Monitoring of Radioactive Substances in Water Bodies and Soils

A significant part of Ukraine’s GDP is formed by agriculture, for which soils (primarily arable land) and water resources are of priority importance. They serve as a source of income for both the state and private farms. Regular environmental and radiation-ecological (radiation) monitoring is conducted to have up-to-date information about their safety and proper ecological condition, as well as to keep from possible negative impacts, first of all – man-made (anthropogenic) contamination.

Radiation-ecological (radiation) monitoring of the environment is an integrated information and technical system for regular observations of environment radiation state, processes of radionuclide migration and accumulation, potentially hazardous phenomena, etc., which is implemented using special equipment (systems or individual devices) to assess and predict environment radiation state. Radiation monitoring of the environment includes measurements of the density of soil contamination with radionuclides and activity concentration of radionuclides in the air, groundwater, surface and waste water, bottom sediments, biota, food, etc.

Soil and water can be a source of both internal and external exposure and have a direct impact on human health, therefore it is very important to have immediate and reliable data on their radiation state. This applies especially to soils of agricultural land, pastures and water bodies, from which water is taken for the public. The purpose of this effort is to familiarize readers with the data on monitoring radioactive substances in soils and water bodies of Ukraine, where they enter directly with discharges and releases or through atmospheric transport and precipitation, therefore, this effort also mentions radiation monitoring of the atmospheric air.

According to map “Radiation Risk in Ukraine”, edition 2001

The main components of environment radioecological monitoring are monitoring of radioactive atmospheric fallout, surface and underground water resources, radiation monitoring of agricultural products and food products, forest products and natural materials that can be used in construction and everyday life.

IAEA safety standards distinguish source monitoring, environmental monitoring and monitoring of human exposure (personal dose monitoring). In 2018, IAEA published General Safety Guidelines N. GSG-8 “Radiation Protection of the Public and the Environment”, which considers the mechanisms to implement the requirements of the International Basic Safety Standards, IAEA Safety Series for protection of the public and the environment against radiation risks.

There is also an approach that distinguishes radiation monitoring as a component of environmental monitoring, which implies continuous monitoring of potentially hazardous radiation facilities and is carried out systematically under normal conditions and in additional scope in case of emergencies. There are basic radiation monitoring, which does not require deployment of additional observation stations or crisis telecommunications, crisis monitoring of territories contaminated by emergencies with the release of radioactive substances into the environment, and scientific monitoring, which is implemented by subdivisions of research institutions working on the development of radiological research programs and methods.

Environment radiation monitoring includes measurements of the specific activity of alpha, beta, and gamma radionuclides and determination of the amount of cesium-137 and strontium-90 in environmental objects, in particular, the density of soil contamination and activity concentration of water, because the amount of these radionuclides in food depends on it and, as a consequence, internal human exposure dose.

According to map “Radiation Risk in Ukraine”, edition 2001

The main tasks of radioecological monitoring are:

  • monitor and control the state of radiation contaminated areas and develop proposals on the possibility to reduce the contamination level;
  • assess the state of environmental objects characterizing the radiation situation in contaminated areas and beyond them;
  • identify trends in changes in radioactive contamination state of the environment associated with the performance of activities in contaminated areas or operation of radiation hazardous facilities (nuclear power plants radioactive waste, spent nuclear fuel storage facilities, uranium mining enterprises, etc.);
  • project changes in the contamination level and its impact on the environment;
  • project possible consequences of the impact on health of people living in contaminated areas and consuming locally produced food;
  • provide information support of monitoring and transfer the information received to relevant authorities and institutions.

Regulatory control of monitoring of radioactive substances in the environment is carried out in accordance with the Law of Ukraine “On Nuclear Energy Use and Radiation Safety”, where, in particular, Article 10 refers to the rights of citizens to receive the information on nuclear energy use and radiation safety.

Similar activities are regulated by relevant regulations of the European Union. The main ones are the Treaty establishing the European Atomic Energy Community (Euratom), Council Directive No. 59/2013/Euratom on basic radiation safety standards, European Commission Recommendation No. 473/2000/Euratom to apply Article 36 of the Euratom Agreement on monitoring radioactivity levels in the environment to assess exposure of the public.

