Radiation chemical behaviour of actinides in extraction system

Pu(4) physicochemical state (valent, complex, aggregation states) in γ-irradiated (Esub(γ)=3H10sup(5) Gr) TBP solutions in dodecane in the presence of U(6) macroamounts has been studied. Pu(4) concertration in extractant constitutes 4x10-3 - 7x10-3 mol/l, J(6) concentration is from 2x10-2 up to 1.25x10-1 mol/l, HNO3 concentration is approximately equal to 0.5 mol/l. It has been established on the base of analysis of absorption spectrum of γ-irradiated solution that a change of Pu(4) valency does not take place, and plutonium di-n-buthyl-phosphate complex is formed. A decrease of a solution optical density with a growth of γ-irradiation dose testifies on complex formation. Spectrophotometric (SP) titration of allowed one to determine effective (seeming) complexing consU(6) and Pu(4) solut ons has been carried out. SP titration tants of Pu(4) and U(6) with DBPK and some peculiarities of this complexing. Identity of qualitative and quantitative characteristics of absorption spectra of model and γ-irradiated solutions allows one to consider the latter as two-component (in an optical respect) and closed (in the absence of deposits) systems. This permits to use the Firordt equations for the calculation of Pu(4) and U(6) complex concentrations in irradiated systems. Possibility to calculate radiation yields of PU(4) complexes with di-n-buthylphosphate acid for Pu(4) concentrations <10-2 mol/l both in the presence of this complex and without it has been revealed