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№3' 2017
HYGIENE, EPIDEMIOLOGY, MEDICAL ECOLOGYInternational Medical Journal, Vol. 23., Iss. 3, 2017, P. 88−92.
STUDY OF THE LEVELS AND STRUCTURE OF DOSES OF POPULATION EXPOSURE DUE TO NATURAL RADIATION SOURCES
Zaporizhzhia State Medical University
Zaporizhzhia Regional Laboratory Center of SES of Ukraine, Ukraine
In Ukraine, total population exposure dose is 5.9 mSv/year−1, the contribution of the natural component is much higher and reaches 3.5 mSv/year−1. The share of radon−222 in it accounts for 2.4 mSv/year−1. In this regard, information on the main factors of population exposure in certain regions of the country is very important for developing measures to reduce them. This problem is especially relevant for Zaporizhzhia region, where the largest in Europe Zaporizhzhia NPP is located. The article deals with investigation of the levels and structure of population exposure doses due to natural radiation sources. The purpose of the work was to study the existing levels of gamma−background in the territory of Zaporizhzhia region in open areas and in residential buildings, with further assessment of possible doses of exposure to the population from the sources of natural origin. Dosimetry, statistics and computational methods were used. To determine the population doses due to natural sources, the results of measurements of radon−222 in indoor air, activity of natural radionuclides in building materials, water of the artesian well, as well as gamma−ray background in the premises and in the territory were used. Measurement of radon−222 was carried out by passive track radonometry. The number of measurements of gamma−background in the open area was 1257, absorbed dose rate in the houses made 848. The number of samples tested for the content of radionuclides in building materials made 5798, in portable water of artesian the wells −− 297. The number of measurements of radon−222 in the air facilities made 693. It was established that due to natural radiation, averaged over the years 2010ЃE014, absorbed dose rate in the air in open areas was 11.3 mR·h−1. Levels of gamma background measured in the premises were equal to 12.2 mR·h−1. Averaged total exposure dose due to external exposure indoors and outdoors was 0.64 mSv per year−1. 80 % of the dose determines the exposure indoors. Averaged population exposure dose due to radon−222 in the portable water of the artesian wells was 0.13 mSv per year −1. It was found that total average annual effective population exposure dose from the main natural sources reached 4.3 mSv, which was almost 1.8 times higher than the world average value and 19.4 % more than the average Ukrainian value. The largest contribution to the dose was made by radon−222 − 76 %.
Key words: radiation sources, population, natural radionuclides, exposure levels and doses.