Physics of Atomic Nuclei最新文献

In the recent past, equipment manufactured by foreign companies was widely used in Russian industry. At present, however, under sanctions imposed against Russia and systemic restrictions, technical support for the operation of such complex equipment is significantly impeded or absent. The Novovoronezh NPP team is successfully responding to these challenges by developing technical solutions that enable the continued efficient operation of imported equipment under the new reality. This article presents one of the many examples of the Novovoronezh NPP team’s efforts aimed at ensuring Russia’s economic security and technological sovereignty. During operation of power units with VVER-1200 reactors, failures were identified in the operation of the turbine unit rotor hydraulic lift pumps manufactured by Allweiler GmbH (Germany). As part of the program for import substitution and improving equipment reliability, on the basis of the available documentation and a comparative analysis of the operating modes of rotor hydraulic lift pumps (RHLP) at the Novovoronezh and Leningrad NPPs, a technology was developed for repairing the RHLP with modernization of internal casing components by installing a bronze bushing and maintaining precise clearances of the pump’s internal casing assemblies. Improved circuit solutions have been proposed for the turbine unit rotor hydrostatic lift system that exclude RHLP damage during power unit operation at load and during planned preventive maintenance (PPM). The modernization of equipment manufactured in Germany and its successful operation at the Novovoronezh NPP is a vivid example of a scientifically grounded technical response to sanctions pressure from foreign countries and can be disseminated to other Russian enterprises as a positive practice.

A gradient method of identification of structural inhomogeneities in the objects of industrial equipment and products control based on the analysis of electric potential distribution inside a single reflex is developed. The computational and graphic method is applied to analyze the results of electrical control of NPP equipment during its manufacture. The research objective under consideration is to determine the degree of reproducibility of electrical inspection results and to develop for this purpose a universal digital identifier of structural inhomogeneities. Single reflexes are characterized by internal pressure and distribution of electric potential, which has a gradient. Single reflexes on potentiograms are isolated by electrophysical chromatography with the help of double amplitude discrimination using developed program codes. The emergence of potential distribution patterns on the surface of the controlled product is associated with the presence of inhomogeneous fields of internal stresses and deformations in it. To determine the local value of internal pressure in structural inhomogeneities, the value of energy density was estimated. This estimate for single reflexes was obtained using the value of electron density in metals and alloys. The magnitude of the gradient corresponds to the electric field strength around the reflex. On the surface, a single reflex represents a figure of concentric hexagons or other geometric figures. In the volumetric image, the reflex has the form of a pyramid with a certain figure at its base. The hexagonal shape of the reflex is associated with a quasi-equilibrium distribution of normal and tangential stresses around the point heterogeneity. The value of internal pressure in steels for the level of fixation in the interval (0 ≤ SLS ≤ 1) is close to the tensile strength; for the interval of negative values (–0.7 ≤ SLS ≤ –0.4), it is close to the yield strength.

The work is devoted to the experimental and theoretical investigation of terahertz (THz) transmission spectra of hexogen (RDX, cyclotrimethylenetrinitramine) film in the frequency range of the strong characteristic absorption band of RDX at approximately 0.8 THz, measured at various angles of incidence (0°–60°) and polarizations of the probing THz radiation. Experimental THz transmission spectra of the RDX sample were recorded using a THz imaging facility with spectral resolution. For mathematical modeling of the spectra, the characteristic matrix method (transfer matrix method) was employed. It is shown that both the experimental and theoretical THz transmission spectra of the RDX film exhibit a clear manifestation of the hexogen absorption band as a local minimum near the frequency of ~0.8 THz for all studied angles of incidence and polarizations of the probing THz radiation. The results of this work can be used in the development of terahertz systems intended for spectral identification of substances in the condensed phase.

