Airborne radiometric surveys through the usev of a handheld spectrometer fitted to a UAV
Matter is made up of small particles called atoms of which some are unstable due to an imbalance between protons and neutrons. This results in the particles being radioactive, which will over time undergo radioactive decay in order to achieve a more stable state. Measuring the radioactive decay of elements in the field is a physical and time-consuming process that is conducted mainly through the use of handheld equipment such as spectrometers and scintillometers. Alternative methods include aerial and car surveys, but are more specialized, costly and situational. This study is aimed at testing the viability of unmanned aerial vehicle (UAV) systems as an alternative measuring platform. UAV systems are faster than walking, more accessible than vehicles and cheaper than airplanes, making it theoretically a great platform for radiometric surveys. Throughout the study, a total of three different UAV systems were used and equipped with a handheld RS 230 spectrometer. A series of tests were conducted in order to determine the measuring capabilities of the spectrometer at different heights above the surface, as well the efficacy and accuracy of using a UAV system equipped with a spectrometer. A number of models were developed simulating the effect of a UAVs speed and height on the spectrometers measuring accuracy. The effect of different radiological source sizes on the measured radiation at a fixed height was measured. Furthermore, radiation was measured at different heights using a constant radiation source. Results indicated that a strong correlation existed between simulated and measured values. The study provides sufficient evidence that the use of a UAV systems equipped with handheld measuring equipment is capable of producing accurate and reliable radiological data. However, the use of any elevated radiometric detection device has its limitations. An area containing a homogenous radioactivity can be measured at greater altitudes than areas having an inconsistent spread of radioactivity. For greater radiometric detection accuracy, UAV systems used in areas with altering levels of radiation, are required to fly at lower altitudes to be able to detect inconsistencies. The effect of the UAV system on the spectrometer measuring capabilities has to be accounted for during data analysis.