Shabalin B. Artificial analogues of minerals are the matrices for the safe isolation of nuclear engineering radioactive waste

The dissertation is concerned with the currently central problems of the safe isolation of fractionated high-level waste being produced as a result of spent nuclear fuel retreatment. The advisability of the application of matrices on the basis of artificial analogues of minerals for the safe isolation of such kinds of waste is grounded. Mineralogical and geochemical data on the most stable rare and accessory minerals as natural analogues of matrices are generalized and analyzed; the criteria of directional search of matrices are developed too. The most perspective matrices for actinoids- and lanthanoids-bearing waste and such ones containing cesium and strontium are defined. The use of geochemically compatible matrices based on the artificial analogues of zirconolite, pyrochlore, garnet or monazite for the safe isolation of actinoids- and lanthanoids-bearing waste within the granitoids being considered as perspective rocks to create the deep-seated repository for waste is grounded. The findings of the complex investigation into the synthesis and research on the properties of artificial analogues of hollandite, zirconolite, pyrochlore, garnet and monazite minerals and multi-substituted solid solutions on their basis, which determine the suitability of their use as matrices for the safe isolation of waste, are given. The features are set and the matrix formation mechanisms during their synthesis are revealed. The chemical and phase composition, structural features of matrix phases, the distribution of elements in the phase structure, the isomorphic substitutions schemes and isomorphic capacity of matrices based on zirconolite, pyrochlore, garnet and monazite to actinoids, rare-earth and other elements of waste, and hollandite - to cesium and strontium are identified. The findings of investigations into experimental determination of solubility and radiation stability of ceramic materials based on the artificial analogues of minerals are outlined.