Chernobyl NPP Accident Research Articles

Cooking of the dried mushrooms as an effective solution for the reduction of the <sup>137</sup>Cs concentration

The aim of the current study was to evaluate the effectiveness of cooking (washing, soaking and boiling) of the mushrooms to reduce the137Cs concentration. The following tubular dried mushrooms were selected for the study: Boletus edilus (cepe), porcini lurid boletus, annulated boletus, orange-cup boletus, variegated boletus and bay bolete. The mushrooms were collected in 2016 in the Bryansk region areas (Gordeevsky, Klintzovsky and Krasnogorskiy districts) with the maximum contamination after the Chernobyl NPP accident. The activity concentration of137Cs was determined by gamma-spectrometry. Effectiveness of cooking was assessed by calculating the coefficient of cooking reduction equal to the ratio of the activity of137Cs in water fraction to the activity in the initial dried mushroom sample. The results of the study indicated that the most effective way of cooking the mushrooms was washing, allowing reducing the concentration of137Cs by 49%. The major part of137Cs was transferred to the water fraction with the first decanting – 32%; with the consecutive two decantings – 11% and 6%, respectively. During the soaking of mushrooms, 26% of137Cs is transferred into the water fraction within the first 3 hours: 14% – during the first hour, 9% – in the second and 3% – in the third. Increase in the soaking time had low effect on the reduction of the concentration of137Cs and reduced the taste characteristics of the meal. The complex use of all three stages of cooking (washing, soaking and boiling) allows reducing the concentration of137Cs up to 75% in the mushroom broth.

Termination of the nuclear and radiation legacy of Russia: scientific basis for the radiation-hygienic regulation

For the provision of the radiation safety of the public during the termination of the nuclear and radiation legacy within the boundaries of the Federal Targeted Program “Provision of the nuclear and radiation safety for 2016-2020 and up to 2030”, the following documents were developed: draft of the sanitary rules “Hygienic requirements for the remediation of the facilities and territories contaminated by man-made and natural radionuclides due to the past activities of the facilities of nuclear and non-nuclear branches of industry” and three methodical guidelines on the survey of the remediated territories, buildings and structures and assessment of the doses of the public residing in the zone of influence of the nuclear legacy facilities. The sanitary rules were based on the directions of the future use of the remediated territories, buildings and structures as well as on the radiation-hygienic safety criteria. It was assumed that dose criteria for the public considering the quota (0.3 mSv/year) is applied for remediated sites of the nuclear facilities (radiation facilities). The remediation of the radioactively contaminated areas with the residing public is based on the requirements of the Federal Law № 1244-1, 15.05.1991 “On the social protection of the citizens exposed due to the Chernobyl NPP accident”. Originally the drafts of documents were developed considering the approval in 2019 of the new Norms of the Radiation Safety – 2019, harmonized with the international recommendations and standards. Due to prolongation of the existing Norms of the Radiation Safety 99//2009 for the extra five years, the drafts of the regulations are adapted to the existing NRB 99/2009 and OSPORB 99/2010.

Radiation-hygienic monitoring and assessment of the doses of the public residing on the radioactively contaminated territories of the Tula region

Aim of the study: analysis of the results of the radiation-hygienic monitoring of the territories of the Tula region, contaminated due to the Chernobyl NPP accident; concentration of 137Cs and 90Sr in the locally produced food products and analysis of the annual effective dose of the public. Materials and methods: the study was performed in the Tula region in 1997-2018. It included the evaluation of the indicators of the radiation safety of more than 50 thousand samples of the main food products, sampled in the areas of the radioactive “Chernobyl” contamination of the region with the simultaneous measurement of the external gamma-radiation dose rate in the stationary control points. Additionally, it included the assessment of the dynamics of concentration of 137Cs and 90Sr in food products, maximal values of mean annual effective doses of the public and contribution of the collective dose from medical exposure into the structure of the annual collective dose of the public. Results: The study allowed estimating the concentration of 137Cs and 90Sr in the main local food products. Estimated values of gamma radiation dose rate were stable and laid in the range of normal variations specific to the middle latitudes of the European part of Russia. The values of maximal mean annual effective doses of the public indicate the stable radiation environment and do not exceed 1 mSv. It should be mentioned that the contribution of collective dose from medical exposure into the annual collective dose of the public as well as the values of mean individual effective doses from medical exposure are reducing with the increase in the number of X-ray examinations. Conclusions: The lack of exceedances of the permissible levels of 137Cs and 90Sr in the locally produced food products and the reduction of the mean annual effective dose of the public indicates the possibility of the transfer of the settlements affected by the Chernobyl NPP accident into the normal living conditions within the program of the transfer of the settlements from the “Chernobyl” zone.

