The safety of radioactive wastes in the repository depends on its capacity to confine radioactivity from being released to the biosphere. The process that most likely process can lead to the release of radionuclides from a repository is the transport by groundwater. The release rate of radionuclides from the solidified blocks is controlled by the solubility limits and leaching rate of radionuclides. The present work aims at investigating the solubility and leaching processes and their effect on the safety assessment of a radioactive waste in the repository. This work studies both processes with different concentrations of elements. The experimental study focused on the elements; strontium (Sr), cobalt (Co) and iron (Fe). To simulate the effect of radiation emitted from the radionuclides of these elements, the cement blocks that confine the elements are irradiated by Gamma (ɣ) Rays of doses; 40, 120, and 240 kGy. The results of non-irradiated and irradiated blocks are compared. The results indicate that ɣ radiation has a significant effect on the pH of the leachate. The relation between leaching rate and solubility is illustrated.

Cement is an important material in radioactive waste management. It is used as a solidifying agent for the concentrated wastes resulting from the treatment process. The solidification process results in immobilized wastes. To protect the human and the environment for long periods of time, the solidified waste forms should withstand the operation and storage conditions. Hence, the cement blocks should have proper mechanical and chemical properties. Moreover, the effect of radiation on the blocks should be studied to assure the retention of radionuclides by the cement matrix under radiation fields. To carry out the study, cement blocks were irradiated by Gamma radiation at doses 40, 120 and 240 KGy. The morphology of the blocks was studied before and after irradiation using X-ray Diffraction Patterns (XRD), and Scanning Electron Microscopy (SEM). The results of morphology studies are presented. The morphology studies indicated an improvement in the fixation of radionuclides on the cement matrix after irradiation.