The use of quantum technologies in the modern world poses significant challenges to the security of critical information infrastructure, which underpins key sectors such as healthcare, energy, transportation, and communications. Cryptographic algorithms like RSA and ECC, long considered reliable, have lost their resilience in the face of quantum computing capabilities, making the search for modern solutions to ensure data protection a top priority. The main risks posed by quantum computers include the potential compromise of encryption algorithms, disruption of data integrity, and destabilization of critical system operations. The methodological foundation of this study is based on the analysis of 318 sources from international databases such as Scopus and Web of Science. From this body of literature, 24 publications most relevant to the topic were selected. A comparative method was employed to analyze classical and quantum threats. The aim of the study is to examine the impact of quantum attacks on the security of critical information infrastructure (CII) at the current level and propose pathways for transitioning to quantum-resilient solutions. The results emphasize the necessity of implementing innovative cryptographic approaches, such as lattice-based and code-based algorithms, as well as combined (hybrid) technologies. Successful protection of the infrastructure requires a systematic approach, including a comprehensive audit of existing systems, training of specialists, and the removal of technical and regulatory barriers. The developed step-by-step plan minimizes risks and establishes a foundation for the secure implementation of new standards.

The pair correlation function of inhomogeneities in samples has been actively studied using small-angle scattering methods. Recently, it has become possible to determine this function from atom probe tomography (APT) data. This study has examined the effect of the finite size and shape of a sample on the pair correlation function of inhomogeneities derived from APT data. The number of impurities near the boundary of a large cubic sample with dimensions in all directions significantly exceeding the characteristic correlation radius, can be considered much smaller than that in the bulk. If this assumption is not fulfilled, there arises a geometric factor for which a general expression is derived. The geometric meaning of this factor represents the probability to find the specific interpoint distance within the sample. For the case in which the sample is an elongated rectangular parallelepiped, an analytical expression for the geometric factor in terms of elementary functions has been obtained. The following model systems have been considered: a completely uncorrelated distribution of centers, a simple cubic lattice, and a densely packed system of polydisperse hard spheres. These systems have been selected owing to their differing degrees of spatial order. It has been shown that accounting for the geometric factor has led to the correct pair correlation function for the selected model systems of inhomogeneities.

In the paper, the numerical model and the results of calculations of equilibrium plasma configurations in the magnetic trap “Belt” from the class of Galatea traps proposed by A.I. Morozov have been clarified. The confining magnetic field is created by current-carrying conductors immersed in the plasma, but not in contact with it. In a series of previous studies, the geometry and basic patterns of configurations in a toroidal trap “Belt” straightened into a cylinder with two conductors parallel to its axis were studied. The two-dimensional plasmastatic model of the configuration is based on the numerical solution of a boundary value problem with the well-known Grad–Shafranov equation for the magnetic flux function in the cross section of a cylinder. It contained a significant simplifying assumption that makes it possible to deal with a simply connected domain of the problem solution: the conductors were not excluded from the domain, and the currents in them were represented by additional terms in the equation. In the proposed study, this simplification is absent, and the problem is posed in a non-singly connected domain outside the conductors of square cross section. The role of the electric current in the formation and maintenance of the equilibrium magnetoplasma configuration is played by the boundary condition containing the circulation of the magnetic field along the boundary of each conductor. In a series of calculations with different values of the dimensionless parameters of the problem in a non-singly connected domain, it has been found that the main properties of the configuration and the patterns of their dependence on the parameters qualitatively coincide with those obtained earlier in a simply connected domain. This indicates the legitimacy of the previous version of the model and at the same time clarifies its result. The dependence of the geometry and quantitative characteristics of the configurations on the dimensionless parameters of the problem has been clarified.

In the paper, information about the radiation situation and radiation doses of the population, as well as occupational exposure in 2022 within the territories served by the FMBA of Russia has been presented. The radiation situation and radiation doses of the population due to the natural and technogenically altered radiation background have been analyzed. Data on the exposure of personnel of groups A and B of enterprises, including nuclear power plants, have been presented. In none of the controlled regions was there any excess of the maximum permissible levels of radioactive contamination of air and water in open waterbodies in the sanitary protection zone and the observation zone. The distribution of the number of personnel working with ionizing radiation sources or exposed to ionizing radiation by dose intervals for individual radiation doses, as well as the value of the collective dose, has been given. The main number of 58 965 personnel (67.5%) received radiation doses up to 1 mSv. The external and internal irradiation of personnel of domestic nuclear power plants, for which data on averages, medians, modes, standard deviations, quantiles, coefficients of variation of effective doses, and collective doses are provided, has been analyzed. Compared to 2017, the collective doses of most nuclear power plants have somewhat decreased. The average dose has not changed significantly for most nuclear power plants compared to 2017. Information on the structure, number of X-ray radiological procedures by types and groups of organs, and collective and average radiation dose of patients for various procedures in 2022 on the territories serviced by the FMBA of Russia has been provided. The quantitative ratio is dominated by chest organ fluorograms. The structure of medical exposure of patients in 2022 has been given. Computer tomography has made the largest contribution to the total dose (75.01%) at a contribution of 6.25% in terms of the number of procedures. Data on the radiation situation and radiation dose in the Russian Federation obtained in 2022 have been compared with similar data for other years.

