STATE INSTITUTION «NATIONAL RESEARCH CENTER FOR RADIATION MEDICINE OF THE NATIONAL ACADEMY OF MEDICAL SCIENCES OF UKRAINE¼ - RESEARCH ACTIVITIES AND SCIENTIFIC ADVANCE IN 2020. / REZUL'TATY ROBOTY DU «NATsIONAL'NYI NAUKOVYI TsENTR RADIATsIINOÏ MEDYTsYNY NATsIONAL'NOÏ AKADEMIÏ MEDYChNYKh NAUK UKRAÏNY¼ U 2020 ROTsI.

Research activities and scientific advance achieved in 2020 at the State Institution «National Research Center for Radiation Medicine of the National Academy of Medical Sciences of Ukraine¼ (NRCRM) concerning medical problems of the Chornobyl disaster, radiation medicine, radiobiology, radiation hygiene and epidemiology in collaboration with the WHO network of medical preparedness and assistance in radiation accidents are outlined in the annual report. The report presents the results of fundamental and applied research works of the study of radiation effects and health effects of the Chornobyl accident. The report also shows the results of scientific-organizational and health care work, staff training. The Scientific Council meeting of NAMS approved the NRCRM Annual Report.

COMPREHENSIVE RADIATION AND HYGIENIC MONITORING IN POPULATION OF THE RIVNE OBLAST RADIOLOGICALLY CONTAMINATED TERRITORIES. / KOMPLEKSNYI RADIATsIINO/GIGIIeNIChNYI MONITORYNG MEShKANTsIV RADIOAKTYVNO ZABRUDNENYKh TERYTORII RIVNENS'KOÏ OBLASTI U 2020 r.

OBJECTIVE: The key factors identification in radiation dose formation in population of radiologically contaminatedareas of Rivne oblast in the current period of accident through comprehensive radiation and hygienic monitoring inreference settlements in 2020 and estimation of their impact on dose formation were the study objectives. MATERIALS AND METHODS: Comprehensive radiation and hygienic monitoring of settlements in Rivne oblast(province) was provided in Stare Selo, Vezhytsia, Perekhodychi, and Drozdyn villages of Rokytne district, where thehighest radiation doses were registered after the ChNPP accident. Studies were conducted in September 2020.Measurements (n=696, 318 adults, and 378 children) were performed using the whole body counters (WBC) to deter-mine the internal radiation doses. The 48 samples of milk, 45 samples of potatoes and vegetables, and 35 samplesof wild products were collected in local farms and measured for the 137Cs and 90Sr content. Residents of the studiedsettlements (n=229, 140 adults, and 89 children) were interviewed about the levels of consumption of staple food-stuffs. External radiation doses were evaluated in all the studied settlements. Mathematical, dosimetric, and radio-chemical methods were applied. RESULTS AND CONCLUSIONS: Annual effective radiation doses of the Rivne oblast population in 2020 were formedmainly due to internal radiation ones that not exceeded 1.24 mSv · year-1 in adults and 0.65 mSv · year-1 in childrenagainst the RCT criterion of 1 mSv · year-1. Further 1.2-1.9-fold decrease in the annual internal radiation doses vs.the results of WBC-monitoring in autumn of 2017 was registered in the surveyed settlements. The latter confirmeda time pattern of radiation levels gradual reduction at the current stage of Chornobyl accident since 2011. Intakeof 137Cs with milk and wild mushrooms, which traditionally occupy a significant part of diet in the Rivne Polissya areaand have consistently high levels of radioactive cesium contamination, remains a key factor of internal radiationdose forming in residents of the surveyed settlements of Rivne oblast.

SOME ISSUES OF LIFE ACTIVITIES OF POPULATION IN THE CHORNOBYL EXCLUSION ZONE IN UKRAINE. / DEIaKI ASPEKTY ZhYTTIeDIIaL'NOSTI NASELENNIa V ChORNOBYL'S'KII ZONI VIDChUZhENNIa UKRAÏNY.

