Chernobyl Exclusion Zone Research Articles

Soybean recovery from stress imposed by multigenerational growth in contaminated Chernobyl environment

Ionizing radiation is a genotoxic anthropogenic stressor. It can cause heritable changes in the plant genome, which can be either adaptive or detrimental. There is still considerable uncertainty about the effects of chronic low-intensity doses since earlier studies reported somewhat contradictory conclusions. Our project focused on the recovery from the multiyear chronic ionizing radiation stress. Soybean (Glycine max) was grown in field plots located at the Chernobyl exclusion zone and transferred to the clean ground in the subsequent generation. We profiled proteome of mature seeds by two-dimensional gel electrophoresis. Overall, 15 differentially abundant protein spots were identified in the field comparison and 11 in the recovery generation, primarily belonging to storage proteins, disease/defense, and metabolism categories. Data suggested that during multigenerational growth in a contaminated environment, detrimental heritable changes were accumulated. Chlorophyll fluorescence parameters were measured on the late vegetative state, pointing to partial recovery of photosynthesis from stress imposed by contaminating radionuclides. A plausible explanation for the observed phenomena is insufficient provisioning of seeds by lower quality resources, causing a persistent effect in the offspring generation. Additionally, we hypothesized that immunity against phytopathogens was compromised in the contaminated field, but perhaps even primed in the clean ground, yet this idea requires direct functional validation in future experiments. Despite showing clear signs of physiological recovery, one season was not enough to normalize biochemical processes. Overall, our data contribute to the more informed agricultural radioprotection.

Features and trends of the Chernobyl tourism development

The author defines Chernobyl tourism as a visit to the exclusion zone, which was formed as a result of a large-scale technological disaster, i.e., an explosion at the Chernobyl nuclear power station in 1986, for educational, scientific, business, recreational and other tourism purposes. The complexity of Chernobyl tourism is proved and schematically presented. The main types of tourism which can be promoted in the Chernobyl Zone (ChZ) such as cultural, cinema, active, scientific, conference, dark, sentimental, adventure, extreme, industrial, business, event, diplomatic and ecotourism had been analyzed. Four stages of the development of Chernobyl tourism are disclosed: 1) illegal visits to the exclusion zone (starting from the late 1980s); 2) official visits (starting from the late 1990s); 3) emergence of Chernobyl tourism companies (starting from the first decade of the 2000s); 4) mass tourism (starting from the second decade of the 2000s). The statistics of visiting the ChZ for the last five years had been analyzed. The number of foreigners visiting ChZ was compared with the total number of foreigners visiting Ukraine. The results of the marketing research of the profile of 1000 random visitors to the ChZ, conducted in November 2019, are presented. The formula of the economic contribution of Chernobyl tourism to the development of the tourism sector of Ukraine and the national economy as a whole has been derived. As a result of generalization of statistical data, as well as the results of marketing research, a number of features of Chernobyl tourism was formulated and analyzed: uniqueness of this tourism product; phasing of development; tours organization; availability of various types of tourism; dominance of foreign tourists; relatively high cost of the product; narrow segmentation of the product; purposefulness of the tours; the game, television and film industry influence; short trips duration; three-level self-organization of Chernobyl tourism; an increase in the number of illegal tourists; the lack of developed tourism infrastructure; the high interest of foreign investors; the lack of a systematic scientific and strategic approach. The recommendations for authorities and representatives of Chernobyl tourism promotion companies were formulated to increase the economic contribution of this type of tourism.

Динаміка вмісту радіонуклідів 137Cs в організмі дітей, які проживають в районах Київської області, що межують з чорнобильською зоною відчуження

Динаміка вмісту радіонуклідів 137Cs в організмі дітей, які проживають в районах Київської області, що межують з чорнобильською зоною відчуження

Relationship between follow-up periods and the low-dose ranges with statistically significant radiation-induced risk of all solid cancers in the Russian cohort of Chernobyl emergency workers.