The main attention is paid to the anthropogenic radionuclides cesium-137, iodine-131 and strontium-90, determination of internal exposure dose reliability by measurements, including in food and animal feed. Article 36 obliges all EU members to inform the European Commission of radiation contamination levels within their country.

International cooperation in radiation-ecological monitoring is implemented by Ukraine within the International Geosphere-Biosphere Program, International Man and the Biosphere Program, Environmental Observance System (EOS) Program, Global Learning and Observation to Benefit the Environment (GLOBE) Program, UNEP/Water Freshwater Monitoring Program and consists primarily in informing on environment state.

Experts of the State Scientific and Technical Center for Nuclear and Radiation Safety are practicing radiation monitoring techniques in the exclusion zone during the international exercises jointly with experts from the German Federal Office for Radiation Protection in September 2021

An example of international cooperation in joint radioactivity measurements in the environment in areas contaminated resulting from the Chornobyl accident was exercises of mobile radiation monitoring laboratories of the German Federal Office for Radiation Protection and crews of Ukrainian organizations, including the mobile radiological laboratory of the State Scientific and Technical Center for Nuclear and Radiation Safety. The training included not only the use of up-to-date methods of airborne gamma surveying with the support of German Federal Police helicopters, but also soil sampling to determine the density of soil contamination with cesium-137, strontium-90 and other radionuclides to update the cartographic information of 1989.

Who Directly Monitors

In Ukraine, radiation and radiation-ecological monitoring of soils and surface water bodies is carried out by organizations in the management sphere of the Ministry of Agrarian Policy, State Water Resources Agency, State Agency for Forest Resources, State Service of Ukraine for Geodesy, Cartography and Cadastre, Ecocentr, Chornobyl Centre for Nuclear Safety, Radioactive Waste and Radioecology managed by the State Agency of Ukraine on Exclusion Zone Management (monitoring of water resources, air, soil and biota in the exclusion zone and the zone of unconditional (mandatory) resettlement), Institute for Soil Protection, Ukrainian Hydrometeorological Institute of the State Emergency Service and the National Academy of Sciences of Ukraine, Central Geophysical Observatory and Ukrainian Hydrometeorological Center, Institute of Environmental Geochemistry of the National Academy of Sciences of Ukraine, laboratory of external dosimetry of nuclear fuel cycle enterprises and specialized radwaste management enterprises in accordance with the Radiation Monitoring Procedures.

Moreover, automated radiation monitoring systems (ARMS) are operated at NPPs and at Radon sites, which allow real-time monitoring of the radiation situation at the industrial site, in the observation and control areas of nuclear facilities and facilities for radioactive waste management. The information on equivalent dose rate values is displayed and available on NPP websites, on the website of the Ministry of Energy of Ukraine and SNRIU.

ARMS sensor in the RNPP observation area. Source: ITV Media Group

The information on the density of soil contamination with radionuclides can be found on the website of the Institute for Soil Protection and on the websites of the departments of ecology and natural resources of regional state administrations, the radiation state of surface water can be presented in reports of the Central Geophysical Observatory of the State Emergency Service of Ukraine.

In addition, the Institute for Soil Protection monitors the radiation state of soils It determines the specific activity of cesium-137 (annually) and strontium-90 (once every 5 years) in the arable and subsurface soil layers. Thus, from 2011 to 2015, a survey of agricultural land was conducted in 1930 farms with a total area of ​​19.8 million hectares, 9.6 million laboratory tests were performed for 1.9 million soil samples to define the content of 20 agrochemical indexes in them, including the content of radionuclides.

If, during systematic observations, an increase in an exposure (equivalent) dose rate of 0.05 mR/h (0.5 μSv/h) and more is revealed, then the duty operator immediately informs  the enterprise management, duty control agency of the Territorial Subsystem of the Unified State System for Civil Protection (USSCP) and duty territorial body of the State Emergency Service of Ukraine, after which clarifies the data by measurements and sends the obtained data to the duty operator of the State Emergency Service of Ukraine. They are transferred to the calculation and analytical group, which summarizes the information received and submits it to the Department of USSCP Territorial Subsystems.