Жиророзчинні вітаміни: фізіологічне значення та роль у житті населення екологічно небезпечних регіонів України

ABSTRACT. The article addresses the value of fat-soluble vitamins as a mean of increasing body radiation resistance under unfavourable environmental conditions resulting from the Chernobyl NPP accident. The radioprotective role of essential organic compounds with high biological activity that contribute to the functioning of the body under complicated environmental conditions. Insufficient dietary intake of vitamins increases the radiosensitivity of the human body. Data are given on the actual dietary intake of vitamins by different age groups (employable adults, children, pregnant women from different settlements in the District of Ivankiv of the Region of Kyiv for 2004–2018) living at the territories contaminated as the result of Chernobyl NPP accident. Analysis of literature and own data indicate that fat-soluble vitamins are essential food components that regulate biochemical and physiological processes in the human body due to the activation of metabolic and enzymatic reactions, have radioprotective properties and should enter the body in sufficient amounts in accordance with age and gender. This is especially true of the population affected because of the Chernobyl NPP accident. Study results have shown that retinol and calciferol deficiency in the body of the population living in the regions affected as a result of Chernobyl NPP accident, is due to changes in the conventional structure of diets and consumption of counterfeit products, first of all, butter and hard cheese. Despite the fact that average daily diet contains a wider range of products compared with the first post-accident years, level of fat-soluble vitamins, in particular vitamin A (even considering b-carotene) and vitamin D does not meet the physiological needs, which may cause dysmetabolic processes in various organs and systems and lead to an increase in alimentary and alimentary-dependent diseases. Key Words: fat-soluble vitamins, physiological role of vitamins, vitamin deficiency, sources of vitamins, recommended daily intake, population of environmentally dangerous regions, Chernobyl NPP accident.

Role of proinflammatory cytokines TNF-[alpha] and IL-6 in pathogenesis of type 2 diabetes mellitus in persons exposed to ionizing radiation after the Chernobyl NPP accident

Role of proinflammatory cytokines TNF-[alpha] and IL-6 in pathogenesis of type 2 diabetes mellitus in persons exposed to ionizing radiation after the Chernobyl NPP accident

Radioecological assessment of the agricultural lands and products in south-west districts of the Bryansk region contaminated by radionuclides as the result of the Chernobyl NPP accident

The aim of this study was to analyze the current radioecological situation in agriculture in five south-west districts of the Bryansk region, which were exposed to the most radiation influence due to the accident at the Chernobyl NPP. Currently, there are 135 collective farms in the observed areas. The total area of agricultural lands was 266.2 thousand hectares. The area of agricultural lands with 137Cs contamination over 37 kBq/m2 was 244.8 thousand hectares in 2018. The area of arable land, hay fields and pastures located in the zone with a 137Cs soil surface activity in a range of 37–185 kBq/m2 is 135.1 thousand hectares, 185–555 kBq/m2– 88.3 thousand hectares, 555-1480 kBq/m2 – 19.8 thousand hectares. At present, only 21.4 thousand hectares (8% of the agricultural lands in the considered areas) don’t exceed contamination levels of 137Cs 37 kBq/m2, and they can be classified as “clean territory”. Analysis of the agricultural products radiation monitoring data from the collective farms of the south-west districts of the Bryansk region showed that the part of feed and crop products exceeded the standards varied from 4 to 15% in 2017-2018. The high content of 137Сs in the feed of several collective farms determined the excess of sanitary and hygienic standards in livestock products from these farms – milk in 4-8% of total samples, beef in 5–8% of total samples. The collective farms located in Krasnogorsky and Novozybkovsky districts of the Bryansk region, with a high risk of exceeding the standards for the content of radionuclides in the agricultural products, was identified. The required volumes of rehabilitation measures in the plant growing and animal husbandry of the south-west districts of the Bryansk region was indicated. It was found that 75 thousand hectares of the total area of agricultural lands need radical improvement and the introduction of higher doses of agromeliorants to produce plant-growing and fodder products corresponding to the legislation standards. To produce milk and beef that comply with sanitary and hygienic standards for livestock products, it is necessary to use ferrocyanide treatment in volumes of 10.5 t/a. It was shown that most radioactively contaminated rural areas need individual programs for the application of rehabilitation technologies. Such programs should provide the population safety and domestic activity.