Radiation-induced risks for all solid cancer incidence and mortality were studied in the cohort of Russian Chernobyl emergency workers. The cohort included 69,440 persons with documented individual radiation dose accrued over the time of working in the Chernobyl zone. The mean age at entry into the zone of recovery operations was 33.9years and accumulated radiation dose was 132.9mGy. A total of 6981 solid cancer incident cases and 4272 deaths occurred in this cohort from 1992 to 2017. Three follow-up periods were studied: 1992-2009, 1992-2013, and 1992-2017. For each follow-up period, the lowest dose range with statistically significant (p < 0.05) radiation-induced risk of all solid cancer incidence and mortality were obtained. For the incidence of all solid cancer during the follow-up period 1992-2009, this lowest dose range was estimated to be 0-250mGy with an excess relative risk per dose of ERRGy-1 = 0.51 and 95% confidence interval (CI) (0.02; 1.05) Gy-1. For the period 1992-2013, the lowest dose range was 0-175mGy with ERRGy-1 = 0.85 (95% CI 0.03; 1.78), while for the whole follow-up period 1992-2017, it was 0-175mGy with ERRGy-1 = 0.81 (95% CI 0.08; 1.62). For mortality from all solid cancers during the follow-up period 1992-2009, the lowest dose range with statistically significant radiation-induced risk was estimated to be 0-225mGy with ERRGy-1 = 1.07 (95% CI 0.31; 0.97). For the period 1992-2013, the lowest dose range was 0-225mGy with ERRGy-1 = 0.86 (95% CI 0.23; 1.58), while for the whole follow-up period 1992-2017, the lowest dose range was 0-200mGy with ERRGy-1 = 0.82 (95% CI 0.10; 1.65). Thus, it was found that the minimal level of significant exposure (Dmin), for which a statistically significant radiation-induced risk of all solid cancers was obtained for Russian emergency workers (with individual doses of 0 - Dmin), decreases with increasing duration of cohort observation, both for cancer incidence and mortality.

THE DEVELOPMENT OF THE CHORNOBYL EXCLUSION AREA: ECONOMIC DYNAMICS

Objectives. The article is devoted to revealing a number of aspects regarding the nature of the Chernobyl accident and the economic dynamics of tourism development in the region. The basic principles of activity of participles of the tourist services market in the Chernobyl exclusion zone which position Ukraine as a tourist country, have been determined. Methods. In order to solve these tasks, the essence of the administrative processes, which were planned to be put info practice by the authorities at different leves, as well as parti cipants in the tourist services market, in substantiated. Results. The scientific article investigates the main causes of the Chernobyl disaster, the economic dynamics of tourism development in the Chernobyl Exclusion Zone, and identifies possible negative impacts on its development due to the pandemic of the world and in Ukraine. Essentially new which has not been the case before, the autors of the scientific article propose to discuss and consolidate their own name for this geographical region «Safe Chernobyl». Scientific novelty. The autors of the scientific article are offered to discuss the new name - of this geographical region in the formulation «Safe Chernobyl» and to establish it legally new, which was not there before. Practical importance. Fixing the name of the geographical region of the Chernobyl Exclusion Zone in the formulation of safe Chernobyl, in the future, will positively affect the economic dynamics of the regions development and popularization of Ukraine asa tourist country.

Mycoremediation affects antioxidative status in winter rye plants grown at Chernobyl exclusion zone site in Ukraine.

Soil contaminated with heavy metals in general and radionuclides in particular represents an escalating problem for all living organisms. Since, Chernobyl nuclear power plant accident in 1986 in Ukraine, an exclusion zone of 30 km around the former power plant is uninhabitable land due to severe contamination. Two most notable beta emitters contributing to dose hazards for decades is radioactive 137Cs/90Sr. However, large parts of the zone are also highly contaminated with uranium particles (hot particles) bearing trace amounts of highly alpha-emitting radionuclides. We established an experiment at exclusion zone with the aim to investigate the influence of two macro fungi (Schizophyllum commune (S.C.) and Leucoagaricus naucinus (L.N.)) on oxidative status and antioxidative responses in winter rye plants; from this, we wanted to test the radionuclide/heavy metals retention capacity of both fungi, and probe their further potential for mycoremediation.Result shows some differences in the concentrations of radionuclides/heavy metals and micro/macronutrients uptake in plants. As a biomarker of oxidative status, lipid peroxidation (LPO) levels and other antioxidative parameters were determined, i.e., superoxide-dismutase (SOD) isoenzymes, cysteine (CYS), and ascorbic acid (AA) concentrations as well as catalase (CAT) and glutathione reductase (GR) activities in winter rye shoots. LPO showed no significant differences between controls and plants cultivated with macro fungi. However, CAT activities were elevated in the presence of S.C/L.N compared with control, while GR activity was significantly higher only in presence of S.C. In contrast, isozyme of SOD (Cu,Zn-SOD) was the most prominent in control. Likewise, CYS content was lower in plants grown with both fungi, while AA concentration was only lower in the presence of L.N. The results showed that presence of fungi in radionuclide contaminated soil caused induction of antioxidative response in shoots of winter rye and that the response depended on the type of fungi used.

