Nuclear Fuel Cycle Enterprises Research Articles

Investigation of tritium assimilation by sunflower crop at uptake through root

This study presents a quantitative assessment of tritium assimilation by sunflower (Helianthus annuus L.) crop at HTO uptake by root in vitro. It is found that at chronic uptake of tritium radionuclide as tritiated water (HTO) by sunflower through root system mean value of OBT/TFWT ratio during vegetation was 0.21. The conversation rate of tissue free water tritium (TFWT) to organic matter as organically bound tritium (OBT) varied from 0.08 to 0.044 % h–1, with a maximum in the leafage phase. Translocation index (TLI) for sunflower crop at root uptake of tritium was 65 %. The distribution nature of tritium in sunflower parts at lasting root uptake of tritium for tissue free water tritium and organically bound tritium decreases in the next rows consequently: “roots>inflorescences>stems>leaves” and “inflorescences>stems>leaves>roots”. At root uptake of tritium by sunflower as HTO form values of TFWT activity closely correlate with the activity of the isotope in water using for plant irrigation (r = 0.89). Established regularities of tritium assimilation and distribution in sunflower parts and OBT/TFWT ratio are of practical importance to biomonitoring of environmental contamination with tritium at impact territories of nuclear fuel cycle enterprises.

Problems of solid radioactive waste management on the example of the radioactive isotope 14C

The management of irradiated graphite waste continues to attract the attention of specialists from a number of related industries, in connection with the technical and economic component, along with the fact that solid radioactive waste entering the environment in the process of disposal acquires biogenic character. The environmental safety of solid radioactive waste management is associated with the possibility of biologically significant 14C to enter the human body.
 Resulting from the development of the nuclear industry, 14C has become one of the causes of global and local pollution. The consequences of thermonuclear explosions, operation of nuclear power plants, as well as nuclear fuel cycle enterprises, isotope production for the production of drugs labeled with 14C, research institutions are considered as sources of 14C.
 The world output of accumulated reactor graphite is estimated at 250,000 tons. In the Russian Federation, the total volume is approximately 60,000 tons of graphite. The share of accumulated irradiated graphite in Russia comprises 24% of the total volume of accumulated graphite.
 Having studied and analyzed the statistical data of scientific research, using the methods of generalized data processing, systematization and comparative analysis, we have taken the liberty to make a general conclusion about modern approaches and the relevance of solving the problem of SRW management on the example of the 14C radioactive isotope.

Distribution of tritium and its compounds in the environment under normal conditions of operating of Kalininskaya nuclear power plant

Tritium is one of the most important dose-forming radionuclides that determine the radiation situation in the area where nuclear fuel cycle enterprises are located. At the same time, it is not possible to catch the tritium formed during the operation of a nuclear power plant using modern, efficient and cheap technologies. This causes an increase in its concentration in environmental objects and an increase in the contribution of technogenic tritium to the radiation load of the population. Therefore, the task of monitoring the formation of tritium during the operation of nuclear power plants, the content of tritium in emissions and discharges of nuclear power plants, as well as the distribution of this radionuclide in the environment is especially urgent today. The study aims to analyze the environmental pollution due to emissions and discharges of tritium from the Kalininskaya nuclear power plant, the process of spreading tritium by air, as well as the accumulation of this radionuclide in water bodies, soil and food products grown in the area of the nuclear power plant. The following methods, developed by the specialists of the Burnasyan Federal Medical Biophysical Center were used during the research: 1) "Method for determining the volumetric activity of organic and inorganic tritium compounds in water bodies by liquid scintillation spectrometry". 2) "Methodology for determining the concentration of organic and inorganic tritium compounds in the air of the environment and industrial premises". 3) "The method for determining the specific activity of tritium compounds in soil and vegetation" was developed and tested in the course of field studies at the Kalinin NPP. As a sample preparation we used the method based on burning a selected sample in a specialized Pyrolyser-6 Trio oven. All prepared counting samples were measured by liquid scintillation spectrometry on a counter Tri-Carb 3180TR/SL. On the basis of an integrated approach to assessing the content of tritium and its compounds in air, water, soil and food, an analysis of the formation of environmental pollution due to emissions and discharges of tritium from the Kalinin NPP was carried out. It is shown that the transport of emissions from the NPP by air and the wind direction prevailing in the territory of the NPP location have a significant importance in the formation of the contribution to the ingress of tritium into foodstuffs. The necessity of taking into account the ingress of tritium and its compounds with nuclear plant emissions into the environment in the task of optimization of radiation protection of the population under conditions of normal operation of NPP is shown.

