Corrosion Phenomena of High Temperature Alloys by Helium Impurities in the Primary Coolant of HTGR

The primary coolant circuit of the high temperature gas-cooled reactor (HTGR) contains trace impurities. A nickel base alloy would corrode when exposed to an atmosphere at a high temperature and for a long time. The protective oxide scale formed by chromium is an important factor to prevent severe corrosion of high temperature alloys. Corrosion tests were conducted on Inconel 617, Incoloy 800H, Hastelloy X, and T-22, which are commonly used in the steam generator of HTGR. The alloys were exposed to helium with trace impurities for 48 hours at 950°C. The corrosion results were analyzed by weighing, scanning electron microscopy (SEM) and electron probe microanalyzer (EPMA). All the four alloys formed oxide scales in this atmosphere, but they differ in the capacity to resist corrosion. Therefore, the carbon transfer phenomenon observed in this experiment varies for the different alloys. In addition, for Cr in Inconel617, the expected depletion phenomenon near the corrosion layer occurred, which is consistent with the results from theoretical analysis.

COMBINED TECHNOLOGY FOR PROCESSING WASTE DUMPS OF THE BAIZHANSAI MINE

Статья посвящена теме переработки отвалов рудника Байжансай в Туркестанской области, который, в настоящее время, является местом отходов полиметаллической руды в количестве примерно 6,5 тонн. В материале рассматривается потенциальная возможность применения данных отходов для извлечения полезных компонентов, таких как из цветных металлов - свинец и цинк, из благородных серебро и из редкоземельных - германий, индий, селен, теллур и таллий. При использовании данной переработки можно не только снизить негативное влияние отходов на окружающую среду, но и добыть полиметаллические руды, которые можно использовать в производстве стекол, оптики, в производстве высокоответственных подшипников для двигателей, для защиты антикоррозионных металлопокрытий и во многих других сферах, указанных в данной статье. Авторами было изучено технологическое решение по переработке отходов Байжансая. На основании полученных данных, была разработана технологическая модель, сочетающего в одном аппарате процессы электрохимической активации воды, флокуляции, газонасыщения и разделения микропримесей редких и рассеянных элементов (РРЭ), цветных металлов из технологических растворов и жидких техногенных отходов. Данный модуль является аналогом "классического" аппарата, но преимуществом предложенного модуля является меньшая энерго затратность, более эффективная работа по временным аспектам и по габаритам. The article is devoted to the topic of processing the dumps of the Baizhansai mine in the Turkestan region, whichis a place of waste of polymetallic ores in the amount of about 6.5 tons. The article discusses the potential use of these wastes for the extraction of useful components, such as non-ferrous metals - lead and zinc, precious silver, and rare-earth metals - germanium, indium, selenium, tellurium and thallium. With the use of this processing, it is possible not only to reduce the negative impact of waste on the environment, but also to extract polymetallic ores that can be used in the production of glass, optics, in the production of highly critical bearings for engines, to protect anti-corrosion metal coatings and in many other areas specified in this article. The authors studied the technological solution for the processing of waste from Baizhansai. Based on the data obtained, the authors of the article have developed a technological module that combines in one apparatus the processes of electrochemical activation of water, flocculation, gas saturation and separation of trace impurities of rare and trace elements (RRE), non-ferrous metals from technological solutions and liquid man-made waste. This module is analogous to the "classical" apparatus, but the advantage of the proposed module is lower energy consumption, more efficient work in terms of time and dimensions.

TO THE QUESTION OF COMPREHENSIVE ASSESSMENT OF SURFACE WATER IN THE CENTRAL CAUCASUS DURING WINTER BETWEEN AND SUMMER FLOOD

Based on long-term observations, the assessment of the pollution of the rivers of the Central Caucasus was carried out by comparing the calculated coefficients of the complexity of pollution and the specific combinatorial index of pollution of surface waters, and the quality classes were determined. The results of chemical analysis of the concentration levels of trace impurities (Mo, Pb, Zn, V, Ni, Cr, Mn, Ag) and inorganic nitrogen compounds (NO2 -, NO3 — and NH4 +) in the waters of 13 rivers in two permanent sections of each watercourse were used. The results of calculating the indicators of pollution in the waters of rivers of winter low water and summer high water are presented. The most polluted watercourses and the frequency of pollution in each river are identified, estimated by the values of the specific combinatorial index of water pollution, the coefficient of complexity of pollution, and the class of water quality is presented. The assessment of the most polluted water bodies during the winter low-water period and summer flood is given according to the classification of water quality. According to long-term observations, the features of watercourses and their differences in terms of pollution are presented.