ANALYSIS OF THE LONG-TERM DYNAMICS OF EXTERNAL DOSES OF THE POPULATION AFTER THE CHERNOBYL ACCIDENT

The paper presents an analysis of the dynamics of individual doses of external exposure among the population living for almost 20 years in the territories affected by the radioactive contamination due to the Chernobyl NPP accident. The dynamics of the average effective dose of the external exposure of the inhabitants in the period of 5 to 20 years after the Chernobyl fallout is well described by processes that consider the radioactive decay of cesium radionuclides and their natural migration. The distribution of individual doses of external exposure among residents, normalized to the average dose in the settlement corresponds to a logarithmically normal law with the time-stable parameters: the geometric mean ~ 0.9 and geometric standard deviation ~ 1.5, which allows, in particular, predicting the dose for the critical group of population or for a representative person. Comparison of the mean effective doses of external exposure of the settlement residents estimated based on the results of two different measurement technologies (using TLD-method and measurements of dose rates in air in various settlement locations) indicated their good agreement for the 17 years period after the fallout. For two settlements, where measurements were performed in 2003, the relative differences in mean effective doses did not exceed 12%. It allows using the previously developed model of external exposure for dose estimation to the population residing on the territories contaminated after the Chernobyl accident.

Проблемы обеспечения радиационной безопасности населения при радиационных авариях

The article presents the results of 25-old activity of the head agency of the Service for Disaster Medicine of the Ministry of Health of the Russian Federation – All Russian Centre for Disaster Medicine «Zaschita» (ARCDM «Zaschita») of the Ministry of Health of the Russian Federation in the sphere of medical support of population in case of radiation accidents. The Service is a functional subsystem of the Unified State system of prevention and liquidation of emergency situations, intended for elimination of medical and sanitary consequences of emergency situation. In Russia, it is legally established that in case of radiation accident the Federal Medical Biological Agency of Russia (the FMBA of Russia) is responsible for radiation safety of the population living in the NPP surveillance zone (approximately 25 km). Responsibility for the radiation safety of the rest of the population living outside the surveillance zone is assigned to the Service for disaster medicine. In accordance with the current document “Model content of the protection plan of the population in case of an accident at the radiation facility” developed by the Ministry of Emergency Situations, mandatory protective measures are provided in the territory that radius is 25 km around the radiation object (planning zones of preventive and emergency measures). Early planning in the restrictive planning zone is not envisaged, and protective measures outside the 100-kilometer zone are considered inappropriate. The article presents the concept developed by the specialists of ARCDM «Zaschita» for drafting protection of the subjects of the Russian Federation for the nuclear power plants operating on the territory of Russia. The concept is based on experience of consequences of the Chernobyl NPP accident. The concept argues that the outer boundary of the planning area for protective measures around nuclear power plants should have an outer radius of 1000 km. Radius of the emergency planning area is 100 km. The problems of preparedness for radiation safety of population support in case of radiation accidents are discussed. They are: the need for elaboration of regulatory and normative documents of the federal level on obligatory advance planning of protective measures against the possibility of radiation accidents on radiation-hazardous objects from the nuclear power plants on the territory of Russia for the population, not supervised by the FMBA of Russia (living both in the observation zone and abroad) and regulating the need and procedure of planning, organization and carrying out in case of necessity iodine prophylaxis for the population on territories up to 1000 km from operating NPPs of Russia. Same approaches to the solution of the considered problems are suggested.

