COMPREHENSIVE RADIATION AND HYGIENIC MONITORING IN POPULATION OF THE RIVNE OBLAST RADIOLOGICALLY CONTAMINATED TERRITORIES.

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.