Глікозидазна та протеолітична активність мікроміцетів, виділених з Чорнобильської зони відчуження

Глікозидазна та протеолітична активність мікроміцетів, виділених з Чорнобильської зони відчуження

Disorders of the initial ontogenesis of seed progeny of the common reed (Phragmites australis) from water bodies within the Chernobyl Exclusion Zone

The peculiarity of seeds germination of the common reed Phragmites australis, which is a cosmopolitan plant and widespread at littoral zone of the Chernobyl Exclusion Zone water bodies, was studied. The complex of vitality, physiological and morphological indices of seedling as seed germination, germination energy, seedling survivability and seed vitality, length of initial leaf and root and abnormalities of seedlings were investigated. The current average absorbed dose rate on the reed vegetative plants ranged from 0.05 to 34 μGy h−1. Data demonstrated correlation between dose rate and seed progeny vitality. All investigated indices of the common reed's progeny from impacted water bodies significantly differed from reference ones – viability indices were decreased, seedling growth was slower and number of seedling abnormalities were increased. Logistic regressions were found for growth of seedlings initial root and leaf from impacted sites and mostly exponential and linear for reference ones. An essential abnormalities percentage up to 75% was registered for reed seedlings from the impacted sites. Significance of dormancy for improvement of reed seeds germination from the Chernobyl Exclusion Zone was discussed.

Animal remains from the late medieval Chornobyl hillfort (12–13th cent. AD) in Ukraine

The paper presents the results of archaeological research on animal remains found in the territory of Chornobyl hillfort and its surroundings. The Medieval Chornobyl was an important settlement of the sparsely populated Kyivan Polesia, a vast land of peat bogs and boreal forests. Today, the city is the centre of Chornobyl Exclusion Zone that was established after the 1986 nuclear disaster. Archaeological surveys have been conducted in this restricted area since 2003 and a significant amount of materials has been amassed during excavations of Chornobyl hillfort. In this paper, we analyse 1060 specimens of fish, birds and small mammal remains in order to reconstruct the economy of the Chornobyl hillfort and the environmental conditions of the surrounding area. The obtained result allow to suggest that (1) fishing and hunting played a considerably higher role in life of the settlement as opposed to animal husbandry, (2) the latter was insignificant because of the surrounding environmental conditions, in particular due to the predominating areas of wetlands and forests, and the small portion of arable lands. When comparing the current species composition of the Chornobyl area with the list of identified medieval remains, we can notice that species dynamics have been affected by both natural (warming, shifts of natural zones) and anthropogenic (fishing, hunting, deforestation disturbance, wetland drainage) factors. In general, our results suggest that the Medieval Chornobyl was surrounded by a typical boreal faunal assemblage with a predominance of water-related (waterfowl and semi-aquatic) species among its terrestrial component.

EXPERIMENTAL RESEARCH ON ENVIRONMENTAL IMPACT ON ENVIRONMENT AFFECTED BY FOREST FIRE UNDER COMPLEX RADIATION CONDITIONS OF FIREFIGHTING

The paper deals with the problem of formation of general procedures for experimental study of environmental impact due to forest fire in complex radiation conditions of fire load formation and its further testing on the example of the ChNPP exclusion zone. The study carried out an experimental verification of the adequacy of the previously proposed methodological apparatus and identified the main directions of its further use as a basis for solving the problems of predicting the negative environmental impact on the environment. To this end, the following tasks have been solved:the general procedures of the methodology of experimental study of environmental impact due to forest fire in complex radiation conditions of fire load formation are formulated; a comprehensive experimental study was carried out using the developed method on the example of the fire load of the Chernobyl exclusion zone. Conducted studies in the field indicate that the content of radioactive smoke in the ground atmosphere of the Exclusion Zone can be dramatically increased by several orders of magnitude due to forest fires. Short-term (sever-al days) increased content of radioactive combustion products in the surface air can reach the level of radiation hazard for both the environment and directly for the life of the population living in a clean area at considerable distances (up to 30 km along the track axis) wildfire. The fires in the forests contaminated with Chornobyl radionuclide in the western trace due to the loss of TUE are of particular environmental danger, since the presence of plutonium combustion products in radioactive products results in significant dose loads for the environment and the population. The practical significance of the obtained results lies in the possibility of their application for carrying out complex ecological audit of the territory, which is subject to secondary radiation influence both inside and outside the exclusion zone of the Chornobyl NPP. Keywords: ecological safety, forest fire, radiation exposure, complex fire load

Effect of Extrusion Processing Conditions on the Phenolic Compound Content and Antioxidant Capacity of Sorghum (Sorghum bicolor (L.) Moench) Bran.