BACKGROUND: Radiation accidents at the Chornobyl Nuclear Power Plant (USSR, 1986) and Fukushima-1 (Japan,2011) have shown that global environmental contamination is an intervention in normal human life making nega-tive effect on population health. These accidents highlighted a number of statutory and regulatory both with me-dical and social problems for individuals, who returned voluntarily for permanent residence in the ChornobylExclusion Zone i.e. a radiation-hazardous area (they are named the «self-settlers¼). OBJECTIVE: generalization of experience in the settlement of normative-legal, ecological-dosimetric and medico-social life issues of population living in the Chornobyl NPP (ChNPP) Exclusion Zone («self-settlers¼). OBJECT AND METHODS: The chosen problem is complex, necessitating the generalization of radiation-hygienic, med-ical-biological, socio-economic, demographic and sociological research results obtained by the national and foreignauthors. A set of theoretical research and analysis of empirical data methods on the principles of interdisciplinaryinteraction was used; the systematic, legal, economic, medical-biological, demographic and retrospective-dosimet-ric approaches of research were applied. RESULTS: It was shown that a part of population refused to evacuate or had returned for permanent residence to theradiation-hazardous lands after the ChNPP accident. In 1986-2009 the number of «self-settlers¼ ranged from 150to 2,000 in different years. In 2021 - the 101 people. Those were mainly people of working age, mostly females, single people or widows/widowers. Рrevious medical and dosimetric studies have shown that long-term residence inthe Exclusion Zone affects physical and mental health of «self-settlers¼ and causes atypical aging, includinginvolvement of the central nervous system. According to calculations, the average effective total radiation doseaccumulated by «self-settlers¼ for the first 3 years was 30 % of dose for the entire post-accident period, and thedose accumulated over 20 years was 54 % of the dose accumulated over 35 years. But the effective radiation dosesaccumulated in different periods after the accident differ significantly in residents of different Exclusion Zone settlements. This information needs further study in terms of the «radiation dose - health status¼ dependence. CONCLUSIONS: The effective radiation doses accumulated in different periods after the accident differ significantlyin the residents of different Exclusion Zone settlements. Тhe average effective total radiation dose accumulated by«self-settlers¼ for the first 3 years was 30 % of the dose for the entire post-accident period, and the dose accumulated over 20 years was 54 % of the dose accumulated over 35 years.

RELATIVE TELOMERE LENGTH OF PERIPHERAL BLOOD LYMPHOCYTES AND STRUCTURAL AND FUNCTIONAL STATE OF THE LEFT VENTRICLE MYOCARDIUM IN CLEAN-UP WORKERS OF THE CHORNOBYL ACCIDENT WHO SUFFERED FROM STENOTIC CORONARY ATHEROSCLEROSIS. / VIDNOSNA DOVZhYNA TELOMER LIMFOTsYTIV PERYFERYChNOÏ KROVI TA STRUKTURNO-FUNKTsIONAL'NYI STAN MIOKARDA LIVOGO ShLUNOChKA SERTsIa V UChASNYKIV LIKVIDATsIÏ NASLIDKIV ChORNOBYL'S'KOÏ AVARIÏ ZI STENOZUIuChYM ATEROSKLEROZOM KORONARNYKh ARTERII.

