γ-RADIOLYSIS OF 0.3 MOL/L HDEHP-0.2 MOL/L TBP/KEROSENE AND ITS EFFECT ON THE EXTRACTION SEPARATION OF Am,Pm AND Eu

This work mainly consists of five parts. 1. The effect of extractant composition, irradiation manner and dosage onγ-radiolysis of extractant was studied. Radiolysis damage slightly depended onthe composition of extractant with the following order: 0.3 mol/l HDEHP/kerosene>HDEHP-neat>0.3 mol/l HDEHP-0. 2 mol/l TBP/kerosene. Radiolysisdamage of extractant irradiated under stirring in the presence of 0. 1 mol/l HNO_3was more serious than that in the absence of aqueous phase. In both cases therate of HDEHP radiolysis increased with the dosage. 2. The distribution coefficients of Am, Pm and Eu in the systems of 0.3mol/l HDEHP-0.2 mol/l TBP/keroseneu-0.1 mol/l HNO_3 and 0.3 mol/l HDEHP-0.2 mol/l TBP/kerosene-2 mol/l HNO_3 before and after irradiation weredetermined respectively. 3. It was also found that distribution coefficients decreased with the increasein the aging time after irradiation of the extractant. 4. Washing experiments were performed with various washing agents andunder different conditions. 1-2 mol/l NaOH solution effectively removedH_2MEHP (a main radiolytic product of HDEHP) from irradiated HDEHPextractant. 80--90% H_2MEHP could be removed by a single washing with 1:1volume ratio. 5. Counter-current cascade extractions were carried out under the conditionsof TALSPEAK flow sheet with 0.3 mol/l HDEHP-0.2 mol/l TBP/keroseneunirradiated and irradiated to 5×10~4, 2×10~5, 5×10~5, and 1×10~6 Gy respectively.It was shown that the recovery of Am and Eu in the coextraction section washigher than 99.99%. The separation factor of Eu from Am increased with thedosage while the separation factor of Am from Eu varied inversely. The irradiatedextractant could be regenerated by washing with 1 mol/l NaOH solution. Itsextraction behaviour was the same as that of the unirradiated extractant.