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Taubin M.L.,National Research Nuclear University MEPhI | Chesnokov D.A.,Moscow Scientific and Industrial Association | Pavlov A.A.,Moscow Scientific and Industrial Association
Journal of Physics: Conference Series | Year: 2017

Results of own works of the authors and works of the Russian, Japanese, Korean and American experts in creation nanocomposites of refractory metals with increased strength characteristics for cathodes are analyzed in this report. It is shown, that though monocrystals have shown the better characteristics in comparison with traditional polycrystals as cathodes, more radical way of increase of operational characteristics of the X-ray tubes is application refractory nanostructural materials. Some results of investigations in which the work function electrons of nanocrystal tungsten is lower by 0.8 eV than that of traditional tungsten are given. This effect is able to increase the intensity of X-radiation considerably (by a factor of more than 5) at the same cathode temperatures or decrease the temperature of a cathode by 400°C at the same intensity of X-radiation. © Published under licence by IOP Publishing Ltd.

Taubin M.L.,National Research Nuclear University MEPhI | Urusov A.A.,Moscow Scientific and Industrial Association | Bratsuk A.V.,Moscow Scientific and Industrial Association
Journal of Physics: Conference Series | Year: 2017

Carbon nanotubes are unique materials being actively investigated in the development of X-ray tubes with a field cathode. The so-called cold-ray tubes. Our contribution in this direction is the use of single crystals W for the anodes and cathodes as substrates. Here are the structures we obtained carbon nanotubes with the catalysts and directly on the surface of tungsten. The report presents results of studies of carbon nanotubes (CNT) formation on metal substrates W and Ni. X-ray microprobe analysis revealed the presence of 8 at. % carbon. Average density of the powder was measured as 5.1 ±0.1 g/cm3. Calculations have shown that this value corresponds to the density of the carbon content of 8 at. %. © Published under licence by IOP Publishing Ltd.

Krivovichev S.V.,Saint Petersburg State University | Yudintsev S.V.,RAS Institute of Geology and Mineralogy | Stefanovsky S.V.,Moscow Scientific and Industrial Association | Organova N.I.,RAS Institute of Geology and Mineralogy | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2010

A polysomatic series of complex oxides for actinide immobilization is based on the incorporation of pyrochlore nanoclusters (light brown) into modified murataite-like frameworks (blue). Oxides from this series may be viewed as a complex form of radioactive waste and are one of the most elaborate families of nanoscale-tuned complex oxides known to date. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stefanovsky S.V.,Moscow Scientific and Industrial Association | Purans J.J.,Institute of Solid State Physics
Physics and Chemistry of Glasses: European Journal of Glass Science and Technology Part B | Year: 2012

Cesiums ion speciation in sodium cesium borosilicate and sodium aluminophosphate glasses potentially suitable for immobilization of Cs-containing radioactive wastes or ionizing radiation sources was studied using x-ray absorption spectroscopy (XAS). At relatively low Cs2O content (~1-2 mol%) in Na-Cs borosilicate glasses, Cs ions are present in a slightly distorted twelve-fold coordinated oxygen environment where nine oxygens are positioned at a distance of 3·22 Å and three - at a distance of 3·37 Å. The closest Si atoms are positioned at a distance of ~3·31 Å. With the increase of Cs2O concentration in the glass both the coordination number (CN) and the average Cs-O distances reduce, whereas, the Cs-Si distances increase. Both the first and the second coordination shells are split into two subshells pointing to distortion of cesium-oxygen polyhedra.

Malinina G.A.,Moscow Scientific and Industrial Association | Stefanovsky O.I.,Moscow Scientific and Industrial Association | Stefanovsky S.V.,Moscow Scientific and Industrial Association
Journal of Nuclear Materials | Year: 2011

Calcined solid radioactive waste (incinerator slag) surrogate and either Na2Si2O5 or Na2B4O 7 (borax) at various mass ratios were melted in silicon carbide crucibles in a resistive furnace at temperatures of up to 1775 K (slag without additives). Portions of the melts were poured onto a metal plate; the residues were slowly cooled in turned-off furnace. Both quenched and slowly cooled materials were composed of the same phases. At high slag contents in silicate-based materials nepheline and britholite were found to be major phases. Britholite formed at higher slag content (85 wt.%) became major phase in the vitrified slag. In the system with borax at low slag contents (25 and 50 wt.%) material are composed of predominant vitreous and minor calcium silicate larnite type phase Ca2SiO4 where Ca2+ ions are replaced by different cations. The materials containing slag in amount of 75 wt.% and more are chemically durable. The changes in the structure of anionic motif of quenched samples depending on slag loading were studied by IR spectroscopy. © 2010 Elsevier B.V. All rights reserved.

