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Direct-drive laser inertial fusion is a potential producer of baseline power that has increased credibility following the achievement at the National Ignition Facility of ignition and net gain using indirect-drive via laser-produced X-rays. Ultraviolet broad band lasers such as argon fluoride, at 193 nm and 10 THz, are predicted by hydrocode simulations to enable energy gains greater than 100 with laser energies less than 0.5 MJ, stimulating renewed reactor design effort in anticipation of experimental verification. The present study attempts to create a reactor design with very few unknowns in materials, corrosion, first wall viability, tritium breeding and ease of servicing. A new variant of magnetic intervention has an increased ion dump surface area combined with a simple structure. Around an inner vacuum vessel an all-ceramic tritium breeder blanket is possible in an unconstrained volume, allowing helium coolant to be used without excessive pressure or flow power. The case is made for development of a lead (Pb) ceramic as the neutron multiplier. [ABSTRACT FROM AUTHOR]

A study of the degradation of diclofenac (DCF) in an electrochemical reactor equipped with two carbon cloth (CC) electrodes operating in recirculation mode, is presented. The analysis of the effects of the operating variables on the degradation of the DCF showed that, as expected, the applied voltage has a direct influence on the reactions that take place at the anode and cathode. In fact, the addition of O2 and Fe(II) to the medium demonstrated that the electro-Fenton (EF) process was taking place and that under the following conditions, 4 V, 0.05 M Na2SO4, 50 mg/L DCF, 0.25 g Fe(II)-loaded resin, and 50 mL/min, 79.8% of DCF mineralization was obtained in a process described by a pseudo-first order kinetics (k = 0.0184 min−1). Using a simulated domestic wastewater effluent, the EF reactor under study not only showed a similar DCF mineralization value (81.8%), but also reasonable energy consumption (2.16 kWh/m3) as well as CC electrode stability upon several treatment cycles. These results suggest that an EF approach using low-cost CC electrodes and neutral pH conditions, constitute a technically and economically viable option for DCF wastewater treatment. [ABSTRACT FROM AUTHOR]

Green chemistry aims at replacing toxic solvents by safer solvents such as supercritical carbon dioxide (scCO2), which displays zero surface tension, outstanding transport properties, high diffusivity, and tuned solubilization by changing the pressure and temperature, or adding cosolvents. Nonetheless, the practical application of scCO2-based technologies under supercritical conditions requires sophisticated systems for optimal operation. Here, we review scCO2-based systems with focus on dyeing, extraction, chromatographic, and cleaning systems. All scCO2-based systems consist of a CO2 supply and pump part, a cosolvent providing part, and a parameters controlling part, yet there are different reaction vessels depending on solute types and practical functions. Developing more normalized, intelligentized, and durable scCO2-based systems should render the scCO2-based technologies be more economic, controllable, flexible, and suitable for wider applications. [ABSTRACT FROM AUTHOR]

The results of thermal calculations of the part of the fuel assembly of the active zone of the VVER-1000 reactor in the stationary mode of operation make it possible to evaluate the mechanical state of the fuel rod cladding, to understand the influence of reactor control methods on the strength and the design acceptance criteria. The main principles of the evaluation of mechanical characteristics of VVER-1000 fuel rods using the START-3 code are presented. The results of the prediction of the mechanical characteristics of the VVER-1000 fuel rods during the 4-year cycle in stationary mode under normal operating conditions and under their violation are illustrated. The maximum values of stress in the fuel rod in the stationary mode of operation are in the range of 60–80 MPa, which cannot cause depressurization of the fuel rod. [ABSTRACT FROM AUTHOR]

Abstract—The article considers the efficiency and possibility of introducing into operation of VVER-1000 power units with the lifetime extended owing to the sliding pressure of the second circuit. The history of research by Russian nuclear engineers on VVER lifetime extension is reviewed. It is shown that reduction of fresh steam pressure within the allowed limits will make it possible to release additional reactivity through release of the temperature effect and to generate additional energy during the period of unit operation on the power effect. A mathematical model of changes in the main parameters of the reactor unit, including reactivity balance equations, Stodola–Flugel equation for the turbine, and heat balance and heat transfer equations in the steam generator, is compiled. The expected increase in power generation for modern fuel loadings of VVER-1000 reactors is calculated. The degree of compliance of the proposed mode with the current technological limitations of the large-series VVER-1000 power units is analyzed. The results of the analysis are confirmed by the numerical experiment on the multifunctional analyzer of the VVER-1000 unit modes developed by the National Research Nuclear University MEPhI built on the basis of the ENICAD environment and the certified diffusion neutronic code PROSTOR. Conclusions are drawn about the possibility of introducing the proposed mode into the operational practice of modern VVER-1000 power units. [ABSTRACT FROM AUTHOR]

