Изучение фильтрационных свойств барьеров безопасности для захоронения радиоактивных отходов на примере глиноземистого бетона

The presented work is the result of studying the filtration properties of engineering safety barriers materials for Class 3 and 4 near-surface radioactive waste disposal facility, as well as the assessment of computational hydrogeological modeling of several near-surface radioactive waste disposals for compliance with certain provisions of the current regulatory documentation in the field of atomic energy use. Since the composition of the materials used for barriers materials is different, predictive calculations of material degradation time using thermodynamic constants can have a high margin of error (300 % and more), and long-term contact of barriers materials with groundwaters or storage solutions can result in changes to the composition, porosity, and, consequently, the filtration, sorption, strength properties of the barrier material. Approaches to studying the evolution of weakly permeable barriers materials under varying  engineering-geological conditions over the long-term application of barriers materials require further development. In the present work a methodical approach to long-term filtration experiments in barriers samples is proposed, on the example of cement stone modified with clay additive, the results of filtration flow rate data through the sample are presented, after which the changes in the sample composition and its pore space structure are evaluated. The present work shows an attempt to apply the equilibrium dissolution model to calculate the inverse problem – calcium loss in the solid phase is estimated by the dissolution time of calcium hydroxide at the moment of increased filtration flow rate, and then a direct calculation of the degradation time of the barrier of the required thickness at the filtration rate possible under burial conditions is performed. The change of properties in barriers shown in the present work agree with the works of researchers, the approach can be useful and can be applied to study the evolution of barrier materials  to confirm the lifetime of barriers and justify the intensity of radionuclide release beyond their limits. The work demonstrates the methodological possibility of estimating the long-term stability of the insulating properties of barriers, considering experimental data and modeling of the kinetics of dissolution of components. Experimental evaluations are the main source of information regarding the justification of the service life of safety barriers.