Evaluation of radiation stability of N,N-didodecyl N',N'-di-octyl diglycolamide. A promising reagent for actinide partitioning

The radiation stability of N,N-di-dodecyl-N',N'-di-octyl-3-oxapentane-1,5-diamide (D3DODGA) was studied by γ-irradiation of the solvent up to a absorbed dose of 1,000 kGy. The effect of γ-irradiation on the radiolytic degradation of D3DODGA was assessed by measuring the distribution ratio of Am(III) (DAm(III)) as well as the third phase formation in the irradiated D3DODGA-n-dodecane solution. The DAm(III) in the irradiated solution decreased with increase of absorbed dose. The critical aqueous concentration of Nd(III) above which the third phase forms, increased with increase of absorbed dose. However, the limiting organic concentration of Nd(III) remained at ∼25 mM irrespective of the absorbed dose. Recovery of Am(III) from the radiolytically degraded organic phase showed that back extraction of Am(III) was quantitative in a few contacts using dilute nitric acid. Our studies clearly indicated that radiolytic degradation of D3DODGA in n-dodecane is marginal even at the absorbed dose of 1,000 kGy, and therefore D3DODGA is a potential candidate for minor actinide partitioning. (author)