Decontamination of liquid radioactive waste concentrates from 60Co using diethyldithiocarbamates

Abstract

Oxidized bottom residue (BR) from installations for reprocessing trap waters of the Leningrad NPP were treated to remove 60 Co by coprecipitation with transition metal diethyldithiocarbamates (DDTC). Coprecipitation of 60 Со with manganese and cobalt diethyldithiocarbamates was examined in relation to pH of solution, temperature, amount of diethyldithiocarbamates, reagent ratio, and number of coprecipitation steps. The effect of diethyldithiocarbamates on the efficiency and conditions of the solution decontamination from 134,137 Cs on nickel potassium ferrocyanides was studied. Oxidative treatment of liquid radioactive waste concentrates to break down organic complexes is a necessary condition for 60 Со removal by coprecipitation with transition metal diethyldithiocarbamates. From a solution initially containing 56 kBq dm -3 60 Co, 60 Co can be removed to a residual content of 0.12-0.16 kBq dm -3 by two-step coprecipitation with Со(DDTC) 2 . The coprecipitation with Со(DDTC) 2 does not affect the efficiency of the subsequent removal of Cs radionuclides on nickel potassium ferrocyanides.