Possible input data of a NPP power unit model for matching model states with prototype states are considered. The most important parameter used to match the states is the thermal power of the reactor unit (RU). Methods for accurate setting of the reactor plant power in the model were examined, namely, by using an automatic power controller (APC) and a mathematical boron controller. As part of matching the state of the nuclear power plant model with the prototype, a numerical experiment was carried out using PROSTOR, a full-scale simulation facility. The experiment was intended to obtain stationary states of the model with power in a range from 94% to 104% with a step of 0.05%. For modeling, the data pertaining to load 3 of unit 4 of the Kalinin NPP on the 248th effective day were used. In analyzing the results of a numerical experiment, two effects were discovered. One of them, exhibited in the derivative of the resulting plot of the dependence of pressure in the steam generator on power, is associated with reaching the upper limit of the capacity to control the pressure in the main steam collector (MSC). The control element of the pressure controller in the MSC is the control valves on the turbogenerator. At the moment that corresponds to the kink on the plot, they fully open, owing to which pressure control is no longer possible. The pressure in the MSC begins to rise. This effect corresponds to real processes occurring at nuclear power plants. In this case, it is proposed to use as one of the parameters of the model settings an adaptive coefficient to the concentration of boric acid in the reactor and control it by means of a mathematical boron controller. The second effect is that the pressure in the reactor cannot be accurately controlled because of the operating characteristics of the automation of tubular heating elements of the pressure balance (THE PB). In relation to this, it is proposed to use an additional mathematical controller of THE PB to match the state of the model with the prototype. These controllers have been successfully tested as part of the PROSTOR software package for matching the power of the reactor unit and the prototype. [ABSTRACT FROM AUTHOR]

In water-water power reactors (VVERs), loose, weakly fixed, and foreign objects can appear in the main circulation circuit (MCC) and pose a threat to the integrity of the equipment and the safety of the reactor. In order to detect these items early, the reactor is equipped with a loose parts monitoring system (LPMS). In addition to the detection of loose/weakly fixed parts, the LPMS functions include the classification of reported events. The possibility of applying the classification algorithm is based on the fact that the signals from the triggering of standard equipment are characterized by a high degree of repeatability, even in the presence of noise, while a loose object is characterized by a large stochastic component, and its own deterministic class cannot be formed for it. Classification reduces false alarms and allows signals from routine operations to be detected; the signals from the same process should be assigned to the same class. The idea of the article is to train the LPMS on some archive of data characterizing routine reactor operation, to create a library of basic classes, and to set the boundaries of each class in order to, on one hand, take into account the possible variability of signal parameters due to noise. Having defined the basic classes, we can assert that, if a newly received signal falls into one of the classes, it reflects routine reactor operation, while signals that do not fall into any of the classes can be from the appearance of a loose/weakly fixed item. The article analyzes a set of events accumulated in the archive of one of the operating LPMS. Their clustering is performed, as a result of which classes of events corresponding to routine unit operations are singled out. For each class, the center of the class and permissible limits of deviations from the center are calculated. All obtained class centers are benchmarks by which the LPMS in real time either classifies a newly detected event or characterizes it as unclassified. [ABSTRACT FROM AUTHOR]

This article considers the fundamental possibility of identifying the kinetic characteristics of a reactor under quasi-stationary operating conditions by observing its power fluctuations under the influence of controlled changes in reactivity, as well as the possibility of optimal stabilization of reactor power. The analysis is carried out under conditions where the reactor reactivity and measurement of its power are influenced by disturbing perturbations in the form of uncontrolled random processes. A point kinetics model of the reactor with a single group of delayed neutrons and instantaneous power feedback is used. Examples are presented that illustrate the proposed identification method and the effectiveness of the optimal controller. [ABSTRACT FROM AUTHOR]

An analysis was made of the developed modified Nusselt number ratio Nu for estimating thermal loads on the surfaces of a flat horizontal layer of metal melt (liquid-metal coolants, metal melt layers formed inside nuclear power plant (NPP) containers during a severe accident, etc.), heated along its lower surface and having an uneven radial temperature distribution. The need for such an analysis is explained by the fact that the use of known relations for the Nusselt numbers Nu for a liquid/melt layer with an uneven longitudinal temperature distribution leads to significant errors in determining the heat transfer conditions at the boundary surfaces of the layer, which is critical, for example, when implementing the concept of retaining molten materials inside the nuclear power plant in case of a severe accident (SA). In the proposed relation for the Nu number on the lateral surface of the melt layer, both traditional (Rayleigh number) and additional parameters are used, taking into account the temperature conditions on its boundary surfaces (including the lateral one) as well as the dimensions of the layer. To find the unknown coefficients in the modified ratio, the results of several series of numerical experiments were used by the domestic ANES CFD code. Using the ratio obtained for the Nu number, a parametric analysis of the heat-transfer conditions on the side surface of the metal layer of the melt formed during an SA was carried out. According to the results of the analysis, the proposed ratio gives good accuracy in calculations (on average, the error did not exceed 7%) and the predictive efficiency of the developed modified ratio for Nu numbers in the range of Rayleigh numbers from 106 to 1012. Such a relation for the Nu numbers on the side surface of the melt layer can be used in assessing the thermal loads on the nuclear power plant container during an SA and in other problems where there is a radial nonuniformity of the temperature distribution in a flat liquid/melt layer heated from below. [ABSTRACT FROM AUTHOR]

By way of mathematical and numerical simulation of an nonisothermic flow of a gas with nanoparticles in a tubular continuous-flow reactor with an nonuniform temperature field, the influence of the diffusion (Brownian diffusion and thermodiffusion) of nanoparticles in this flow and their diffusion deposition on the walls of the reactor on the parameters of the gas-suspension flow in it was investigated. The problem on the two-dimensional flow of a nanogas suspension with a nonuniform transverse velocity profile in such a reactor was solved. The longitudinal and transverse distributions of the concentration of nanoparticles in this suspension and its temperature in the reactor were obtained by the numerical finite difference method. The influence of the initial concentration of nanoparticles in the gas flow at the inlet cross section of the reactor and the Knudsen number of the nanoparticles (their sizes in fact) on the distributions of the characteristics of the disperse-mixture flow in the reactor was determined. [ABSTRACT FROM AUTHOR]

