EXPERIMENTAL STUDIES ON DEVELOPMENT OF THE METHOD FOR DETERMINING THE AMOUNT OF IMPURITATED GASES IN NUCLEAR FUEL

The article is devoted to an issue of estimating the impurity gas amount in nuclear fuel in the aspect of the distracting contribution from released gases to the total pressure inside ampoule of the device in the simulating a severe accident with core melting. The paper presents a method based on measuring the pressure and temperature of gas in a closed values of the fuel elements during the fuel melting. The correctness of the developed methodology is confirmed by the results of experiments on the melting of fuel in a pulsed graphite reactor IGR with the implementation of a controlled neutron pulse.

RADIATION SAFETY ASSESSMENT OF CARROT AND BEET PRODUCTS CULTIVATED IN THE BLACK EARTH ZONE OF RUSSIA IN THE OREOL OF THE EASTERN CHERNOBYL TRACE

On the territory of the Plavsky radioactive hotspot of the Tula region of Russia, formed as a result of the accident at the Chernobyl nuclear power plant in 1986, an assessment of the radiation safety of growing carrots and beets was carried out in 2019. It has been established that at present the content of 137Cs in arable leached chernozems of the surveyed lands is 90–170 kBq/m2 , which is 2.5–4.5 times higher than the permissible level of density of surface radioactive contamination of soils. However, the specific activity of the radionuclide in carrot and beetroot crops does not exceed 5 Bq/kg, which is significantly less than the maximum permissible level of 137Cs accumulation in vegetables (600 Bq/kg for absolutely dry weight). The accumulation coefficients of 137Cs in the total biomass of carrots and beets are 2.0·10−2 and 7.5·10−2, and in eaten root crops – 1.1·10−2 and 2.0·10−2, respectively, which is in good agreement with the IAEA estimate for the intensity of the transition 137Cs in the production of vegetable roots from loamy and clayey soils.

SPECIFIC FEATURES OF APPLICATION OF CADMIUM AS A NEUTRON-ABSORBING SCREEN WHILE DOPING SILICON IN A NUCLEAR REACTOR

The gradient of the neutron field in a nuclear reactor and the requirements for the permissible spread of the specific electrical resistance over the volume of the silicon ingot makes it necessary to develop an irradiation device. This is especially true for large silicon ingots. One of the options for reducing the gradient of the neutron flux along the height of the ingot is the use of neutron-absorbing screens in the design of the irradiation device. At the WWR-K reactor, cadmium with a natural isotopic composition is used as a neutron-absorbing screen material. The paper presents the results of a study of an irradiation device with a cadmium screen. The effect of a cadmium screen on the neutron-physical characteristics of an irradiation device for silicon doping is shown.

INVESTIGATION OF TUNGSTEN SURFACE CARBIDIZATION UNDER PLASMA IRRADIATION

This paper presents the results of a study of the formation of a carbidized layer under various experimental conditions and the choice of optimal parameters for carbidization of a tungsten surface under plasma irradiation. To study the effect of the surface temperature of a tungsten sample and the duration of plasma irradiation, experiments were carried out at a sample surface temperature of 1300 °C and 1700 °C with an irradiation duration of 300–2400 s. Analysis of the research results showed that the maximum formation of W2C on the surface is observed at a test temperature of 1700 °C. At a temperature of 1300 °C, the phase composition of the carbidized layer depends on the duration of plasma irradiation. According to the literature analysis, the formation of WC occurs on the surface of tungsten, from which C diffuses into the particle and forms the underlying layer of W2C. With an increase in the ion fluence, depending on the irradiation time and the temperature of the sample surface, the diffusion of C into W accelerates, the WC content decreases, and W2C becomes the dominant carbide compound.

KAZAKHSTAN’S NUCLEAR GOVERNANCE AS A FOREIGN POLICY ASSET

Kazakhstan’s nonproliferation initiatives are recognized worldwide. Kazakhstan is a party to almost all major nuclear treaties, a key driver in the creation of a Central Asian nuclear-weapon-free zone, initiated the Universal Declaration on Building a World Free of Nuclear Weapons, established a low-enriched uranium bank under the auspices of the IAEA in Ust-Kamenogorsk to be used for peaceful purposes in the event of a disruption in the supply of fuel for nuclear power plants.While the foreign policy acts of Kazakhstan in non-proliferation are well known and internationally appreciated, the transfer of Kazakh experience in the governance of the nuclear sector is lesser known asset. For example, the experience of the Committee for Atomic and Energy Supervision and Control and KAZATOMPROM in uranium mining and transport was shared with countries from the Southern African Development Community, under an EU project, implemented by the International Science and Technology Center. This example reveals the great potential this themes have for the further input of Kazakhstan in international development cooperation.

