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106 Ru is one of the major radionuclides of concern in the aqueous radioactive waste generated during the reprocessing of the spent fuel. Intermediate level radioactive liquid waste (ILW) stream is generated during reprocessing of spent fuel and is neutralised with alkali to enable it to be stored in carbon steel tank. The waste is initially treated for 137 Cs recovery using a specific resorcinol formaldehyde (RF) ion exchange resin. The effluent stream from the ion exchange treatment process has significant activity due to 106 Ru. The present paper deals with a chemical treatment study for removal of 106 Ru in the effluent using sulphides of cobalt and nickel. The decontamination factor of 250 obtained using NiS (at 2500 ppm concentration of Ni 2þ ) is distinctly better than that obtained using CoS (at 7200 ppm concentration of Co 2þ ).

Use of NiS coprecipitation was found to be very effective at a concentration level of 2500 ppm of Ni þ2 and 1300 ppm of S À2 for the effective removal of 106 Ru from the effluent stream. However, the NiS precipitate increases the sludge volume. Efforts were made to form the composite material of NiS in combination with Poly methyl metha acrylate (PMMA) polymer beads. The NiS-PMMA composite beads were loaded in a column and its ruthenium uptake behavior was studied. The NiS-PMMA beads were found to be functioning satisfactorily in alkaline conditions. It has shown a K d value of about 8000-9000. The NiS-PMMA composite material has also shown the potential for the uptake of 125 Sb. The effect of salt concentration on the K d value is negligible. The equilibrium conditions are achieved in around 25-30 min in batch mode of operation. The composite material can be suitably used in the column mode of operation.

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