The methods used for identifying the fact of food product irradiation are described. As an example, experimental data on the use of electron paramagnetic resonance (EPR) spectrometry to assess the fact of fish irradiation are presented. Pink salmon was chosen as the object of study and was irradiated at doses of 3 and 6 kGy. An increase in the intensity of the EPR signal is observed with an increase in the irradiation dose. To analyze signal decay kinetics, repeat spectrometry was performed on samples after 10 days and 1 month. A decrease in EPR signal intensity was initially observed post-irradiation due to the decay of short-lived radicals. However, the signal decay became less significant after 1 month. The obtained results demonstrate that EPR spectrometry is a sensitive and reliable method for evaluating fish irradiation.

The ranges and average values of the specific activity of natural radionuclides (226Ra, 232Th, and 40K) have been established in the main lithological types of soil-forming rocks (red–brown clays, loess, cover, glacial, lake–glacial, fluvioglacial, and alluvial deposits, and the eluvial–deluvial group of primary carbonate deposits). The lowest content of radionuclides is characteristic of alluvial and fluvioglacial deposits and their highest content is in lake–glacial, eluvial–deluvial carbonate deposits, and moraines. The inheritance of natural radionuclides by soil-forming rocks from weathering crusts has been revealed, which is most clearly manifested for rocks of glacial genesis and eluvial–deluvial carbonate deposits. The relationship between the content of radionuclides and the particle size distribution has been established.

The vertical distribution of 137Cs in peat bog soils in the remote period after the Chernobyl Nuclear Power Plant accident (ChNPP, 1986) was investigated. The study was conducted on bog meadows in the Bryansk region of Russia. Soil samples were taken at 4 locations: 2 sites on lowland bogs and 2 sites on transitional bogs. Fifteen years after the accident, analysis of soils showed that the peak of 137Cs activity was still in the upper 10-cm layer. The highest percentage of the initial 137Cs deposition (92%) has been observed in the top 10-cm layer in the drained transitional bog. The lowest part of the initial 137Cs deposition (40%) has been found in 0–10-cm horizon in lowland bog with the deep peat layer. The findings revealed that elevated soil moisture promotes 137Cs downward migration. It was shown that ammonium has a major impact on mobility of 137Cs in bog soils. On average, the soil solution NH4+ concentrations exceeded the K+ concentrations by about a factor 5. A significant linear relationship was found between the rates of 137Cs removal from the top layers with the soil solution NH4+ concentrations.

The article presents methodological approaches to the organization of radioecological monitoring in the regions where nuclear power plants are located. The analysis of the monitoring results at the Beloyarsk, Kursk, Leningrad and Rostov NPPs showed that the contribution of the natural radiation background to the public exposure dose is within a narrow range from 3.13 to 4.16 mSv per year, and the dose from the existing technogenic contamination varies from 0.47 μSv (Rostov NPP) up to 150 μSv per year (Beloyarsk NPP). The variability of the exposure doses is determined by the influence of natural climatic conditions and by differences in characteristics of contamination sources, including differences in electricity generation technologies. The technogenic radiation background in the area of the Beloyarsk NPP is determined by environmental contamination as a result of previous activities, whereas in the areas of the Leningrad NPP and the Kursk NPP it is associated with Chernobyl fallout (91 and 14 μSv per year, respectively). The contribution of NPPs to the existing technogenic radiation background varies from 1% (Rostov NPP) to 10–11% (Kursk and Beloyarsk NPPs).

A wide range of countermeasures and remedial actions has been developed and used to mitigate the consequences of the Chernobyl accident. This article summarizes the basic information on the application of countermeasures in agriculture over the 35 years after the accident and provides data on their effectiveness. The experience of using agricultural remedial measures and their influence on the radiological situation in different periods after the accident are analyzed. The most important aspects are highlighted, and the necessity of using the aftermath experience for improving emergency response systems in agriculture for potential emergencies is demonstrated.

