This work is devoted to hydrogen safety security during severe accidents at NPP as well as the validation of equipment performance of passive safety systems under these conditions. The results of an experimental investigation of the performance of the primary means of measurement module of the hydrogen concentration control system under physicochemical actions on them due to the precipitation of insoluble aerosols, non-condensable gases, and oil vapor during severe accidents at NPP are presented. It is shown that the physicochemical actions do not significantly affect the performance of the primary means of measurement module of the hydrogen concentration control system.

The processes of forsterite, enstatite, and talc treatment by ammonium fluoride have been studied. The phase-formation processes occurring during firing of fluorinated minerals were studied. It was established that structural silica of the minerals reacts with ammonium hydrogen difluoride with the formation of ammonium hexafluorosilicate, sublimation of which leads to removal of structural silica from the minerals with partial destruction of their structure. The firing of fluorinated minerals leads to their structural transformation with formation of magnesium nesosilicates and fluoronesosilicates.

The results of an experimental investigation of the changes occurring in the properties of heat-exchanger material and the thermal conductivity as a result of non-soluble aerosol deposition on heat-exchange surfaces of the passive system removing heat from the containment during severe accidents at NPP are reported. As the investigations showed, the deposited aerosol does not significantly influence the heat exchange between the steam-gas mixture and the cooling water flowing through the heat exchanger.

One of the problems of accidents in NPP with VVER is the evaporation of the primary coolant in the containment. Boric acid H3BO3 can ingress into the containment together with steam and crystallize, independently or in the form of salts, on heat-exchange and other surfaces of equipment placed in the containment, thereby lowering the efficiency of passive systems removing heat from the containment and the removal of hydrogen. The results of an experimental investigation of the deposition of insoluble aerosols and salts of boric acid on heat-exchange surfaces of the passive heat-removal system and the surfaces of autocatalytic hydrogen recombiners during serious accidents in NPP are reported. It is shown that the impact of crystallization of boric acid and its salts on the operability of these systems is very small.

The influence of the small addition of topaz on the processes of mineral formation in the "mullite-cordierite" system with a variable ratio of cordierite and mullite has been investigated. For this purpose, a series of experiments with different compositions of the initial mixtures, that is, with predominance of cordierite over mullite (KM mixtures) and predominance of mullite over cordierite (MK mixtures), has been performed. The addition of topaz in the form of topaz concentrate has been introduced in the amount of 1% by the weight of the investigated mixtures. The samples have been fired at various temperatures, that is, samples from KM mixtures (at a temperature of 1100-1300 degrees C) and samples from MK mixtures (at a temperature of 1400-1550 degrees C. The activating effect of topaz on mineral formation and sintering processes is determined by complex influence of fluoride products of topaz thermal decomposition. These reactively gaseous fluorides partially activate the solid phase mass transfer processes and then reduce the viscosity of high-temperature melt formed during firing that intensifies the processes of ceramic matrix consolidation. Porous polycrystalline cordierite mullite corundum ceramics from the KM mixtures, which contains 70%-87% cordierite, 3%-12% mullite, and 4%-11% corundum with water absorption of 3.5%-8% and bulk density of 2.10%-2.12 g/cm(3) at the firing temperature of 1300 degrees C, has been developed. Mullite ceramics with notably corundum content (not more than 8%) from the MK mixtures with various density degrees at the firing temperature of 1500-1550 degrees C, porous ceramics with water absorption of 3%-11%, and dense ceramics with water absorption of less than 1% have been produced.

Results are provided for development of mullite-corundum materials based on refractory filler (mullite or corundum) and a high-alumina ceramic binder (acicular mullite and fine-grained corundum). A model is presented and implemented for a structure of fragmentary type of mullite-corundum material providing good refractory qualities.

In order to provide a good resistance for refractory structures towards high-temperature deformation during manufacture of engineering ceramic during firing at 1650°C a corundum refractory material is developed with a weight faction of more than 95 wt.% Al2O3. The ceramic binder used is high-temperature calcium hexa-aluminate formed during firing molded objects from a thixotropic mixture consisting of refractory filler of electromelted corundum and components for forming a binder, i.e., high-alumina cement (HAC) and finely ground alumina.

A fractional (rational) chemical analytical method is proposed by which the material composition of clay rocks can be quantified and the clay-forming minerals present can be characterised. Subjecting raw clay to this procedure allows for the determination of the chemical composition of its fine-grained fraction, the amount and composition of exchangeable cations, water-soluble salts, carbonates and colloidal minerals, and the amount of amorphous silica and free quartz. A new, effective method is proposed for the qualitative and quantitative evaluation of the amorphous component in clays. This involves extracting colloids by treating the clay fractions with Tamm's reagent, a buffer solution of oxalic acid and ammonium oxalate with a pH of 3.25. Additionally, through calculations based on the results of chemical analyses, the illite content (derived from the content of non-exchangeable potassium oxide) and the chemical composition of the clay residue are determined. This enables the rock-forming clay mineral to be characterised and its structural chemical formula to be determined. This allows prediction of the physico-chemical and technological properties of the clay.

This article describes investigations into the properties of thin films of tungsten sulfide and copper sulfide produced by magnetron sputtering on glass substrates in argon atmosphere. Transmittance spectra of the obtained films are studied by spectrophotometry in the range from 300 to 900 nm; the band gaps are determined. The thickness of the obtained films varies in the range of 0.5–1 μm.

