{"title":"CONVECTION OF A VISCOUS INCOMPRESSIBLE COOLANT IN A HORIZONTAL CYLINDRICAL PIPE HEATED FROM BELOW. AN ANALYTICAL SOLUTION","authors":"O.L. Andrieieva, K.V. Abelentseva, V.I. Tkachenko","doi":"10.46813/2023-147-046","DOIUrl":"https://doi.org/10.46813/2023-147-046","url":null,"abstract":"To intensify heat transfer processes in nuclear power, it is proposed to use natural convection in horizontal heat exchange tubes. In the article, the problem of convection of a viscous, incompressible fluid in a horizontal cylinder heated from below is analyzed analytically. The proposed analytical method is based upon the use of basic functions that satisfy the initial equation but do not satisfy the boundary conditions. The problem with boundary conditions with a sufficient degree of accuracy is solved by dividing the area of the square described around the cylinder into a large number of smaller element cells. This separation has made it possible to obtain analytical expressions of critical Rayleigh numbers for different positions of current lines in a horizontal cylinder with a viscous, incompressible fluid.","PeriodicalId":54580,"journal":{"name":"Problems of Atomic Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136013769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"CAVITATION EROSION RESISTANCE OF VACUUM-ARC COATINGS BASED ON TiN","authors":"І.О. Klimenko, V.G. Marinin, V.А. Belous, N.A. Azarenkov, М.G. Ishchenko, V.S. Goltvyanytsya, A.S. Kuprin","doi":"10.46813/2023-147-126","DOIUrl":"https://doi.org/10.46813/2023-147-126","url":null,"abstract":"This review presents an examination of various studies investigating the impact of deposition process conditions and structural characteristics of TiN-based vacuum-arc coatings on their ability to withstand cavitation erosion in water. The structural and phase composition of TiN coatings is influenced by two key technological parameters: the nitrogen pressure in the vacuum chamber and the substrate bias potential. However, it has been observed that vacuum-arc alloy coatings such as TiSiN and TiAlYN exhibit notably lower resistance to cavitation erosion. Additionally, research on multilayer Ti-TiN coatings with varying numbers and thickness ratios of layers has not shown an improvement in resistance to cavitation wear when compared to single-layer coatings deposited under optimal conditions. On the other hand, single-phase stoichiometric TiN coatings deposited at a higher nitrogen pressure of 2 Pa and a bias potential of up to -300 V have demonstrated remarkable resistance to cavitation wear. These coatings could be effectively utilized to protect the titanium alloy Ti-6Al-4V against cavitation damage.","PeriodicalId":54580,"journal":{"name":"Problems of Atomic Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136013904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"THE GAS IMPURITIES INFLUENCE ON THE CHARACTERISTICS OF VT1-0 AND VT6 TITANIUM ALLOYS","authors":"Serhii Polishko","doi":"10.46813/2023-147-137","DOIUrl":"https://doi.org/10.46813/2023-147-137","url":null,"abstract":"This article dials with methods for producing titanium alloys VT1-0 and VT6 and the gaseous impurities effect on plasticity characteristics. It has been shown that electron-beam melting with an intermediate capacity makes it possible to remove a significant number of impurities in titanium alloys VT1-0 and VT6. It has been proven that industrialscale modification of titanium ingots with a total weight of more than 18 t, followed by their pressure treatment without remelting, allows minimizing the energy costs for obtaining finished semi-finished products.","PeriodicalId":54580,"journal":{"name":"Problems of Atomic Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136013910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"MODIFIED STEFAN CONDITION IN STEFAN PROBLEM","authors":"D.G. Bielykh, S.F. Skoromnaya, V.I. Tkachenko","doi":"10.46813/2023-147-021","DOIUrl":"https://doi.org/10.46813/2023-147-021","url":null,"abstract":"The two-phase one-dimensional Stefan problem (SP) with the boundary between the phases moving with time is considered. The position of the boundary is determined by the modified Stefan condition (MSC), which is obtained from the original nonlinear diffusion equation by integrating over a thin transition layer, and by tending its thickness to zero. Upon receipt of the MSC, the diffusion coefficient is represented by the sum of the Heaviside step functions. It is shown that the MSC differs from the standard one in that in the latter, the derivatives of the concentrations with respect to the phase coordinates are interchanged. An expression for the displacement of the interphase boundary is obtained, which, as in the standard SP, is proportional to the square root of time. The results of using the MSC are confirmed by experimental data on the displacement of the Cu/Sn interface during diffusion bonding during isothermal annealing.","PeriodicalId":54580,"journal":{"name":"Problems of Atomic Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136013918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Tolstolutska, M. Tikhonovsky, О. Velikodny, S. Karpov, V. Ruzhytskyi, G. Tolmachova, R. Vasilenko
