Decontamination of nuclear steam generator of secondary coolant side line involves removal of the deposits by using complexing agent. The resulting effluent containing the radioactive ions in complex state can’t be treated further unless freed from the complexant. The freeing of the ions necessitate oxidation of the complaxant using chemical and photo chemical technique, complexant freed ions amenable for further treatment by chemical precipitation. The slurry obtained from sludge containing the activity has been immobilized using matrices like cement , bitumen glass etc. Study on the fixation of Cs137activity carried along with Cu3(PO4)2 in cement matrix shows that compressive strength was not different from cement matrix without containing the Cs137 activity along with slurry. Leaching behavior of the cement matrix included with cesium activity was found to be better at high pH of the slurry included in the matrix. The diffusion coefficient of Cs137 from the cement matrix was found to be in the range of 1.3*10-3cm2/day and 1.2*10-4cm2/day with pH of slurry in the range of 2-10. When aluminum phyllosilicate and hydrous phyllosilicate were included in the cement matrix, the diffusion coefficient of Cs137 was found to be reduced in the range of 1.4*10-4cm2/day to 1.3*10-5cm2/day with the pH of slurry in the range of 2-10.