Sorghum is a cereal with little use in human diet; however, this grain can provide several nutrients and, additionally, has a high content of phenolic compounds concentrated in bran, which could be beneficial to human health due to its high antioxidant capacity. However, these bioactive compounds are bound within the cell wall matrix; it is necessary to release these compounds to take advantage of their antioxidant properties. The extrusion process increases the accessibility of bound phenolic compounds, breaking their bonds from the bran matrix. The aim of this study was to determine the optimal extrusion conditions for maximizing the phenolic compound content and antioxidant capacity of sorghum bran extrudate. The extrusion process factors evaluated were feed moisture (FM) from 25 to 35% and the fourth extrusion zone temperature (T) in the range of 140-180°C. Analysis of variance and response surface analysis were used in the evaluation. The prediction coefficient, (FM)2, (T)2 and their interaction (FM)(T) significantly affected the free total phenolic compounds. The antioxidant capacity of the free total phenolic compounds was significantly affected by (FM)2 and (T)2. The optimal extrusion conditions were FM = 30% and T = 160°C, which provided free total phenolic compounds with a value of 7428.95μg GAE/g (predicted value: 7810.90μg GAE/g) and antioxidant capacity with a value of 14.12μmol TE/g (predicted value: 14.85μmol TE/g). Results confirmed that extrusion process optimization was useful to increase the content of phenolic compounds and improved the antioxidant capacity of sorghum bran.

About Total Alpha Activity of Underground Water Sources

Artesian wells remain strategically important sources of drinking water for the Kyiv megacity, especially in the vicinity of radioactively contaminated areas of the Chornobyl exclusion zone. The contribution of groundwater to the total volume of drinking water was indicated. The water from 144 artesian wells was investigated in terms of total alpha activity: 67 of them were drilled up to the Cenomanian aquifer of the Upper Cretaceous, 77 - up to the Bajocian aquifer of the Middle Jurassic.&#x0D; Studies have found that the total alpha activity in 39 wells exceeds the regulatory limit, with 37 of the 39 wells supplying water from the Bajocian aquifer. The average total alpha activity of the Cenomanian water is 0.033 ± 0.003 Bq/dm3, the most active water of this aquifer is produced in the Obolon area where the average value equals 0.045 ± 0.004 Bq/dm3. The average total alpha activity of the Bajocian water is 0.115 ± 0.012 Bq/dm3, the most active water of this aquifer is produced in the Obolon and Troyeshchyna areas where the average values equal 0.097 ± 0.010 Bq/dm3 and 0.188 ± 0.018 Bq/dm3, respectively. Therefore, in average, the Bajoian water is 3.5 times more active than the Cenomanian one: the average activity reaches 0.115 ± 0.012 Bq/dm3 against 0.033 ± 0.003 Bq/dm3.&#x0D; GIS mapping of the total content of α-emitters in the groundwater of both aquifers was created. The dynamics of the gross alpha activity of artesian water from both aquifers was monitored for the Obolon area. It was determined that when consuming the Bajocian water, two times more alpha-emitters enter the human body than from the Cenomanian water.&#x0D; The processing of the results through the spline interpolation with the Spatial Analyst Tools module ArcGIS 10.1 made it possible to analyze this trend for the megacity area: geological and tectonic factors such as block movement of the foundation, unequal incision of ancient watercourses into the pre-Bajocian surface and the erosion of sediments had always had the greatest influence on the enhanced alpha activity of the Bajocian water.

