Treatment of liquid waste from the production of molybdenum-99 by 235U(n, f) 99Mo reaction, 2

Production and distribution of 99Mo by the reaction of 235U(n, f) had been carried out during the period from July 1977 to March 1979. Liquid wastes arose from this production we re divided into three categories of high level, medium level and high radioactive organic liquid wastes, and stored separately. The results of treating work related to the high level liquid waste and organic wastes were already repoted. In this report, the results of experimental work and semi-scale treatment as well as the result of actual liquid wastes(0.6m3) treatment were described. As to the method of treatment, U, Pu and 144Ce were initially removed with the electrolysis-filtration process and then 90Sr was removed by using ortho titanic acid column. Futhermore, the residual U and Pu which were failed to be removed at initial stage were removed with meta titanic acid column. Consequently, only 106Ru remained in the liquid waste after these procedures. It becomes more important subject thesedays to establish the method of removal of 106Ru in the view point of liquid waste reprocessing technology. We applied the column containing the mixture of zinc and charcoal, which has been already reported by us for the removal of 106Ru. Twenty two times of treatment were conducted within three months started in March 1981 using the treating facility, having a capacity of 30 litters per batch, constructed based on the results of fundamental experiment. As the results, following values of the average Decontamination Factor (DF) for overall process were obtained. α-emitting nuclides : 7.0 x 102 β-emitting nuclides : 4.6 x 103144Ce : > 105137Cs : 2.8 x 103106Ru : 8.4 x 102 Particularly, the column of Zinc-Charcoalmixture showed considerable effectiveness in comparison with the conventional methods. (J.P.N.)