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The paper analyzes the gas phase, the behavior uranium, the calculation of thermophysical properties during heating of nuclear reactor graphite containing various actinides. The study was carried out by thermodynamic modeling using the TERRA software package in the range from 423 to 2123 K at a constant pressure of 0.1 MPa. Up to a temperature of 623 K, the main components of the gas phase are water vapor, carbon dioxide, methane and hydrogen. Above 1023 K, the gas phase contains predominantly carbon dioxide and monoxide. It was revealed that in the range of 423-923 K uranium is present in the form of condensed compounds - uranium dioxide and uranyl chloride. Up to a temperature of 1623 K, uranium is present in the form of condensed uranium dioxide and calcium uranate. At temperatures above 2023 K, condensed uranium compounds are converted into gaseous and ionized compounds of uranium trioxide and dioxide. The thermophysical characteristics change unevenly up to a temperature of 923 K.

The article discusses emergencies that occurred at nuclear power plants in the Russian Federation for the period from 1992 to 2019. In the work, a systematic and statistical analysis was carried out, the number of emergency events was counted, the nuclear power plants at which accidents and incidents occurred, the year of occurrence of the emergency event was indicated, the main objects, the causes of emergencies were identified, the types of reactors at which accidents often occurred were identified, conclusions are drawn.

In this work, the composition and thermophysical properties of the “Reactor graphite-H2O” system at temperatures from 2123 to 3223 K are calculated. It was found that the main components of the vapor phase at a temperature of 2123-2923 K: carbon dioxide, carbon monoxide, water vapor, hydroxide, hydrogen, atomic hydrogen. At temperatures above 3223 K, oxygen and atomic oxygen are added to the gases present. The balances of uranium and plutonium are considered. Uranium at temperatures above 2123 K is present in the system in the form of gaseous and ionized uranium dioxide and trioxide. Plutonium at temperatures above 2123 K is present in the system in the form of gaseous and ionized plutonium oxide, gaseous plutonium dioxide. The calculation of thermophysical properties for the considered system is carried out.

The problems faced by the mining and construction industries are analyzed in the article. A unified concept is formulated to eliminate the problems that arise in the region of mineral extraction, together with solving the problems of expanding the raw material base of the construction sector. The idea of rational use of man-made waste from local mining enterprises and industrial waste for the construction and backfill mixes preparation is presented. The aspects of their application as an aggregate in mixtures are considered on the example of man-made waste (halite enrichment waste). It is noted that the use of man-made waste in construction and backfill mixes must be carried out after deep additional processing. Deep processing allows to maximize the use of useful components of man-made waste and eliminate the negative consequences of harmful ones. It is established that the best way of additional processing is the activation of man-made waste in disintegrators. It is proved that activation increases the strength of structures or cemented mass by 25-30%, reduces the consumption of binder by 40-50%, while maintaining the same strength characteristics. The use of man-made waste in construction and backfill mixtures expands the raw material base for the construction and mining sectors, allows to implement the concept of sustainable development of the region, and reduces the impact on the environment.

The admissibility of replacing traditional cement, used as a binder with magnesium-containing man-made waste in the preparation of a construction and fill mixture is justified. The possibility of replacing the traditional specially mined aggregate in construction and fill mixtures is proved. The results of testing samples after cementing and a construction-fill mixture prepared on the basis of man-made waste are presented. The positive effect of mechanical activation of the backfill mixture components on its rheological properties and strength characteristics of the fill mass is studied. The use of lignosulfonate as an additive was confirmed to improve the binding and rheological properties of the backfill mixture. The involvement of man-made waste in the closed cycle of the main and auxiliary production reduces the volume of man-made massifs, which significantly reduces the impact of mining production on the environment.

The paper presents the circuitry solutions on the basis of which a precision programmable DC power supply was created and tested. The principle of operation of the DC power supply uses a high-precision method of controlling a pulse current stabilizer, based on the adaptation of the duty cycle of the pulse-width modulation (PWM) signal to control the inverter when the load mode changes. From the output of the inverter, the signal is converted by the rectifier into a DC signal with subsequent smoothing of the ripple and enters the load circuit. From a precision low-resistance shunt connected to the load circuit, the signal through the ADC in digital form enters the control unit (CU), implemented on the basis of FPGA, which has a embedded programme for controlling the voltage / current stabilization modes in the load circuit. In addition, the paper shows the use of a precision programmable DC power supply for solving the problem of calibrating the BTC-110S spectrometer. The block diagram of the test stand for spectrometer calibration is presented and relations for the correction of the recorded signals of the thermal radiation spectrum of the objects under study are derived.