The paper presents results of long-term monitoring of radioecological situation in the area sur-rounding the Leningrad NPP (LNPP), that covers the periods before the Chernobyl accident (1980-1985), during and immediately after the accident (1986-1992) and the late period (2013-2014). After the Chernobyl accident the enhanced radioactivity level in the environment including soil and vegetation was registered in the area surrounded the Leningrad NPP. Several test points for sampling were selected inside the 30-km zone around the LNPP. Before the accident, in 1985, 137Cs soil contamination density was 3 kBq/m2; immediately after the accident, in 1986, the contamination density increased by 10 fold. In the late period, in 2013, the 137Cs soil contamina-tion density reduced significantly, however it exceeded the levels registered in 1985 by 2.6-7.3 times. 90Sr soil contamination density was 1.4-1.6 kBq/m2 both before and after the accident (1985-1992). The presence of artificial radionuclides in agricultural produce before 1985 was caused by global radioactive fall-outs, however no radionuclides emissions from the Leningrad NPP were registered. Average 137Cs content in grain and intertilled crops exceeded their content before 1986 by 19-44 times; the high content was associated with the contamination of the vege-tation by airway. The 137Cs content in agricultural produce is still higher than the level registered before the Chernobyl accident by 1.4-2.1 times, but the current levels are many times less than the current acceptable level. The levels exceeding the acceptable magnitude are found in wild berries only, that grow in some swampland with 137Cs soil contamination density of 3-9 kBq/m2 near the LNPP. Dynamics of transfer factors of 90Sr and 137Cs from soil to agricultural produce in the LNPP area was evaluated. The soil properties and the Chernobyl fall-out are shown to affect the factor magnitude. Presented data demonstrate that the Leningrad NPP operating in the standard way does not influence strongly on radiological situation in the 30-km zone around the NPP.

The results of a study of the content of natural radionuclides (NRN) (226Ra, 232Th, 40K) and technogenic 137Cs in soil samples formed on red-brown clays collected at the period of time from 1927 to 2017 are presented. Soil sections were laid on the territory of the «Kamennaya Step’» wild life sanctuary and the island oak grove “Shipov Les” under three types of land: arable land, fallow and forest (forest protection belt. For the first time, data on the specific activity of NRN (226Ra, 232Th and 40K) was obtained in the soils of the “Kamennaya Step’’” wild life sanctuary and the island oak forest “Shipov Les” before the first nuclear tests (before 1954). The highest specific activity of NRN, as well as technogenic 137Cs, is observed in soils under forest, and the lowest: for radium-226 and cesium-137 in arable soils, and thorium-232 and cadium-40 in fallow soils. 137Cs was found in modern soil samples (0–20 cm), as well as in the 1962 sample (at a depth of 0–5 cm). Its specific activity varies in the range of 26.9–124.4 Bq/kg, with the highest content in soils under forest.

Представлены этапы развития радиоэкологических исследований, связанные с необходимостью защиты человека и окружающей среды в условиях загрязнения природных и аграрных экосистем после ядерных испытаний, крупных радиационных аварий и функционированием предприятий ядерного топливного цикла. Описаны основные пути миграции радионуклидов и особенности их поведения в окружающей среды в зависимости источника загрязнения, характеристик и состава выпадений. Рассмотрены особенности радиоэкологических проблем на настоящем этапе и перспективы их решения во ВНИИРАЭ. The stages of development of radio-ecological research addressed to the need to protect human beings and the environment in conditions of contamination of natural and agricultural ecosystems after nuclear tests, radiation accidents and operation of nuclear fuel cycle facilities are considered. The main pathways of radionuclide transfer in the environment and peculiarities of their behavior in the environment depending on the source of contamination, characteristics and composition of deposition are described. Major features of radioecological problems at the present stage and prospects of their solution in RIRAE are presented.

The problems of radioactive contamination of biosphere with the 238U in recent years have attracted a large number of experts in various fields of knowledge. Natural radionuclides are an integral part of the biosphere. They are concentrated everywhere: in rocks, in soil, water, air and food. Various types of phosphorus fertilizers and other natural ameliorants used in agriculture are also an additional source of heavy natural radionuclides. The review describes the behaviour and migration of 238U in biosphere, which depend on various factors acting simultaneously. It is noted that the behaviour of 238U in the soil depends on the forms of its presence in it and the physical and chemical properties of the soil. The processes of sorption and desorption of 238U by different soil types are significant indicators.