The objective was to analyze the relative telomere length (RTL) of peripheral blood lymphocytes depending onmyocardium structural and functional state in emergency workers (EW) of the Chornobyl accident who suffered fromcoronary arteries stenotic atherosclerosis. MATERIALS AND METHODS: There were examined 60 male EW who operated at the Chornobyl nuclear power plant at1986 and 25 male non-irradiated persons (control group - CG) with coronary heart disease (CHD). Everyone EW andCG patients were almost healthy before the accident. During the period 2016-2021, they underwent a comprehen-sive clinical and laboratory examination, echodopplercardiographic examination and determination of RTL by fluo-rescent hybridization in situ using laser flow cytometry. RESULTS: EW almost did not differ from CG according to its clinical characteristics, the presence of risk factors,indices of systolic and diastolic heart functions, as well as RTL. The analysis of variance showed that RTL was influ-enced by the fact of irradiation in combination with obesity (p = 0.020). At normal body weight, RTL average valuein CG was significantly higher than in EW (p = 0.023). According to the results of hierarchical cluster analysis of twovariables as RTL and end-diastolic volume normalized by body surface area (EDV/BSA), EW and CG patients togeth-er were divided into two subgroups. The first subgroup (1st cluster) differed from the second (2nd cluster) by signi-ficantly larger average values of left ventricle (LV) EDV and end-systolic volume (ESV) as well as EDV/BSA andESV/BSA, LV myocardial mass (MM) and MM/BSA, reduced ejection fraction (EF). In patients of the 1st cluster telom-eres were significantly shorter than in the 2nd one (10,3 ± 1.7 vs. 14.3 ± 2.0 at p = 0.000). The increase of myocar-dial mass and LV wall thickness caused the development of its hypertrophy. The number of people with hypertrophyLV was significantly higher among patients of the 1st cluster (91.6 vs. 67.2 %, p < 0.001) due to eccentric hypertro-phy LV. Accordingly, concentric hypertrophy LV was more common among patients in the 2nd cluster (24.6 vs. 4.2 %at p < 0.01). Patients of the 1st cluster was characterized by a more severe course of heart failure. CONCLUSIONS: In patients who suffered from CHD with stenotic atherosclerosis of the coronary arteries and wereexposed to radiation 30-35 years earlier, having normal body weight, there was a reduction in telomere. Hierarchicalcluster analysis proved to be a good tool that allows by the value of RTL and EDV/BSA to separate the group ofpatients with the most severe clinical course of CHD and LV systolic dysfunction among patients with the samepathology.

COMORBID INTERNAL DISEASES IN MILITARY SERVANTS WHO HAVE SENSED THE EXPOSURE OF EXTREME FACTORS OF MILITARY SERVICE. / KOMORBIDNI VNUTRIShNI ZAKhVORIuVANNIa U VIIS'KOVOSLUZhBOVTsIV, IaKI ZAZNALY VPLYVU EKSTREMAL'NYKh FAKTORIV VIIS'KOVOÏ SLUZhBY.

OBJECTIVE: to analyze comorbid pathology by methods of its quantitative assessment in servicemen exposed toextreme factors of military service (a set of factors of radiation accidents, the influence of modern armed conflictsand modern combat trauma without blood loss). MATERIALS AND METHODS: Studies of comorbid pathology were performed in 613 servicemen who were treated at theclinical base of the Ukrainian Military Medical Academy (UMMA) in National Military Medical Clinical Center «MainMilitary Clinical Hospital¼ NMMCC «MMCH¼ during 1989-2018 years. Soldiers who suffered from acute radiation sick-ness (ARS) in 1961 (n = 34), participants in the liquidation of the consequences of the Chornobyl catastrophe(PLCChC) 15 years after participating in the elimination of its consequences and in a later period (respectivelyPLCChC 1st group (n = 59) and the 2nd group (n = 337)). Soldiers are participants in the anti-terrorist operation(ATO)/Combined Forces (CFO) operation who did not receive modern combat injuries with blood loss (participants inthe ATO/CFO, n = 183). All servicemen did not have any diseases limiting their fitness capabilities for military serv-ice before being exposed to extreme factors of military service. A cumulative CIRS scale was used to comprehensive-ly assess comorbidity. RESULTS: With increasing time after participation in the elimination of the consequences of radiation accidents, thecourse of arterial hypertension (AH) is aggravated, but the dose-dependence of the severity of AH on the receivedradiation dose has not been established. The easier course of hypertension in ATO/CFO servicemen compared to ARSremote servicemen and group 2 PLCChC servicemen can be explained by their younger age at the time of the surveyand less time after exposure to extreme military service factors. In the military in the remote period after exposureto a complex of factors of radiation accidents, the frequency of diagnosing diseases by individual organs and bodysystem increases comparing to non-irradiated servicemen. The total number of disease severity scores on the cumu-lative scale of CIRS diseases is also higher. However, a dose-dependent effect of the severity of comorbid patholo-gy was also not found. These data indicate a higher prevalence of comorbid pathology in servicemen affected by acomplex of factors of radiation accf5idents, compared with participants in the anti-terrorist operation / environ-mental protection. However, the lower severity of comorbid pathology in ATO/CFO participants can also be explainedby their younger age at the time of the survey and less time after exposure to extreme factors of military service. CONCLUSIONS: For servicemen, with increasing time after participation in the elimination of the consequences ofradiation accidents, the course of hypertension without its dose dependence becomes more difficult. The total num-ber of disease severity scores on the cumulative scale of CIRS diseases in servicemen in the remote period after participation in the elimination of the consequences of radiation accidents is higher than in non-irradiated service-men. However, a dose-dependent effect of the severity of comorbid pathology was also not found.

