The work was aimed to the study the Cs-137 and I-131 transport dynamics along the trophic chain, from the atmosphere to soil, vegetation, dairy cattle, milk, and the human body. This was done with the use of the radioecological simulation model based on instrumental data from the "Warsaw" scenario of the International Atomic Energy Agency's (IAEA) EMRAS project, which were collected after the Chernobyl nuclear accident. The created simulated radioecological model was used for reconstruction of the I-131 radioactivity in dairy cattle milk in the Warsaw and Ostroleka areas located in the central part of Mazovia, where the cattle dairy milk radiometry was performed in April-May 1986. The aim of the study was to verify the radioecological model, to assess the reliability and uncertainty of the milk block of the computed model. It was found that the successive account of discrepancies between computed and reconstructed instrumental data of I-131 radioactivity dynamics in green fodder on farms in Mazovia areas and the shortage of clean fodder stocks harvest lead to a successive improvement of the agreement between computed and instrumental data of 131I activity in the dairy milk. For all variants of accounting correction the ratio of computed data to instrumental data with recalculated I-131 activities in the atmosphere of the Ostroleka Area is on average 2.5-3 times closer to their ideal value of 1 than in calculations with instrumental data for a cloud. The prognostic properties of the computational model at the stage of reconstruction of the specific 131I activity in milk, estimated as the ratio of computed data to instrumental data, can be estimated as 1.05+/-2.0; the values of these ratios for correction of thyroid radiation doses to the population due to the contaminated milk consumption are estimated as 1.3+/-2.5.

The study is aimed at investigation of the properties of distribution of effective dose convolutions for estimating parametric dependence on the ratio of geometric mean internal radiation doses to external radiation doses and standard geometric mean deviations of lognormal distributions. For research the average annual personal dosimetric information for the period from 1986 over 2022, kept in the database of the National Radiation Epidemiological Register (NRER) was used. Information on internal and external radiation doses received by each resident of 13,000 Russian settlements, the most contaminated with radioactive material from the destroyed Chernobyl NPP is kept in the NRER. The results of the study demonstrated the different values of ratio of geometric mean convolutions of annual radiation doses to effective doses. Their standard deviations are 1.05-1.28 and 2.2-2.8 respectively. The ratio of the arithmetic mean convolutions values to deterministic effective doses stored in the database included in the study is 1.0. With the account of uncertainties included in the estimates of the effective dose and doses of external and internal radiation exposure, the difference between probabilistic and deterministic estimates of effective doses received by the residents of the Russian settlements contaminated with Chernobyl radioactive releases is insignificant.

Purpose: Forecasting the lifetime attributable radiation risk of incidence with malignant neoplasm (MN) of the thyroid gland and identifying groups of increased radiation risk (HR) for the population of the Bryansk region currently (at the beginning of 2023) living in six areas most contaminated with radionuclides after the accident at Chernobyl NPP, based on a conservative approach, taking into account dose uncertainty factors and parameters of mathematical risk models. Material and methods: The mathematical model of the radiation risk of thyroid cancer is the model recommended by the International Commission on Radiological Protection (ICRP). The uncertainty assessment of radiation risks was carried out by simulation modeling, i.e. by multiple calculation of random realizations of the risk using the normal or log-normal distribution of all parameters involved in the calculation of this risk. Based on a set of random realizations, 95 % confidence limits of risks were estimated. The Unified Federal Database of the National Radiation and Epidemiological Register (NRER) containing reconstructed absorbed doses in the thyroid gland in the population was used as the initial data for the calculation. Results: At the beginning of 2023, the group of 37–40-year-old women is characterized by the maximum radiation risks of thyroid cancer. According to conservative estimates (according to the upper 95 % confidence limits of radiation risk assessments), up to 19.9 % of people from this group may experience the development of radiation-induced thyroid cancer in the future, and for 37-year-old women this proportion can be up to 30.0 %. The greatest risk is predicted for people living in the Krasnogorsk district of the Bryansk region. Radiation-induced thyroid cancer can develop in 40.1 % of individuals from this group. Radiation risks of thyroid cancer in men are up to 10 times lower than in women. For 74.5 % of the population of the entire studied cohort, it is predicted that the maximum individual risk of 5.0×10-5, established by NRB-99/2009 for the population under normal operation of ionizing radiation sources, will be exceeded. Conclusions: At present (since 2023 and for life), the population of the most polluted districts of the Bryansk region continues to be at a high risk of developing radiation-induced thyroid cancers. Women at the age of 0–3 years at the time of exposure (in 1986) should be allocated to the maximum risk group. The results of this work can be used in the preparation of recommendations by health authorities to improve medical monitoring of exposed citizens.