Features of training specialists for responsibility centers of the project direction “Proryv”

National Research Nuclear University “MEPhI” (NRNU MEPhI) is the leading university of the consortium of reference universities of the State Atomic Energy Corporation Rosatom (ROSATOM), a regular supplier of young specialists of the highest level. Since 2014 NRNU MEPhI has been training graduates for responsibility centers of the project direction “Proryv”. University responds quickly to staffing challenges, and provides the project “Proryv” the personnel with relevant unique competencies. These competencies include the ability to apply the knowledge gained to develop a new technological platform for nuclear power with the involvement of uranium-238 and spent nuclear fuel reprocessing products in the fuel cycle. Obtaining such unique knowledge is impossible without the use of external resources, namely, the involvement of leading scientists and practitioners of ROSATOM for conducting classes with students, organizing practices in scientific centers and at nuclear fuel cycle enterprises. The article discusses the features of the organization of the educational process in this area.

Analysis of ultra-low radionuclide concentrations in water samples with baromembrane method

This work demonstrates the use of baromembrane method based on reverse osmosis (RO) process. The method is realized on mobile complex, which allows to concentrate and determine ultra-low activity of radionuclides in water cooling ponds of Russian nuclear fuel cycle enterprises. The existence level of radionuclide background creates difficult conditions for identification the contribution of liquid discharges enterprise, as standard monitoring methods have a very high detection level for radionuclides. Traditional methods for determining the background radionuclides concentrations require the selection of at least 500 liters (l) of water, followed by their evaporation to form a dry residue. This procedure with RO membranes requires at least 5 days. It is possible to reduce the time and energy spent on evaporation of hundreds of water liters by pre-concentrating radionuclides in a smaller sample volume with baromembrane method. This approach allows preliminary concentration of water samples from 500 l volume till 20 l volume during several hours. This approach is universal for the concentration of dissolved salts of any heavy metals, other organic compounds and allows the preparation of water countable samples in much shorter time compared to the traditional evaporation method.

АНОМАЛІЇ СКЕЛЕТА РИБ У ВОДОЙМАХ ІЗ РІЗНИМ РІВНЕМ ЗАБРУДНЕННЯ РАДІОНУКЛІДАМИ

The development features of morphological anomalies of the sunbleak (Leucaspius delineates Heckel) skeleton in water bodies, characterized by background (neighbourhood of Kyiv City) and high (Chornobyl exclusion zone) levels of radionuclide contamination were studied. The impact of radionuclide contamination on the appearance of morphological skeletal anomalies of fish was established. The level of radiation background of the natural environment is constantly increasing due to the continuous flow of radioactive substances into the aquatic and terrestrial ecosystems. The causes of the significant deterioration of the existing state are the emergencies at the nuclear fuel cycle enterprises, related to the radionuclide emissions, among which the Chornobyl NPP accident is the most massive catastrophe in the history of nuclear energy, both in terms of the amount of radioactive substances that have been released into the environment and the area of territories that have been contaminated. Despite the fact that part of the radionuclides has decayed more than three decades after the accident, other long-lived substances remain sources of additional ionizing radiation in the environment. This necessitates the study and evaluation of all processes related to radioactive contamination. One of the important tasks of radioecology is to study the characteristics of the receipt, migration and accumulation of radioactive substances by components of aquatic biogeocenosa and their impact on the biota. The radionuclides released into aquatic ecosystems migrate and are most effectively accumulated by the upper trophic levels to which the fish belongs, serving as an important object of radioecological monitoring. The relevance of this study is to detect the influence of radionuclide contamination on the appearance of morphological skeletal anomalies in the fish species typical for the reservoirs of the Chornobyl Exclusion Zone, which is a representative exemplar of fresh aquatic ecosystems, taking into account the peculiarities of its way of existence. The novelty of the work is determined by the fact that for the mentioned reservoirs the relevant study was conducted for the first time.

