Atomic Energy最新文献

The paper considers the concentration of ^95–97Mo in a square cascade with large stage separation coefficients corresponding to gas centrifuges. Cascades were calculated using a method for varying the sections of partial stage streams and minimizing the deviation of calculated stage feeding streams from the specified one. A computational experiment on the multi-step separation of a molybdenum hexafluoride mixture was carried out. Isotopes of ^95–97Mo can be efficiently concentrated in a single square cascade. In streams depleted of these isotopes, isotopically modified molybdenum is accumulated for use as a structural material for fuel element claddings having improved thermophysical characteristics.

The paper describes the development and verification of the RING 2.0 software designed for thermal-hydraulic calculations of cores and fuel assemblies with annular fuel elements. Results from a set of experimental and theoretical studies carried out on the basis of a computational model embedded in code to verify the RING 2.0 software regarding the cores of research and isotope production reactors are presented.

Based on a conducted literature review, a training sample was compiled. The selected optimal parameters for training an artificial neural network included its structure, activation function, output layer transfer function, and the number of neurons in hidden layers. The results of calculations using the developed artificial neural network have an uncertainty of less than 1%, which confirms its suitability for creating a digital twin of a technological process.

The work was carried out as part of the computational and experimental justification of the operability of U and U‑Gd fuel rods of the VVER reactor in cycling power operating modes as part of the process of licensing domestically-produced fuel according to the requirements of Russian and foreign supervisory authorities. A methodology for forming the requirements for the rate of change in the local linear power of VVER reactors during tests in the research reactor simulating the cycling mode was developed.

The PIK research reactor includes circuits of heavy-water reflector and liquid regulation representing systems important for nuclear safety. Therefore, the issue of organizing the optimal water-chemical mode and chemical control of coolants for these two systems is relevant. The volume of chemical control for coolants of heavy water circuits was developed taking into account existing experience and the physicochemical characteristics of heavy water. In order to return heavy water to the heavy-water reflector circuit and reduce the dose load on laboratory personnel, a unique automated system of sampling and analysis was created for online monitoring of heavy water in the heavy-water reflector of the PIK reactor.

The present article reviews the innovative MNT-CUDA software package designed for engineering calculations of the neutron-physical characteristics of RBMK-1000 reactors according to the multi-group Monte Carlo method. An essential feature of the software is the ability to conduct multi-group fuel element calculations of the entire reactor volume with the restoration of in-core sensor data using the Monte Carlo method. Thanks to NVIDIA CUDA GPU parallel computing technology, a counting speed of about 0.2–1 billion neutron events per minute is achieved on a personal computer equipped with a state-of-engineering video card. The history of creating the software package from the first version to the latest at the moment, as well as some results of verification and certification are given. A brief information on the methods used in the software package is provided. The concept of building its complex architecture, the prospects for development, and the results of testing in the calculations of fast and uranium-water systems are set out.

Results of experiments to test the modes of plutonium and neptunium displacement re-extraction with a nitrate solution of uranium (VI) are presented. The developed method of plutonium displacement re-extraction was tested at the refining extraction and crystallization facility of JSC SChC as part of the comprehensive program “Development of equipment, technologies, and scientific research in the field of nuclear energy use in the Russian Federation”. Due to a high accumulation of plutonium in the fuel of fast reactors, the main task of plutonium re-extraction consists in ensuring the re-extract ratio of Pu / (Pu + U) specified by the manufacturers of oxide fuel. According to the results of the performed tests, the developed method of plutonium displacement re-extraction with a solution of uranyl (VI) nitrate allows uranium, plutonium, and neptunium to be re-extracted in the ratio specified by fuel manufacturers. In this case, the completeness of plutonium extraction into the re-extract and its purification according to the proposed method are comparable to the results obtained in the process of reductive plutonium re-extraction.

An assessment of the radioecological state of water bodies on the territory of the uranium mining enterprise represented by the decommissioned Almaz Scientific and Production Association (LPO Almaz) uranium mining plant located in the town of Lermontov and in the adjacent residential area was carried out. Water bodies represent a critical factor for characterization of the radiation factor in terms of its impact on the population. After measuring the content of natural radionuclides in water and bottom sediments, the current radioecological state of water bodies as a whole was assessed. The content of natural radionuclides in water was estimated by multiplying the excess of the intervention level for each radionuclide present in a significant amount; for several radionuclides, the summarized ratios of specific activity to the corresponding level of intervention were used. The content of natural radionuclides in bottom sediments was estimated according to the effective specific activity of solid materials. A conservative average annual effective dose potential for the population in the residential area due to water bodies was calculated. Radium-226 was identified as the main radionuclide forming a dose load of internal exposure due to water bodies of the residential area in the immediate vicinity of the decommissioned LPO Almaz plant. Based on this radionuclide, an individual potential radiation risk to public health was calculated for recreational and agricultural modes of water use.

An algorithm for estimating tritium emission during the evaporation of water from spray cooling ponds of nuclear power plants is considered. The factors determining the intensity of evaporation and intake of tritium into the atmospheric air are analyzed. For the considered meteorological and technological factors of area source operation, the intensity of tritium emission averages 6.2 Bq/h from each 1·m² of the spray cooling pond area per each 1 Bq/L of specific water activity. The possibility of regulating the emission activity is demonstrated taking into account the data of controlled technological parameters for the water-cooling system of spray cooling ponds and the meteorological parameters of the atmosphere in the NPP location area.

The paper presents the results of validating the severe accident block of the EVKLID/V2 integral code used to calculate the processes of fission product release from the oxide fuel melt and dissociation of nitride fuel observed during the destruction of the core in a fast neutron reactor with liquid metal cooling. Based on the obtained results, the uncertainty of calculating individual parameters, including the fraction of released fission products and the loss of the fuel mass during dissociation, is presented.