The current recommendations of the International Commission on Radiological Protection (ICRP) are based on the classification of exposure situations as: planned, emergency and existing exposure situations. In planned situations, annual risk limits are set to limit human exposure. However, in emergency exposure situations or in existing exposure situations, permanent (annual) source control is not always possible, so the radiation protection strategy by monitoring the individual annual risk limit cannot always be practically implemented either. The purpose of this work is to assess the radiation safety of the population currently residing (at the beginning of 2022) in six districts of the Bryansk region: contaminated with radionuclides as a result of the Chernobyl accident: in Gordeevsky, Zlynkovsky, Klimovsky, Klintsovsky, Krasnogorsky and Novozybkovsky districts. Assessment of the current state of radiation safety of the population is based on calculations of the radiation detriment from chronic exposure due to living in contaminated areas, considering uncertainties of the reconstructed exposure doses and the parameters of mathematical risk models for the population. Radiation damage is calculated according to the modern ICRP methodology. Based on the general principle of conservative assessment of safety, the calculated upper 95% confidence limits (95% CL) of radiation detriment are compared with the corresponding lifetime radiation detriment limit, 3.510-3, determined by the Russian radiation safety standards (NRB-99/2009) under normal exposure conditions for the nominal period 70 years of life for the public. The radiation safety of the population of the Klimovsky district corresponds to the normal conditions of exposure from technogenic sources of ionizing radiation. Among the population of the remaining five contaminated districts of the Bryansk region, critical groups have been identified, the radiation detriment for which exceeds the limit 3.510-3 for normal conditions of public exposure in planned situations. The results of this work can be used in the preparation of recommendations for health authorities to improve medical monitoring of exposed citizens living in territories contaminated with radionuclides, as well as in the development of regulatory documents for the provision of targeted medical care to people from high radiation risk groups with the use of personalized medicine methods.

The paper presents the results estimation of uncertainties in doses to the thyroid, from external and internal exposure to radiation following the Chernobyl accident. For the estimation the data-base of radiometry activities of Cs-134+137 in the body and I-131 to the thyroid in 1986 for 28,311 residents of Kaluga region and 16,470 residents of Bryansk region. Whole body radiation spectrome-try measurements made for 167,325 residents of Bryansk region from 1990 through 1994 were used. The computational model for reassessment of I-131 activities into individual exposure doses is an analytical relationship that describes the relative dynamics of radionuclide activities in a chain consisting “vegetation”, “milk”, “thyroid” and “inside the human body”, that is the chain of successive single-chamber models with time-constant transition rates between chambers and depending on the age of a person after single deposition of radionuclides on vegetation. The dy-namics of specific activities of I-131, Cs-134+137 in the vegetation chamber is calculated according to the agroclimatic model, with account of the dynamics of precipitation, the growth of forage and food vegetation biomass according to the data of the annual variation of average daily air tem-peratures in the surface layer of the atmosphere. The official methodology was used to calculate external exposure doses and reassess whole body radiation spectrometry measurements into in-ternal exposure doses. Based on the results of the studies, uncertainty estimates were obtained in terms of standard geometric deviations in the year of the accident – for individual, average in populated areas and integral dose estimates: (minimum/average/maximum) doses of internal thyroid and whole body exposure, respectively (1.1/2,0/3.0), (1.2/1.5/2.3) and (1.3/2.9/3.3); for doses since 1987, respectively (1.2/1.9/4.0), (1.2/1.9/2.1) and (1.4/5.2/8.2). The uncertainty of the calculation model for internal doses since 1987 is estimated at 2.1 times; the uncertainties estimated from the data of individual dosimetry of external and internal exposure of the population with the allocation of critical groups are equal to 1.5 and (1.9-2.2) times, respectively.

