The construction of the top engineered barrier of a near-surface repository is developed and validated. Thermophysical calculations are performed to estimate the zone of seasonal freezing of the cover structure. The optimal thickness of a multifunctional coating is validated. The multifunctional cover structure has successfully passed an experimental-industrial check under natural conditions. Computational and experimental investigations have shown that the development of a multifunctional seven-layer cover for a near-surface repository makes it possible to arrange a positive temperature field inside the structure year round irrespective of the outside air temperature. Thus, the repository structure and the wastes will be reliably protected from freezing and the destructive effect of temperature-induce deformations.Near-surface repositories, consisting of concrete or reinforced concrete structures, are widely used in world practice for long-term storage of low-and medium-level radwastes. The exterior side walls and the interior compartment barriers are made of reinforced concrete; the bottom consists of a 0.5 m thick concrete bed. The repository is constructed below ground in 4-5 m deep trenches and covered with reinforced concrete plates which themselves are covered with asphalt. The wastes are placed in layers inside the compartments, each layer being covered with a cement solution. Engineered barriers are used to protect the environment from the wastes: a cement matrix, containers, and structural elements of the repository. The drawback of such repositories is that they are located close to the surface of the ground, as a result of which natural external factors affect the construction material and the wastes placed inside the repository structure.The main destructive factors are: • atmospheric precipitation, which destroys the engineered barriers and structural components of the repository as a result of leaching and washing out of the constituent components; • seasonal freeze-thaw cycles, which result in deformation of the structural components and destruction of the integrity of the waste matrix as a result of the nonuniform expansion and compression of the waste components. To increase their reliability, near-surface repositories are also equipped with multifunctional engineered barriers, which must perform two functions -thermal insulation and water proofing. As a rule, natural soils and rock (loam, clay, bentonite, and so forth) or, less often, artificial (geotekstil, polymers, and others) materials with low thermal conductivity are used for this. Such a multifunctional cover, based on alternating layers, contains from two to five drainage and water impermeable layers and from one to three heat-insulating layers. The overall thickness of the top engineering barrier is determined on the basis of physical simulation and mathematical calculations depending on the construction materials and the climatic conditions in the territory.The objective of the present investigations was to optimize the structure and ...
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