If the situation requires USSCP transfer to the high alert mode, “the members of the calculation and analytical group arrive at a place designated for work and project possible radiation and chemical situation according to the Observation Methodology to Assess the Radiation and Chemical Situation approved by Order of the Ministry of Internal Affairs of Ukraine No. 986 of 27 November 2019.

Source: State Emergency Service of Ukraine

Sources of Environment Contamination with Radionuclides

As a result of the Chornobyl accident, a significant amount of radionuclides with different half-lives entered the environment – air, soil, waterways.

Some of them, such as iodine-131, have a short half-life, others – several decades (cesium-137 – 30 years, strontium-90 – 29), but the complete decay of cesium and strontium will last for centuries. During all this time they will be hazardous for the environment and the public due to an increase in the share of their decay products and accumulation of radionuclides with a long half-life, such as promethium-147, plutonium-239 and 240, americium-241. It should also be recalled that the territory of contamination is not limited to the exclusion zone and the zone of unconditional (mandatory) resettlement: in general, only in Ukraine, the accident consequences became noticeable for the area of 53.5 thousand km2, of which 4 million hectares of forests, 1.13 million hectares of arable land.

Some of soils contaminated due to the Chornobyl accident were subject to decontamination, during which measures were taken to reduce the transfer of isotopes to plants, sometimes with cutting off the top soil layer and its subsequent burial into the soil to a depth of 30-35 cm, which allowed reducing radionuclide accessibility for plants by 1.4-1.7 times.

Waterways, in particular the Dnipro River, were also affected by radionuclides, as it is the confluence of the Prypiat River, on whose banks the ChNPP satellite city of the same name is located. Now, 35 years after the accident, the radiation situation has changed, but the current situation is still hazardous and therefore requires increased control and continued monitoring. The results of radiation monitoring of rivers in the exclusion zone are presented in the Certificate on the State of Radiation Safety and Labor Protection in the Exclusion Zone and Zone of Unconditional (Mandatory) Resettlement prepared by experts of the Department for Radiation Safety, Labor Protection and Civil Protection of the State Emergency Service of Ukraine, Ecocentr, Sector for Labor Protection and Radiation Safety of, the information on the condition of reservoirs in the region, including the Chornobyl exclusion zone can be found in the Information and Analytical Reviews of Environment Condition.

The Chornobyl accident is not the only source of radionuclide contamination. There are also industrial nuclear explosions (on the territory of Ukraine, two of them were carried out: Kharkiv region, Khrestyshche village (1972) and Donetsk region, Yunkom mine (1979), discharges of nuclear power facilities, nuclear fuel production and spent fuel reprocessing – which although is not presented in Ukraine, but is in a neighboring country, radwaste disposal sites, uranium mining waste, etc. In countries with arsenals of nuclear weapons, radionuclide contamination may be caused by their tests and incidents in warehouses where they are stored.

According to map “Radiation Risks in Ukraine”, edition 2001

Monitoring of Radioactive Materials in Soil

Soil is the most capacious and inert link, which the rate of radionuclide distribution in the food chain depends on. It is a multicomponent inhomogeneous complex substance, sensitive to moisture and atmospheric conditions, which can have different adsorbing properties, therefore, soil of different composition interacts with radionuclides in different ways. Soil can affect not only external, but also internal exposure, after the entry of radionuclides into the body with food and water (from the atmosphere to the soil, from the soil to plants, from plants to the human body, or from the atmosphere to the soil, from there – into plants, from plants – into the body of an animal, and then into the human body through meat and dairy products).

In addition to the mentioned above, a source of soil contamination with radionuclides of man-made (anthropogenic) origin is also global radioactive fallout of nuclear test products, some chemical fertilizers (primarily phosphorus), waste from thermal power plants, etc. The complexity and ambiguity of the processes associated with the spread of radionuclides, primarily of man-made origin, require continuous monitoring and analysis. The relevant information can be found in “PERIODIC REPORT on the Results of the X Round (2011-2015) of Agrochemical Land Survey” (Kyiv 2020)

Source: “PERIODIC REPORT on the Results of the X Round (2011-2015) of Agrochemical Land Survey” (Kyiv 2020)

Soil consists of solid (mineral, organic compounds), liquid (soil solution), gaseous (air-gas soil mixture) and living (soil flora and fauna) components. Soil chemicals change, some are mineralized and transformed into substances that do not affect living organisms. Soils with a high humus content and large absorbing capacity have the greatest buffer capacity and the ability to reduce the negative impact of contamination.