The paper reviews methods for reconstruction of dynamics of radiation doses to the public ex-posed to radiation after the Chernobyl accident. The methods are used in radiation-epidemiological studies carried out at the National Radiation and Epidemiological Registry (NRER). The methods development was based on the joint NRER-RIRH (the Saint Petersburg Re-search Institute of Radiation Hygiene) base of radiometric data and modified RIRH methods, ap-proved by the Federal Service for Surveillance on Consumer Rights Protection and Human Well-being (Rospotrebnadzor). Radiation dosimetry data for NRER radiation-epidemiological studies analytical model is used. The model is the modified version of formally approved method for re-construction of thyroid internal radiation doses received by people lived in areas of Russia con-taminated with radionuclides after the Chernobyl accident. The paper describes the joint NRER-RIRH database of radiometry data on 131I activity in the thyroid, 137Cs activity in the whole-body of residents of Bryansk and Kaluga regions collected in 1986, as well as whole body counting per-formed in the Bryansk region in later years. The mode of modification of formally approved methods for computation of internal thyroid and whole-body radiation doses to the people irradi-ated in 1986 is described in the paper. Magnitudes of standard errors of calculated mean values of radiation doses to the population of a specific settlement and individual internal radiation dos-es are given in the paper.

Thirty five years ago, the All-Union Distributed Registry of Persons Exposed to Radiation as a re-sult of the accident at the Chernobyl Nuclear power plant (Chernobyl Registry) was created. The Computing Center of the Research Institute of Medical Radiology of the USSR Academy of Sci-ences (Obninsk) became the core of the Chernobyl Registry. Their contribution to the creation of the registry was made by all former Soviet republics. Currently, the registry is called the National Radiation and Epidemiological Register (NRER), which is a state information system for personal data of Russian citizens exposed to radiation as a result of radiation accidents and incidents. The NRER is a multi-level system consisting of 85 regional segments in subjects of Russian Federa-tion and 4 departmental sub-registries. Currently, the NRER stores information about 811 thou-sand people, of which 751 thousand people represent the so-called “Chernobyl contingent”. The article presents the description of regulatory framework, organizational structure and technologi-cal approaches to the management of NRER. The article also describes the specific elements and subsystems of the registry that ensure the effective functioning of the NRER system for many years. The final part of the article presents the main results of research on the assessment of the radiological consequences of the Chernobyl disaster, obtained on the basis of the analysis of da-ta accumulated in the NRER for the period 1986-2020.

Some areas of the Russian Federation were contaminated with radionuclides released as a re-sult of the Chernobyl accident. The current paper clarifies some items of the previously published study based on NRER (National Radiation-Epidemiological Registry, the Registry) data. The pre-vious issue presented estimates of radiation risks of cancer incidence among the population of four the most contaminated regions of the Russian Federation: Bryansk, Kaluga, Oryol and Tula oblasts. Risks of thyroid cancer are estimated with account of screening effect. The cohort con-sisted of more than 327 thousand people resided in the contaminated areas. The average dose to the thyroid of children and adolescents was 0.174 Gy, the average dose to the thyroid of adults was 0.035 Gy. Thyroid cancer was diagnosed in 1549 members of the cohort during the follow-up period from 1991 over 2019, among them 423 cases were children and adolescents at the accident and 1126 cases were adults. Significant increase in thyroid cancer incidence was ob-served in adults exposed internally through the intake of iodine-131 at a young age. The statisti-cally significant radiation risk of thyroid cancer persists over 30 years after exposure. The risk de-creases with increasing the attained age. In people exposed to radiation before the age of 1 year and reaching the age of 20 years, the coefficient of excess relative risk of thyroid cancer (ERR/Gy) was 4.61. Radiation associated thyroid cancer is attributed to 20.6% of the cohort mem-bers exposed internally through the intake of radioiodine isotopes in their childhood and adoles-cence, and thyroid cancer from intake of radioiodine is attributed to 58% of cases exposed to ra-diation under 4 years of age. Marked screening effect (ES) was found during the disease diag-nosing, screening coefficient was 5.6 for children and 2.1 for adults. There were not attributed to radiation statistically significant risks of solid cancers, including radiation induced breast cancer in females, in the cohort of people resided in the areas contaminated with radionuclides. Radia-tion risk of leukemia was also not identified, although the average value of excess relative risk in men exceeded zero. Further observations of the cohort of persons resided in areas contaminated with radionuclides will increase the statistical power of radiation-epidemiological studies and clarify the assessment of radiation risks of human for chronic exposure at low doses.