{"title":"HARDENING OF LIGHTWEIGHT MULTI-PRINCIPAL ELEMENT TITANIUM-BASED ALLOY UNDER AR ION IRRADIATION","authors":"G. Tolstolutska, M. Tikhonovsky, О. Velikodny, S. Karpov, V. Ruzhytskyi, G. Tolmachova, R. Vasilenko","doi":"10.46813/2023-147-003","DOIUrl":"https://doi.org/10.46813/2023-147-003","url":null,"abstract":"Among new prospective materials multi-principal element alloys (MPEA) have attracted considerable attention in recent years due to their excellent corrosion and irradiation resistance as well as their good mechanical properties over a wide temperature range. The new lightweight multi-principal element titanium-based alloy 61Ti-10Cr-7Al11V-11Nb (at. %) with high ductility at room and elevated temperatures is studied. This single-phase bcc alloy was irradiated with 1.4 MeV Ar ions at room temperature and mid-range doses from 1 to 10 displacements per atom. The effect of irradiation is studied by examining the hardening. A comparison was performed with irradiation-induced hardening behaviour of MPEA, 316 austenitic stainless steel irradiated under an identical condition. It was shown that hardness increases with irradiation dose for all the materials studied, but this increase is lower in multi-principal element alloys both face-centered cubic (FCC) and body-centered cubic (BCC) structures than in stainless conventional steel.","PeriodicalId":54580,"journal":{"name":"Problems of Atomic Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136013766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"TECHNOLOGICAL BASIS OF THE PROCESS OF ZIRCONIUM AND HAFNIUM SEPARATION","authors":"A.P. Mukhachev, D.O. Yelatontsev, O.A. Kharytonova, V.G. Shevchenko","doi":"10.46813/2023-147-103","DOIUrl":"https://doi.org/10.46813/2023-147-103","url":null,"abstract":"The paper presents the results of industrial testing of the process and equipment for the extraction separation of zirconium and hafnium in a single technological cycle with the production of high-purity nitrate compounds and pure nitric acid solutions as raw materials for the production of sodium nitrate. It is shown that the efficiency of the extraction process is determined primarily by the purity of the nitric acid solution by the content of a critical impurity – silicic acid, which causes an undesirable emulsification process and disrupts the stability of the process. Optimal conditions have been determined under which the formation of non-extractable forms of zirconium and hafnium is excluded. The replacement of pulsating columns with centrifugal extractors reduced operating costs by reducing the volume of a one-time load of a flammable extractant and its losses as a result of hydrolysis. This increased the degree of separation of zirconium and hafnium. Centrifugal extractors provided high process kinetics, reduced production areas, and increased labor productivity and product quality.","PeriodicalId":54580,"journal":{"name":"Problems of Atomic Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136013771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"TEXTURAL AND STRUCTURAL REGULARITIES OF DEFORMATION BY ROLLING OF Zr-2.5%Nb ALLOY","authors":"D.G. Malykhin, V.M. Grytsyna, K.V. Kovtun","doi":"10.46813/2023-147-077","DOIUrl":"https://doi.org/10.46813/2023-147-077","url":null,"abstract":"A review of studies of regularities of changes in the crystallographic texture of the longitudinal and cross rolling of the Zr-2.5%Nb alloy is given. Accordingly with this, plates were made from longitudinal fragments and rings of a tube 15.01.5 mm from the fuel assemblies of Russian RBMK reactors. The plates were annealed at 580 °C for 3 h. X-ray studies of texture changes with the degree of deformation of the plates by rolling were carried out. The principle of method of inverse pole figures was used with the calculation of the Kearns texture coefficients, as well as measurements of tilt curves (0002) was. Non-uniformiity of deformation during straightening of the tube blanks was taken into account. It is found that the main rotations of crystallographic c-axes in the plates at any rolling direction are carried out in the plane corresponding to the cross-section of the original tube. Existence of an initial stage of