APPLICATION OF THE VOLUME OF FLUID METHOD TO SIMULATE THE PROCESS OF MELTING AND MOVEMENT OF FUEL

The article considers the possibility of using the method of multiphase fluid Volume of Fluid (VOF), the Ansys Fluent program, for numerical simulation of the melting process of the materials of the experimental device and their movement over the volume of the computational domain. For modeling the design of a typical experimental device tested in the reactor was selected, a two-dimensional computational model was developed, methods for solving the thermal problem were described, and the simulation results were presented.

MONITORING OF TRITIUM POLLUTION OF THE SHAGAN RIVER WATERS

The article presents the results of monitoring the waters of the Shagan river on the change in the specific activity of tritium for 2016–2020. The Shagan river is the longest surface watercourse on the territory of the Semipalatinsk Test Site, flowing along the eastern part of the Balapan site, where, together with the tributary, the Ashisu, flows into the “Atomic Lake”. Further, at a distance of 110 km downstream, the river forms a left-bank tributary of the Irtysh river. Previous studies have revealed and repeatedly confirmed the fact of radioactive contamination of the surface and ground waters of the Shagan river technogenic radionuclide 3H. It was revealed that the main source of pollution is groundwater entering the surface waters of the river. In this regard, in order to ensure long-term monitoring of 3H pollution of river waters, seasonal monitoring was carried out in three sections of the river located along its channel, starting from the outlet from the “Atomic Lake” heap and further downstream to the confluence with the Irtysh river.As a result of the observations, it was found that the specific activity of 3H in surface and ground waters, depending on the observation time, varies in a wide range of values. So, in the area of maximum pollution, the content of 3H changes from the minimum – 8 Bq/kg in the spring, to the maximum 370 000 Bq/kg in the summer-autumn period. At the exit points of the Shagan river outside the landfill, the concentration of 3H varies from 90 Bq/kg to 12 400 Bq/kg. In the area of the confluence of the Shagan river in Irtysh river content of 3H does not exceed 110 Bq/kg.

DEVELOPMENT OF FIELD SPECTROMETRY DATABASE

The paper considers the issues in design and development of databases for storage and processing gamma-spectrometric information. A model is presented that allows one to describe the conceptual schemes for storing and processing data obtained during field gamma-spectrometric surveys in principle and, in particular, on the territory of the Semipalatinsk test site. The possibilities of the database of field spectrometry are described. The interface for interaction between the user and the database management system has been implemented.

HISTORICAL SEISMIC STATIONS IN USSR AND REGISTRATION UNDERGROUND NUCLEAR EXPLOSIONS

During the Cold War of the 20th century and the classification of information between the largest nuclear states the Soviet Union (USSR) and the United States of America (USA), data on the registration of nuclear explosions were not published in the reports of the Unitied Seismic Observation Service. However, underground nuclear explosions were recorded. For example, underground nuclear explosions, produced by the United States on Amchitka island, were recorded by more than 30 stations of the USSR at epicentral distances Δ ~ 8–160°. Tests at the Nevada Test Site were found especially well throughout the USSR seismic stations. As a result of processing the bulletins of registered events, checking the values with the time service, the registration parameters for the Soviet stations were destroyed. However, thanks to an employee of the laboratory 5-s of the Institute of Physics of the Earth named after O.Yu. Schmidt of the USSR Academy of Sciences Kh.D. Rubinstein is kept at the Institute for the Dynamics of Geospheres of the Russian Academy of Sciences named after Academician M.A. Sadovsky. Only after 1985 messages from some seismic stations of the former USSR began to be published in the operational reports of the Geophysical Service of the Russian Academy of Sciences. This material is intended to publish that layer of invaluable information on the registration of underground nuclear explosions, made by the United States, which has been so carefully created for decades, and has not been published anywhere at the moment.

REVIEW OF METHODIC INSTRUCTIONS AND RECOMMENDATIONS FOR EVALUATION OF ANNUAL EFFECTIVE DOSE TO HUMAN BEING IN CASES OF LIVING AT RADIOACTIVE CONTAMINATED AREAS

The proposed paper provides a review of recommendations, methodic instructions and software for evaluation of exposure doses to population domiciling radioactive contaminated territories. There is a review of dose calculation methods which are most common in neighbouring countries and beyond. The paper presents basic approaches, factors required for dose assessment with review of main pathways for artificial radionuclides intake. It addresses the need to develop methodic instructions and software for the cases of people living at Semipalatinsk test site area.