bluuebunny/crossref_metadata_2025_split huggingface dataset:
Research study of possibility producing radioisotope Mo-99 in the active core of the BN-600 reactor using an irradiated assembly with a high flux of thermal and resonance neutrons
Authors: Klimenko D S , Ignatiev I A , Kolesov V V , Korobeynikov V V 
Published: December 2020

Abstract
It is fact that production of secondary fuel isotopes (plutonium) is carried out in fast neutron reactors, and the possibility of production of non-fuel radioactive isotopes for use in medicine and industry is being considered. BN-600 has a high power density in the core. This makes it possible to achieve a high rate of fission of target nuclei, which is especially important in the case of the production of radioisotopes, due to their short half-life. To meet the growing demand for isotopes, it is planned to use irradiation devices in high-power sodium fast reactors. This type of irradiation device assumes a massive production of the necessary isotopes. The paper considers the design of irradiation devices for the production of molybdenum-99 isotope in the BN reactor. The presented design of the irradiation assembly contains a moderator in order to combine the advantages of the high neutron flux inherent in fast reactors and the thermal neutron spectrum inherent in thermal reactors.
Modeling the core of a lead-cooled reactor
Authors: Chudinova V A , Nikonov S P 
Published: December 2020

Abstract
This paper presents the results of thermohydraulic modeling of the reactor core with a lead coolant, which is based on the calculation scheme for the ATHLET code, obtained on the basis of open information on the BREST-OD-300 reactor plant. Only the reactor core and methods of its modeling are considered. The work also presents the results on the development of the division of the in-reactor space of the BREST-OD-300 reactor into a system of parallel channels. The subdivision of the in-core space is based on the type and number of different core elements. This way of modeling the core allows you to see changes in different parts of the reactor when calculating transients. The developed model of the partitioning of the in-core space will be further used in the calculation of various transient modes (MCP shutdown, steam generator tube rupture, etc.). Neutron physics is not considered in this paper. There are plans to carry out joint neutron-physical and thermohydraulic calculations using the model from this paper.
Prospective methods for optimization of minor actinides transmutation technology
Authors: Ryzhov S N , Tikhomirov G V 
Published: December 2020

Abstract
Among the various international policies for the management of spent nuclear fuel and radioactive waste (RW), an important issue is the need to reprocess this waste. The aim of this work is to analyze current modern methods for transmutation of minor actinides (MA) in the reactor cores of thermal, fast (with homogeneous and heterogeneous placement) and in accelerated driven systems in order to identify factors limiting the efficiency of transmutation. This work is an analytical review and it defines the main methods for removing the limitations of the effectiveness of the transmutation process. On the basis of MA formation sources data and MA decay chains, namely americium, neptunium and curium, as well as transmutation methods in the latest reactor systems, factors limiting the efficiency of the transmutation process and methods of reducing their influence are investigated. The main factors are: an increased level of gassing during transmutation, industrial restrictions and the influence of the transmutation process on the processes occurring in the core during transient processes. The main current problem of transmutation is the high activity in terms of heat release level and neutron emission of irradiated assemblies due to the presence of curium isotopes.
Development and testing of algorithms for performing computation of detector readings from a pulsed neutron source
Authors: Gurevich M I , Kalugin M A , Kuznetsov A N , Oleynik D S , Shkarovsky D A 
Published: December 2020

Abstract
To provide the possibility of computation of detector readings from a pulsed neutron source (time dependent readings) the development of algorithms and their realization to upgrade precision Monte Carlo code MCU are considered in this work. New version of the MCU code was tested, which included comparison with experimental results. The experiments were made by Lawrence Livermore National Laboratory in the late sixties. Neutron transport from a pulsed source through layers of various materials was studied in these experiments. The comparison of the MCU calculation results obtained for these experiments with the corresponding MCNP-6 calculations results is also given in this work.
Testing the multigroup, group and subgroup options of the CONSYST / ABBN-RF system on criticality calculations of fast reactor models with MNUP fuel
Authors: Ternovykh M Y , Bogdanova E V 
Published: December 2020

Abstract
The unified code CONSYST-2020 for neutron constants preparation and the ABBN-RF-2020 neutron data library are being testing as part of the new generation codes development for neutronic calculations of fast reactors with mixed nitride uranium-plutonium fuel (MNUP). Testing was carried out on prototype models of fast reactors with MNUP fuel. The errors of the multigroup, group and subgroup approximation are analyzed in comparison with the calculations performed using point-wise cross-sections libraries. The results obtained with point-wise cross-sections libraries are accepted in the final cross-verification as reference results. An assessment was made of the influence of approximations associated with averaging and preparing group cross-sections, and methodological errors determined by the selected spatial and angular computational grids. It was shown that the transition to the direct use of 299-group blocked constants reduces the error to 0.1 – 0.2%. The assessment of the efficiency of using the subgroup approximation shows the possibility of reducing the constant component of the error below 0.05%.
Development of virtual analogues of nuclear facilities in virtual reality
Authors: Dashanova E A , Zadeba E A , Kiryukhin P K , Pugachev P A , Romanenko V I , Tikhomirov G V , Khomyakov D A , Shcherbakov A A , Yushin I M 
Published: December 2020