Ôåäåðàëüíîå ãîñóäàðñòâåííîå áþäaeåòíîå íàó÷íîå ó÷ðåaeäåíèå "Âñåðîññèéñêèé íàó÷íî-èññëåäîâàòåëüñêèé èíñòèòóò ðàäèîëîãèè è àãðîýêîëîãèè" Êëþ÷åâûå ñëîâà: àâàðèÿ íà ×åðíîáûëüñêîé àòîìíîé ýëåêòðîñòàíöèè, aeèâîòíîâîäñòâî, ìîëîêî, ìÿñî, çàùèòíûå ìåðîïðèÿòèÿ Ðåçþìå.Ïîñëå àâàðèè íà ×ÀÝÑ áûë âûïîëíåí îáøèðíûé êîìïëåêñ çàùèòíûõ è ðåàáèëèòàöèîííûõ ìåðîïðèÿòèé.Ñëåäñòâèåì ðåàëèçàöèè êðóïíîìàñøòàáíûõ ïðîãðàìì ïî ëèêâèäàöèè ïîñëåäñòâèé àâàðèè â àãðîïðîìûøëåííîì ïðîèçâîäñòâå ñòàëî ðåçêîå ñíèaeåíèå (äî 10-20 ðàç) êîíöåíòðàöèè ðàäèîíóêëèäîâ â îñíîâíûõ âèäàõ ñåëüñêîõîçÿéñòâåííîé ïðîäóêöèè (ìîëîêå, ìÿñå, ïðîäóêöèè ðàñòåíèåâîäñòâà), ÷òî îáóñëîâèëî çíà÷èòåëüíîå óìåíüøåíèå äîçî

The paper presents the main tasks and main stages for implementing the radiation-ecological monitoring (RM) system in the vicinity of nuclear fuel cycle facilities. The principles for performing the RM of environmental objects are determined. A relationship has been established between the stages and principles of radioecological monitoring included in the program of radioecological survey of the territory in the area of the location of radiation-hazardous objects. To improve the efficiency and quality of work in the implementation of projects on radioecological research of the territory, there is a need to develop algorithm for implementing programs of RM and its introduction into the environmental monitoring system, including the assessment and forecast of changes in indicators of this state. The authors have developed the algorithm of investigations in the framework of environmental RM in the region where nuclear and radiation hazardous facilities are located. A set of independent algorithms has been elaborated for each stage of work, describing the order of actions during conducting radiation and environmental monitoring. The paper presents the conceptual outline for realizing the RM program. The elements of the effective work within the framework of contaminants control in the components of ecosystems and radiation safety assurance of humans and biota are identified. The authors have developed an approach, whereby the researcher has the opportunity to properly organize the sequence of actions to create a network of RM, performing field and cameral work. The implementation of the proposed approach will allow optimizing the work on radiation and environmental monitoring in the areas where nuclear fuel cycle enterprises are located and obtaining results that provide a reliable radioecological assessment of the object under consideration.

Environmental contamination by U-238 occurs in the resting places of rocks with high uranium content in the points, where the ground waters come out on the Earth surface. U-238 enters the atmosphere because of volcanic outbursts, forest fires, meteoric dust and soil transfer by the wind. A significant fraction of environmental contamination is formed by the products of U-238 leaching from the wastes of uranium mines and plants and releases of uranium fusion (yellow substance) from the stacks of the enterprises processing the uranium concentrate. Entrance into the environment with the wastes of phosphate industry (at phosphate rock processing), application of phosphoric fertilisers (superphosphate, precipitated phosphate and others), coil burning at thermal power plants and primary metal establishments are considered as the intensive source of agrocoenosis contamination. The conducted studies established that the accumulation of U-238 by crops is closely related to the content of humus, mobile calcium and physical clay in the soils. The correlation coefficient between the accumulation of U-238 in the oats grain and the humus content in the soil is R = 0.91 +/- 0.04. Differences in the accumulation of U-238 in plants depend on the texture of sod-podzolic soils and come up to 1.2-1.6 times. The uptake of U-238 from sod-podzolic soils to barley is 1.4-3.4 times higher than that of chernozem-type soils with a high content of humus and mobile calcium.