Depending on their mineral composition, soils have a different content of natural radionuclides. As a rule, natural radioactivity of the soil in most cases does not have a serious effect on the body, in contrast to man-made radionuclides, which have spread as a result of anthropogenic activities and led to contamination with cesium-137 and strontium-90. Their number is unstable and they are in constant dynamics and interact in different ways with the soil: cesium-137 is firmly fixed by soil mineral part in analogy with isomorphic replacement in the crystal lattices of clay minerals, strontium-90 interacts mainly in analogy with ion exchange with soil absorption system.

An important feature of radionuclide existence in the environment is their continuous migration: radionuclides from the atmosphere are deposited on plants and buildings, washed into the soil or get there with fallen leaves, peeled bark slices, etc. Further, some of them are absorbed by the root systems of plants, migrate by plant body, from where they can enter the bodies of humans and animals. In the soil itself, at the same time, there is also a vertical and horizontal biotic (as a result of the vital activity of plants, fungi, microorganisms of other fauna) and abiotic (diffusion, lessivage, transport by water flows, etc.) migration of radionuclides.

Thus, in particular, the horizontal migration of radionuclides in soils occurs due to wind transport, forest fires, traffic, animal life, flood water. The most active horizontal migration of radionuclides is characteristic of light soils subjected to agricultural treatment, the least active migration is characteristic of heavy forest soils. Intensive migration of radionuclides from light soils caused by leaching can lead to an increase in radionuclide concentration in water bodies, but contributes to a relatively rapid removal of radionuclides from soils.

The vertical migration is slower than the horizontal one and is up to two centimeters per year. According to studies carried out in the exclusion zone and zone of unconditional (mandatory) resettlement, the bulk of radionuclides is located within the upper soil layer for a significant period. The vertical migration of radionuclides is associated with agricultural activities (plowing, irrigation, drainage), transfer of radionuclides by the root systems of plants, water regime that occurs in the soil.

The vertical and horizontal migration of radionuclides became the reason that, according to the Ministry of Emergencies (now the State Emergency Service) of Ukraine, in the first 20 years after the Chornobyl accident, areas with a high density of radionuclide contamination due to the Chornobyl accident became a zone of less contamination, in particular the area of ​​territories with the level of soil contamination over 555 kBq/m2 decreased by one and a half, and with levels from 185 to 555 kBq/m2 – almost twice.

It should be taken into account that radionuclides in the soil are characterized by the properties of the isotopes themselves, their concentration and migration rate, and in a certain way depend on soil physical properties and its chemical composition, climatic parameters, landscape features, etc. It is believed that by introducing certain organic and inorganic compounds into the soil and special acidification, it is possible to impact the migration of radionuclides, which, in turn, will speed up soil cleaning from radionuclides.

Schematic map indicating observation points of the hydrometeorological service for radioactive contamination of the environment on the territory of Ukraine Source:

The following soil characteristics can also impact the migration of radionuclides:

  • Multifunctionality: unlike ion-exchange resins, the adsorption of ions in soils in different places is different, which is caused by complex multicomponent, multi-mineral composition of the soil.
  • Various particle sizes: soil consists of particles of different sizes, which influences the kinetics of ion absorption and desorption.
  • Presence of organic substances: various organic substances interact differently with radionuclides, some of them form soluble complex compounds with minerals that have the property of shielding, others, such as humic acids that are humus components, adsorb strontium well. … That is why, in soils with a significant humus content, the migration of strontium-90 will be very slow.
  • Presence of microorganisms: some of living microorganisms can absorb radionuclide ions during metabolic processes and release them later along with organic substances into the environment.
  • Ability of certain minerals to fix some ions, in particular K +, Rb +, Cs +, etc.
  • Soil variability: it easily changes under the impact of atmospheric phenomena, season, under the impact of an anthropogenic factor, etc.