Long-term effects of ionizing radiation after the Chernobyl accident: Possible contribution of historic dose

The impact of the Chernobyl NPP accident on the environment is documented to be greater than expected, with higher mutation rates than expected at the current, chronic low dose rate. In this paper we suggest that the historic acute exposure and resulting non-targeted effects (NTE) such as delayed mutations and genomic instability could account at least in part for currently measured mutation rates and provide an initial test of this concept. Data from Møller and Mousseau on the phenotypic mutation rates of Chernobyl birds 9–11 generations post the Chernobyl accident were used and the reconstructed dose response for mutations was compared with delayed reproductive death dose responses (as a measure of genomic instability) in cell cultures exposed to a similar range of doses. The dose to birds present during the Chernobyl NPP accident was reconstructed through the external pathway due to Cs-137 with an estimate of the uncertainty associated with such reconstruction. The percentage of Chernobyl birds several generations after the accident without mutations followed the general shape of the clonogenic survival percentage of the progeny of irradiated cells, and it plateaued at low doses. This is the expected result if NTE of radiation are involved. We suggest therefore, that NTE induced by the historic dose may play a role in generating mutations in progeny many generations following the initial disaster.

Sources of inflow and nature of redistribution of 90Sr in the salt lakes of the Crimea

At the first time for the period after the Chernobyl NPP accident the nature of the redistribution of the 90Sr concentrations in components of the ecosystems of the salt lakes of the Crimea were identified and described. Concentration of 90Sr in water of the salt lakes depends on the sources of the inflow this radionuclide into aquatic ecosystems and salinity level of lakes water. Until April 2014 the flow of the Dnieper river water through the Northern-Crimean canal was more important factor of contamination of salt lakes of the Crimea by 90Sr, than atmospheric fallout of this radionuclide after the Chernobyl NPP accident. Concentrations of 90Sr in water of the salt lakes of the Crimea exceeded 2.4–156.5 times its concentrations in their bottom sediments. The 90Sr dose commitments to hydrophytes, which were sampled from the salt lakes of the Crimea have not reached values which could impact them during entire the after-accident period.

Об установлении границ зон радиоактивного загрязнения в результате крупных радиационных аварий. Сообщение I. Ретроспективный анализ опыта зонирования при аварии на ЧАЭС

Purpose: Retrospective analysis of the process of defining the zones of radioactive contamination zones formed after the Chernobyl accident.
 Results: Summary of events related to liquidation of the Chernobyl NPP (ChNPP) accident consequences is given in the context of defining the radioactive contamination zones.
 Experience of zoning of the territories exposed to radioactive contamination due to the Chernobyl NPP accident during 1986–2015 in Belarus and the Russian Federation has revealed the following:
 - Zones of radioactive contamination as a result of the ChNPP accident have been finally defined by the regulatory-legal acts only by 1991 – in five years after the Chernobyl accident;
 - At present, the zones of radioactive contamination zones legally correspond to the borders of settlements that were given a certain status of the radioactively contaminated territory. 
 This leads, in particular, to paradoxical "automatic" reduction of radioactive contamination zonesareas due to abolition of settlements with no inhabitants. Absence of the established borders of radioactive contamination zones creates difficulties in substantiation of the measures related to radiation monitoring, rehabilitation of radioactively contaminated areas and their return to economic circulation.
 Conclusions: Experience of eliminating mitigation of the Chernobyl NPP accident consequences shows that the absence of modern and scientifically justified procedures of defining the borders of radioactive contamination zones results not only in an inadequate assessment of the scales of consequences, but also does not allow effective differentiating the inventory and scale of necessary measures on population protection.

