Method of processing radioactive liquid

Purpose: To condense liquid concentrates containing radioactive materials thereby facilitate the subsequent solidifying step. Method: In the case of separating the radioactive liquid into a treated solution with concentrated radioactivity and a treated solution at a low radioactivity by using an osmotic separation device, the radioactivity density of the treating liquid at a low radioactivity is reduced to less than 1 x 10-5 μCi/ml through the pretreatment step of concentrating the degree of concentration at least to more than 15 by using an ultrafiltration membrane device and a step of concentrating the liquid to the degree of concentration of from 10 - 30 by using a reverse osmotic membrane device having sodium chloride permeation rate of less than 10 %. By maintaining the liquid concentrates containing radioactive materials at a high concentration, the subsequent solidifying step can be facilitated. (Yoshihara, H.)