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Crystalline phases are promising materials (matrices) for isolating nuclear waste with long-lived radionuclides, actinides first of all. Melting in an induction-heated cold crucible was used to produce a potential matrix with the following nominal composition: 50 wt % TiO2, 10 wt % MnO, 10 wt % CaO, 5 wt % Al2O3, 5 wt % Fe2O3, 10 wt % ZrO2, and 10 wt % CeO2 (actinide simulator). The target murataite phase is the predominant phase in the sample; crichtonite and glass are present as well. The emergence of glass is due to contamination of the melt by the refractory coating of the crucible. As in other samples produced by melting, murataite is represented by zonal crystals, the center of which is enriched in heavy elements (Zr and Ce). Murataite accounts for up to 80% of simulated radioactive waste. Irradiation with a dose of 22 million Gray resulted in partial amorphization of crichtonite. According to the results of a dynamic test (single pass flow test, SPFT), the rate of Ce leaching (powder, water, 70°C) is 10–4–10–5 g/(m2 day).
S. V. Yudintsev; O. I. Stefanovskaya; M. S. Nikolsky; M. V. Skvortsov; B. S. Nikonov. Cold Crucible Induction Melting for Production of Murataite Matrices for Immobilization of Actinides. Doklady Earth Sciences 2021, 498, 444 -449.
AMA StyleS. V. Yudintsev, O. I. Stefanovskaya, M. S. Nikolsky, M. V. Skvortsov, B. S. Nikonov. Cold Crucible Induction Melting for Production of Murataite Matrices for Immobilization of Actinides. Doklady Earth Sciences. 2021; 498 (1):444-449.
Chicago/Turabian StyleS. V. Yudintsev; O. I. Stefanovskaya; M. S. Nikolsky; M. V. Skvortsov; B. S. Nikonov. 2021. "Cold Crucible Induction Melting for Production of Murataite Matrices for Immobilization of Actinides." Doklady Earth Sciences 498, no. 1: 444-449.
Electron backscattered diffraction (EBSD) has been used to analyze structures of natural minerals and artificial compounds for almost three decades. In recent years, it is applied in nuclear power engineering to study irradiated nuclear fuel and matrices for immobilization of radionuclides. The potential of EBSD for studying the structures of ceramics consisting of murataite-type phases, which are proposed for immobilization of actinides, is considered. A specific feature of these matrices is the presence of a few structurally related compounds (zirconolite, murataite, their polytypes, and pyrochlore), forming zonal crystals. The combined use of EBSD, scanning electron microscopy/energy-dispersive spectroscopy, and X-ray diffraction analysis would allow one to determine more reliably the structure of these phases.
M. S. Nickolsky; S. V. Yudintsev. Electron Backscattered Diffraction for the Study of Matrices for Immobilization of Actinides Composed of the Murataite-Type Phases. Crystallography Reports 2021, 66, 130 -141.
AMA StyleM. S. Nickolsky, S. V. Yudintsev. Electron Backscattered Diffraction for the Study of Matrices for Immobilization of Actinides Composed of the Murataite-Type Phases. Crystallography Reports. 2021; 66 (1):130-141.
Chicago/Turabian StyleM. S. Nickolsky; S. V. Yudintsev. 2021. "Electron Backscattered Diffraction for the Study of Matrices for Immobilization of Actinides Composed of the Murataite-Type Phases." Crystallography Reports 66, no. 1: 130-141.
The influence exerted by the composition of ceramics with imitators of radioactive wastes (Nd, U) on their stability against leaching in water at 90 and 150°C has been studied. Raising the content of TiO2 in a ceramic with Nd led to an increase in the fraction of perovskite and decrease in the amount of murataite. Samples with perovskite have the lowest stability in solution, especially at 150°C. Making smaller the fraction of perovskite lowers the rate of Nd leaching by a factor of 2 (90°C) and 5 (150°C). The weaker influence exerted by temperature on the U leaching from the samples is observed because more stable pyrochlore or zirconolite appear in the samples instead of perovskite.
S. V. Yudintsev; S. S. Danilov; S. E. Vinokurov; O. I. Stefanovskaya; B. S. Nikonov; M. S. Nikol’Sky; M. V. Skvortsov; B. F. Myasoedov. Phase Composition and Hydrothermal Stability of Ceramics Based on Murataite. Radiochemistry 2020, 62, 744 -751.
AMA StyleS. V. Yudintsev, S. S. Danilov, S. E. Vinokurov, O. I. Stefanovskaya, B. S. Nikonov, M. S. Nikol’Sky, M. V. Skvortsov, B. F. Myasoedov. Phase Composition and Hydrothermal Stability of Ceramics Based on Murataite. Radiochemistry. 2020; 62 (6):744-751.
Chicago/Turabian StyleS. V. Yudintsev; S. S. Danilov; S. E. Vinokurov; O. I. Stefanovskaya; B. S. Nikonov; M. S. Nikol’Sky; M. V. Skvortsov; B. F. Myasoedov. 2020. "Phase Composition and Hydrothermal Stability of Ceramics Based on Murataite." Radiochemistry 62, no. 6: 744-751.
