The thesis for the degree of doctor of technical sciences, specialty 21.06.01 –ecological safety. – National Aviation University. Kyiv, 2020.
The thesis is dedicated to solving the scientific and applied problem of reducing the negative effects of radon hazards on the ecological situation around uranium mining and adjacent areas by improving methodological approach to assessing and justifying the model of environmental hazard control for territories with technogenically enhanced sources of natural origin.
The areas of uranium ore mining and processing from the point of "post-uranium legacy sites» are identified and outlined as affected by past practices and radioactively contaminated, where the level of radioactivity significantly exceeds the background, the value of the equivalent dose rate reaches 350 μSv / h, and environmental components are characterized by high content of uranium (rocks – up to 40-53 g/t; soils – up to 0.5-1.9∙10-4%; water – 5∙10-6g/l – 9∙10-2g/l), its decay products and associated elements. It is proposed to use remote sensing methods for geospatial modeling of radon-prone areas, first at regional and then at local levels.
The method for identifying radon-prone areas within the territories of economic entities is developed. It includes classification of potential radon hazard levels, takes into account the natural radioactivity of environmental components, spatial density of faults and lineaments, and allows classifying correctly the level of potential radon hazard with 97,50 %±0,94% probability. As a whole 13 radon hazard factors for identification of radon hazardous zones within the territories of economic entities at the local level are identified and generalized. The radon survey can be further prioritized based on potential level identified on geospatial and mathematical modeling data. The basic parameters for the initial mapping stage are proposed to be the faults and the lineaments of the 3-d and 4-th order spatial density. Other parameters are added for more detailed analysis, depending on the particular location under consideration. In a limited number of direct indoor radon measurements, remote methods are supposed to be a good help in identification of potentially radon hazard areas.
It is substantiated that time series of radar interferometry and remote thermometry data of the earth's surface are worth considering as indicators of environmental hazard for mining territories. The analysis of time series of remote sensing data of the study area for long-term trends and periodic components mapping was carried out. The linear trends of the time series of remote sensing data were described by average values for the entire analysis period and average growths for a certain period. Based on the results of processing multispectral space images and geospatial modeling, a series of thematic maps of soil-vegetation cover degradation within the locations of uranium legacy sites in Ukraine were created. At that the methods of remote mapping of land degradation based on the processing of multispectral space images and geospatial modeling for areas around potentially hazardous radiation facilities were further developed.
The main ways to predict the potential hazard from air dust, radiation doses and radiation risk from dust radionuclides intake into the atmosphere from uranium mining rock heaps are identified. It was established that the highest radiation dose that a person can receive is 11 μber/year. It is proved that the lifetime radiation risk from radioactive dust entry into the atmosphere equals to 10–9 years– 1, and it is negligibly low. The radiation risk is maximum near the boundary of the heaps. Increasing the area of rock heaps will increase the dose to the population.
Key words: environmental safety, technogenically enhanced sources of natural radiation, radon hazard, radiation hazard, uranium legacy sites, remote sensing of the Earth, multispectral space images.