The results of a study of the content of natural radionuclides (NR) (226Ra, 232Th, 40K) and technogenic 137Cs in soil samples formed on the most common types of soil-forming rocks of the North-West: lakeglacial (non-boulder and tape clay), glacial and water-glacial deposits are presented. Soil sections laid in the Pskov, Novgorod and Leningrad regions. The granulometric composition in the upper part of the soil profile is lighter than in the parent rock. This is reflected in the NR content in the profile of these soils: with a decrease in the fractions of physical clay and silt, the content of 226Ra, 232Th and 40K decreases. This is due to the fixation of natural radionuclides by secondary clay minerals. According to the increase in the average specific activity of all NRs, the soils form the following sequence: soils on water-glacial deposits soils on moraines - soils on lake-glacial deposits. A comparison of the average specific activity of natural radionuclides and their ranges in the upper part of the soil (0-5, 5-10 and 10-20 cm) and in the parent rock (90-100 cm) revealed a higher content of radionuclides in parent rocks (lake-glacial and moraine deposits). In the soils on water-glacial deposits, no significant difference was found.

Purpose: Justification of the necessity to establish and maintain a system of radioecological monitoring of agricultural ecosystems in the vicinity of nuclear power plants at all stages of the life cycle of a radiation-hazardous facility. Material and methods: The paper presents methodological approaches (sanitary-hygienic and environmental) to radioecological monitoring of agricultural ecosystems in the region of the NPP location. The tasks of the radioecological monitoring of agricultural ecosystems are defined, and its organisation and management stages are highlighted. The article displays the features of the development of programs and regulations of radioecological monitoring of agricultural ecosystems. The main objects of radioecological monitoring, parameters to be monitored, and also the frequency of monitoring observations are determined. The principles of locating the control points on the monitoring network are substantiated. Results: The results of radioecological monitoring of agricultural ecosystems in the impact zones of the Kursk and Rostov NPPs are presented. The approaches to the creation of a monitoring network, taking into account the peculiarities of the regions of the NPPs’ location (landscape, soil, economic), are demonstrated. It is shown that the contamination density of agricultural lands by 90Sr varies in the range of 0.47–1.74 kBq/m2, and by 137Cs – 2.7–9.7 kBq/m2 for Kursk NPP and, for Rostov NPP it is 0.36–2.57 kBq/m2 by 90Sr and 2.25–4.55 kBq/m2 by 137Cs. Over the entire period of monitoring observations, none of the samples of agricultural products appeared to have an excess of sanitary and hygienic standards for the content of radionuclides. Due to the consumption of food produced in 30-km observation zones, about 63 Bq/a of 90Sr and 195 Bq/a of 137Cs in the Kursk NPP observation zone and, respectively,133 and 184 Bq/a in the vicinity of Rostov NPP enter the diet of the local population, which is almost 400 times for 137Cs and 10–20 times for 90Sr below the annual ingestion limits respectively. Differences in the accumulation of radionuclides for the same crop in different years of observation come up to 1.5 times, due to the influence of soil and weather conditions, as well as different doses of ameliorants application. Conclusion: The results of the radioecological monitoring of agricultural ecosystems confirm that the operation of the Kursk and Rostov NPPs in normal mode does not lead to a deterioration of the radiation situation in the regions where they are located. Radiation doses on the local population do not exceed the established standard values. The system of radioecological monitoring of agricultural ecosystems should be an integral component in the general system of radiation safety in the vicinities of NPPs and other radiation-hazardous facilities.