Abstract
Using virtual reality technology - a modern trend. The nuclear industry is no exception. This article provides an overview of mathematical models used to create virtual analogue of critical assembly Godiva in virtual reality. Godiva - there is a simple example that allows to hone techniques for creating more complex virtual analogues of nuclear reactors and nuclear facilities. Mathematical models include stationary and dynamic ones. The stationary model is based on data from calculations carried out using Monte Carlo programs such as MCU, Serpent and Geant4. An approach is also described that makes it possible to calculate the reverse multiplication from the values of the effective multiplication factor for various states of the subcritical assembly. The dynamic model allows one to calculate the neutron-physical characteristics of the supercritical assembly during fast processes such as a neutron burst. In conclusion, there are other examples of virtual analogs created using similar approaches.
Use of Am-241 in RTGs
Authors: Mikhalev A V , Chernov D O , Korobeinikov V V 
Published: December 2020

Abstract
Currently, transuranic elements are a serious problem. They are formed in spent nuclear fuel as a result of the operation of reactors. These elements have a sufficiently high radioactivity and a huge half-life, thus they remain dangerous for a very long time and must be burned out on specialized reactors. However, not all of them can be classified exclusively as waste. Am-241, which has a low heat release due to its alpha decay, can be used as a radionuclide source for RTGs. However, this nuclide can maintain a fission chain reaction and emits gamma rays as a result of decay. The article investigates some properties of possible devices, as well as an assessment of the radiation protection for such devices.
Adaptation of the model method for estimating sample uncertainty
Authors: Dashanova E A , Shcherbakov A A 
Published: December 2020

Abstract
This approach to assessing the uncertainty of measurements of sample activity was developed taking into account the requirements of the laboratory for dosimetry of incorporated radionuclides within the framework of the Methodology for measuring the activity of uranium isotopes by the spectrometric method after extraction-chromatographic isolation from urine samples. A detailed analysis of the sources of uncertainties in the activity of the sample was carried out: the uncertainty of the chemical yield, the uncertainties in the measurements of the activity of the sample, the working radioactive solution (WRS), and the uncertainty in the volume. All uncertainties are divided into two types: type A and type B. Estimation of measurement uncertainty is based on a model approach. The procedure for estimating the uncertainty of the activity of the sample was successfully verified using the specialized software GUM Workbench Pro during their construction.
The influence of neutron reflector with special properties on fast reactor kinetics
Authors: Kudriavtseva A S , Shmelev A N 
Published: December 2020

AbstractThe paper substantiates the possibility of increasing the safety of fast reactors by surrounding the reactor core with a neutron reflector with special properties. The particular case of using lead isotope as a neutron reflector has been considered in the lead-cooled fast reactor in an exemplary manner. An asymptotic point kinetics model, which takes into account neutrons returning from the reflector to the reactor core and participating in the development of fission chain reaction, was proposed for assessment of the emerging effects. The in-hour equation for fast reactors, surrounded by a neutron reflector with special properties, has been developed. It was revealed that the neutron lifetime can be substantially increased. Therefore, the contribution of the neutron reflector would mitigate the consequences of accidents when inserted reactivity exceeds the effective fraction of delayed neutron. In addition, the maximum rates of power increase have been calculated for different cases of reactivity insertion. The obtained results have considerable practical value for scientific and advanced studies of reactor accidents.
Comparing Metrological Characteristics of Methodologies for Determining Uranium Enrichment Using NaI and LEGe Detectors
Authors: Bartev N O , Aleeva T B , Zubarev V N 
Published: December 2020

Abstract
The purpose of this work was to compare metrological characteristics of methodologies for determining uranium enrichment using different types of detectors and the IMCA software. This software includes several programs (applications), two of which were used in this work: IMCN was used for NaI detector, and IMCG was used for LEGe detector. The principle of enrichment measurement is that the uranium enrichment is directly proportional to the count rate at the 185.7 keV peak resulting from decay of 235U, provided that the sample’s thickness is sufficient (“infinite thickness” method). Based on the results of repeated measurements of samples with known enrichment, metrological characteristics of methodologies for different count times were calculated and compared. Analysis of the results led us to the following conclusions: reproducibility of results when performing measurements using LEGe detector is just as good as when using NaI detector; at that, uncertainty reported by the IMCG program is almost the same as the reproducibility estimate, while the IMCN program reports uncertainties that are several times smaller than the estimated reproducibility.
Determination of integral turbulence model parameters as applied to the calculation of flows in fuel assemblies of fast reactors in porous-body approximation
Authors: Vlasov M N , Korsun A S , Maslov Yu A , Merinov I G , Kharitonov V S 
Published: December 2020