A 1 GS/s 12-Bit Pipelined/SAR Hybrid ADC in 40 nm CMOS Technology

A 1 GS/s 12-bit pipelined/successive-approximation-register (pipelined/SAR) hybrid analog-to-digital converter (ADC) is presented in this paper, where the five most significant bits are resolved by two cascading 2.5-bit multiplying digital-to-analog converters, and the eight least significant bits are determined by a two-channel time-interleaved successive-approximation-register (TI-SAR) quantizer. An integrated input buffer and an operational amplifier with improved voltage efficiency at 1.8 V are adopted to achieve high-linearity stably in wide band for 1 GS/s. By designing a 500 MS/s 8-bit SAR quantizer at 1 V, the number of required interleaved channels is minimized to simplify the complexity and an adaptive power/ground is used to compensate the common-mode mismatch between the blocks in different power supply voltages. The offset and gain mismatches due to the TI-SAR quantizer are compensated by a calibration scheme based on virtually-interleaved channels. This ADC is fabricated in a 40 nm complementary metal-oxide-semiconductor (CMOS) technology, and it achieves a signal-to-noise-and-distortion ratio (SNDR) of 58.2 dB and a spurious free dynamic range (SFDR) of 72 dB with a 69 MHz input tone. When the input frequency increases to 1814 MHz in the fourth Nyquist zone, it can maintain an SNDR of 55.3 dB and an SFDR of 64 dB. The differential and integral nonlinearities are −0.94/+0.85 least significant bit (LSB) and −3.4/+3.9 LSB, respectively. The core ADC consumes 94 mW, occupies an active area of 0.47 mm × 0.25 mm. The Walden figure of merit reaches 0.14 pJ/step with a Nyquist input.

Aerosol activity measurements associated with the burning of peat materials (evacuation zone of the Bryansk Region)

In April and August 2015, a massive fire occurred in the Chernobyl Exclusion zone. The fire spread to neighboring areas due to the prevailing strong winds. In this paper, we analyze the peat fires as a unique source of radioactive contamination. After an expedition directly to the peat fire site (the evacuation zone of the Bryansk region), we collected a number of aerosol samples. We came to the conclusion that peat fires cannot be the reason for radioactive particle transport in the Bryansk region as well as in the Chernobyl evacuation zone. During the peat fire, radioactive contamination was not transferred by aerosols beyond 500 m. The 137Cs concentration in the aerosol filters varied between 0.55 and 0.64 Bq/m3, and that at the same distance from the fire seat and peat edge was 4.4∙10−3 Bq/m3; the activity values in the peat bog and in the nearest inhabited locality did not exceed the background values. Strontium-90 was not found in aerosol samples. The soil-to-air transport rate of 137Cs was 2.7∙10−6. After the Chernobyl accident, the majority of the 137Cs was incorporated into the structure of clay minerals, and these did not change during the peat fire. The mobility of 137Cs in the flight peat material particles was established. To confirm the territory status of the evacuation zone, we also collected some food samples. Berries and mushrooms consumed at the assumed rate for dose estimation would result in doses that exceed the public dose limit by approximately a factor of five.

Exposure to environmental radionuclides alters mitochondrial DNA maintenance in a wild rodent

Mitochondria are sensitive to oxidative stress, including that derived from ionizing radiation. To quantify the effects of exposure to environmental radionuclides on mitochondrial DNA (mtDNA) dynamics in wildlife, bank voles (Myodes glareolus) were collected from the chernobyl exclusion zone (CEZ), where animals are exposed to elevated levels of radionuclides, and from uncontaminated areas within the CEZ and elsewhere in Ukraine. Brains of bank voles from outside the CEZ were characterized by low mtDNA copy number and low mtDNA damage; by contrast, bank voles within the CEZ had high mtDNA copy number and high mtDNA damage, consistent with putative damaging effects of elevated radiation and a compensatory response to maintain sufficient functioning mitochondria. In animals outside the CEZ, the expression levels of PGC-1α gene and mtDNA copy number were positively correlated as expected from this gene’s prominent role in mitochondrial biogenesis; this PGC-1α-mtDNA copy number association is absent in samples from the CEZ. Our data imply that exposure to radionuclides is associated with altered mitochondrial dynamics, evident in level of mtDNA and mtDNA damage and the level of activity in mitochondrial synthesis.

Radiological Mapping of Post-Disaster Nuclear Environments Using Fixed-Wing Unmanned Aerial Systems: A Study From Chornobyl.