The results of studying the effect of modifying additives LiF, ZnO, Ce 2 O 3 on the synthesis and properties of cordieritomullite ceramics from Kazakhstan raw materials are presented. It has been established that the additions of LiF, ZnO, and Ce 2 O 3 contribute to the activation of the synthesis of cordieritomullite ceramics based on natural raw materials. The addition of LiF reduces the temperature of the onset of the appearance of the eutectic melt, which contributes to the intensification of cordierite formation, and ZnO and Ce 2 O 3 act on a solid-phase mechanism. The addition of LiF, ZnO, and Ce 2 O 3 additives to the composition of cordieritommullite ceramics in the amount of 0,5‒2,0 % has made it possible to lower the temperature of its calcination and to increase the density, strength, chemical and thermal stability. Ill. 6. Ref. 11. Tab. 3.

The paper focuses on a glass–ceramic composite consisting of lead borate glass matrix containing isolated eucryptite granules (hereafter called inhomogeneities) having negative thermal expansion coefficient. We discuss the dependence of the overall thermal expansion on the size of the particles and the temperature of sintering as well as the process of the diffusion of lithium from eucryptite into the glass matrix. The latter leads to the formation of interphase zones between the matrix and inhomogeneities. The overall thermal expansion coefficient is measured experimentally and modeled using various micromechanical schemes. The best agreement for the entire range of variation of the eucryptite volume fraction is provided by Maxwell homogenization scheme.

Results are given for a study of the effect of LiF, ZnO, and Ce2O3 modifying additions on synthesis and properties of cordierite-mullite ceramic from Kazakhstan resources. It is established that addition of LiF, ZnO, and Ce2O3 facilitates activation of synthesis for cordierite-mullite ceramic based on natural raw material. Addition of LiF reduces the temperature for the start of eutectic melt development, facilitating intensification of cordierite formation, and ZnO and Ce2O3 act by a solid-phase mechanism. Introduction of LiF, ZnO, and Ce2O3 into the composition of cordierite-mullite ceramic in an amount of 0.5 – 2.0% makes it possible to reduce its firing temperature and increase density, strength, and chemical and thermal stability.

The investigating results are given in the article for the development of the mullite-corundum materials on base of the high-melting aggregate (mullite or corundum) and high-alumina ceramic bond (acicular mullite and fine-grained corundum). The structural fragmentary models for the mullite-corundum material are presented and implemented, which provide high refractory properties. Ill. 7. Ref. 21. Tab. 6.

Наноструктурный порошок сульфида цинка был получен методом самораспространяющегося высокотемпературного синтеза (СВС) с участием элементарной серы и нанопорошка цинка в атмосфере аргона. В работе в качестве исходного материала использовался нанопорошок цинка, приготовленный путем электроискровой эрозии цинковых гранул в гексане. Фазовый состав и морфология продуктов самораспространяющегося высокотемпературного синтеза были исследованы с помощью рентгенофазового анализа и просвечивающей электронной микроскопии. Представлены температурный профиль и фотографии процесса горения стехиометрической смеси металла с серой, снятые с помощью скоростной фотовидеокамеры. Показано, что при горении стехиометрической смеси основной фазой в продукте является гексагональный сульфид цинка ZnS. Найдена взаимосвязь между содержанием серы в исходной шихте и эффективностью процесса синтеза.

This work contains results of investigation of obtaining high thermally conductive ceramics from commercial powders of aluminum nitride and yttrium oxide by the method of monoaxial compaction of granulate. The principal scheme of preparation is proposed and technological properties of granulate are defined. Compaction conditions for simple items to use as heat removal in microelectronics and power electrical engineering have been established. Investigations of thermophysical properties of obtained ceramics and its structure by the XRD and SEM methods have been carried out. Ceramics with thermal conductivity from 172 to 174 W/m·K has been obtained as result of this work.

Solid-phase synthesis of wollastonite has been determined to be primarily affected by the structural and mineralogical properties of the siliceous stock – its chemico-mineralogical composition (purity and presence of amorphous component) and granularity, as well as variations in phase change behaviour at high temperatures. Wollastonite synthesis occurs most completely in the mixtures of calcium carbonate with amorphous (microsilica) or semi-crystalline (gaize or diatomite) siliceous stock, yielding 92–96% wollastonite at 1200°С. For natural quartz-based stock (marshallite), wollastonite yield does not exceed 60–80%. Solid-phase wollastonite synthesis in mixtures of reactive amorphous or semi-crystalline siliceous stock with varying quantities of calciferous stock (10–50wt% CaO) produces wollastonitic ceramics chemically resistant to molten aluminium with the specific gravity of 1.1–1.7g/cm3 and the compressive strength of 28–76MPa, which exceeds the requirements for ceramics in foundry equipment by a factor of 3–3.5.

This work contains results of investigation of obtaining high thermally conductive ceramics from commercial powders of aluminum nitride and yttrium oxide by the method of monoaxial compaction of granulate. The principal scheme of preparation is proposed and technological properties of granulate are defined. Compaction conditions for simple items to use as heat removal in microelectronics and power electrical engineering have been established. Investigations of thermophysical properties of obtained ceramics and its structure by the XRD and SEM methods have been carried out. Ceramics with thermal conductivity from 172 to 174 W/m.K has been obtained as result of this work.