The secondary sex ratio in Italy over the past eighty years (1940 to 2019) and potential impact of radiological contamination after atmospheric nuclear testing and after Chernobyl: Temporal change-point analysis using Markov Chain Monte Carlo.

In Europe, the male to female ratio at birth (secondary sex ratio: SSR; sex odds: SO) is 1.04-1.06, is influenced by many factors and is declining in industrialized countries. This study was carried out to identify possible impacts of fallout by atomic bomb tests or by the Chernobyl event on SSR in Italy. Italy is a country without commercial nuclear power generation for the last four decades and thus nearly free of radiological confounders. Counts of annual male and female live births in Italy are provided by the World Health Organization (WHO) and by the Italian Istituto Nazionale di Statistica (ISTAT). This study included 57.7 million live births (1940-2019) with overall SSR 1.05829. The Italian SSR trend was modelled with linear and non-linear logistic regression. Trend changes, i.e., periods with level shifts were estimated with Markov Chain Monte Carlo (MCMC). Two distinct idealized level shifts were identified superimposed on a uniform secular downward trend. The first one is seen towards the end of the 1960s with a jump sex odds ratio (SOR) 1.00681, p < 0.0001. The second one occurred in 1987 with SOR 1.00474, p < 0.0001. In each of the 3 periods separated by the two jumps, SSR uniformly decreased with trend SOR per 100 years of 0.98549, p < 0.0001. In conclusion, the secular trend in the Italian SSR showed two marked level shifts, at the end of the 1960s and from 1987 onward. These follow the release of radioactivity by atmospheric atomic bomb tests during the 1960s and by Chernobyl in 1986 and corroborate the hypothesis that ionizing radiation increases SSR.

Cytogenetic follow-up of an individual after accidental exposure to industrial radiation using dicentric frequency in blood lymphocytes.

A radiation accident occurred in Bursa, Turkey, in July 2005. An industrial radiographer was exposed to industrial iridium-192 gamma rays for 5 h while laying the natural gas line. After 5 h, the victim had a break because of vomiting and nausea. He ended his work, considering that he might have been exposed to radiation. In a few days, erythema, pain, desquamation, edema started in both hands of the victim. The biological dose assessment was started based on frequencies of dicentrics and rings in peripheral blood lymphocytes ten days after the radiation accident. 6 repeated blood samples were taken for 9 years and analyzed staining after giemsa. After 9 years, decline at dicentric frequencies is significant, but still, dicentric contain cells were detected, which were a strong indicator for external radiation exposure.

Retrospective cytogenetic analysis of unstable and stable chromosome aberrations in the victims of radiation accident in Bulgaria.