Chemoenzymatic epoxidation of olefin mediated by lipase is a green and environmentally friendly alternative process. However, the mass transfer barrier and lipase deactivation caused by the traditional organic–water biphasic reaction system have always been the focus of researchers' attention. To overcome these issues, we investigated the effects of reaction temperature and two important substrates (H2O2 and acyl donor) on the epoxidation reaction and interfacial mass transfer. As a result, we determined the optimal reaction conditions: a temperature of 30 °C, 30 wt-% H2O2 as the oxygen source, and 1 M lauric acid as the oxygen carrier. Additionally, by simulating the conditions of shaking flask reactions, we designed a batch reactor and added a metal mesh to effectively block the direct contact between high-concentration hydrogen peroxide and the enzyme. Under these optimal conditions, the epoxidation reaction was carried out for 5 h, and the product yield reached a maximum of 93.2%. Furthermore, after seven repetitive experiments, the lipase still maintained a relative activity of 51.2%. [ABSTRACT FROM AUTHOR]

Enhancement of sulfuric acid alkylation process efficiency in oil refineries by introducing a newly designed jet reactor into the process is proposed. The process efficiency increase has been proved by numerical modeling based on the obtained hydrodynamic flow rate distribution patterns in the apparatus. [ABSTRACT FROM AUTHOR]

To improve the parameters of reactors and reduce the cost of generated electricity, we carry out research aimed at determining the most rational use of fuel. Different methods use different mathematical and physical models, which leads to some difference in the obtained data. One of these methods is the profiling of fuel assemblies. In this paper, we present the theory used in modeling and calculations by the Serpent 2 software package, consider methods of axial profiling of compositions in a reactor, and provide a comparison of the obtained results and substantiation of their reliability at an intermediate stage of the study. [ABSTRACT FROM AUTHOR]

An improved higher-efficiency alkylation reactor design has been developed and the principle of operation of such reactor is given. The components of the reactor are described. The flow velocity isocontours in the control sections of the reactors of conventional and modernized designs, based on which the efficiency of use of new technical solutions is confirmed, are obtained. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to investigate the estimated people's fatalities percentage due to methanol reactor incident from a newly proposed plant in Perak, Malaysia. This work investigated the possibility of (1) various events occurring in term of toxicity, thermal radiation, and overpressure, and (2) the fatalities percentage when these events occurred due to the release of chemical mixtures from the reference plant, which has 42 m3 reactor volume and operates at 76.4 bar; and three reactor scenarios in which the reactor volume is reduced to 7.6 m3, while operating pressures are 76.4, 150, and 300 bars. HYSYS software was employed to simulate the process and obtain the mass density of the mixture, mass fraction, and volume fraction, while ALOHA and MARPLOT software was used to calculate the amount of toxicity, thermal radiation, overpressure and area affected. The methanol reactor contains a mixture of hydrogen, carbon dioxide, methanol, carbon monoxide, and water, where only water is not considered hazardous. Release of chemical mixture via three-hole size scenarios, 10 mm, 25 mm, and 160 mm was proposed, and the simulation was carried out. Results showed that reference plant and plant 300 bar exhibit the highest fatalities percentage for overall and reduced reactor volume (15.7% and 11.2%), both caused from the release of carbon dioxide at night through a 160 mm hole leakage. This study can be used to suggest the best location for the methanol plant to be built to avoid any deaths to people living surrounding area. [ABSTRACT FROM AUTHOR]

The operation of an unsteady-state well-stirred flow-through biochemical reactor is studied. Nonlinear boundary-value problems describing the operation of such reactors are considered. Nontrivial solutions under homogeneous boundary conditions are sought. The analysis is based on the equations of the diffusion model. The switch of the operating modes of the reactors in the case of several solutions of the equations of the process is analyzed. [ABSTRACT FROM AUTHOR]

Zr1 –хUхN nitrides have been synthesized via nitridation of solid solutions of uranium in zirconium. High-temperature saturation of the solid solutions with nitrogen has been shown to yield Zr1 –хUхN ceramics uranium-enriched in their central part. We have presented the concept of a new type of fuel, based on Zr1 –хUхN, for high-temperature gas-cooled reactors. Nuclear calculations of a reactor core demonstrate the feasibility of reaching the critical mass at uranium contents of 10 and 20 wt %. The core size of a conceptual reactor has been determined. We have performed thermophysical calculations of the reactor core and demonstrated the feasibility of obtaining high-grade heat. [ABSTRACT FROM AUTHOR]

In this work, the photodegradation of methylene blue was investigated by constructing a novel photocatalysis reactor, which was filled with aqueous foam. Nanoscale TiO2 particles were used as photocatalyst. In order to obtain stable foam phase, cetyl trimethyl ammonium bromide (CTAB) was used as the frother, and its suitable initial concentration in the feeding solution was 0.20 g/L. Under the suitable conditions of loading liquid volume 200 mL, initial concentration of TiO2 nano-catalysts in the feeding solution 5.0 g/L, inner diameter of foam column 18 mm, aperture diameter of gas distributor 125 μm, and circulating velocity of bulk solution 500 mL/h, the maximum degradation percentage of methylene blue was 97.6 ± 1.2%. Atomic force microscopy (AFM) analysis suggested that the entrainment effect of rising bubbles and the circulation flow of bulk solution inside the aqueous foam did not cause the conspicuous aggregation of TiO2 nano-catalysts under the suitable conditions, but their surface roughness decreased. Meanwhile, foam entrainment had not a significant impact on the polydispersity of TiO2 nano-catalysts. In contrast to the photodegradation of methylene blue in aqueous solution, the photocatalysis process using aqueous foam is the intensity of light received by TiO2 nano-catalyst increases, and irradiation period is less. This work is expected to provide new insight into the rational design of photocatalysis reactor, to facilitate the harmless treatment of dyestuff wastewater. [ABSTRACT FROM AUTHOR]

