[en] The behavior of melts in the uranium oxide-silicon dioxide system is experimentally investigated in air upon induction melting in a 'cold crucible'. The existence of the two-phase liquid region in this system is confirmed. It is demonstrated that the melts absorb oxygen from air, which leads to crystallization of the UO_2.25 compound upon cooling. In the case of considerable internal heat release, sharp cooling of the melt surface results in the liberation of gas, which brings about bulging and, sometimes, melt ejection from the crucible. (authors)

[en] The behavior of uranium oxide-silica, zirconia-alumina, zirconia-iron oxide, uranium oxide-iron oxide, zirconia-alumina-iron oxide, and uranium oxide-iron oxide-zirconia melts was experimentally investigated in the air. The existence of two phase fluids in these systems was confirmed. It is proposed that the reason for the phase separation is the formation of complexes with the general formula x[M³⁺O_8/2] [Me⁴⁺O_8/2]. The influence of a complex concentration on the density and surface tension of melts in the ZrO₂-Al₂O₃ system was demonstrated. (authors)

[en] The behavior of melts and the phase composition of crystallization products of six compositions in the uranium oxide-zirconium oxide-iron oxide system in air have been investigated. It has been revealed that crystallized samples containing 20-50 wt % uranium oxide and 25-80 wt % iron oxide (the rest is zirconium oxide) consist of five crystalline phases and involve two types of eutectic structures. The possible factors responsible for this phenomenon have been considered. (authors)

[en] The spectral-luminescent properties of radiophotoluminescent phosphate glasses are studied in the Ag₂O concentration range 0.05-4.0 wt% and at the γ-irradiation dose 10²-10⁴ Gy. At the Ag₂O concentrations not over 0.1 wt%, the radiophotoluminescence spectrum consists of a broad band, whose contour is well described by Gauss' function, with a maximum at 650 nm. At Ag₂O concentrations higher than 0.1 wt%, the radiophotoluminescence spectrum is the superposition of two Gaussian bands with intensity maxima at 650 and 450 nm. The ratio of band intensities depends on the Ag₂O concentration, conditions of the heat treatment of the irradiated samples, and irradiation dose. The correlation between the concentration dependences of radio-photoluminescence spectra and those of luminescence spectra for unirradiated glasses, which are activated with silver, is revealed

[en] The behavior of some components of high-level liquid wastes (uranium, plutonium, and radiogenic americium) when introduced into phosphate and borosilicate glassy composites was studied. By the examples of natural uranium, ²³⁹Pu, and ²⁴¹Am, the distribution of these α-particle emitters over the bulk of a glass melt was shown; their solubilities in the composites were studied; and the compositions of the heterogeneous phases formed in melts and the valence state of dissolved uranium were determined. The results of these investigations indicated the restricted solubility of some radionuclides in glassy composites

[en] The absorption spectra induced by γ-irradiation and by the recording of writing the quadratic-susceptibility χ⁽²⁾ gratings are obtained for the samarium-, terbium-, and erbium-doped aluminosilicate optical fibers. The nature of the color centers, which are responsible for microscopic changes in the glass structure, is investigated

[en] The effect of vitrification parameters on heterogeneous phases that are formed by the platinum group metals (Ru, Rh, and Pd) in the phosphate and borosilicate melts under laboratory conditions is studied in simulating the solidification of high-level liquid wastes in an induction furnace with a water-cooled crucible. Among the factors affecting behavior of nuclides in these processes, most important are considerable temperature gradients (triangle T ∼ 200 K) and convective flows in the melt, small time of glass melt processing (30 min), and possibility of interaction of high-frequency field with heterogeneities of the melt