Five occupational workers in an industrial sterilization unit at Stamboliyski in Bulgaria were accidentally exposed to a very high specific activity of Cobalt-60 source on June 14, 2011. Initial cytogenetic analysis performed on days 2 and 7 after radiation exposure revealed the whole body absorbed radiation doses of 5.32 Gy for patient 1, 3.40 Gy for patient 2, 2.50 Gy for patient 3, 1.91 Gy for patient 4 and 1.24 Gy for patient 5 [1]. Here, a retrospective multicolor FISH analysis was performed on three patients (patients 1, 2 and 3) using the blood samples collected over a period of 4 years from 2012 through 2015. In all the three patients, cells with stable chromosome aberrations (simple and complex chromosome translocations) were 3-4 folds more than cells with unstable chromosome aberrations (dicentric, rings and excess acentric chromosome fragments). In corroboration with the results reported in the literature, we observed that the time dependent decline of dicentrics, rings and excess acentric fragments occurred much more rapidly than chromosome translocations in the blood samples of the three victims. Further, inter-individual variation in the decline of radiation induced chromosome aberrations was also noticed among the three victims. The reason for the increased persistence of balanced chromosome translocations is not entirely clear but may be attributed to certain subsets of long-lived T-lymphocytes. The retrospective cytogenetic follow up studies on radiation-exposed victims may be useful for determining the extent of genomic/chromosomal instability in the hematopoietic system.

Comparative assessment of impact analysis methods applied to large commercial aircraft crash on reinforced concrete containment.

The precise evaluation of the potential damage caused by large commercial aircraft crash into civil structures, especially nuclear power plants (NPPs), has become essential design consideration. In this study, impact of Boeing 767 against rigid wall and outer containment building (reinforced concrete) of an NPP are simulated in ANSYS/LS-DYNA by using both force time history and missile target interaction methods with impact velocities ranging from 100 m/s to 150 m/s. The results show that impact loads, displacements, stresses for concrete and steel reinforcement, and damaged elements are higher in case of force time history method than missile target interaction method, making the former relatively conservative. It is observed that no perforation or scabbing takes place in case of 100 m/s impact speed, thus preventing any potential leakage. With full mass of Boeing 767 and impact velocity slightly above 100 m/s, the outer containment building can prevent local failure modes. At impact velocity higher than 120 m/s, scabbing and perforations are dominant. This concludes that in design and assessment of NPP structures against aircraft loadings, sufficient thickness or consideration of steel plates are essential to account for local failure modes and overall structural integrity. Furthermore, validation and application of detail 3D finite element and material models to full-scale impact analysis have been carried out to expand the existing database. In rigid wall impact analysis, the impact forces and impulses from FE analysis and Riera's method correspond well, which satisfies the recommendations of relevant standards and further ensure the accuracy of results in full-scale impact analysis. The methodology presented in this paper is extremely effective in simulating structural evaluation of full-scale aircraft impact on important facilities such as NPPs.

Usefulness of the whole-body counter for infants and small children (BABYSCAN) as a risk communication tool after the Fukushima Daiichi nuclear power plant incident.

Responding to the radiation-related concerns of parents/guardians with infants/small children is an important public health issue for regional recovery after radioactive contamination. This study summarizes the results of a systematic internal contamination screening of infants/small children, aged 0-6 years, using BABYSCAN and individual counselling sessions with physicians about radiation concerns from 2014 to 2018 in Minamisoma City. Of 3,114 participants, no one was found to have internal contamination with radioactive caesium with a detection limit of 50 Bq/body. The questionnaire survey showed a decreasing trend of concerns about food contamination and playing outside as possible causes of internal contamination over time. Because people's concerns were diverse in counselling sessions, individual responses are required. This study showed that examinations using BABYSCAN provide an opportunity for direct dialogue between the parents/guardians of infants/small children and experts. This can be considered a model case for risk communication conducted by the local government after a radioactive contamination incident.

Estimation of Radiation Doses for a Case-control Study of Thyroid Cancer Among Ukrainian Chernobyl Cleanup Workers.

