Nowadays, with the increasing use of nuclear energy technology, one of the most important concerns of human societies is the burial and prevention of the spread of radiation pollution caused by low-level nuclear waste in the environment. Low-level nuclear waste is more important than other types of nuclear waste due to its very high volume. Since nuclear waste can remain active for thousands of years and cause significant damage to the environment and living organisms, safe and proper burial of this type of waste is essential. Low-level nuclear waste is usually buried in surface repositories, and a suitable protective layer must be used around these repositories to prevent the release of emitted radiation, hydraulic permeability, and long-term strength. Due to its high absorption capacity, compactness, uniformity, low cost, and availability, bentonite clay is a suitable option for use as a protective layer in these facilities. The aim of this study is to improve the performance of bentonite clay against radiation emission and hydraulic permeability using different percentages of goethite additive. Also, due to the importance of sustainability and maintenance of these facilities for many years, the strength parameters have been examined and eva‎luated. In this study, first, by performing a density test at the optimum moisture content for each combination, the optimum moisture content was obtained. Then, using the samples made at the optimum moisture content, the linear attenuation coefficient of radiation at energy levels of 1173, 662, and 1332 kiloelectron volts, The amount of hydraulic permeability of different compounds by the Falling-head test ,and strength parameters such as adhesion, elasticity modulus, etc. by the direct shear test and compressive strength tests were calculated. The results of the linear attenuation coefficient of radiation were calculated experimentally using a sodium iodide detector and compared with simulated values by the MCNP code and XCOM database. The results show that adding goethite powder at different percentages increases the linear attenuation coefficient of radiation while slightly increasing hydraulic permeability but still within an acceptable range. It was also observed that adding goethite powder would not have a significant effect on the strength performance of the compounds. The results of this study showed that the combination of sodium bentonite containing 30% goethite improved the performance of the linear attenuation coefficient of radiation (μ), and other strength parameters and hydraulic permeability were also in an acceptable range.

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هاجر شرع اصفهاني

حميد هاشم الحسيني , عليرضا باغبانان