Structural properties and water dissolution of six sodium–aluminum–phosphate (NAP) glasses have been investigated before and after irradiation by a gamma-ray source based on 60Co. Two of these samples were of simple composition, and four samples had a complex composition with radionuclide simulants representing actinides, fission, and activated corrosion products. Samples of the simple composition are fully vitreous, whereas samples of the complex composition contained up to 10 vol.% of aluminum–phosphate, AlPO4, and traces of ruthenium dioxide, RuO2. Based on the study of pristine and irradiated glasses, it was established that the radiation dose of 62 million Gray had practically no effect on the phase composition and structure of samples. At the same time, the rate of leaching of elements from the irradiated samples by water was decreased by about two times.
Alexey V. Luzhetsky; Vladislav A. Petrov; Sergey V. Yudintsev; Viktor I. Malkovsky; Michael I. Ojovan; Maximilian S. Nickolsky; Andrey A. Shiryaev; Sergey S. Danilov; Elizaveta E. Ostashkina. Effect of Gamma Irradiation on Structural Features and Dissolution of Nuclear Waste Na–Al–P Glasses in Water. Sustainability 2020, 12, 4137 .
AMA StyleAlexey V. Luzhetsky, Vladislav A. Petrov, Sergey V. Yudintsev, Viktor I. Malkovsky, Michael I. Ojovan, Maximilian S. Nickolsky, Andrey A. Shiryaev, Sergey S. Danilov, Elizaveta E. Ostashkina. Effect of Gamma Irradiation on Structural Features and Dissolution of Nuclear Waste Na–Al–P Glasses in Water. Sustainability. 2020; 12 (10):4137.
Chicago/Turabian StyleAlexey V. Luzhetsky; Vladislav A. Petrov; Sergey V. Yudintsev; Viktor I. Malkovsky; Michael I. Ojovan; Maximilian S. Nickolsky; Andrey A. Shiryaev; Sergey S. Danilov; Elizaveta E. Ostashkina. 2020. "Effect of Gamma Irradiation on Structural Features and Dissolution of Nuclear Waste Na–Al–P Glasses in Water." Sustainability 12, no. 10: 4137.
In Russia, highly active wastes (HAWs) from nuclear power engineering are incorporated in Na–Al–P glass (matrix) for final deposition in a geological repository at a depth of about 500 m. The reliability of such a repository is largely determined by the stability of the HAW matrix in underground water and by its ability to firmly retain radionuclides during the whole time of their being hazardous. Electron microscopy was used to examine the composition and structure of colloid particles formed in the interaction of water with a glass and products of its crystallization at 95°C. To isolate particles, solutions were passed after an experiment through filters with pore size decreasing from 450 to 25 nm. The colloids were represented by Na and Al or Sr, Ln, and U phosphates, with their particle size exceeding 200 nm. The migration of colloids from a repository can be restricted by a barrier based on densified bentonite because particles can be mechanically retained due to the low permeability of rocks.
S. V. Yudintsev; V. I. Mal’Kovskii; E. V. Aleksandrova. Primary Colloids at Hydrothermally Modifed Aluminophosphate Glass with Imitators of Radionuclides. Radiochemistry 2020, 62, 411 -423.
AMA StyleS. V. Yudintsev, V. I. Mal’Kovskii, E. V. Aleksandrova. Primary Colloids at Hydrothermally Modifed Aluminophosphate Glass with Imitators of Radionuclides. Radiochemistry. 2020; 62 (3):411-423.
Chicago/Turabian StyleS. V. Yudintsev; V. I. Mal’Kovskii; E. V. Aleksandrova. 2020. "Primary Colloids at Hydrothermally Modifed Aluminophosphate Glass with Imitators of Radionuclides." Radiochemistry 62, no. 3: 411-423.
Murataite-based ceramics containing 10 wt% rare earth (REs = La, Ce, Nd, Ho) or actinide (An = Th, U) oxides were produced in a resistive furnace at a temperature of 1500 °C. The samples were composed of major murataite-type phases and minor perovskite, crichtonite, and zirconolite/pyrochlore. Light (Ce-group) REs are concentrated in the perovskite whereas Nd and Ho are mainly accommodated in the murataite. U and Th enter predominantly murataite. Ce and U regardless from their oxidation state in the batch (Ce2O3/CeO2, UO2/UO3) exist in the murataite as Ce(III) or U(IV) with some contribution due to U(V) for the uranium-doped sample.
S.V. Stefanovsky; S.V. Yudintsev; Max Nickolsky; O.I. Stefanovsky; M.V. Skvortsov. Characterization of modified murataite based ceramics as a perspective hosts for actinides, fission, and corrosion products of HLW. Journal of Nuclear Materials 2019, 529, 151958 .
AMA StyleS.V. Stefanovsky, S.V. Yudintsev, Max Nickolsky, O.I. Stefanovsky, M.V. Skvortsov. Characterization of modified murataite based ceramics as a perspective hosts for actinides, fission, and corrosion products of HLW. Journal of Nuclear Materials. 2019; 529 ():151958.
Chicago/Turabian StyleS.V. Stefanovsky; S.V. Yudintsev; Max Nickolsky; O.I. Stefanovsky; M.V. Skvortsov. 2019. "Characterization of modified murataite based ceramics as a perspective hosts for actinides, fission, and corrosion products of HLW." Journal of Nuclear Materials 529, no. : 151958.