Performance study and influence of radiation emission energy and soil contamination level on γ-radiation shielding of stabilised/solidified radionuclide-polluted soils

This work focuses on the stabilisation/solidification (S/S) of radionuclide-polluted soils at different Th-232 levels using Portland cement alone and with barite aggregates. The potential of S/S was assessed applying a full testing protocol and calculating gamma-radiation shielding (gamma RS) index, that included the measurement of soil radioactivity before and after the S/S as a function of the emission energy and soil contamination level. The results indicate that setting processes are strongly dependent on the contaminant concentration, and for contamination level higher than 5%, setting time values longer than 72 h. The addition of barite aggregates to the cement gout leads to a slight improvement of the S/S performance in terms of durability and contaminant leaching but reduces the mechanical resistance of the treated soils samples. Barite addition also causes an increase in the gamma-rays shielding properties of the S/S treatment up to about 20%. Gamma-ray measurements show that gamma RS strongly depends on the energy, and that the radioactivity with the contamination level was governed by a linear trend, while, gamma RS index does not depend on the radionuclide concentration. Results allow the calculated gamma RS values and those available from other experiments to be applied to hazard radioactive soil contaminations. (C) 2015 Elsevier Ltd. All rights reserved.