Abstract: A procedure has been developed for the separation and purification of 99Tc from acidic and several other kinds of high level radioactive liquid wastes. Continued from page 99)The feed, a simulated solution of high level liquid waste from reprocessing of spent fuel, was passed through a column with NH4CNS as eluant, after it had been denitrated by formic acid to a pH value of 2.The quantity of 99Tc adsorbed in the resin should be limited to one-fifth of full capacity on the column to give best decontamination. Other optimum conditions are: concentration of NH4CNS, 0.6 M at pH 8.5; flow rate of eluant, less than 0.35 ml/cm2·min.By this procedure, the radioactive nuclei such as 90Sr, 95Zr-95Nb, 137Cs etc. and even the most trouble some 106Ru can be easily removed.The procedure is simple, rapid and inexpensive. It has been applied to the purification of raw product of 99Tc obtained from reprocessing of spent fuel with satisfactoryresults. The decontamination factors of 99Tc fromγ-emitters——106Ru106Rh,125Sb,137Cs are 1.5×107, 5.0×,107, 1.2×107 respectively after two cycles of operation and recovery of 99Tc in the produce is better than 99.9%.