increased textural changes during deformation of the plates is found, what is qualitatively and quantitatively related to activity of tensile twins of the {1012}[1011] system. Regularities in texture changes at the subsequent moderate stage of deformation with the participation of compression twins are considered. The purely twinning nature of the textural doublet, which latter is characteristic of the rolling texture of metals of the titanium subgroup, is explained. It is noted and explained a fact that during cross rolling of plates (made from tube rings), textural changes occur at a rate twice as high as during longitudinal rolling. As considered, all similar regularities can be carried out for the metals of the titanium subgroup.","PeriodicalId":54580,"journal":{"name":"Problems of Atomic Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136013913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"REVIEW: INVESTIGATION OF PROCESSES OF DAMAGE TO THE HEAT TRANSFER TUBE OF WWER-1000 STEAM GENERATORS","authors":"O.G. Rudenko, S.V. Gozhenko","doi":"10.46813/2023-147-034","DOIUrl":"https://doi.org/10.46813/2023-147-034","url":null,"abstract":"The analysis of operational damages of heat transfer tubes (HTT) in steam generators (SG) of WWER-1000 power units was carried out. The processes of contamination of the surfaces of HTT of SG PGV-1000M are considered. The processes of formation and growth of corrosion pits on the surface of heat transfer tubes are analyzed. The process for the initiation of corrosion pits and the development of cracks in the heat transfer tubes metal, which includes the combined action of a corrosive environment and non-metallic inclusions in heat transfer tubes, was proposed.","PeriodicalId":54580,"journal":{"name":"Problems of Atomic Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136013915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"SPECTRAL-LUMINESCENT AND ELECTROPHYSICAL STUDY OF RADIATION OXIDATION OF BERYLLIUM IN WATER","authors":"N.N. Gadzhieva, S.Z. Melikova, F.N. Nurmammadova, Sh.N. Nasirov, F.G. Asadov, B.A. Mammadov","doi":"10.46813/2023-147-030","DOIUrl":"https://doi.org/10.46813/2023-147-030","url":null,"abstract":"The radiation oxidation of Be in water at room temperature in the absorbed dose range Dγ = 0.5…180 kGy was studied by radiothermoluminescence (RTL), infrared reflection-adsorption spectroscopy (IRRAS), and electrical conductivity. The participation and role of surface relaxing intermediate-active particles in the dynamics of changes in the oxidation process are considered. Using the RTL method, the role of surface oxygen hole centers generated by γ-irradiation and chemisorbed oxygen in the formation of nanooxide films was experimentally established. The formation of nanooxide films on the surface of Be in water was traced in the IR reflection spectra. The kinetics of radiation oxidation of beryllium has been studied and its radiation passivation has been established. According to the logarithmic dose dependence of the surface resistivity Be, two stages of the oxidation process were revealed. It is shown that the formation of nano oxide films leads to a decrease in the surface electrical conductivity of beryllium by 2 orders of magnitude and an increase in the thickness of oxide films by 1.6 times.","PeriodicalId":54580,"journal":{"name":"Problems of Atomic Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136013917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"ON THE POSSIBILITY OF COEXISTENCE OF DISLOCATION LOOPS OF DIFFERENT NATURE IN ZIRCONIA WITHIN THE FRAMEWORK OF CLASSICAL ELASTIC THEORY","authors":"O.G. Trotsenko, A.V. Babich, P.M. Ostapchuk","doi":"10.46813/2023-147-009","DOIUrl":"https://doi.org/10.46813/2023-147-009","url":null,"abstract":"A distinctive feature of the radiation-induced microstructure of zirconium is, firstly, the coexistence of prismatic loops of different natures, and secondly, the nucleation and growth to large sizes of vacancy basis loops. In the work, within the framework of classical concepts of elastic interaction between a point defect and internal sink the results of numerical calculations of the dependence of bias loops of different natures lying in the basal and prismatic planes of zirconium on their radius are presented. The essential role of the form of the boundary condition on the outer surface of loop area of influence in toroidal geometry is shown. Possibilities, both the coexistence of prismatic loops of different natures and the growth of vacancy basis loops are discussed.","PeriodicalId":54580,"journal":{"name":"Problems of Atomic Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136013920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}