Sulphur and Molybdenum Incorporation at the Calcite-Water Interface: Insights from Ab Initio Molecular Dynamics

<p>Sulphur and molybdenum trace impurities in speleothems (stalagmites and stalactites) can provide long and continuous records of volcanic activity, which are important for past climatic and environmental reconstructions. However, the chemistry governing the incorporation of the trace-element bearing species into the calcium carbonate phases forming speleothems is not well understood. Our previous work has shown that substitution as tetrahedral oxyanions [<i>X</i>O₄]^2- (<i>X</i>=S, Mo) replacing [CO₃]^2- in CaCO₃ bulk phases (except perhaps for vaterite) is thermodynamically unfavourable with respect to the formation of competing phases, due to the larger size and different shape of the [<i>X</i>O₄]^2-tetrahedral anions in comparison with the flat [CO₃]^2- anions, which implied that most of the incorporation would happen at the surface rather than the bulk of the mineral. Here we present an ab initio molecular dynamics study exploring the incorporation of these impurities at the mineral-water interface. We show that the oxyanions substitution at the aqueous calcite (10.4) surface is clearly favoured over bulk incorporation, due to the lower structural strain on the calcium carbonate solid. Incorporation at surface step sites is even more favourable for both oxyanions, thanks to the additional interface space afforded by the surface line defect to accommodate the tetrahedral anion. Differences between sulphate and molybdate substitution can be mostly explained by the size of the anions. The molybdate oxyanion is more difficult to incorporate in the calcite bulk than the smaller sulphate oxyanion. However, when molybdate is substituted at the surface, the elastic cost is avoided because the oxyanion protrudes out of the surface and gains stability via the interaction with water at the interface, which in balance results in more favourable surface substitution for molybdate than for sulphate. The detailed molecular-level insights provided by our calculations will be useful to understand the chemical basis of S- and Mo-based speleothem records.</p>

Sulphur and Molybdenum Incorporation at the Calcite-Water Interface: Insights from Ab Initio Molecular Dynamics

<p>Sulphur and molybdenum trace impurities in speleothems (stalagmites and stalactites) can provide long and continuous records of volcanic activity, which are important for past climatic and environmental reconstructions. However, the chemistry governing the incorporation of the trace-element bearing species into the calcium carbonate phases forming speleothems is not well understood. Our previous work has shown that substitution as tetrahedral oxyanions [<i>X</i>O₄]^2- (<i>X</i>=S, Mo) replacing [CO₃]^2- in CaCO₃ bulk phases (except perhaps for vaterite) is thermodynamically unfavourable with respect to the formation of competing phases, due to the larger size and different shape of the [<i>X</i>O₄]^2-tetrahedral anions in comparison with the flat [CO₃]^2- anions, which implied that most of the incorporation would happen at the surface rather than the bulk of the mineral. Here we present an ab initio molecular dynamics study exploring the incorporation of these impurities at the mineral-water interface. We show that the oxyanions substitution at the aqueous calcite (10.4) surface is clearly favoured over bulk incorporation, due to the lower structural strain on the calcium carbonate solid. Incorporation at surface step sites is even more favourable for both oxyanions, thanks to the additional interface space afforded by the surface line defect to accommodate the tetrahedral anion. Differences between sulphate and molybdate substitution can be mostly explained by the size of the anions. The molybdate oxyanion is more difficult to incorporate in the calcite bulk than the smaller sulphate oxyanion. However, when molybdate is substituted at the surface, the elastic cost is avoided because the oxyanion protrudes out of the surface and gains stability via the interaction with water at the interface, which in balance results in more favourable surface substitution for molybdate than for sulphate. The detailed molecular-level insights provided by our calculations will be useful to understand the chemical basis of S- and Mo-based speleothem records.</p>

Engendering persistent organic room temperature phosphorescence by trace ingredient incorporation

Pure organic persistent room temperature phosphorescence (RTP) has shown great potential in information encryption, optoelectronic devices, and bio-applications. However, trace impurities are generated in synthesis, causing unpredictable effects on the luminescence properties. Here, an impurity is isolated from a pure organic RTP system and structurally characterized that caused an unusual ultralong RTP in matrix even at 0.01 mole percent content. Inspired by this effect, a series of compounds are screened out to form the bicomponent RTP system by the trace ingredient incorporation method. The RTP quantum yields reach as high as 74.2%, and the lifetimes reach up to 430 ms. Flexible application of trace ingredients to construct RTP materials has become an eye-catching strategy with high efficiency, economy, and potential for applications as well as easy preparation.