Thyroid doses were estimated for 607 subjects of a case-control study of thyroid cancer nested in the cohort of 150,813 male Ukrainian cleanup workers who were exposed to radiation as a result of the 1986 Chernobyl nuclear power plant accident. Individual thyroid doses due to external irradiation, inhalation of I and short-lived radioiodine and radiotellurium isotopes (I, I, I, Te, and Te) during the cleanup mission, and intake of I during residence in contaminated settlements were calculated for all study subjects, along with associated uncertainty distributions. The average thyroid dose due to all exposure pathways combined was estimated to be 199 mGy (median: 47 mGy; range: 0.15 mGy to 9.0 Gy), with averages of 140 mGy (median: 20 mGy; range: 0.015 mGy to 3.6 Gy) from external irradiation during the cleanup mission, 44 mGy (median: 12 mGy; range: ~0 mGy to 1.7 Gy) due to I inhalation, 42 mGy (median: 7.3 mGy; range: 0.001 mGy to 3.4 Gy) due to I intake during residence, and 11 mGy (median: 1.6 mGy; range: ~0 mGy to 0.38 Gy) due to inhalation of short-lived radionuclides. Internal exposure of the thyroid gland to I contributed more than 50% of the total thyroid dose in 45% of the study subjects. The uncertainties in the individual stochastic doses were characterized by a mean geometric standard deviation of 2.0, 1.8, 2.0, and 2.6 for external irradiation, inhalation of I, inhalation of short-lived radionuclides, and residential exposure, respectively. The models used for dose calculations were validated against instrument measurements done shortly after the accident. Results of the validation showed that thyroid doses could be estimated retrospectively for Chernobyl cleanup workers two to three decades after the accident with a reasonable degree of reliability.

Thyroid cancer incidence near nuclear sites in Belgium: An ecological study at small geographical level.

In Belgium, variations in thyroid cancer incidence were observed around the major nuclear sites. The present ecological study investigates whether there is an excess incidence of thyroid cancer among people living in the vicinity of the four nuclear sites at the smallest Belgian geographical level. Rate ratios were obtained from a Bayesian hierarchical model for areas of varying sizes around the nuclear sites. Focused hypothesis tests and generalized additive models were performed to test the hypothesis of a gradient in thyroid cancer incidence with increasing levels of surrogate exposures. No evidence was found for more incident cases of thyroid cancer near the two nuclear power plants. Regarding the two industrial and research nuclear sites, no evidence for a higher incidence in the vicinity of Mol-Dessel was observed, whereas a slightly nonsignificant higher incidence was found in the close vicinity of Fleurus. In addition, significant gradients for thyroid cancer incidence were observed with the different types of surrogate exposure considered in the 20 km area around the site of Fleurus (decreasing distance, increasing wind direction frequency and increasing exposure to estimated hypothetical radioactive discharges of iodine-131). In the investigation at the smallest Belgian geographical level, variations in thyroid cancer incidence were found around the Belgian nuclear sites. Significant exposure-response relationships were also observed for the site of Fleurus. Further investigations into these findings could be useful to allow inferring causal relationships on the origin of variations in incidence and to provide information at the individual level.

Trends in the Incidence of Breast Cancer Following the Radiological Accident in Goiânia: A 25-Year Analysis.

BACKGROUND: The largest radiological accident to occur in any urban area happened in Goiânia, Brazil, in 1987. One major concern regarding deleterious effects in the population was a possible increase in the breast cancer incidence. This study analyzed trends in the incidence of breast cancer over the 25-year period following the radiological accident. METHODS: This ecological, population-based study was conducted to determine the incidence of breast cancer in female residents of Goiânia, Goiás, Brazil, between 1988 and 2012. The data were collected from the Goiânia population-based cancer registry. Crude and age-standardized incidence rates were calculated. The Joinpoint software program was used to calculate annual percent changes (APC) in the incidence of breast cancer. RESULTS: Overall, 7,365 new cases of breast cancer were identified, with an annual crude incidence rate of 23.09/100,000 women in 1988 and of 71.65/100,000 women in 2012. The age-standardized incidence rate was 35.63/100,000 women in 1988 and 65.63/100,000 women in 2012. Analysis of the APC showed a significant annual increase of 4.8% in the incidence between 1988 and 2005 (p<0.0001) followed by stabilization in 2005-2012, with an APC of -3.5% (p=0.1). CONCLUSION: There was an increase in the incidence of breast cancer in the female residents of Goiânia, Goiás in the first 17 years of evaluation (1988-2004) followed by a period of stabilization until 2012. However, the trends in the incidence suggest a lack of association with the radiological accident.