Overcoming the consequences of the accident at the Chernobyl nuclear power plant in the Ukrainian agrosphere

The contribution of scientists of the Institute of Agroecology and Environmental Management of NAAS in overcoming and minimizing the consequences of the Chernobyl disaster has been elucidated. It was shown that the history of Radioecology Research Institute dates back from the first days after the Chernobyl accident. Analysis of the institution employees research activities shows that during the post accident period the radioecologists team has collected and systematized a lot of information. It has been transformed into various databases, cartographic materials, mathematical models, guidelines, regulations, draft regulations etc. Information on the Institute employees’ contribution to radiology development, restoration of agricultural production at the radioactively contaminated lands and rehabilitation of territories affected by Chernobyl NPP accident has been presented

Increased incidence of diabetes mellitus 30 years after the radiation impact in persons exposed to ionizing radiation during the Chernobyl NPP accident

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Радиоэкологические закономерности перераспределения альфа-радионуклидов плутония в экосистеме Чёрного моря

Работа посвящена исследованию радиоэкологических процессов перераспределения альфа-радионуклидов плутония (239+240Pu) как основных дозообразующих техногенных альфа-радионуклидов в период после аварии на Чернобыльской АЭС. 239+240Pu ― долгоживущие радиоизотопы, количество которых накапливается в природных экосистемах от инцидента к инциденту. Радиотоксичность этих радионуклидов высока, и необходимы научно обоснованные подходы к оценке и прогнозу радиоэкологического состояния водоёмов, подверженных риску повторного радиоактивного загрязнения 239+240Pu. К таким водоёмам относится Чёрное море, как внутренне море, расположенное в регионе высокоразвитых стран, использующих ядерные технологии. Работа выполнена современными методами, основными из которых были: радиохимический анализ, альфа-спектрометрия и радиотрассерные технологии. В результате исследования выявлены радиоэкологические закономерности поведения плутония (Pu) в экосистеме Чёрного моря в постчернобыльский период. Определены количественные параметры миграции 239+240Pu в море: скорость осадконакопления в разных районах моря, период полууменьшения удельной активности поверхностных вод по 239+240Pu, фактор радиоёмкости для донных отложений, потоки плутония, уровни содержания 239+240Pu в компонентах экосистемы, коэффициенты накопления биотическими и абиотическими составляющими. Выявлены особенности биогеохимического поведения плутония в экосистеме Чёрного моря и указаны условия и процессы, их обуславливающие. Отмечены повышенная способность черноморских поверхностных вод к самоочищению в отношении 239+240Pu, короткий период пребывания плутония в поверхностных водах, относительно быстрое накопление плутония в осадках за счёт биогеохимической седиментации элемента, высокая концентрационная способность иловых донных отложений в отношении 239+240Pu, тип биогеохимического поведения плутония в экосистеме Чёрного моря.