Basic principles for assessing the safety of fish products from the ponds exposed to the influence of nuclear fuel cycle enterprises

Relevance. In connection with the development of nuclear energy, many aquatic ecosystems have been exposed to radioactive substances. Fish, as an element of biota, is capable to accumulate radionuclides. However, fish is a traditional food. The control of the technogenic radionuclides accumulation level in the ichthyofauna is an important link in ensuring human security.Intention. To analyze the long-term data on the content of long-lived technogenic radionuclides 90Sr and 137Cs in the ichthyofauna of the Ob-Irtysh river system for the period from 2004 to 2016 and Beloyarsky pond for the period from 1977 to 2018.Methodology. Fish as a food product was assessed according to two criteria: a) permissible levels of specific activity of radionuclides (SanPiN 2.3.2.1078-01); b) using the indicator of conformity B and the uncertainty of its definition В (GOST 32161-2013 and GOST 32163-2013).Results and Discussion. Fish of all species that live in the river Tetcha, is not suitable for food use according to the criteria of SanPiN 2.3.2.1078-01, GOST 32161-2013 and GOST 32163-2013. The fish of the Ob-Irtysh river system, the habitat of which is located outside the Tetcha, meets the requirements for fish products. In the period from 1977 to 1989 in the Beloyarsk pond the accumulations of technogenic radionuclides in fish in quantities exceeding sanitary and hygienic standards were possible. Currently, the fish of the Beloyarsky pond fully complies with the sanitary and hygienic requirements for the radiation factor and is safe for human consumption.Conclusion. In the ponds exposed to the atomic energy enterprises, it is necessary to continuously monitor the content of long-lived technogenic radionuclides in fish and assess their amount in accordance with the requirements of SanPiN 2.3.2.1078-01 and using the conformity indicator В and the uncertainty of its determination В.

К вопросу об оптимизации радиоэкологического мониторинга в регионе размещения предприятий ядерного топливного цикла

К вопросу об оптимизации радиоэкологического мониторинга в регионе размещения предприятий ядерного топливного цикла

The Results of the Long-Term Monitoring of the Cross-Border Air Transport of the Artificial Radionuclides to the Territory of the Sverdlovsk Region from the Nuclear Fuel Cycle Facilities Located in the Chelyabinsk region

Relevance. Due to the imperfection of the used gas cleaning equipment in the early years of the Production Association «Mayak» existence, the significant additional contribution to the exposure of the population of the south of the Sverdlovsk region were made by the gas and aerosol emissions of radionuclides into the atmosphere. Even today the PA «Mayak» continues to be a source of the radioactive contamination of the surrounding areas, and there is the potential threat of the new large-scale radiation disasters. It is impossible to completely eliminate the occurrence of any emergency situations in the enterprise, as well as the likelihood of the cross-border air transport of the radionuclides from the areas contaminated earlier. Intention. To assess radiation background levels in the southern part of the Sverdlovsk region subject to the probable air transport of radionuclides from the nuclear fuel cycle facilities located in the Chelyabinsk region. Methodology. The conceptual model of the radiation monitoring on the way of the cross-border air transport of radionuclides into the territory of Sverdlovsk region from the nuclear fuel cycle facilities located in the Chelyabinsk region was designed and tested. It includes the determination of the content of the long-lived radionuclides (90Sr and, 137Cs) in the environmental objects playing the role of natural plates. These include snow cover, the upper layer of the soil (0-20 cm), and open ponds water. Results and Discussion. The results confirm that the current atmospheric precipitates for the period of 2004–2016 had no significant effect on the radiation situation at the controlled territory. Soils of the southern part of the Sverdlovsk region and the waters of Chervyanoe lake and the ponds of Komarova village are characterized by a higher content of 90Sr, that may result from the additional radiation contamination in the previous years. Conclusion. The developed conceptual model of the radiation monitoring can be successfully used for studying the impact of the existing nuclear fuel cycle enterprises on the surrounding areas, and also for organizing the protection of the population in various radiation accidents and emergency situations involving the uncontrolled release of the radionuclides into the atmosphere or water objects.