The results of studies on the decomposition of surfactants in reactor bleed-off water by corrective treatment with hydrogen peroxide followed by heating are presented. A method for determining the type and concentration of surfactants in aqueous solutions based on high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS) is proposed. The dependences of the purification efficiency of the solution on initial surfactant concentration, treatment time and temperature, and the presence of an additional contaminant (potassium permanganate) are investigated. It is shown that, in order to satisfy regulatory document requirements under a conservative approach, surfactant removal efficiency should be at least 81% when evaporating the bottoms before cementing to 150 g/L and at least 95% when evaporating to 450 g/L. It is demonstrated that dosing hydrogen peroxide into aqueous solutions leads to the decomposition of complexing agents during processing at temperatures between 80–100°C. At temperatures of 80°C and above, the surfactant concentration reaches 62%, which corresponds, without a conservative approach, to the surfactant content in the bottoms not exceeding 1% after 4 h of treatment. Dosing potassium permanganate into the water to be purified makes it possible to remove almost 100% of surfactants without resorting to heating the water to the boiling point. The efficiency of surfactant removal down to the level of complexing agents in the bottoms below 1% is achieved by dosing potassium permanganate 70 min after the start of the experiment, and when heating to 100°C, in less than 40 min. The results obtained can be used to justify the safety of radioactive waste management technologies used in the nuclear power industry.

A calculated estimate of the neutronic characteristics of a light-water reactor core with a changing neutron spectrum is presented. The software tool DESNA-7 neutron physics module, designed for three-dimensional modeling of the core in a two-group approximation, is used. The calculation of the neutron cross sections is carried out in the software tool SAPHIR-95.1. Fuel assembly models with guide channels for the placement of absorbing elements or mobile displacers is developed, forming two cores with the same thermal power and different ways of regulating reactivity: boron and spectral (with partial boron). To compensate the excess reactivity partially, gadolinium fuel rods in the form of Gd₂O₃ with a concentration of 5 wt % are used. Uranium oxide with natural content of U²³⁵ is used as the material for the displacers. The two methods of displacer extraction are considered: linear displacement during the campaign and complete extraction of displacers (stationary from the beginning of the campaign) on day 326. They do not lead to a significant change in the critical concentration of boric acid. It is shown that the use of spectral regulation makes it possible to reduce the concentration of boric acid in the coolant by 35%. It is shown that the reactivity coefficients in terms of temperature of fuel and coolant and density of coolant increase in absolute value during the campaign, maintaining their sign. The value of the reactivity coefficient for the concentration of boric acid in the first reactor circuit, depending on the water–uranium ratio, decreases in absolute value. The maximum value of the axial power peaking factor in the core with spectral regulation is 1.6. The possibility of using absorbing rods placed in the fuel assembly guide channels as emergency protection devices is considered.

The effect of UV radiation on deuterium retention in codeposited lithium-deuterium layers has been investigated. The samples were obtained by sputtering a liquid lithium cathode with a deuterium plasma of a magnetron discharge. The deuterium content in the films was analyzed by in-vacuo thermal desorption spectroscopy. After deposition, the deuterium content in the films averaged D/Li = 15 at %. Irradiation with ultraviolet radiation led to the formation of additional low-temperature desorption peaks (T ~ 500 K), as well as to the disappearance of high-temperature peaks (T > 700 K) or to their shift to a lower-temperature region. In the future, the results obtained may form the basis for methods for detecting the places of predominant accumulation of lithium hydride in tokamaks, as well as facilitating the process of removing tritium from the internal elements of thermonuclear installations.