A nonlinear boundary value problem is considered that describes the operation of a flow-through biochemical reactor with allowance for the relaxation of the substance flow. A logistic law is adopted as the source of the substance. Nontrivial solutions are sought under homogeneous boundary conditions. The analysis is based on the limiting form of the equations of the relaxation model (RM). The change of operating modes of reactors is analyzed in the presence of two solutions of the equations of the process. [ABSTRACT FROM AUTHOR]

Globally, the reserves of heavy crude oil are seven times more abundant than that of light crude, and yet, they are underutilized because of their high viscosity and density, which is largely due to the presence of large amounts of asphaltenes. Biotransformation of heavy oil asphaltenes into smaller metabolites can be used for reducing their viscosity. Several microorganisms capable of asphaltene biodegradation have been reported but only few have been characterized for its biotransformation. In the present study, a 9-membered microbial consortium was isolated from an oil contaminated soil. About 72% and 75% asphaltene biotransformation was achieved by growing cells at shake flask level and in a 1.5 l bioreactor, respectively. A representative structure of asphaltene was constructed based on LC–MS, 1H-NMR, 13C-NMR, FT-IR, ICPMS and elemental analysis (CHNS) of n-heptane purified asphaltene from Maya crude oil. Biotransformation of asphaltene, as analyzed by performing 1H-NMR, FT-IR and elemental analysis, resulted in 80% decrease in S and N when compared to the control along with incorporation of oxygen in the structure of asphaltene. About 91% decrease in the viscosity of the Maya crude oil was observed after two weeks when oil: aqueous phase ratio was 1:9. The results suggest that the isolated microbial consortium can be used for biological upgradation of heavy crude oil. To our knowledge, this is the first report where a microbial consortium resulted in such high asphaltene biotransformation. [ABSTRACT FROM AUTHOR]

The digital acoustic model of a nuclear reactor (NRDAM) is represented as a self-oscillatory system belonging to a special class of nonlinear dissipative systems that can generate sustained oscillations whose parameters do not depend on the initial conditions and are only governed by the properties of the system itself. It has been found that a pressurized water reactor with coolant flowing in a turbulent mode is an open system of high complexity with a large number of components with links between them being probabilistic rather than predetermined in nature. The coolant loop components featuring negative dissipation (negative friction) are revealed. It is shown that chaotic turbulent pulsations and vortices are self-organized in these components into ordered wave oscillations, the frequency of which is determined according to the Thomson (Kelvin) formula. An electronic generator of self-oscillations with a transformer feedback used in radio engineering circuits has similar properties. A nozzle is an acoustic analog of a transformer. A negative resistance contained in nonlinear dynamic systems like a nozzle or a natural circulation loop results in that chaotic turbulent disturbances become self-organized, and self-oscillations are generated in the form of acoustic standing waves (ASW). Based on theoretical and experimental data, the certainty of the ability of a reactor together with the pipelines connected to it to simultaneously generate several ASWs—a property that has not been known previously—is confirmed. By using the NRDAM in designing and operation of nuclear power plants (NPPs), it becomes possible to reveal the sources of ASWs arising in the coolant, their occurrence conditions, and frequency. The use of the NRDAM is also necessary for determining the effect that the coolant circuit equipment geometrical parameters and layout have on the interaction of neutronic, thermal-hydraulic, and vibroacoustic processes. By applying the NRDAM, it becomes possible to optimize the engineering and design solutions in developing new-generation NPPs by eliminating the conditions causing the occurrence of undesirable self-oscillations of coolant and vibroacoustic resonances resulting from the coincidence of the ASW frequencies with the vibration frequencies of nuclear fuel and equipment in normal and emergency operation modes and also under the conditions of shock impacts and seismic loads. [ABSTRACT FROM AUTHOR]

State of the art in the field of the development of catalytic reactors for dehydrogenation of liquid organic hydrogen carriers is analyzed. Rapid and complete dehydrogenation and the possibility of repeated use of the carrier can be ensured by intensifying the heat exchange and reducing the dehydrogenation temperature; these factors should be taken into account in choosing the reactor design. Examples of using reactors with fixed, suspended, and monolithic catalysts, membrane reactors, reactors operating in the reactant vaporization/condensation modes, etc., and also universal reactors for hydrogenation/dehydrogenation of liquid organic hydrogen carriers are considered. A comparative analysis of the advantages and drawbacks of various reactor systems is made. [ABSTRACT FROM AUTHOR]

It is shown that a rotary vortex thermal unit can be used in order to produce a high quality gypsum binder (fast-setting A grade gypsum) including the utilization of gypsum-containing wastes taken from gas cleaning facilities, with obtaining a marketable product and reducing the accumulation of solid wastes, which should promote solving economic and environmental problems. By varying the maximum roasting temperature and the holding time, controlling both the binding properties of gypsum and its strength has been achieved. These properties are inversely related: as the roasting temperature increases, the binding properties get improved, whereas the strength of the hardened mortar exhibit a decrease. Increasing high-temperature exposure time, on the contrary, leads to worsening gypsum binding properties and improving gypsum strength properties. [ABSTRACT FROM AUTHOR]