Radioecological monitoring of the soil consists in assessing the indexes of the density of its contamination with radionuclides, determining its type, prospects for radionuclide migration (primarily cesium-137 and strontium-90) into plants and their inclusion in the food chain. This is especially important when it refers to agricultural land (arable land, perennial plantations, hayfields, pastures and fallow lands), which means that radionuclides can get into agricultural products.

Due to radiation monitoring of soils, the information obtained determines not only short-term temporary changes, but also long-term trends and allows projection of further situation, which helps to assess the prospects for using sites for various types of agricultural use, construction, recreational and other needs.

Monitoring of Radioactive Substances in Water and Bottom Sediments

As a result of the Chornobyl accident, a significant amount of radionuclides entered the water catchment areas of the Prypiat, Dnipro, Desna and Dnister rivers, which are the main waterways of Ukraine. To ensure that drinking water is radiation safe, water bodies, from which water is taken, are subject to the strictest control.

In Ukraine, the state of drinking water can be found in the annual “National Report on Drinking Water Quality and State of Drinking Water Supply in Ukraine” of the Ministry of Communities and Territories Development of Ukraine, which is prepared upon the materials from the Ministry of Health, Ministry of Environment, Ministry of Defense, etc., as well as on the Sreznevskyi Central Geophysical Observatory website and from the resources of the departments for ecology and natural resources of regional state administrations.

Requirements for drinking water quality are regulated by the State Health and Safety Standards and Rules DSanPiN 2.2.4-171-10, which set the maximum allowable indexes for the specific total alpha- and beta-activity of drinking water and radiation safety indexes for drinking water.

Ecological situation and condition of drinking water in Ukraine

Map source: All Ukrainian Ecological League

The already mentioned IAEA document notes: “The regulatory body or other national authority should establish a process to determine the compliance of drinking water in the State with the guideline levels for drinking water published by the World Health Organization (WHO). The WHO guideline levels for specific radionuclides are calculated using a generic criterion of 0.1 mSv per year for ingestion”.

“If the recommended levels of radionuclides in drinking water are consistently exceeded by one of them or a combination of them, the regulatory body or other national body should decide whether to implement protective measures or establish certain limits,” the same document says.

All the main rivers of Ukraine, water catchment areas, reservoirs, irrigation systems and underground sources are monitored to control the level of radiation contamination. Surface water monitoring is a system of sequential periodic observations, collection and processing of information on the state of water bodies, projection of possible changes in water quality and development of scientifically based recommendations for making management decisions to improve the state of open water bodies.

As for the actual contamination of the aquatic environment with radionuclides, despite all the technological barriers, an insignificant share of radionuclides from NPPs still gets into the aquatic environment.

To control the state of groundwater and surface water due to the Chornobyl accident and arrangement of radwaste disposal and storage sites in the exclusion zone and zone of unconditional (mandatory) resettlement after it, continuous monitoring is provided at hydrogeological posts, drainage systems, wells, rivers, lakes, etc.

According to map “Radiation Risk in Ukraine”, edition 2001

In the aquatic environment, radionuclides interact with the available organic and inorganic substances and undergo sorption-desorption reactions, deposit, are absorbed by aquatic organisms with subsequent release with metabolic products. This determines the level of water contamination with radionuclides. In general, the interaction of radionuclides with components is rather complicated and includes complexation, hydrolysis, formation of colloids and suspensions. Therefore, experts carrying out radiation monitoring of water also take into account physicochemical forms of radionuclides contained in it.

Adsorption of Radionuclides by the Bottom of Water Bodies

Like the soil, the bottom layer of water bodies is a natural body formed under the impact of a number of natural factors; it includes organic and inorganic substances. Like the soil, it readily adsorbs radionuclides and ions in general. Radioactive substances that get in the atmosphere and on soil surface, later, under the influence of atmospheric precipitation, get in water bodies, and if these water bodies are not flowing, then, very likely, fall to the bottom. In any case, it should be possible to monitor and predict radionuclide concentration in water bodies, especially those into which radioactive substances have entered or could have entered.