The analysis of instrumental data of “Prague” and “Warsaw” scenarios on the dynamics of 131I specific activities in the grass is carried out. Reconstruction of the 131I the specific activities dynamics in the grass in the Mazovia and Bohemia localities is performed in three models: direct calculation the input data of the “Prague” and “Warsaw” scenarios, homogeneous cloud, heterogeneous rain and heterogeneous cloudhomogeneousrain. The actual 137Cs fallout densities in the grass sampling sites in average more than 2.9 times for Prague and 2 times for Warsaw. Effective rain during the main fallout at the grass sampling sites, reconstructed on the model of a homogeneous cloud is 3–4 times more than at the nearest weather stations during this time. A realistic scenario of the input data leading to the optimal agreement of the calculated and instrumental data is revealed. It is shown that direct calculations and the homogeneous cloud model give almost identical results and lead to a significantly better agreement with the instrumental data than the an inhomogeneous cloud model. The calculated and instrumental data show a significant decrease in the 131I specific activity in the grass after the end of the main fallout due to its flushing from the grass surface by strong prolonged rain 13 and 19 days after the accident in Mazovia and 30 and 35 days in Bohemia. Uncertainties in the results of reconstruction of the dynamics of 131I and 137Cs activities in vegetation are estimated. The meangeometric values and standard mean-geometric deviations of the calculation/ 8instrumental data ratios are: 0.8–1.1 and 1.8–1.9 for grass.

The paper analyzes the consistency of the input data of the radioecological model: the results of measurements of 137Cs and 131I concentrations in the atmosphere after the Chernobyl accident in Warsaw, the meteo-data on precipitation during the main radioactive fallout, the values of minimum 137Cs deposition densities on the territories of two dairy areas of Warsaw Area and Ostroleka Area in the central part of Mazovia. According to meteorological data in Warsaw Area during the period of radioactive fallout there were local rains. In Ostroleka Area, according to all weather stations, there was no rainfall during this period. In Warsaw Area, a minimum 137Cs deposition density of 1.3 kBq/m2 with an error of less than 10% was found to be consistent with the “dry” deposition density of 137Cs (1.2 kBq/m2) reconstructed by a simulated agroclimatic model based on atmospheric 137Cs measurements. This agreement, taking into account the amount of precipitation recorded at weather stations during the period of radioactive fallout and the significant, more than 10 times, dispersion of 137Cs fallout densities across the Warsaw Area, suggests that a homogeneous cloud-uniform fallout model is preferable for this region in radio-ecological modeling. For the Ostroleka Area, the variation in deposition densities of 137Cs was relatively small, at 3.2, and the estimated dry deposition density of 137Cs was 2.0-2.7 times lower than the measured minimum deposition densities in districts and settlements. This discrepancy, given the absence of precipitation recorded by all weather stations during the deposition period, led to the assumption that the 137Cs and 131I atmospheric concentrations in Ostroleka Area were 2-2.7 times higher than those in Warsaw Area. The adjustment of the 137Cs and 131I atmospheric concentrations in the Ostroleka Area for this region will be verified by measuring the 131I specific activity in milk under the Warsaw scenario.

Верификация радиационных рисков смертности российских участников ликвидации последствий аварии на Чернобыльской АЭС на основе дозового критерияЧекин С.Ю., Ловачёв С.С., Кащеева П.В., Туманов К

MRRC, Obninsk According to the current Russian OSPORB, the indicator of radiation risk is one of key indicators of radiation safety establishments, where radioactive substances and other sources of ionizing radiation are used. The IAEA BSS and Russian NRB-99/2009 require that individual radiation risks for emergency workers should be estimated. However, neither the Russian nor international normative documents contain recommendations what radiation risk assessment models should be used for these purposes. This article presents comparative analysis of applicability of current models of radiation risks intensity recommended by UNSCEAR, ICRP and WHO to predict risk values in case of radiation emergency situations. Radiation risks should be estimated on the basis of the general principle of conservativity, with account of the following statements. To predict risks in case of radiation emergency exposure to doses above 50 mSv, unmodified models of radiation risks intensity developed by UNSCEAR, ICRP and WHO with the use of radiation epidemiological data following single acute radiation exposure should be used. Comparative analysis of current radiation risks models demonstrates that for people who do not attain the age of 85 years the most conservative predictive estimates can be obtained with the use of the DDREF-free ICRP models or with the use of WHO models, both options give practically the same forecast. In men with attained age younger than 49 years the most conservative predicted risk of leukaemia is obtained with ICRP models. For men older than 49 years – with UNSCEAR and