Based on the analysis of experiments carried out on simulators of fuel elements with a cladding of low-melting metals, models of melting and movement of the melt over the surface of fuel elements are proposed. The presented work is a continuation of experimental and theoretical work carried out jointly at the Nuclear Safety Institute, Russian Academy of Sciences, and Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, to study the features of the movement of a melt over a cylindrical surface that simulates the surface of a fuel element. It analyzes the factors that determine the thermal destruction of fuel elements. One of the important conclusions drawn from the analysis of experimental data was the conclusion about the prevailing film laminar runoff in the heated part of the fuel element simulator. Using this assumption, an analytical model was built that allows predicting the mass of a fuel element carried out of its limits during melting. As a result of calculations using the proposed model, it was shown that, for an accident with the introduction of positive reactivity, when the power increase can reach ten ratings, a modification of the model is necessary to take into account the turbulent runoff regime. For this purpose, a simplified model of the flow of the melt was built. A comparison is made with known techniques and it is shown that the proposed approach makes it possible to describe the turbulent flow regime with satisfactory accuracy. The modified model made it possible to calculate the features of the movement of a stainless steel melt over the surface of a fuel element of a fast neutron (BN) reactor. Information was obtained on the thickness of the melt, its velocity and Reynolds number, depending on the conditions of drainage, and on the mass carried outside the core. [ABSTRACT FROM AUTHOR]

The review provides a comparative analysis of the basic technologies for production of bimodal polyethylenes by the leading world companies, their technical characteristics, and the applied catalysts and reactor systems; the preferred application areas of bimodal polyethylenes are also considered. The global bimodal polyethylene producers and the leading licensors of polyethylene technologies are presented. The state and development prospects of the global and regional polyethylene markets are studied; the market development forecast for the coming years is given. [ABSTRACT FROM AUTHOR]

Abstract—One of the joints of a liquid metal fast neutron reactor is the main circulation pump. The fabrication technology of the most labor-intensive joint of the main circulation pump, the pressure chamber, which is a complex welded structure made of 10Kh15N9S3B3 (EP-302Sh) sheet steel, is optimized and the fixtures and accessories are developed and fabricated, as a result of which the metal content of the structure is decreased. The process documentation for bending and stamping of the parts of the pressure chamber and welding of the components and their thermal and mechanical treatment and assembling is developed. The existing process documentation is adjusted as applied to the pressure chamber of the main circulation pump following the results of fabrication of this structure. [ABSTRACT FROM AUTHOR]

Nuclear reaction rates in the nickel and uranium detectors placed at different positions within the reactor cores of the TIRAN nuclear reactor complex are measured. The measured reaction rates are found to be consistent with those simulated using the PRISMA-D Monte Carlo code with the values of neutron constants as quoted in the ENDF-BVI library. Relying on the simulation, the signals of nickel neutron activation monitors are more precisely related to energy releases in the reactor core. [ABSTRACT FROM AUTHOR]

Versions of the neutron source multiplication (NSM) method are considered. The method developed at foreign research institutes to determine the reactivity of deeply subcritical reactors uses reactivity of the "reference" level. Further, the results of the use in the above methods and in the area ratio method of the computational experiment simulation technique that yields sufficiently precise data without involving the reference level are discussed. The practicability of applying the method of the computational experiment simulation to the versions of the neutron source multiplication methods used at some institutes of Russia in the procedure of critical mass experiments is validated. [ABSTRACT FROM AUTHOR]

The reactor dynamics of suspension polymerization of styrene has been studied in a specially designed unit controlled by a computer. It is found that the changes under control actions (measure of heating power and measure of stirrer shaft power) consistently describe the changes in the physical (relaxation) state of polymer–monomer particles. This phenomenon is proposed to be used to control the process. [ABSTRACT FROM AUTHOR]

A device is proposed for producing sulfur, in the form of a cylindrical reactor with several catalyst blocks consisting of heat exchange elements with an internal space for the passage of the coolant; the space between the elements is filled with a granular catalyst. The device additionally contains a steam heater for hydrogen sulfide-containing gas, a section for condensing sulfur vapors (surface condenser located below the catalyst units), and a thermosyphon device for removing reaction heat from the catalyst blocks. In this case, the catalyst units are equipped with devices for distribution of oxygen-containing gas over the cross section of the apparatus. The thermosyphon device is composed of a manifold distributor of the liquid heat carrier, a manifold-collector of the vapor-liquid mixture, and a separation space, which houses a steam heater of the hydrogen sulfide-containing gas. When highly concentrated hydrogen sulfide is oxidized (up to 90 vol. %) on the experimental apparatus, the sulfur removal is 4.0–4.1 kg/hr for every 1 liter of catalyst, the sulfur yield is 99.6% and a high-potential vapor is obtained (250°C, 4.0 MPa). [ABSTRACT FROM AUTHOR]