Abstract
This work aimed to correct the integral turbulence model developed earlier for assemblies of smooth rods. Two variants of the fuel assembly design were considered. In the first variant, the fuel rods were spaced using spacer grids. The presence of a spacer grid does not require a change in the form of the system of equations but leads to a change in the form of the resistance tensor and the generation of turbulence in the spacer grid region. In the second variant, a wire-wrapped fuel bundle was analyzed. The presence of a wire-wrapped fuel bundle requires an additional term in the equation for the conservation of momentum and change in the form of the resistance tensor. The simulations were obtained by CFD code ANSYS CFX and aimed at the determination of parameters involved in an integral model of turbulence being developed for modeling nuclear-reactor cores and heat exchangers in anisotropic porous-body approximation.
Investigation of radiation levels in the region of fuel-transfer cask for transportation of spent fuel of light-water reactors
Authors: Shorov V Y , Ternovykh M Y , Gerasimov A S 
Published: December 2020

Abstract
The paper formulates the main problems associated with research on transmutation, which should be paid attention to by today’s young researchers. The processes of production of hazardous nuclides during transmutation in reactor facilities are considered. The goals of transmutation and the choice of nuclides to be transmuted are discussed. The concept of radiotoxicity is explained as a measure of the radiological hazard of radioactive nuclides, based on the maximum permissible concentration of nuclides according to the IAEA standards. The problem of the formation of secondary radioactive nuclides in nuclear fuel during generation of neutrons for transmutation is discussed. The advantages and disadvantages of various methods of transmutation in nuclear installations are considered: inclusion of transmutable nuclides in nuclear fuel in fast reactors, transmutation in specialized thermal and fast transmutation reactor installations and ADS systems. The problem of accumulation of highly radioactive actinides in a transmutation facility during long-term transmutation and the problem of a potential hazard of the transmutation facility itself are discussed. The unacceptability of application of common-type power reactors for the transmutation of long-lived fission products is demonstrated.
Parallel calculation of the stationary diffusion equation
Authors: Soldatov E O , Volkov Yu N , Zizin M N 
Published: December 2020

Abstract
Considering the complex neutron-physical systems with the number of calculation points than 1 million, the calculation time can be an hour or more, and in case of non-stationary process with the small step of time, the waiting can be a month. The aim of the study is to develop effective techniques for the stationary computational modeling using parallelization technology to imply in non-stationary calculations. The parallelization scheme with height decomposition for stationary model was developed. The calculated speedup on the parallel part of the code are in good agreement with the linear dependence. The theoretical possible acceleration was derived using Amdal’s law. Comparing the obtained and theoretical curves demonstrates that the developed parallelization scheme has less acceleration due to losses. The losses and their relative contribution were identified.
Staff training experience for Uzbekistan nuclear industry in Branch of MEPhI in Tashkent
Authors: Bayaskhalanov M V , Maslov Y A , Sanetullaev A , Skrytnyy V I 
Published: December 2020

Abstract
The article describes history of creation Branch of National Research Nuclear University MEPhI in Tashkent, which will provide training of highly qualified national staff for solving the most important tasks of Uzbekistan nuclear industry.
Structural analysis across length scales of the scorpion pincer cuticle
Authors: Kellersztein Israel , Greenfeld Israel , Wagner H Daniel 
Published: December 2020

Abstract
Biological structures such as bone, nacre and exoskeletons are organized hierarchically, with the degree of isotropy correlating with the length-scale. In these structures, the basic components are nanofibers or nanoplatelets, which are strong and stiff but anisotropic, whereas at the macrolevel, isotropy is preferred because the direction and magnitude of loads is unpredictable. The structural features and mechanisms, which drive the transition from anisotropy to isotropy across length scales, raise fundamental questions and are therefore the subject of the current study. Focusing on the tibia (fixed finger) of the scorpion pincer, bending tests of cuticle samples confirm the macroscale isotropy of the strength, stiffness, and toughness. Imaging analysis of the cuticle reveals an intricate multilayer laminated structure, with varying chitin–protein fiber orientations, arranged in eight hierarchical levels. We show that the cuticle flexural stiffness is increased by the existence of a thick intermediate layer, not seen before in the claws of crustaceans. Using laminate analysis to model the cuticle structure, we were able to correlate the nanostructure to the macro-mechanical properties, uncovering shear enhancing mechanisms at different length scales. These mechanisms, together with the hierarchical structure, are essential for achieving macro-scale isotropy. Interlaminar failure (ILF) analysis of the cuticle leads to an estimation of the protein matrix shear strength, previously not measured. A similar structural approach can be adopted to the design of future synthetic composites with balanced strength, stiffness, toughness, and isotropy.
Increasing importance of temperature as a contributor to the spatial extent of streamflow drought
Authors: Brunner Manuela I , Swain Daniel L , Gilleland Eric , Wood Andrew W 
Published: December 2020