Integral Indices of the Radiological Effect of Open and Closed Fuel Cycle Objects on the General Population

The collective dose is examined as an integral characteristic of the radiological effect of nuclear fuel cycle enterprises on the general population. A relation is obtained for evaluating the ecological factor, which takes account of the specifics of radionuclides from the standpoint of their migration capacity and the particularities of dose load formation. The ecological factors are calculated for 241Am, 242mAm, 242Am, 243Am, 242Cm, 243Cm, 244Cm, 245Cm, 246Cm, 247Cm, 248Cm, 237Np, 238Pu, 239Pu, 240Pu, 241Pu, 242Pu, 244Pu, 235U, 236U, and 238U. Links where the activity of the daughter radionuclides was taken as equal to the activity of long-lived precursors are singled out in the decay chains of the actinides. The dynamics of the yearly collective dose for the general population, formed by individual actinides with activity 1 Bq in the emissions and their decay products, for a long period of time is calculated. The results are suitable for performing comparative radioecological assessments of enterprises in open and closed nuclear fuel cycles.

Chemical absorbent for catching halogen-containing gases discharged from isotope separation plants

The results of industrial tests of a cascade of chemical absorbents for catching spent halogen-containing processes gases during discharge into the atmosphere are discussed. It is noted that the volume of the discharged gases decreases as a result of CO2 absorption. The HF and Cl2 content in passing gas can serve as a criterion for the completion of each catching step; Cl2 detection after the last step is a service life criterion for all chemical absorbents of a facility without exception. The average catching efficiency is 99.7 and 98.5% with respect to fluorine- and chlorine-containing components, respectively. An approximate calculation of the near-ground concentration of HF and Cl2 is performed. The gases discharged by the isotope separation plant at the Siberian Chemical Combine were purified at the level of the maximum admissible concentration for the working zone and not at the level of the technical norm established individually for each industrial enterprise. Equipping nuclear fuel cycle enterprises with such systems will make it possible to decrease environmental contamination considerably.

Galvanochemical treatment of solutions from nitric acid process of uranium refining

A procedure was developed for galvanochemical treatment of solutions from nitric acid process of uranium refining at nuclear fuel cycle enterprises. The main features of galvanochemical treatment of uranium-containing process solutions, followed by leaching and recycling of uranium, were determined.

Problems of ranging of radioactive waste storage and disposal objects and their solution using a database

The database “Objects for Storage and Disposal of Radioactive Wastes from Nuclear Fuel Cycle Enterprises” has been developed. Criteria were chosen for assessment of the hazard of storage and disposal (SD) objects for staff and population, and parameters based on these criteria were suggested: local hazard parameter and geospheric hazard parameter. To calculate the latter parameter, it is recommended to use simple models of radionuclide egress into the geosphere. The database can be used as an effective tool for ranging of SD objects of nuclear fuel cycle (NFC) enterprises in the order of decreasing hazard parameters. The use of a procedure for ranging of SD objects, tested with one of NFC enterprises as example, makes it possible to reveal the most hazardous SD objects at NFC enterprises and to decide on priority in decommissioning.

Foam-forming compositions and technical means for normalizing the radiation conditions at nuclear fuel cycle enterprises

on surfaces; • possibility of a self-maintained chain reaction when water solutions which do not contain neutron moderating materials are poured into the combustion zone. The objective of the present work is to develop multipurpose foam-forming compositions based on standard modified additives which have been pretested on limited scales or by-products from the cellulose-paper industry which have not been used previously. These compositions are intended for nuclear- and radiation-hazardous fire suppression, dust suppression in the rooms of a damaged power-generating unit of a nuclear power plant, and power-generating units which are being taken out of operation, as well as for localizing radioactive contamination in rooms and on site. The search for compositions and the choice of additives for standard foam-forming substances was conducted taking account of the experience gained in using foam- and film-forming compositions during the liquidation of the consequences of the accident at the Chernobyl nuclear power plant as well as previous investigations [2, 3]. A comparison of dust-suppressing prescriptions and compositions that can be used for foam formation taking account of the technological, operational, economic, and ecological aspects of their use shows that the most promising materials are by-products from the

Substantiation of the concept of ecological safety of nuclear plants and other nuclear fuel cycle enterprises

Substantiation of the concept of ecological safety of nuclear plants and other nuclear fuel cycle enterprises