Savkin A.E.,Moscow Scientific and Industrial Association
Radiochemistry | Year: 2011

Laboratory trials of a process for sorption decontamination of real NPP bottom residues from Cs radionuclides with Termoksid-35 ferrocyanide sorbent and rig and pilot trials of the technology for reprocessing of bottom residues from a number of Russian nuclear power plants were performed. The efficiency of the Cs sorption drastically decreases in the presence of organic complexing agents (EDTA, oxalate ions). Preliminary ozonation of the bottom residue allows the working life of Termoksid-35 sorbent in the decontamination process to be increased by a factor of several tens. Rig and pilot trials showed that ozonation of bottom residues, followed by microfiltration separation of the precipitate formed, ensures efficient decontamination of the solutions from Co, Mn, and Sr radionuclides and from α-emitters. A technology was suggested for decontamination of NPP bottom residues from radionuclides, involving ozonation, microfiltration, and selective sorption of Cs radionuclides on Termoksid-35 ferrocyanide sorbent. Process and technical solutions obtained in the course of trials were implemented in an industrial installation for reprocessing of bottom residues from the Kola NPP. © 2011 Pleiades Publishing, Ltd.

Ojovan M.I.,University of Sheffield | Varlackova G.A.,Moscow Scientific and Industrial Association | Golubeva Z.I.,Moscow Scientific and Industrial Association | Burlaka O.N.,Moscow Scientific and Industrial Association
Journal of Hazardous Materials | Year: 2011

Experiments with real and simulated radioactive cementitious wasteforms were set up to compare the leaching behaviour of cementitious wasteforms containing nuclear power plant operational waste in field and laboratory test conditions. Experiments revealed that the average annual 137Cs leach rate in deionised water was about thirty-five times greater compared with the measured average value for the 1st year of the field test. Cumulative leached fraction of 137Cs for 1st year (3.74%) was close to values reported in literature for similar laboratory experiments in deionised water, however more than two orders of magnitude higher than the 1st year leached fraction of 137Cs in the repository test (0.01%). Therefore, to compare field and laboratory test results, a scaling factor is required in order to account for surface to volume factor difference, multiplied by a temperature factor and a leach rate decrease coefficient related to the ground water composition. © 2011 Elsevier B.V.

Demina N.M.,Moscow Scientific and Industrial Association | Tikhomirov P.L.,Moscow Scientific and Industrial Association
Glass and Ceramics (English translation of Steklo i Keramika) | Year: 2016

Comparative studies of the impregnability of high-strength and basalt fibers, treated and untreated by emulsions of film-formers, by epoxy binders with different curing agents were conducted. Differences in the surface treatment of high-strength and basalt fibers were found by determining the impregnation along the height of capillary rise of the binder. The effect of surface treatment on the change in strength of the tested filaments and microplastics based on them was determined. © 2016 Springer Science+Business Media New York

Stefanovsky S.V.,Moscow Scientific and Industrial Association | Sorokaletova A.N.,Moscow Scientific and Industrial Association | Nikonov B.S.,RAS Institute of Geology and Mineralogy
Journal of Nuclear Materials | Year: 2012

Mixtures of surrogates of high level waste with high sodium and aluminum contents and sodium-lithium borosilicate frit were melted in alumina crucibles in a resistive furnace followed by quenching of one portion of the melt and annealing of the residual material in a turned-off furnace. The annealed materials with waste loading of up to 45 wt.% contained minor spinel type phase and trace of nepheline (Na,K)AlSiO 4. In the annealed materials contained waste oxides in amount of 50 wt.% and more nepheline and spinel were found to be major and minor phases, respectively. At high waste loadings two extra phases: Cs-aluminosilicate (CsAlSiO 4) and mixed Na/Cs-aluminosilicate were found in amount of 3-5 vol.% each. The latter phase contains of up to ∼5.7 wt.% SO 3 or 0.13 formula units S (Na 0.75K 0.05Cs 0.29Ca 0.02Sr 0.02Al 0.99Fe 0.03Si 0.76S 0.13O 4). Sulfur incorporation as S 6+ or SO42- ions into crystal lattice may be facilitated in the presence of large-size Cs + cations. Simplified suggested formula of this phase may be represented as Na 0.8Cs 0.3AlSi 0.8S 0.1O 3.95. It was also synthesized by sintering of mixture of chemicals at 1300°C and found to be instable at temperatures higher than 1300°C. © 2012 Elsevier B.V. All rights reserved.

Kozlovsky I.V.,Moscow Scientific and Industrial Association
Atomic Energy | Year: 2012

A γ-spectroscopic method of monitoring the activity of solid radwastes with different composition was studied. The method developed is intended for direct measurement of the activity of radionuclides with γ-ray energy 50 1000 keV in solid radwastes with density 100-2500 kg/m 3. A series of control measurements was performed to determine the reliability of the calculation of the activity of γ-emitting nuclides in containers by means of the gamma-spectrometric complex and to establish the uncertainties. The additive was placed at the top and center on the axis of rotation of the container. Next, the activity of the containers with the additives was determined. The desired values were obtained by subtracting the activity of the additive material from the total activity. For each container with different materials, 21 measurements without additives were performed to estimate the average activity and statistical error. This method of analysis can be used to monitor the activity of radioactive wastes and other radiation hazardous objects.

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