Methods of Radiation Monitoring for Soil and Water

Radiation monitoring of the soil includes the following stages:

– field radiometry, dosimetry, which consists in measurements on the ground;

– sampling;

– preparation of samples for measurement;

– qualitative and quantitative measurements of radionuclides by express methods;

– radiochemical determination of radionuclides;

– radiometry of certain radionuclides and activity calculation.

Field radiometry and dosimetry is the first stage of radiation control and monitoring of the environment and its objective is to obtain the data on background gamma radiation levels and flux density of radioactive particles, which allows obtaining the information on the radiation status of the territory.

Special samplers are used for soil sampling, which allow reaching a depth of 20 cm or more. If the top layer of the soil is under analysis, the sampling depth is approximately 5 cm. Inclusions of biotic and abiotic origin (stones, debris, plant roots, animal remains, etc.) are removed from the obtained sample. It is dried, sieved through a sieve with a hole diameter of 1-2 mm, and ground if necessary. Probes and slime pumping devices are used for sampling of the bottom sediments, known as Tsorigo slime pumping device, Ekman-Berg dredge, Lenz probe, etc.

During soil sampling to measure cesium and strontium after determination of homogeneity in gamma background, at each section, a square with an area of at least 10 × 10 m should be selected, from which individual soil samples are taken at a depth of the arable layer. After that, all samples are thoroughly mixed, and then a mixed sample is formed with a weight of 1-3 kg.

Soil samples taken to monitor the content of radionuclides during the international exercises to practice radiation monitoring techniques in the exclusion zone, September 2021

During water sampling, to provide the most correct and representative picture by the measurement result, the sample should contain all the components and in the same proportions as the water body as a whole. For most water bodies, sampling is carried out 7 times a year: during a flood – on the rise, maximum and decline; during the summer runoff flow- at the lowest flow rate and during the rain flood; in the fall, before freezing the water body and during the winter runoff flow. According to another methodology, sampling is carried out 4 times a year (during a flood – on the rise; during the summer runoff flow – at the lowest flow rate; in the fall before freezing and during the winter runoff flow).

The sampling point is selected taking into account factors that can impact sample composition, in particular tributaries and sources that flow upstream. Water composition depends on the place and time of sampling, precipitation, season, etc. Therefore, sampling can be done pointwise – to find out the current condition, or sequentially – to have more substantive information. If we are talking about a water body with running water, then the sampling point is selected where the fastest current is.

For continuous automatic sampling, special installations are used. They can operate during a specified period (day, two, etc.) with a certain frequency of point sampling.

When it is necessary to analyze surface water in water bodies with stagnant water (reservoirs, lakes or ponds) or slow current rivers with a low flow rate and a depth of more than 3 meters, then zonal sampling is carried out at different depths using bathometers.

Groundwater sampling is conducted using holes, pits, etc. During sampling, pumps that allow sampling or special sampling glasses are used, which represent a metal cylinder with a bottom and a place to fix a rope from above. The diameter of the sampling glass is selected to fit pipe diameter in the hole, usually glasses with a volume of 1 liter or more are selected.

During sampling with a pump, a certain volume of water in the hole is pumped through it, also sample container is thoroughly rinsed with water from the hole and the required sample volume is taken to perform measurements. During sampling with a sampling glass, it is lowered into the hole pipe by a rope below the filling level, after filling, the glass is raised to the surface. The first portions of the selected water are usually discarded, after which the sample container is thoroughly rinsed with water from the hole and the required sample volume is taken to perform measurements.

Soil and water samples taken during the international exercises to practice radiation monitoring techniques in the exclusion zone, September 2021

Acceptance and preliminary processing of samples is carried out in a special room equipped with fume chambers and drying cabinets, muffle furnaces, mills, sieve installations, devices to wash dishes, containers and, if necessary, samples. The range of equipment for sample preparation is almost exhaustless and depends on the intended research method, sensitivity of measuring tools, radionuclide composition and contamination level.