RADIATION CONDITIONS IN KALUGA REGION 30 YEARS AFTER CHERNOBYL NPP ACCIDENT

The article describes radiation conditions in the Kaluga region 30 years after the Chernobyl NPP accident. The Chernobyl NPP accident caused radioactive contamination of nine Kaluga region territories: Duminichsky, Zhizdrinsky, Kuibyshevsky, Kirovsky, Kozelsky, Ludinovsky, Meshchovsky, Ulyanovsky and Hvastovichsky districts. Radioactive fallout was the strongest in three southern districts: Zhizdrinsky, Ulyanovsky and Hvastovichsky, over there cesium-137 contamination density is from 1 to 15Ci/km. According to the Russian Federation Government Order in 2015 there are 300 settlements (S) in the radioactive contamination zone, including 14 settlements with caesium-137 soil contamination density from 5 to 15 Ci/ km2 and 286 settlements with the contamination density ranging from 1 to 5 Ci/km2. In the first years after the Chernobyl NPP accident in Kaluga region territories, contaminated with caesium-137, there were introduced restrictive land usage, were carried out agrochemical activities (ploughing, mineral fertilizer dressing), there was toughened laboratory radiation control over the main doze-forming foodstuff. All these measures facilitated considerable decrease of caesium-137 content in local agricultural produce. Proceeding from the achieved result, in 2002 there took place the transition to more tough requirements SanPiN 2.3.2.1078-01. Analysis of investigated samples from Zhizdrinsky, Ulyanovsky and Hvastovichsky districts demonstrated that since 2005 meat samples didn’t exceed the standard values, same for milk samples since 2007. Till the present time, the use of wild-growing mushrooms, berries and wild animals meat involves radiation issues. It was demonstrated that average specific activity of caesium-137 in milk samples keeps decreasing year after year. Long after the Chernobyl NPP accident, the main products forming internal irradiation doses in population are the wild-growing mushrooms and berries. Population average annual effective doses, caused90by Chernobyl fallouts, do not exceed 1 mSv/year. In 2014 AAEDmaximum calculated value for adultpopulation of 0,91 mSv was established in the following settlements:, Martynki village(Ulyanovsky district) and Lovatyanka village (Hvastovichsky district). The doses, accumulated in the period after the accident, are generally not high. According to calculations numerical value of forecasted accumulated doses varies from 0,23 to 21 mSv. Maximum calculated values of 21 mSv are established in Hvastovichsky district (Lovatyanka village) and Ulyanovsky district (Martynki village). Between 1986 and 2005, the effective irradiation doses did not exceed 29 mSv. Hence, in 70 years after the Chernobyl NPP accident standard value of 70 mSv will not be exceeded in the Kaluga region settlements. After 30 years, the main cause of population internal exposure is consumption of products from private subsidiary farms and especially of wild-growing products. There was conducted radiation monitoring of local agricultural foodstuff produce and of products from the forest. It demonstrated that caesium-137 average specific activity in samples of milk from private subsidiary farms in settlements of Zhizdrinsky, Ulyanovsky and Hvastovichsky districts decreased several-fold. It is between 20,0 Bq/l in 2007 and 1,7 Bq/l in 2015. In 2015, maximum levels of caesium-137 contamination in milk was 3,1% of the standard value, in potatoes - 4,7%, in meat - 4,4%.Average specific activity of caesium-137 in forest mushrooms samples from Zhizdrinsky, Ulyanovsky and Hvastovichsky districts doesn’t decline. Peaks of average caesium-137 activity were observed in 2012, 2013 and 2014; they depend on mushrooms abundance, species, dry summer weather and locations of sampling in the forest. In 2015 in three southern districts, the maximum content of caesium-137 in mushrooms exceeded the permissible level (500 Bq/kg) 4,5-fold; about 2% of the samples do not correspond to it. The maximum contamination of berries with caesium-137 also exceeds the permissible level (160 Bq/kg) nearly 5-fold, and about 43% of samples don’t correspond to it. Obtained results have demonstrated that long after the Chernobyl NPP accident (30 years) the main part of population internal exposure is caused by consumption of wild- growing mushrooms and berries. In the recent years, milk consumption does not play a considerable role in forming of internal dose any more. Conclusion: in 30 years since Chernobyl NPP accident in the Kaluga region radiation and environment conditions have considerably improved on the territories with radionuclides contamination. However, problems remain. The major task for mitigation of the Chernobyl NPP accident consequences is comprehensive radiation, social and economic rehabilitation of the contaminated territories.

Radiation conditions in the Oryol region territory impacted by radioactive contamination caused by the Chernobyl NPP accident