RESULTS AND DISCUSSION ON JAPANESE PUBLIC OPINION SURVEYS (2006-17) ABOUT NUCLEAR AND RADIATION APPLICATIONS.

Public opinion on the application of nuclear technology and radiation could change when a nuclear related event occurs. Japan Atomic Energy Relations Organization has tracked its variation through a nationwide opinion survey in Japan by almost the same way every year since FY 2006. We can identify a continuous long-term fluctuation of Japanese opinion before and after the TEPCO Fukushima Daiichi nuclear disaster using the data. In this study we focused on the trends of public opinion for nuclear energy, impressions and knowledge on radiation, and zero-risk request. For example, radiation can be recognised that it is dangerous and complicated matter by Japanese public regardless of that accident. However, a big change of opinions on radiation was shown on the impression for the word of 'Useful' between before and after the accident.

A Critical Assessment of the Linear No-Threshold Hypothesis: Its Validity and Applicability for Use in Risk Assessment and Radiation Protection.

The Society of Nuclear Medicine and Molecular Imaging convened a task group to examine the evidence for the risk of carcinogenesis from low-dose radiation exposure and to assess evidence in the scientific literature related to the overall validity of the linear no-threshold (LNT) hypothesis and its applicability for use in risk assessment and radiation protection. In the low-dose and dose-rate region, the group concluded that the LNT hypothesis is invalid as it is not supported by the available scientific evidence and, instead, is actually refuted by published epidemiology and radiation biology. The task group concluded that the evidence does not support the use of LNT either for risk assessment or radiation protection in the low-dose and dose-rate region.

Modelling the effective dose to a population from fallout after a nuclear power plant accident-A scenario-based study with mitigating actions.

The radiological consequences of a nuclear power plant (NPP) accident, resulting in the release of radionuclides to the environment, will depend largely on the mitigating actions instigated shortly after the accident. It is therefore important to make predictions of the radiation dose to the affected population, from external as well as internal exposure, soon after an accident, despite the fact that data are scarce. The aim of this study was to develop a model for the prediction of the cumulative effective dose up to 84 years of age based on the ground deposition of 137Cs that is determined soon after fallout. The model accounts for different assumptions regarding external and internal dose contributions, and the model parameters in this study were chosen to reflect various mitigating actions. Furthermore, the relative importance of these parameters was determined by sensitivity analysis. To the best of our knowledge, this model is unique as it allows quantification of both the external and the internal effective dose using only a fallout map of 137Cs after a nuclear power plant accident. The cumulative effective dose over a period of 50 years following the accident per unit 137Cs deposited was found to range from 0.14 mSv/kBq m-2 to 1.5 mSv/kBq m-2, depending on the mitigating actions undertaken. According to the sensitivity analysis, the most important parameters governing the cumulative effective dose to various adult populations during 50 years after the fallout appear to be: the correlation factor between the local areal deposition of 137Cs and the maximum initial ambient dose rate; the maximum transfer from regional average fallout on the ground to body burden; the local areal deposition of 137Cs; and the regional average 137Cs deposition. Therefore, it is important that mapping of local 137Cs deposition is carried out immediately after fallout from a nuclear power plant accident, followed by calculations of radiation doses for different scenarios using well-known parameters, in order to identify the most efficient mitigation strategies. Given this 137Cs mapping, we believe our model is a valuable tool for long-term radiological assessment in the early phase after NPP accidents.

SESAME: A TOOL FOR NUMERICAL DOSIMETRIC RECONSTRUCTION OF PATIENTS OVEREXPOSURES IN INTERVENTIONAL RADIOLOGY.