Abstract
Widespread streamflow droughts can pose substantially greater societal challenges than spatially less extensive events because of the complex realities of trans-regional water management. In a warming climate, drought spatial extent may change along with changes in underlying hydro-meteorological contributors. Here, we assess changes in streamflow drought spatial extent over the period 1981–2018 across the conterminous United States, and how the importance of potential hydro-meteorological contributors has changed over time. We first derive a monthly time series of drought spatial extent and look at trends in streamflow drought spatial extent. We then determine the spatial percentage ‘overlap’ of precipitation droughts, temperature anomalies, snow-water-equivalent deficits, and soil moisture deficits with the area under streamflow drought to look at the changing influence of these contributors on spatial extent. Our results show that (1) the spatial extent of droughts has increased, mainly because of increases in the extent of small droughts; (2) streamflow drought extents overall substantially overlap with soil moisture deficits and the relationship of drought to precipitation and temperature anomalies varies seasonally; and (3) the importance of temperature as a contributor to drought extent has increased over time. We therefore conclude that continued global warming may further increase drought extents, requiring adaptation of regional drought management strategies.
SU(2|1) supersymmetric spinning models of chiral superfields
Authors: Sidorov Stepan 
Published: December 2020

Abstract
We construct SU(2|1), d = 1 supersymmetric models based on the coupling of dynamical and semi-dynamical (spin) multiplets, where the interaction term of both multiplets is defined on the generalized chiral superspace. The dynamical multiplet is defined as a chiral multiplet (2, 4, 2), while the semi-dynamical multiplet is associated with a multiplet (4, 4, 0) of the mirror type.
Absence of nematic quasi-long-range order in two-dimensional liquid crystals with three director components
Authors: Delfino Gesualdo , Diouane Youness , Lamsen Noel 
Published: December 2020

Abstract
The Lebwohl–Lasher model describes the isotropic–nematic transition in liquid crystals. In two dimensions, where its continuous symmetry cannot break spontaneously, it is investigated numerically since decades to verify, in particular, the conjecture of a topological transition leading to a nematic phase with quasi-long-range order. We use scale invariant scattering theory to exactly determine the renormalization group fixed points in the general case of N director components (RP

N−1 model), which yields the Lebwohl–Lasher model for N = 3. For N > 2 we show the absence of quasi-long-range order and the presence of a zero temperature critical point in the universality class of the O(N(N + 1)/2 − 1) model. For N = 2 the fixed point equations yield the Berezinskii–Kosterlitz–Thouless transition required by the correspondence RP
1 ∼ O(2).
Study on the Effects of Agricultural Land Transfer on Agricultural Economic Growth
Authors: Li Chunmei , He Ge 
Published: December 2020

Abstract
This study aims to examine the impact of agricultural land transfer on agricultural economic growth by using annual time series data of Guangxi province of China over the period of 2003 to 2015. we employed ARDL-bound test to test the long-run and short-run relationship between dependent and independent variables. The empirical results show that there is no significant short-term impact on agricultural economic development, and the coefficient is 0.0399. In the long run, agricultural land transfer has a significant impact on agricultural economic growth, with a coefficient of 0.1857. Agricultural land transfer restraining the drag effect of rural surplus labour force on agricultural economic growth and did not increase the output effect of agricultural machinery. Our findings conclude that the adjustment caused by the transfer of agricultural land is beneficial to the development of agricultural economy for a long time, and plays an important role in the allocation of agricultural labour force but not in agricultural capital investment.
Development Status and Trend Analysis of Four-way Purification Technology for Automobile Exhaust
Authors: Hui Wang Ying , Song Liang Qiu , Sheng Lu Zhen , Long Wang Jiu , Xin Chen Nan 
Published: December 2020

Abstract
Automobile exhaust has seriously polluted the environment and endangered human health, in order to satisfy strict China VI regulation, four-way purification technology will become effective engine after-treatment technology for purifying automobile exhaust. This paper firstly introduces reaction mechanism of purifying particular matter, nitrogen oxide, carbon monoxide and hydrocarbon. Secondly, this paper summaries the development status of four-way purification technology for automobile exhaust from two aspects. Finally, this paper suggests that automobile exhaust can be purified by plasma combined with modified perovskite catalyst technology, this method has the advantages of low back pressure, low cost, simple structure and strong stability compared with the traditional automobile exhaust purifier, which canachievethe purification of PM, NOx, CO and HC simultaneously, and open up a new direction for automobile exhaust purification technology.