Research objective is retrospective analysis of radiation conditions in the Oryol region during 1986- 2015 and assessment of efficacy of the carried out sanitary and preventive activities for population protection against radiation contamination caused by the Chernobyl NPP accident.Article materials were own memoirs of events participants, analysis of federal state statistic surveillance forms 3-DOZ across the Oryol region, f-35 “Data on patients with malignant neoplasms, f-12 “Report on MPI activities”. Risk assessment of oncological diseases occurrence is carried out on the basis of AAED for 1986- 2014 using the method of population exposure risk assessment due to long uniform man-made irradiation in small doses. Results of medical and sociological research of genetic, environmental, professional and lifestyle factors were obtained using the method of cancer patients’ anonymous survey. Data on "risk" factors were obtained from 467 patients hospitalized at the Budgetary Health Care Institution of the Oryol region “Oryol oncology clinic”; a specially developed questionnaire with 60 questions was filled out.The article employs the method of retrospective analysis of laboratory and tool research and calculation of dose loads on the Oryol region population, executed throughout the whole period after the accident.This article provides results of the carried out laboratory research of foodstuff, environment objects describing the radiation conditions in the Oryol region since the first days after the Chernobyl NPP accident in 1986 till 2015.We presented a number of activities aimed at liquidation of man-caused radiation accident consequences which were developed and executed by the experts of the Oryol region sanitary and epidemiology service in 1986-2015. On the basis of the above-stated one may draw the conclusions listed below. Due to interdepartmental interaction and active work of executive authorities in the Oryol region, the population of the territories impacted by radioactive contamination is provided with conditions in compliance with radiation safety requirements and hygienic specifications.Since January 1987 according to radiation and hygienic monitoring in the Oryol region, the local foodstuff did not exceed the hygienic specifications on radiation. In the territories included in the zone of radioactive contamination, the economic activities may be carried out without special protective measures for decrease of caesium-137 and strontium-90 content in produce, there are no restrictions on picking of wild-growing berries, herbs and mushrooms.Being direct participants of development and carrying out of activities for the region protection in case of emergency situation at the radiation hazardous site, we believe that the data presented in this article may be useful both for experts and general population.

The Thirty Years’ Results of Radiation Hygienic Monitoring of Tula Region territories contaminated due to the Chernobyl NPP accident

Over 50% of Tula Region areas were contaminated after the Chernobyl NPP accident. The article provides the thirty years’ results of radiation hygienic monitoring of the Chernobyl accidental fallout - affected areas in Tula Region. The radiation situation is assessed at the initial accidental period and at the current stage. The initial levels of gamma - radiation dose intensity (up to 35 mcSv/hr ) are identified for the period of the “iodine” hazard along with the tabular data on the dose intensity relative stabilization by the beginning of August 1986 due to iodine-131 decay. The information is presented regarding iodine-131 tentative maximum permissible level exceedance in the dairy products of the two most contaminated regional areas - Plavskoye and Arsenievskoye. The article also provides the laboratory data on the total beta - activity in the foodstuffs in 1986-1987 and cesium-137 maximum permissible level exceedence in 1986. The radionuclide maximum permissible level exceedances in foodstuffs were registered only in 1986 due to the plants surface contamination whereas in the forest mushrooms those exceedances were repeatedly found until 2004. The black earths and grey forest soils had a benign impact upon the intensity of the radionuclide transfer into plants which resulted in the formation of internal radiation doses.At the current stage, the content of cesium-137 and strontium- 90 in the foodstuffs can only be quantified by a radiochemical method. The table covers all the districts within the boundaries of radiation contaminated zones. The radiochemical studies indicate the main dose - forming products. The article contains the table of internal and external radiation doses of the population in Plavsk town over 1986-1990 and displays the factors impacting population’s internal and external exposure. The Chernobyl - affected exposure dose of the population is mostly attributed to the external radiation and, for over twenty years, it does not exceed 1 mSv/ year. The annual effective dose of the population from 96,2% of the settlements is below 0,3 mSv/year.

Nuclear Accidents: Consequences for Human, Society and Energy Sector

The article examines radiation and hygienic regulations with regard to the elimination of consequences of the Chernobyl NPP accident in the context of relationships with other aspects, primarily socio-economic and political factors. This experience is reasonable to take into account when defining criteria in other regulatory fields, for example, in radioactive waste classification and remediation of areas. The article presents an analysis of joint features and peculiarities of nuclear accidents in the industry and energy sectors. It is noted that the scale of global consequences of the Chernobyl NPP accident is defined by the large-scale release of radioactivity into the environment, as well as an affiliation of the nuclear installation with the energy sector. Large-scale radiation accidents affect the most diverse spheres of human activities, what, in its turn, evokes the reverse reaction from the society and its institutions, including involvement of political means of settlement. If the latter is seeing for criteria that are scientifically justified and feasible, then the preconditions for minimizing socio-economic impacts are created. In other cases, political decisions, such as nuclear units’ shutdown and phasing out of nuclear energy, appear to be an economic price which society, as a whole and a single industry sector, pay to compensate the negative public response. The article describes fundamental changes in approaches to ensure nuclear and radiation safety that occurred after the Chernobyl NPP accident. Multiple and negative consequences of the Chernobyl accident for human and society are balanced to some extent by a higher level of operational safety, emergency preparedness, and life-cycle safety. The article indicates that harmonization and ensuring consistency of regulations that involve different aspects of nuclear and radiation safety are important to implement practical solutions to the nuclear legacy problems. The development of regulations on criteria for the classification of radioactive waste and the issues of remediation of radioactively contaminated areas are discussed as the examples.