Создание и верификация взаимосогласованной базы входной информации имитационной модели транспорта радионуклидов 137 Cs и 131 I по пищевой цепочке на инструментальных радиоэкологических данных (по материалам «Пражского» и «Варшавского» сценариев проекта МАГАТЭ EMRAS) Власов О.К. 1 , Краевский П. 2 , Бартускова М. 3 , Малатова И. 4 , Щукина Н.В. 1 , Чекин С.Ю. 1 , Туманов К.А. 1 , Звонова И.А.5  1 МРНЦ им.А.Ф.Цыба -филиал «НМИЦ радиологии» Минздрава России, Обнинск; 2 Центральная лаборатория радиологической защиты, Варшава, Польша; 3 Филиал Национального института радиационной защиты, Острава, Чехия; 4 Национальный институт радиационной защиты, Прага, Чехия; 5 ФБУН НИИРГ им.П.В.Рамзаева, Санкт-Петербург Излагается технология создания взаимосогласованной базы входных данных имитационной радиоэкологической модели после радиационной аварии с выбросом продуктов в атмосферу.В набор данных для объектов исследования (населённые пункты или их ареалы) входят средние за период основных выпадений или временные зависимости удельных объёмных активностей 137 Cs в атмосфере, осадки в период выпадений, плотности выпадения 137Cs. Данные плотностей выпадения 137 Cs на территориях центральных частей регионов Мазовии (Польша) и Богемии (Чехия) после аварии на ЧАЭС, метеоданные об осадках и инструментальные данные о динамике активностей 131 I и 137 Cs в атмосфере указывают на их слабую пространственную вариабельность, что свидетельствует о сравнительно однородной структуре параметров радиоактивного загрязнения атмосферы и слабых локальных осадках в период основных радиоактивных выпадений в этих регионах.Максимальные значения удельных объёмных активностей 131 I и 137 Cs атмосфере в период первого пика выпадений в Богемии и Мазовии практически совпадают.В Мазовии в период с 11 по 13 сутки после аварии, в отличие от Богемии, наблюдался второй пик активностей 131 I и 137 Cs в атмосфере с их максимальными значениями приблизительно на порядок меньшими, чем в первом пике.Интегралы удельных объёмных активностей 131 I и 137 Cs в кБк/м 3 сут составили в Мазовии 0,39 и 0,023 соответственно; в Богемии -0,2 и 0,03 соответственно.Среднее за период основных выпадений значение отношения удельных объёмных активностей 131 I к 137 Cs в атмосфере Мазовии было равно 17,2, что в 2,3 раза больше, чем в Богемии, равном 7,1.Несогласование базы входных данных проявляется в существенных различиях в инструментальных плотностях выпадения 137 Cs в населённых пунктах и реконструированных по модели прямого расчёта: активность 137 Cs в атмосфере -метеоданные об осадках.Для согласования входных данных используются модели однородного облака -неоднородных осадков и неоднородного облака -однородных осадков.В целом для населённых пунктов прямой расчёт плотностей выпадения 137 Cs по модели несогласованных данных (однородное облако -метеоданные об осадках) даёт существенное отличие как от инструментальных данных, так и от моделей согласованных данных (однородное облако -неоднородные эффективные осадки) и (неоднородное облако -однородные осадки по метеоданным).Причём тем большее, чем больше плотность выпадения 137 Cs.При существовавшей динамике параметров активностей радионуклидов в атмосфере влияние осадков на плотности выпадения 131 I и 137 Cs и удельные активности 131 I и 137 Cs в растительности начинает проявляться только при их величинах, больших 0,2 мм.Для травы оно заканчивается при осадках, больших 1-2 мм.Для 131 I это влияние меньше, чем для 137 Cs.Существовавшие в регионах различия в динамике активностей 137 Cs и 131 I в атмосфере привели к тому, что плотности «сухих» выпадений 131 I и его выпадений с осадками 10 мм на растительность были в 1,8 и 2,1 раз больше, чем в Богемии, а для 137 Cs -меньше соответственно в 1,8 и в 1,4 раза.Фактически это означает, что в таком же соотношении были и дозы внутреннего облучения щитовидной железы и доз на всё тело населения Мазовии и Богемии.Использование взаимосогласованных данных, в первую очередь осадков в период выпадений и параметров загрязнения атмосферы, приводит к адекватному воспроизведению инструментальных данных о плотностях выпадений 137 Cs на местность, к существенному уменьшению неопределённостей транспорта 137 Cs и 131 I по пищевой цепочке и, как следствие, более точной реконструкции доз внутреннего облучения населения загрязнённых территорий.Ключевые слова: авария на ЧАЭС, имитационная модель в радиоэкологических исследованиях, проект МАГАТЭ EMRAS, активность 137 Cs и

