacts; however, the separation factor of Eu(III) over Am(III) during stripping decreased marginally with increase of absorbed dose.