Basic approaches are outlined to solving complex engineering problems arising in the design and operation of power units at nuclear power stations (NPS) and based on large-scale physical simulation of dynamic conditions and parameters of dynamics and structural strength of modern power facilities. A procedure for physical simulation of specific dynamic processes in hydroelastic systems has been developed. Taking into account the identified distributions of pressure pulsations and flow rates on the surfaces of the structures of the investigated reactor plants (RU), hydrodynamic loads in various structures and facilities of modern power-machine buildings were determined considering the found distribution of fluctuations in flow pressure and velocity acting on the structure surfaces. The dynamic response parameters of the main structural members, such as dynamic strains and stresses, were obtained and analyzed. The effect of added masses of liquid, damping, and other factors on the dynamic processes in hydroelastic systems and ways for its reduction to increase the durability and service life of structures, first of all the critical elements of the studied power systems for each commissioned reactor, are determined. This approach is based on a comprehensive investigation of the interaction of a turbulent flow with the multicomponent structure of a reactor unit. The results of investigation confirmed the structure serviceability as to the relative error. The fitness for service of a structure during a specified operation time of the power unit was assessed. The implementation of the proposed approach involving large-scale physical simulation and, in many cases, numerical modeling, confirmed its effectiveness and the validity of the results obtained by the authors. [ABSTRACT FROM AUTHOR]

In the paper, the authors have presented local hydrodynamic characteristics (averaged-velocity vector fields) of the flow behind various types of intensifier grids of TVS-Kvadrat fuel assemblies intended for operation in pressurizedwater- reactor (PWR) cores. The structure of the flow behind these structural elements of the cassette has been revealed and the influence of the shape and orientation of turbulizers on the stabilization (equalization) length of transverse velocities in the characteristic regions of an assembly has been determined. The acquired information of the experimental investigations was used during the engineering substantiation of the TVS-Kvadrat structure for installing these assemblies into rector plants. [ABSTRACT FROM AUTHOR]

Ultrafine rare-earth oxides (REOs) are widely applied in all fields of daily life, but the conventional preparation methods are limited by a long procedure, low efficiency and severe environmental pollution. Our team has independently developed a jet pyrolysis reactor for the preparation of ultrafine cerium oxides, and this process has theoretical significance and practical application values. In this study, gas–solid pyrolysis reactions inside the jet-flow pyrolysis reactor were numerically simulated. We performed a coupling computation of the combustion, phase transformation and gas–solid reaction on Fluent and user-defined functions. We characterized the flows of different phases as well as the compositions and distributive laws of the reactants/products in the reactor. The gas-phase inlet velocity and dynamic pressure/additional pressure were related by a quadratic function. The velocity at the throat inlet changed the most, and the outlet velocity was very stable. The CeO2 concentrations were obviously stratified. This study enriches theories of jet-flow pyrolysis and theoretically underlies the optimization and popularization of self-developed pyrolysis reactors. [ABSTRACT FROM AUTHOR]

This study developed a submerged membrane adsorption reactor system and conducted laboratory scale experiments to remove cesium using copper ferrocyanide (CuFC). The differences in cesium removal efficiency and membrane fouling by using a countercurrent two-stage adsorption (CTA) process and the conventional adsorption process were discussed. The 144 h of the continuous experiment showed that the effluent concentration remained constant with time, and the highest value of the decontamination factor approached 103. The CTA process possesses a higher concentration of suspended CuFC and a lower membrane fouling rate. [ABSTRACT FROM AUTHOR]

The possible formation of a solid phase in the lead coolant in the BREST-OD-300 reactor, a problem common for reactors of such type, is numerically investigated. For modeling unsteady processes in the steam generator operating with a liquid-metal coolant under the conditions involving the occurrence of crystallization–melting phenomena, a procedure that makes it possible to take into account the process ambiguity depending on the state of the heat-transfer contact surface oxide layer was used. Accidents caused by a rupture of the main steam header and by failure of the regenerative feedwater heating system are considered. The influence of certain reactor parameters on the solid phase formation dynamics in such accidents is estimated. If loss of tightness occurs in the main steam header with simultaneous loss of power supply to the reactor and failure of the steam generators' shutoff and control valves and also in the case of regenerative feedwater heating system failure with retaining the supply of feedwater to the steam generators, the solid phase fully blocks the flow section in all four loops of the primary coolant circuit. Depending on the state of the heat-transfer contact surface oxide layer, the flow sections of the steam generators themselves or those of the steam generator cavities in the concrete shell can be blocked. The main factor causing the lead coolant to become solidified in the case of steam header rupture is a sufficiently large amount of feedwater in the secondary coolant circuit pipelines and heat-transfer equipment at high pressure. At the same time, in an accident involving failure of the regenerative feedwater heating system, this volume is not of key importance for the solid phase formation dynamics in the lead coolant. The study results can be used in elaborating the designs of lead cooled reactors. [ABSTRACT FROM AUTHOR]

A nonlinear boundary-value problem describing the operation of an isothermal flow reactor with account for the substance flow relaxation is considered. The examined substance source is described by a kinetic law that corresponds to a definite type of autocatalytic reaction. Possible solutions under the Dankwerts standard boundary conditions are determined. The limiting form of equations of the relaxation model has been taken as a basis for the mathematical model. The change in the regimes of operation of reactors in the presence of three solutions of the process equations is analyzed. [ABSTRACT FROM AUTHOR]