The article describes the main causes of emergencies at nuclear power plants. For the twenty-year period from (1952-1972), reviewed and described in which countries and at which nuclear power plants accidents and incidents occurred. The main objects of emergencies are considered. It was determined that more accidents occurred at NRX reactors.

The development and research of micro and nanostructures for the manufacture of ultrasonic piezoacoustic elements has been carried out. The structures obtained in this work have practical applications for the manufacture of piezoelectric and piezoacoustic elements, in particular, for using in liquid flowmeters as receivers and emitters of an ultrasonic signal. A structure of nanocells was obtained that was different from standard piezoelectric elements (disk, cylinder), but with the same coefficients, characteristics, and radiation pattern.

The method of thermodynamic modeling was used to determine composition and thermophysical properties of a gas-plasma phase of a system of radioactive graphite – water vapor in the temperature range from 1000 to 3200 K. It has been established that in the temperature range from 1000 to 1100 K, the main components of the gas-plasma phase are H2, CO, H2O, CO2, CH4. In the temperature range from 1100 to 2200 K – H2, CO, H2O, CO2. At temperatures from 2200 to 2600 K those are H2, CO, H2O, CO2, H. In the temperature range from 2600 to 3000 K those are H2, CO, H2O, CO2, H, OH. In the temperature range from 3000 to 3200 K those are H2, CO, H2O, H, CO2, OH, O, O2. The thermophysical properties of the system under consideration have been calculated: specific volume, entropy, enthalpy, total internal energy, number of moles in the system.

Using the method of thermodynamic modeling the composition and quantity of generator gas formed during the processing of radioactive graphite in water vapor in the temperature range from 773 to 1073 K were determined. It has been established that the main components of the gas phase are CO, H2, CO2, CH4, H2O, HCl. The technological scheme and the scheme of a gas generator for the processing of radioactive graphite are developed.

The work is devoted to the numerical-analytical solution of the contact problem when reinforcing the floor slab with beams using the mathematical apparatus of generalized functions. Such tasks arise during the reconstruction of existing buildings, when reinforcement of floor slabs is required to increase their bearing capacity under load. The contact of a slab with reinforcing beams is considered for various types of one-sided local restrictions on its deflections. To solve the structurally nonlinear problem of contact interaction between the slab and the reinforcement beams, a stepwise loading method is used in combination with the method of variational approximations. At each loading step, to ensure the convergence of the desired function of the plate deflections from the action of local contact forces of the beams resistance, the procedure of the method of variational approximations is used. Based on the use of the mathematical apparatus of generalized functions and the use of the method of variational approximations with the help of a stepwise algorithm, numerical-analytical solutions for the problem of contact interaction of an elastic plate with reinforcement beams are obtained. Two types of elastic one-way connections were considered: discrete supports and support along rectilinear segments. Due to the rational choice of approximating functions that describe with a high degree of accuracy the irregular parameters of the considered constructive-nonlinear system while keeping a small number of members of the series, a higher calculation accuracy is achieved in comparison with computational complexes that implement numerical methods of strength calculation of the indicated building structures.

To assess the burn resistance air tuyere in blast furnace using the finite element method (axisymmetric problem), DEFORM-2D software was used. Ceramics with a slurry coating applied to it was used as thermal insulation for protection against air tuyere burnout. The resistance to air tuyere burnout with the selected thermal insulation on its outer surface is estimated by calculating the stress intensity.

The paper is devoted to the development of the mixed form of finite element method for the calculation of constructions and structures. We consider the approach based on the approximation of discontinuous stress fields and the use of the penalty function method to satisfy the equilibrium equations. It is shown that the continuity of both normal and tangential stresses only on the adjacent sides of the finite elements contributes to the expansion of the class of statically admissible stress fields. At the same time, the consistent approximation is provided, both of the main part of the functional of additional energy, and its penalty part. Using the given approach, solutions of some problems were obtained and analyzed, in particular, the calculation of the cantilever beam-wall. The results obtained were compared with the decisions on the FEM in displacements and stresses, as well as with the exact solutions. It is shown that solutions based on the approximation of discontinuous stress fields in mixed form FEM converge to exact values from below and are more flexible in comparison with the solutions obtained by FEM in displacements. In addition, the accuracy of determining stresses is higher here.

