Immobilization of uranium contaminated soil in cement matrix and estimation of leaching fraction for immobilized waste

Nuclear Fuel Complex, Hyderabad is involved in manufacture and supply of nuclear fuel and core structural components for all operating PHWRs across the country. During the dismantling of various civil structures in radioactive plants, significant amount of civil debris/soil is generated which is radioactive in nature and cannot be disposed as exempt level waste. Cementitious materials are being widely used as solidification/stabilisation and barrier materials for a variety of chemical and radioactive wastes. Cement has many favourable properties, both chemical and physical, making it a desirable barrier or matrix for the encapsulation of radioactive and toxic wastes. Leaching characteristics of uranium immobilized in the solidified matrices was investigated through the semi-dynamic leaching test. The leaching behaviour was evaluated by several leaching parameters and predicted by one-dimensional radionuclide decay model based on the Fick's second law. The leach rate coefficient for uranium at neutral pH condition was found to be 2.35×10^-6 cm/d. The total uranium leached from the sample after the end of the experiment was 5.75 percent. Authors are grateful to the Lab staff of Health Physics Unit for their constant support during the analysis of samples