This paper continues a series of publications that analyze the impact of radiation on incidence of circulatory system diseases in the cohort of Russian recovery operation workers (liquidators) and presents the results of the analysis of cardiovascular disease (CVD) incidence. The studied cohort consists of 53,772 liquidators who arrived in the Chernobyl accident zone within the first year after the accident (26 April 1986 to 26 April 1987). The individual doses varied from 0.0001 Gy to 1.42 Gy, and the mean external whole body dose in the cohort was 0.161 Gy. A total of 27,456 cases of CVD were diagnosed during the follow-up period 1986-2012 as a result of annual health examinations. A Poisson regression model was applied to estimate radiation risks and other risk factors associated with CVD. The following factors were identified as risk factors for CVD: the dose, duration of the liquidators' work in the Chernobyl zone, and concomitant diseases (diabetes mellitus, hypertension, overweight, and alcohol dependence). The baseline incidence of CVD is statistically significantly (p < 0.001) associated with all studied concomitant diseases. The incidence of CVD has revealed a statistically significant dose response with the lack of a latent period and with the average ERR Gy(-1) = 0.47, 95% CI = 0.31, 0.63, p < 0.001. Radiation risks of CVD statistically significantly (p = 0.01) varied with the duration of liquidators' stay in the Chernobyl zone; for those who stayed in the Chernobyl zone less than 6 wk, ERR/Gy = 0.80, 95% CI = 0.53; 1.08, p < 0.001.

Методы и критерии формирования групп повышенного радиационного риска для оказания адресной специализированной медицинской помощи населению России и Республики Беларусь, подвергшемуся радиационному воздействию вследствие аварии на Чернобыльской АЭС Чекин С

В данной работе представлена методика выполнения Требования 49 Основных норм безопас­но­сти МАГАТЭ, касающаяся определения масштаба мер послевосстановительного контроля в виде оказания адресной специализированной медицинской помощи населению России и Рес­публики Беларусь, подвергшемуся радиационному воздействию вследствие аварии на Чер­нобыльской АЭС, с надлежащим учётом остаточных радиационных рисков населения. На ос­нове выбранных контрольных уровней риска (LARF) сформированы группы повышенного ра­диационного риска из числа лиц, зарегистрированных в Едином чернобыльском регистре России и Беларуси, по основным радиационно-обусловленным заболеваниям: по заболева­е­мо­сти лейкозами, раком молочной железы и раком щитовидной железы. К группе риска по за­болеваемости лейкозами в 2016 г. (31933 человека) относится население с пожизненной ат­рибутивной долей радиации LARF, превышающей 70%. К группам риска по заболеваемости раком молочной железы относятся 15790 человек, по заболеваемости раком щитовидной железы 12668 человек, с LARF, превышающей 50% от соответствующих максимальных значений в рассматриваемой популяции в 2016 г. Общая численность групп риска в 2016 г. населения, проживающего на загрязнённых территориях Брянской и Гомельской областей, составляет 60391 человек.

Разработка и верификация технологии реконструкции эффективных доз облучения населения России после аварии на ЧАЭСВласов О.К. 1 , Брук Г