Long-term environmental behaviour of radioactive particles released during the Chernobyl accident and deposited in sandy topsoil in Ivankiv district of Kyiv Region (Ukraine), in radioactive trench waste materials from the Red forest, and in bottom sediments from the Cooling pond has been assessed. The efficiency of the models describing the dissolution/weathering rates of U fuel particles developed 15-20 years ago was tested, and their predictions for the dynamics of remobilization, mobility and plants uptake of Sr-90 were confirmed. It was found that at present in the topsoil and in radioactive trench waste material, total dissolution of fuel particles of low chemical stability (UO2+x) has occurred and about half of the non-oxidized chemically stable fuel particles (UO2) has also dissolved, indicating radiological stabilization of the environment and that the mobile fraction of radionuclides would be reduced in the future. The biological availability of Sr-90 in topsoil due to fuel particles dissolution has reached maximum values and further decrease is expected. The presence of chemically extra-stable fuel particles (U-Zr-y-O-x) in environments should be taken into account when the total radionuclides activity concentrations are assessed during radioactive materials management. It was shown that nearly half of the Sr-90 activity remained as part of the non-dissolved UO2 fuel particles at the time of the study. Taking into consideration that 31 +/- 4% of the radionuclide activities were still associated with non-dissolved chemically extra-stable particles (U-Zr-y-O-x) in radioactive trench waste materials from the Red forest, increased dissolution should not be expected in the near future. The physico-chemical form of radionuclides in air exposed sediments from the Cooling pond were determined, and results showed that about 70-80% of total Sr-90, Am-241 and plutonium isotopes activity were associated with U fuel particles. The low dissolution rate of radionuclides from the pond sediments is attributed to prolonged slightly alkaline pH in the medium due to zebra mussel residues. According to new data, the emission value of Pu-238 associated with fuel particles released during the Chernobyl accident amounted to 1.8 x 10(13)Bq (1.2% of the activity in the reactor) and Sr-90 amounted to 2.6 x 10(15)Bq (1.5% of the activity in the reactor).

Studies performed in the former Soviet Union were reviewed to provide interception and weathering values for radioactive particles. None of these studies were available in the English language literature before or were considered in the international reviews. The estimated mass interception fractions ranged 0.2-1.4 m(2) kg(-1) may be explained by the size of the particles used in the research. The interrelationships among the interception fractions, plants biomass and size of radioactive particles were determined for different plants: spring and winter wheat, maize, rice, pasture and sown grass. A filtration model rather accurately approximated data for pasture grass and some other crops but does not reflect properly patterns of the interception fraction dependence on biomass for perennial sown grass. The values derived have been compared with some expected values reported by the IAEA's Handbook of parameter values for the prediction of radionuclide transfer in temperate environments (TRS 472) where possible. The information presented can be used in the current updating of parameters recommended for environmental impact assessments.

Obninsk Methodological approaches to the organization of state and departmental systems for environmental monitoring environment in order to ensure the radiation and ecological safety of population and biota in the vicinity of nuclear and radiation hazardous facilities (NF) are reviewed. The authors jus-tify the need for implementation of the monitoring at all stages of the facilities life cycle, tailored to the facilities features, regional-specific factors, as well as personnel, the public and biota exposure situations. The authors defined directions of radioecological monitoring of a facility (facility level), radiation-hygienic level (evaluation of exposure of the public, biota and ecosystems to released ra-dionuclides), socio-hygienic level, prospective (evaluation of health effects), agroecological, biologi-cal and ecological levels. The impact of the facilities operations on the public and biota is evaluated on the basis of data of the long-term surveillance of radionuclides concentration in the lowest atmospheric layer, terrestrial (agro- and natural) and aquatic ecosystems. Various aspects of radia-tion-ecological monitoring, strengths and shortcomings of used methods are reviewed. Analysis of the current organization system of radioecological monitoring allows making the following conclu-sions: efficiency and organization of radioecological monitoring need to be enhanced and opti-mized. The comprehensive radioecological monitoring integrated elements of different systems of the monitoring due to interaction of different agencies should be developed. Implementation of integrated radioecological monitoring on areas of NF location should be based on integrated risk values for population and biota from wide range sources of pollution considering migration pathways of toxicants in critical