Radiation-chemical behaviour of Np6+ in irradiated tri-n-butyl phosphate solutions

Radiation-chemical behaviour of Np(6) in γ-irradiated 30% TBP solutions in dodecane with Np concentration of 2x10-2 mol/l in the absorbed dose value range from 1x104 to 6x106 Gy is studied using spectrophotometric method. A possibility of determining physico-chemical state of Np(6), Np(5) and Np(4) in irradiated TBP solutions is demonstrated on the base of absorption spectrum analysis. DBP complex concentration values of various valent forms of neptunium in irradiated solutions are presented and it is ascertained that dependence of these concentrations on the absorbed dose is of vibrational character. The values of radiation-chemical yields of Np(6), Np(5), and Np(4) complexes with DBP are determined. It is shown that in irradiated TBP solutions any valent form of neptunium is transformed into 4-valent state