PURPOSE: To elute and recover Tc from activated carbon without causing a decrease in the adsorption capacity of the activated carbon and the nitration due to use of nitric acid by bringing a soln. contg. thiocyanate ion or iodine ion into contact with activated carbon having a adsorbed Tc.

CONSTITUTION: A high-level redioactive waste soln. generated in the reprocessing of spent nuclear fuel or a soln. contg. Tc such as a soln. of spent nuclear fuel is treated with activated carbon to adsorb Tc on the activated carbon. The activated carbon is washed in water, then brought into contact with an eluent contg. thiocyanate ion or iodine ion to elute the Tc adsorbed on the activated carbon in high yield. Since nitric acid is not used unlike the conventional method, the Tc adsorption capacity of the activated carbon is not decreased, and an explosion due to nitration can be obviated.