In the immediate aftermath following a large-scale release of radioactive material into the environment, it is necessary to determine the spatial distribution of radioactivity quickly. At present, this is conducted by utilizing manned aircraft equipped with large-volume radiation detection systems. Whilst these are capable of mapping large areas quickly, they suffer from a low spatial resolution due to the operating altitude of the aircraft. They are also expensive to deploy and their manned nature means that the operators are still at risk of exposure to potentially harmful ionizing radiation. Previous studies have identified the feasibility of utilizing unmanned aerial systems (UASs) in monitoring radiation in post-disaster environments. However, the majority of these systems suffer from a limited range or are too heavy to be easily integrated into regulatory restrictions that exist on the deployment of UASs worldwide. This study presents a new radiation mapping UAS based on a lightweight (8 kg) fixed-wing unmanned aircraft and tests its suitability to mapping post-disaster radiation in the Chornobyl Exclusion Zone (CEZ). The system is capable of continuous flight for more than 1 h and can resolve small scale changes in dose-rate in high resolution (sub-20 m). It is envisaged that with some minor development, these systems could be utilized to map large areas of hazardous land without exposing a single operator to a harmful dose of ionizing radiation.

МОНІТОРИНГ РАДІАЦІЙНОГО ЗАБРУДНЕННЯ ТЕРИТОРІЇ ЧОРНОБИЛЬСЬКОЇ ЗОНИ

Urgency of the Research. Thirty-five years have passed since the Chernobyl accident. During this time, the environment has undergone constant changes under the influence of natural and human factors. Knowledge of these changes is impossible without the separation of anthropogenic processes from natural, which is why they organize special observations on various parameters of the biosphere, which change as a result of human activity. It is in the observation of the environment, the assessment of its actual state, and the forecasting of its development, that the essence of monitoring of radiation pollution of the territory of the Chernobyl zone is under the present conditions. Target setting. Investigation of modern technological procedures and technical means of monitoring to further create a system of integrated radiological control of the environment will ensure the prevention and elimination of negative changes in the state of the environment in the territory of both the Chernobyl Exclusion Zone (ChEZ) and throughout Ukraine. Actual scientific researches and issues analysis. Recent publications and reports on open access concerning the problems of monitoring of radiation pollution of the Chernobyl zone in the current conditions have been considered. Uninvestigated parts of general matters defining. Maintaining integrated radio-ecological environmental monitoring in areas where radiation hazards are located requires constant monitoring and monitoring of the radiation environment in the environment in order to determine its level of contamination and respond quickly to emergencies and prevent possible radiation accidents, as well as to prevent their occurrence. and the environment. The research objective. Comprehensive monitoring of radiation pollution requires the adaptation of the RODOS system to the conditions of the Chernobyl Exclusion Zone and potential specific sources of emissions in the ChEZ, the creation of a complete register of collected data for the adaptation of the RODOS system to the conditions of the ChEZ, a systematic description of sources of emissions from forest fires, fires, during the decommissioning of the ChNPP. The statement of basic materials. The article deals with the issues of integrated radio-ecological monitoring of the environment in the areas of radiation hazard objects, the use of an automated radiation monitoring system (ASCRO), the implementation of a real time decision support system in response to nuclear accidents - RODOS in Chernobyl. Conclusions. The implementation of ASCRO and RODOS systems in the Chernobyl zone has allowed to create a comprehensive system of radio-ecological environmental monitoring of the state, regional and local levels, which is intended to solve the main tasks of environmental safety management, including, at high risk objects.