Usually, solid samples (soil, bottom sediments, etc.) are prepared for measurements by homogenizing them (grinding, sieving, quartering, etc.), drying or ashing (if the method requires it). Biota samples are prepared according to the same principle, but they are first dried and, if necessary, ashed, and then grinded and prepared for analysis. The method of evaporation or filtration through special filters and sorbents can be used to prepare water samples. In addition to standard sample preparation methods, for the use of analytical tools for gamma, beta and alpha spectrometry, methods using ion exchange resins can be used to determine certain radionuclides. Sample preparation is based on the method of radionuclide concentration. The initial result should be a representative homogeneous sample necessary to perform measurements of sample weight or shape.

Express methods of radiation monitoring are used to quickly clarify the situation of radioactive contamination for environmental objects. Express methods are based on measuring the radiation dose rate from cleanly washed and crushed samples of a certain mass contained in a liter jar or Marinelli vessel and its recalculation into activity units (Bq/kg). Such rapid methods are usually used to determine the specific activity and activity concentration in the range of 2 × 103–4 × 104 Bq/l (kg).

Thick-layer preparations are prepared (the sample is crushed), particle reading rate is measured and mathematical calculation of the activity is performed during the determination of specific activity and activity concentration of beta-emitting radionuclides. The measurement error margin in both cases is 50%.

To determine the level of radioactive contamination for soil and water, after sampling and preparation of samples, they are analyzed in laboratory conditions.

To measure specific activity of a wide spectrum of radionuclides in soil, surface and groundwater samples, various analytical tools are used, in particular popular methods of alpha, beta and gamma spectrometry, liquid scintillation spectrometry.

Alpha spectrometry is the registration of alpha particles emitted by a source in the form of an electrical pulse height distribution. A semiconductor alpha spectrometer (Alpha-Analyst, Canberra, USA) can be used for this.

UMF-2000 radiometer-spectrometer can be used to determine beta radiation activity of radionuclides (plumbum-210, bismuth-210, strontium-90, yttrium-90). The duration of strontium measurement using this device will last a sufficiently long time required for the natural decay of yttrium.

Using gamma-spectrometric equipment, it is possible to simultaneously determine the content of many radionuclides, in particular potassium-40, uranium-238 and uranium-235, thorium-226 and others.

Liquid scintillation spectrometry is used to determine the activity of radium and tritium isotopes, especially in liquids.

To measure radioactivity of water and discharges, flow-through liquid radiometer RZhB-11M (designed to measure the specific activity of beta-emitting radionuclides in purified process water) can be used, submersible detecting unit BDIG-31P2Zh can be used to measure specific activity in a liquid medium, amount of beta- and gamma-emitting radionuclides and other equipment.

Mobile radiological laboratory of the State Scientific and Technical Center for Nuclear and Radiation Safety

It should be noted that radiation monitoring is carried out not only with using foreign equipment, but also domestic, and it is highly appreciated not only in Ukraine, but also abroad. Thus, in particular, upon inventions of Scientific and Production Association Impuls (Severodonetsk, Luhansk region), more than 20 thousand monitoring systems were produced. They were put into operation in Bulgaria, Hungary, Vietnam, Finland, Japan and other countries. Scientific and Production Enterprise Radiy (Kropyvnytskyi, Kirovohrad region) is a leading developer and supplier of up-to-date I&C systems and electrical equipment for nuclear power plants.

The efforts of many experts from both Ukraine and the world are aimed at minimizing the consequences of the Chornobyl accident in 1986 and preventing this in the future, organizations responsible for radiation monitoring are clearly defined, and upon the information they receive, relevant reports are prepared. In Ukraine, ARMS monitoring systems and RODOS decision support system are operated. The regulatory and legal framework has been developed and is constantly being improved, international cooperation and experience exchange with EU countries and the USA have been established.

A number of organizations, including the State Scientific and Technical Center for Nuclear and Radiation Safety, are equipped with mobile radiological laboratories that can qualitatively and promptly analyze the radiation situation, however, the need to update measuring tools remains relevant for the country. Now this is implemented by national manufacturers of radiometric and dosimetric equipment and foreign partners.

It should be noted that Ukrainian experts are constantly improving their knowledge and skills by participation in specialized workshops, studies, training, because ensuring an acceptable level of nuclear and radiation safety for society is a continuous process, whose main aspect is obtaining timely and reliable information on radiation state of objects, the environment and environment of human life and activities. Editorial Board