ON THE METHODOLOGY OF PASSPORT DOSES CALCULATION FOR UKRAINIAN SETTLEMENTS RADIOACTIVELY CONTAMINATED DUE TO THE CHORNOBYL NPP ACCIDENT. / ЩОДО МЕТОДИКИ РОЗРАХУНКУ ПАСПОРТНИХ ДОЗ НАСЕЛЕНИХ ПУНКТІВ УКРАЇНИ, ЯКІ ЗАЗНАЛИ РАДІОАКТИВНОГО ЗАБРУДНЕННЯ В РЕЗУЛЬТАТІ АВАРІЇ НА ЧАЕС.

OBJECTIVE: scientific substantiation of the new methodology for estimation of passport doses of the settlementswhich belong to Zone of Unconditional (obligatory) Resettlement, or 2nd zone and Zone of Granted VoluntaryResettlement, or 3rd zone in the framework of dosimetric passportization in accordance with the legislation ofUkraine. MATERIALS AND METHODS: 37 years after the accident, radioactive contamination of the environment has significantly decreased. However, it is still necessary to carry out ecological and dosimetric monitoring and apply countermeasures in certain territories of Ukraine affected by the accident at the Chornobyl Nuclear Power Plant: restriction of the consumption of locally produced milk, forest products, etc. The methodology, which was since 1996 used to estimate the passport doses of Ukrainian settlements, no longer corresponds to the current level of scientific knowledge about radioactive contamination of environment. The new methods of passport doses calculating presented in the work involves the use of a model whose parameters are determined by the types, quality and completeness of radio-ecological and dosimetric monitoring carried out on the radioactively contaminated territories in 1986-2013. The methodology takes into account the specific of radioactive contamination of each settlement. The passport dose of external exposure is reconstructed only from 137Cs radionuclide, because the contributions of other Chornobyl radionuclides influence the radiation dose only in the first years after the accident. The passport dose of internal exposure is formed as a result of the consumption of 137Cs contaminated food products. It is calculated depending on the availability in the settlement in the current year of the results of measurements of the 137Cs radionuclide activity incorporated in the human body using a whole body counter (WBC) and the activity of 137Cs in the private milk. At the same time, priority is given precisely to the results of WBC measurements of 137Cs. RESULTS AND CONCLUSIONS: A new methodology (Methodology-2023) for passport doses calculation of Ukrainian settlements was substantiated. A comparison of passport doses based on the results of radioecological and dosimetric monitoring in 2011 calculated by Methodology-2023 and passport doses calculated by Methodology-96 was made.Passport doses calculated by Methodology-2023 increased by 40 % on average compared to doses calculated by Methodology-96. At the same time, passport doses of internal radiation calculated by the new methodologyincreased by 1.5 times, and passport doses of external radiation increased by 1.7 times. The passport dose of 2011, calculated by Methodology-2023, exceeds the legally established limit of 1 mSv in 71 settlements, most of which are located in Korostenkyi raion of Zhytomyr Oblast.

COMPLEX RADIATION AND HYGIENIC MONITORING OF POPULATION ON RADIOLOGICALLY CONTAMINATED TERRITORIES OF ZHYTOMYR OBLAST IN 2021. / KOMPLEKSNYI RADIATsIINO-GIGIIeNIChNYI MONITORYNG MEShKANTsIV RADIOAKTYVNO ZABRUDNENYKh TERYTORII ZhYTOMYRS'KOÏ OBLASTI U 2021 ROTsI.