RADIATION HYGIENIC MONITORING AND ASSESSMENT OF POPULATION DOSES IN RADIOACTIVELY CONTAMINATED AREAS OF TULA REGION

The goal. The analyses of radiation hygienic monitoring conducted in Tula region territories affected by the Chernobyl NPP accident regarding cesium-137 and strontium- 90 in the local foodstuffs and the analyses of populational annual effective dose. The materials and methods. The survey was conducted in Tula Region since 1997 to 2015. Over that period, more than fifty thousand samples of the main foodstuffs from the post-Chernobyl contaminated area were analyzed. Simultaneously with that, the external gamma - radiation dose rate was measured in the fixed control points. The dynamics of cesium -137 and strontium-90 content in foodstuffs were assessed along with the maximum values of the mean annual effective doses to the population and the contribution of the collective dose from medical exposures into the structure of the annual effective collective dose to the population. The results. The amount of cesium-137 and strontium -90 in the local foodstuffs was identified. The external gamma- radiation dose rate values were found to be stable and not exceeding the natural fluctuations range typical for the middle latitudes of Russia’s European territory. The maximum mean annual effective dose to the population reflects the stable radiation situation and does not exceed the permissible value of 1 mSv. The contribution of the collective dose from medical exposures of the population has been continuously reducing as well as the average individual dose to the population per one medical treatment under the annual increase of the medical treatments quantities. The conclusion. There is no exceedance of the admissible levels of cesium-137 and strontium- 90 content in the local foodstuffs. The mean annual effective dose to the population has decreased which makes it possible to transfer the settlements affected by the Chernobyl NPP accident to normal life style. This is covered by the draft concept of the settlements’ transfer to normal life style.

Radionuclides and mercury in the salt lakes of the Crimea

90Sr concentrations, resulting from the Chernobyl NPP accident, were determined in the salt lakes of the Crimea (Lakes Kiyatskoe, Kirleutskoe, Kizil-Yar, Bakalskoe and Donuzlav), together with the redistribution between the components of the ecosystems. The content of mercury in the waters of the studied reservoirs was also established. Vertical distributions of natural radionuclide activities (238U, 232Th, 226Ra, 210Pb, 40K) and anthropogenic 137Cs concentrations (as radiotracers) were determined in the bottom sediments of the Koyashskoe salt lake (located in the south-eastern Crimea) to evaluate the longterm dynamics and biogeochemical processes. Radiochemical and chemical analysis was undertaken and radiotracer and statistical methods were applied to the analytical data. The highest concentrations of 90Sr in the water of Lake Kiyatskoe (350.5 and 98.0 Bq/m3) and Lake Kirleutskoe (121.3 Bq/m3) were due to the discharge of the Dnieper water from the North-Crimean Canal. The high content of mercury in Lake Kiyatskoe (363.2 ng/L) and in seawater near Lake Kizil-Yar (364 ng/L) exceeded the maximum permissible concentration (3.5 times the maximum). Natural radionuclides provide the main contribution to the total radioactivity (artificial and natural combined) in the bottom sediments of Lake Koyashskoe. The significant concentration of 210Pb in the upper layer of bottom sediments of the lake indicates an active inflow of its parent radionuclide—gaseous 222Rn from the lower layers of the bottom sediment. The average sedimentation rates in Lake Koyashskoe, determined using 210Pb and 137Cs data, were 0.117 and 0.109 cm per year, respectively.