The aim of this work was to evaluate the scale-up of a laboratory reactor to full-scale plant for the electroflocculation of dairy food industry wastewater. The structural, operational and financial feasibilities were evaluated in reactors with either aluminum or iron electrodes. The laboratory reactor contained a beaker of 500.0 mL, two metal electrodes (thickness: 0.10 cm, length: 15.0 cm, width: 7.0 cm, distance between electrodes: 2.0 cm, total area for two electrodes in the laboratory reactor: 210.0 cm2), power source and magnetic stirring. The employed operational parameters included operation time of 1.0 h, applied potential intensity of 5.0 V, and electric currents of 0.94 A for aluminum electrodes and 0.71 A for iron electrodes. The scale-up was evaluated considering 110 m3 generated wastewater per day in a dairy food industry. The total applied electric power, electrode consumption, and final temperature after 1 h operation were 64.89 kWh, 1220 g m−3, and 32.19 °C using aluminum electrodes, whereas these values were 30.01 kWh, 1483 g m−3, and 25.64 °C using iron electrodes. Effective structural and operational costs higher than 65.0% in relation to the total costs of operation of the system were associated with the mass consumption of either aluminum or iron electrodes. In general, the scale-up of the laboratory reactor to full-scale plant was structurally, operationally and economically viable compared to the conventional wastewater treatment systems. [ABSTRACT FROM AUTHOR]

The problem of developing a 12-phase compensated rectifier unit for dc traction substations in railway transport has been considered. The importance of the problem is dictated by the growing scale and speed of freight service, as well as the occurrence of new types of freight traffic by dc railways. This requires increasing the energy efficiency of traction power supply. In view of this, it is suggested to introduce compensated units in the form of two three-phase reactors and a capacitor bank that works at the fifth and seventh harmonic frequencies in the 12-phase uncompensated rectifier units of traction substations. When solving the problem, an analytical method for studying electromagnetic processes with calculations of all the necessary characteristics and simulations in MATLAB were used, as well as design solutions for development of the compensated equipment and plan of equipment layout at dc traction substations of Russian Railways. The most important results of the problem being solved are the possibility of complete compensation of the reactive power supplied by substations, the guarantee of high efficiency of a capacitor bank of a compensated unit, and the maintenance and stabilization of rectified voltage in the contact circuit at the necessary level under conditions of intensification of freight service. The implementation of the problem being solved is provided by the innovative development of the Russian Railways. [ABSTRACT FROM AUTHOR]

Chinese magnetic confinement fusion (MCF) development has made significant progress during the past decade. With successful construction and operation of the EAST superconducting tokamak, China is playing a key role in advanced steady-state operations towards the next step ITER. The Chinese Fusion Engineering Testing Reactor (CFETR) is the next device for the Chinese MCF program which aims to bridge the gaps between the fusion experiment ITER and the demonstration reactor DEMO. Fusion power of CFETR will be in the range of 200 MW to over 1 GW. It will be operated in two phases: Steady-state operation and tritium self-sustainment will be the two key issues for the first phase with a modest fusion power up to 200 MW. The second phase aims for DEMO validation with a fusion power over 1 GW. The Chinese government has approved to proceed with the CFETR engineering design, and the project started on December 2017. Roadmap of Chinese MCF, gaps for construction and operation of CFETR, efforts to fill these gaps and speedup the fusion energy application in China are presented. [ABSTRACT FROM AUTHOR]

Electrochemistry constitutes a mild, green and versatile activation method of organic molecules. Despite these innate advantages, its widespread use in organic chemistry has been hampered due to technical limitations, such as mass and heat transfer limitations which restraints the scalability of electrochemical methods. Herein, we describe an undivided-cell electrochemical flow reactor with a flexible reactor volume. This enables its use in two different modes, which are highly relevant for flow chemistry applications, including a serial (volume ranging from 88 μL/channel up to 704 μL) or a parallel mode (numbering-up). The electrochemical flow reactor was subsequently assessed in two synthetic transformations, which confirms its versatility and scale-up potential. [ABSTRACT FROM AUTHOR]

This paper presents the results of an experimental study, numerical calculation, and analysis within the framework of a gas-dynamic model of silicon film deposition by a gas-jet plasmachemical method. A numerical model of gas mixtures flowing out of an annular nozzle unit and into a reactor is developed, and it allows one to determine a film thickness distribution over the surface of substrates placed in the reactor and satisfactorily describes the experimental data obtained. [ABSTRACT FROM AUTHOR]

Low-hydrogen-containing polydimethylsiloxane (l-HPDMS) with different hydrogen contents and relative molecular mass was prepared via ring opening equilibrium polymerization, in the fixed-bed reactor which was filled with catalyst particles. The kinetics of D4 ring opening reaction was studied to obtain the kinetic rate model. The physical model was determined by investigating the viscosity of the products at different aspect ratios and reaction temperature. According to the kinetic rate model and physical model, one-dimensional and pseudo-homogeneous ideal plug model was developed to simulate the fixed-bed reactor of l-HPDMS. The concentration of D4 and relative molecular mass curves of products predicted by this model were compared to those experimentally measured in a bench-scale reactor. It can also calculate the bed height of reactor and provide the basis for the design of fixed-bed reactor, for the preparation of different l-HPDMS. Moreover, the effects of liquid hourly space velocity on the relative molecular mass were investigated. [ABSTRACT FROM AUTHOR]

An analytical review of achievements in the field of the design of industrial equipment for mixing liquids, suspensions, and gas-liquid dispersions is presented. Various methods of mixing are discussed: mechanical, pneumatic, jet, vibrational, and magnetic. Nonconventional mixing devices with reversible movement of mixer parts, as well as static, rotary, rotor-stator, vortex, and ultrasonic devices, are considered. Miniaturization of equipment and micromixers were also reviewed. [ABSTRACT FROM AUTHOR]