A proposed method to increase the service life of the heat-insulating insert in the air passage of the blast furnace tuyere suggested gluing heat-resistant siliceous fabric onto its outer surface, and to reduce heat loss and increase the tuyere resistance to burnout, fixing a ceramic disk to the end of the tuyere’s nose. The necessity of measures to increase the service life of a heat-insulating insert in the tuyere was justified by simulating its stress state in Ansys. The use of heat-resistant siliceous fabric on the entire outer surface of the insert allowed a more than twofold increase in the insert’s service life compared to the option when the fabric was glued to the insert part from the flange to the gas pipe. Using simulation of the tuyere’s thermal state in a DEFORM–2D environment and industrial experiments, the possibility of reducing heat loss and protecting the tuyere from burnout by thermal insulation of the end of its nose using a ceramic disk is shown.

Problems of contact interaction of structures and their parts have a wide range of applications in construction. In particular, this problem arises during the reconstruction of existing buildings, when strengthen of floor slabs is required to increase their bearing capacity. In this case, the contact of the slab with the strengthening beams occurs along a continuous line of a given shape with a contact zone unknown in advance. In this paper, with the aim of constructing high-accuracy numerical-analytical solutions for the contact problem while keeping some series members, the mathematical apparatus of the theory of generalized functions is widely used. To solve the structurally nonlinear problem of strengthening the floor slab with an elastic beam, a step-by-step loading method is used. At each step, the deflection functions, the length of the contact segment, the value of the reaction along the contact segment are determined and the working scheme of the plate-beam reinforcement system is specified from the minimum functional condition of the potential energy of the contacting elastic elements. Using the proposed numerical-analytical approach, we obtained and analyzed solutions to the problem of one-sided support of a slab to an elastic gain beam. Due to the twodimensional approximation of the function of a slab deflection by discontinuous functions, the proposed approach shows satisfactory convergence, stability and accuracy of the solution while keeping some terms of the series.

In many countries in the world the strong wind can break wires very easily. In this case many regions and very important objects will be without of the electrical energy and lighting. To find quickly the place where this situation had happened it takes many hours. It is a great problem. Everybody knows that it is rather difficult to reach this damaged place (maybe in the forest or among the high hills). Strictly any repair takes usually many hours too. That’s why it is needed to find the simplest method to defend any long wires against their break under the strong wind. In this situation if the strong rushes of the wind begin to swing wires intensively, they cannot sustain such overloads too long. Moreover, the resonance phenomenon in these oscillations will be without fail and breaks wires very quickly. In this article there is a new way how to protect any wires against the break using only several hard rods fixed firmly on the wires. How it can be done it is described in detail below and some of recommendations including the results of experiments are shown also.

In modern day industry of heavy engineering, parts made from billets comprising large-sized pipe forgings are widely used. The paper presents results of the study of various methods of broaching on mandrel of large-sized pipe forgings and presents the results of industrial testing of the developed methods of broaching and designs of mandrels.

The behavior of Am, Eu, Sr radionuclides was investigated by thermodynamic modeling method at heating of radioactive graphite in NaCl – KCl – Na2CO3 – K2CO3 molten salt with additives of nickel oxide NiO. The integrated thermodynamic analysis was carried out by means of TERRA software in temperature range 373-3273 K to determine possible composition of condensed and gaseous phases. It was established that americium is in gaseous state in temperature range 2773-3273 K. Europium is in the forms of gaseous EuO and Eu in temperature range 2373-3273 K. Strontium is in the forms of gaseous SrCl2, SrCl, Sr, SrO in temperature range 2373-3273 K.

Molecular dynamics was used to calculate the melting phase transition properties in classical ionic systems. A simplified model of pair potential is considered, with only two terms the Born-Mayer repulsion and the Coulomb interaction. Preliminary ab initio calculation of the potential parameters was carried out for sodium halides. Regularities in changes of temperature, enthalpy and entropy of melting have been analyzed by direct heating method. It was found that the calculated values of the enthalpy of melting differ from the experimental data less than 5%.

During the filming by a high-speed video camera, the images of a particle flux moving in a plasma jet during the spraying of powder coatings on machine parts are recorded. The distributions of key physical parameters of particles in the flux cross sections of the plasma jet with the help of algorithms of the filtering and selection of the particle tracks from the images are computed. The distribution of the particle velocities along the jet axis was computed. The processing of the image stream with a small frame exposition time allowed determining the particle bulk density distribution along the plasma jet axis. As a result of images processing for cross section at the end of the flux the dependence of differential density distribution of particles vs. orientation angle of their tracks directions relative to the flux axis has been obtained.