OBJECTIVE: the key factors identification in radiation dose formation in population of radiologically contaminatedareas of Zhytomyr oblast in the current period of accident through complex radiation and hygienic monitoring in reference settlements in 2021. MATERIALS AND METHODS: For complex radiationhygienic monitoring in Zhytomyr oblast, 10 settlements were chosen - Narodychi, Selets, Bazar, Rudnya Bazarska, Khrystynivka - zone 2, Motiyki, Zalissya, Davydky, Radcha, Nova Radcha - zone 3 of Narodychi district, in which the highest radiation doses were recorded after the accident at the Chornobyl Nuclear Power Plant. The research was carried out in June 2021. In order to determine the doses of internal radiation, 645 measurements were performed on whole body counters (WBC) (478 adults and 167 children). The 44 samples of milk, 45 samples of potatoes and vegetables, and 38 samples of wild products were collected in local farms and measured for the 137Cs and 90Sr content. Residents of the studied settlements (n = 220, 175 adults, and 45 children) were interviewed about the levels of consumption of staple foodstuffs. External radiation doses were evaluated in all the studied settlements. Mathematical, dosimetry, and radiochemical methods were applied. RESULTS AND CONCLUSIONS: Annual effective radiation doses of Zhytomyr oblast population in 2021 were formedmainly due to internal radiation ones that not exceeded 1.8 mSv * year-1 in adults and 0.5 mSv * year-1 in children against the radiologically contaminated territories (RCT) criterion of 1 mSv * year-1. Intake of 137Cs with milk and wild mushrooms, which traditionally occupy a significant part of diet in Zhytomyr oblast area and have consistently high levels of radioactive cesium contamination, remains a key factor of internal radiation dose forming in residents of the surveyed settlements of Zhytomyr oblast.

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.

Way to improve the radiation hygenic monitoring on contaminated territories.

STUDY OBJECTIVE: To provide an effective radiation hygienic inspection and population protection from ionizing radiation in the late period after the Chornobyl NPP (ChNPP) accident within reforming of the state sanitary & epidemiological supervision services. MATERIALS AND METHODS: The radiation hygienic monitoring (RHM) is performed in Ukraine within the scope of state sanitary & epidemiologic supervision by 158 radiological subdivisions of the sanitary & epidemiological station (SES). The structure of these subdivisions has been created taking into account the territorial regional bounds, a presence of radiological supervision services and ChNPP accident consequences. Nowadays it consists of regional, district, municipal subdivisions, central SESs of Crimea autonomous republic and transport subdivision. In 2012-2013 the State Sanitary & Epidemiological Service of Ukraine had been reformed and reorganized and then in several cases it wasn't optimal for RHM performance. RESULTS AND CONCLUSIONS: The fulfilled analysis of radiation hygienic supervision and protection of population of contaminated regions and efficiency analysis of that supervision and protection allowed to find out and to propose some methods to improve the actual radiation hygienic supervision monitoring system on contaminated Ukrainian areas after the ChNPP accident. It is essential to restore the radiological subdivision (departments, units, labs or groups) work in the State sanitary & epidemiology service structure and to design coordinated and approved methodical recommendations to implement the RHM on contaminated areas to improve and optimize the RHM performance there.

Peculiarities of internal radiation doses due to ¹³7Cs and 9°Sr intake in population from Zhytomyr oblast in a late period after the Chornobyl NPP accident.

STUDY OBJECTIVE: To reveal the peculiarities of internal radiation doses in the inhabitants of Zhytomyr oblast and to provide a scientific ground for arrangements on internal irradiation dose reducing in population from contaminated regions in long-term period after the ChNPP accident. MATERIALS AND METHODS: Comprehensive radiation monitoring was carried out in 4 settlements in Narodychi region of Zhytomyr oblast. The radiochemical, dosimetric methods (instrumental and numerical) were used in the study. RESULTS AND CONCLUSIONS: Significant (2-3.5 times) seasonal increase of incorporated ¹³7Cs level was revealed through a WBC-monitoring in residents (both for adults and children) of the supervised settlements of Narodytsky region, Zhytomyr oblast. The exceeding of 1.0 mSv x year⁻¹ dose was revealed in up to 5 % of inspected persons. The maximal registered in those settlements ¹³7Cs content of 350 kBq is the source of 10 mSv x year⁻¹ annual dose. ¹³7Cs content in milk samples from those settlements didn't change much during a year. Elevation of ¹³7Cs content exceeding the permissible level of 100 Bq x litre⁻¹ was found in ~30-50 % of milk samples from Narodychi and Selets villages, whereas in Motiyky and Khrystynivka villages the ¹³7Cs content didn't exceed permissible levels. 90Sr content both in potatoes and milk samples was much under the permissible level of 20 Bq x litre⁻¹. ¹³7Cs content in potato samples was under the permissible levels. It was found out that main part of internal irradiation doses in the settlements of concern is due to consumption of locally produced victuals i.e. milk and natural/forest-originated products like berries and mushrooms.