Radiation overexposure accidents are rare but can have severe health consequences. Evaluating the dose received by the patient is a crucial step in the medical management. For that purpose, for more than 15 years, IRSN has been developing an in-house tool named SESAME for the numerical reconstruction of radiological accidents due to external sources. Recently, two new functionalities were implemented in SESAME to allow accurate reconstructions of interventional radiology (IR) overexposures. The experimental validation of SESAME for the reconstruction of overexposures in IR is presented. First, an anthropomorphic dummy equipped with dosemeters was irradiated following conditions similar to a fluoroscopically guided interventional procedure. Then the procedure was simulated using SESAME. Finally measured doses were compared to calculated doses. Even with a limited amount of data available, SESAME can provide valuable dose information for the medical team in charge of the patient, such as skin dose mapping and dose distribution in depth.

Radiological Risks From Potential Exposure of the Population to Radiation From Orphan Radioactive Sources.

People in their everyday lives are exposed to radiation. Natural radiation is emitted from space, subsoil, and various materials which contain radioactive materials. Humans are also exposed to radiation from medical and industrial applications that use radioactive sources with artificial radioactive materials. Such radioactive sources may nevertheless get out of the control system and become orphan sources. Because these radiation sources are usually contained within metal shields such as lead and iron, the shields can end up as scrap metal being used in the metallurgical industry as raw material. Incidents have been recorded around the world, and several are reported in the literature and described here, where orphan sources have caused direct radiation exposure and/or environmental and personal contamination when the sources leaked. Timely and prompt recognition of an orphan radioactive source or device is crucial in order to minimize the radiological risk and its implications for the general population.

INITIAL EVALUATION OF INDIVIDUAL DOSES IN THE EARLY PHASE OF A NUCLEAR REACTOR ACCIDENT BASED ON IN-VIVO MONITORING DATA AND SIMULATED RADIOLOGICAL CONSEQUENCES.

In the early phase of a nuclear reactor accident, in-vivo monitoring of impacted population would be highly useful to detect potential contamination during the passage of the cloud and to estimate the dose from inhalation of measured radionuclides. However, it would be important to take into account other exposure components: (1) inhalation of unmeasured radionuclides and (2) external irradiation from the plume and from the radionuclides deposited on the soil. This article presents a methodology to calculate coefficients used to convert in-vivo measurement results directly into doses, not only from the measured radionuclides but from all sources of exposure according to model-based projected doses. This early interpretation of in-vivo measurements will provide an initial indication of individual exposure levels. As an illustration, the methodology is applied to two scenarios of accidents affecting a nuclear power plant: a loss-of-coolant accident leading to core meltdown and a steam generator tube rupture accident.

An approach to identifying the relative importance of different radionuclides in ecological radiological risk assessment: Application to nuclear power plant releases.

There is a need to prioritise the requirements for data to assess the radiological risk for fauna and flora, as inevitable large data gaps occur due to the large number of combinations of radionuclides and organisms for which doses need to be assessed. The potentially most important dose-forming radionuclide-pathways combinations need to be identified to optimize filling these gaps. Few attempts have been made to classify the importance of isotopes with regard to radiation protection of the environment. A hierarchical approach is described here for radionuclides that are potentially present in generic ecosystems (freshwater, marine or terrestrial) and is applied for scenarios considering ecologically relevant chronic exposure. In each ecosystem, the top ten radionuclides that may contribute to doses were identified using a qualitative Chronic Hazard Index. Including quantitative aspects by incorporating discharge quantities changed the priority list, and increased the relative importance of radionuclides contributing most to the authorized releases of nuclear facilities (14C and 3H followed by 60C). The potentially most important dose-contributing radionuclides in the framework of environmental radiation protection under a chronic exposure situation included isotopes of about 20 elements. The five most important in order of decreasing importance were: carbon, hydrogen, caesium, cobalt and americium. Consideration of acute exposure situations was hampered by data gaps that were even greater than that for chronic exposure situations, so it was only possible to consider the feasibility of developing a consistent approach.