Biofilms are found at the inner surfaces of drinking water pipes and, therefore, it is essential to understand biofilm processes to control their formation. Hydrodynamics play a crucial role in shaping biofilms. Thus, knowing how biofilms form, develop and disperse under different flow conditions is critical in the successful management of these systems. Here, the development of biofilms after 4 weeks, the initial formation of biofilms within 10 h and finally, the response of already established biofilms within 24-h intervals in which the flow regime was changed, were studied using a rotating annular reactor under three different flow regimes: turbulent, transition and laminar. Using fluorescence microscopy, information about the number of microcolonies on the reactor slides, the surface area of biofilms and of extracellular polymeric substances and the biofilm structures was acquired. Gravimetric measurements were conducted to characterise the thickness and density of biofilms, and spatial statistics were used to characterise the heterogeneity and spatial correlation of biofilm structures. Contrary to the prevailing view, it was shown that turbulent flow did not correlate with a reduction in biofilms; turbulence was found to enhance both the initial formation and the development of biofilms on the accessible surfaces. Additionally, after 24-h changes of the flow regime it was indicated that biofilms responded to the quick changes of the flow regime. Overall, this work suggests that different flow conditions can cause substantial changes in biofilm morphology and growth and specifically that turbulent flow can accelerate biofilm growth in drinking water. [ABSTRACT FROM AUTHOR]

A detailed analysis of interdiffusion processes in emitter shells of electrogenerating channels (EGC) of reactors for space application after long term reactor irradiation is performed. Interdiffusion of Mo and W in the mono- and polycrystalline manufacturing technology with the W layer applied over them with thickness on the order of 10-4 m with irradiation time from 3000 to 12 350 h and at temperatures from 1350 to 1670°C is studied. One of the mechanisms which facilitate the pore-formation process in the W layer and its separation is demonstrated. A method of calculating the activation energy, temperature, and residual thickness of the W layer on the basis of which the state of the shells can be estimated for a long time from the start of irradiation is proposed. [ABSTRACT FROM AUTHOR]

The existing biochemical system in the coke plant at Bhilai Steel Plant is inspected and assessed, with a view to introducing nitrification and denitrification, without reconstruction. It is shown that the existing biochemical-treatment facility will accommodate a nitrification and denitrification system capable of processing coke at a rate of 3.0-3.5 million t/yr. With reconstruction of the aeration system, the throughput may be increased to 4.8 million t/yr. That entails continuous dosing of alkaline reagent in the treated water. Recommendations are made for improved operation of the biochemical system. [ABSTRACT FROM AUTHOR]

The introduction of wastewater purification of nitrification-denitrification type in coke production at Visakhapatnam Steel Plant involves reconstruction of the existing biochemical system and the construction of additional units. That permits compliance with the standards for most pollutants. The results of introducing the new process are described, and the basic problems of biochemical water treatment before and after reconstruction are noted. [ABSTRACT FROM AUTHOR]

Physical experiments and mathematical modeling are used to study the kinetics of the reactions of carbon dioxide and water with potassium superoxide accompanied by oxygen release at various values of the temperature and humidity of the breathing gas mixture. The kinetics of the chemisorption is demonstrated to be limited by the rate of air regeneration in an airtight habitable facility. Experimental and analytical approaches are applied to determine the kinetic coefficients of the chemical reactions using the experimental data and a mathematical model of chemisorption kinetics. To perform the above chemical reactions, an original-design chemisorption reactor was developed, which contains plates with potassium superoxide nanocrystalline fixed on the fibers and pore surface of a fibrous polymer matrix. A mathematical model of chemical air regeneration is developed to calculate the guaranteed values of the parameters of the reactor and the protective effect time of the chemisorbent during which, at a given load, the reactor provides the appropriate concentrations of oxygen and carbon dioxide in the breathing gas mixture in an airtight habitable. [ABSTRACT FROM AUTHOR]

In order to promote the plasma technology for commercial application and improve the energy efficiency of non-thermal plasma, a series of experiments on energy efficiency of plasma reactor were carried out for volatile organic compounds removal. This research adopts a pipe-line reaction device with plasma generated by dielectric barrier discharge technology to examine the effects of different experimental parameters, including medium packing, electric field strength, the pollutant initial concentration, and gas velocity, on the energy efficiency. In the study, four kinds of packed materials were packed into the plasma reactor: a complex catalyst, BaSrZrTiO, MnO/γ-AlO, and γ-AlO. Through optimizing the experimental parameters, the best decomposition efficiency of toluene and the best energy efficiency were achieved. The experimental results show that the energy efficiency has a trend from increasing to decreasing with increasing pollutant gas velocity, and the energy efficiency changes from increasing to decreasing with the increasing of initial concentration of pollutants, and the decomposition efficiency and the energy efficiency have the same order from high to low with different packed materials in the plasma reactors, in turn, packed with complex catalyst, BaSrZrTiO, MnO/γ-AlO, γ-AlO and no padding. The optimized parameters for toluene decomposition are: the gas flow rate of 2 mL/min, the initial concentration range of 1500-2000 mg/m, the field strength intensity of 9.6 kV/cm, and the plasma reactor packed with a complex catalyst, which results in the best energy efficiency of 10 g/kWh. This research provides not only a new way to develop the plasma technology, but also a reference for the commercial application. [ABSTRACT FROM AUTHOR]