RESULTS OF WBC/MONITORING OF FIREFIGHTERS PARTICIPATING IN RESPONSE TO CHORNOBYL FOREST FIRES IN APRIL–MAY 2020

Objective.of this study was to determine the levels of radionuclides in the rescuers’ bodies of the SES during firefighting in the exclusion zone of the Chornobyl nuclear power plant and to assess the dose of internal radiation due to this receipt. Materials and methods. From 06.04.2020 to 19.05.2020 in the State Institution «National Research Center for Radiation Medicine of the National Academy of Medical Sciences of Ukraine» (NRCRM) measurements of the content of incorporated gamma radionuclides on whole body counters (WBC) operational class «Screener-3M» (Minimum detected activity (MDA) is 300–500 Bq for 5 minutes of measurement at 137Cs) and expert high-sensitivity WBC (MDA is 20 Bq for 10 minutes of measurement at 137Cs). 470 people (523 measurements) in three groups of personnel of the SES of Ukraine who took part in the forest fire liquidation in the exclusion zone in the period from April 4 to May 5, 2020 were examined. Mathematical and spectrometric methods are used in the work. Results and conclusions. In the vast majority (95 %) of the personnel of the SES of Ukraine, examined at the WBC operational class «Screener-3M» (more than 500 measurements), the assessment of the values of the individual effective dose of internal radiation due to 137Cs in the body during firefighting, assuming that it receipt occurred during operation in the exclusion zone, did not exceed the minimum dose detected by MDD (5–14 μSv). The average value of the effective dose of internal radiation in the group of personnel of the State Emergency Service of Ukraine in Kyiv, which participated in the elimination of forest fires in the exclusion zone from April 4 to May 5, 2020 (26 people) studied at the expert WBC, is 2.5 ± 1.1 μSv, in the group of personnel of the SES of Ukraine in Cherkasy region, which participated in the fire on April 19–24, 2020 (9 people) – 2.2 ± 0.6 μSv, in the group of personnel of the SES of Ukraine in the Kyiv region, which took part in the elimination of the forest fire in the exclusion zone on April 4 – May 5, 2020 (42 people) – 4.4 ± 2.4 μSv. Maximum values of 5.1 μSv, 3.5 μSv, 11.8 μSv in the groups of Kyiv city, Cherkasy and Kyiv regions, respectively, which is much lower than the basic dose limit for the population from man-made sources of 1000 μSv · year-1 according to the Law of Ukraine about protection of the person against influence of ionizing radiation. Key words: forest fire, Chornobyl Exclusion Zone, internal irradiation, whole body counters, 137Сs.

Моделювання атмосферного розповсюдження радіоактивності, винесеної в повітря в результаті лісових пожеж у зоні відчуження у квітні 2020 р.

In April 2020, the largest forest fire occurred in the Chornobyl Exclusion zone in its history. The results of modeling the atmospheric transport of radioactive aerosols raised into the atmosphere as a result of fires in forest and grass areas in the Exclusion zone, as well as in radioactively contaminated forests outside it in Kyiv and Zhytomyr regions are presented in the paper. To assess the consequences of forest fires, a set of models of lifting, atmospheric transport and deposition of radionuclides on the underlying surface LEDI, developed at the Institute for Safety Problems of Nuclear Power Plants of the National Academy of Sciences of Ukraine, was used. Calculations of the dynamics of the 137Cs activity concentration field in the surface air on a regional scale (in Ukraine) and on a local scale (within the Exclusion zone) were performed. According to the simulation results, the maximum values of the 137Cs activity in the surface air of Kyiv in some periods during April 4−20 could reach 2−4 mBq/m3, and the integral value of 137Cs activity in the air of Kyiv for the whole period was about 450 mBq⋅s/m3. The obtained results are generally consistent with the data of measurements of radioactive contamination of the nearground air in Kyiv and areas of the nuclear power plants in Ukraine. The analysis of the consistency of the simulation results with the data of measurements of the 137Cs activity concentration in the air in the Exclusion zone was performed. The main ways to improve the methodology for assessing the consequences of forest fires by modeling the atmospheric transport of radionuclides are identified.

Ecological and economic analysis of forest use in the exclusion zone

The article considers the problem of radiation pollution, which requires constant research, monitoring, and control. The safety and health of the population, the environment, and the possibility of sustainable development and restoration of natural capacity depend on this topical issue. The paper analyzes the problems of forest use in radiation-contaminated areas and examines the current environmental condition in forest areas of the exclusion zone. The forest use in radioactively contaminated areas is established to be associated with the use of forest resources and functions of forest ecosystems, taking into account the degree of radioactive contamination. Its main goal is to obtain clean products with economic benefits over total environmental, economic, and social costs. Prolonged radioactive contamination of forestry lands, slow self-clearing of forests, and legal restrictions on forest management in conditions of radioactive contamination have determined the special forestry conditions in such areas. Thus, the need to overcome the consequences of the Chornobyl disaster as well as rehabilitation and sustainable development of radioactively contaminated areas determine the study of criteria that are important when choosing a strategy for forest management in environmentally problematic regions. The issue of the consequences of forest fires in the Chornobyl zone is revealed. Emphasis is placed on the issue of environmental and economic principles of assessing the efficiency of forest management in radioactively contaminated areas, which, in contrast to the existing ones, are based on taking into account the peculiarities of forest management in such areas. The dynamics of forest reproduction in the context of the last decade is presented. A model of forestry development in areas contaminated with radionuclides is proposed.