Comparative investigation of airborne and ground-based radiometric survey techniques

• Main Author: Larkin, James Francis Shenton
• Format: Others
• Language: en
• Published: 2014
• Subjects: Radiation - Measurements.; Radioisotopes.
• Online Access: http://hdl.handle.net10539/14034

An investigation was undertaken to compare airborne and ground-based radiometric survey techniques and to compare and contrast their relative merits and how they can be used in determining the environmental distribution of environmental radioisotopes, particularly those in the decay chains of 238U, 232Th and 40K. Before a detailed investigation was done of the survey techniques, it was necessary to look at the underlying physical principles of detection of ionizing radiation and the types of detector that are generally used in these different types of survey techniques. Having looked at the physics of detection, a detailed examination of the potential distribution of these environmental radioisotopes was undertaken. In these surveys, an assumption is often made, that the daughter isotopes in a decay chain are in secular equilibrium with one another. This assumption was examined and the various possible ways in which secular equilibrium could break down were considered, these included looking at biological, meteorological and chemical processes. Only after all the influences on assumptions used in these survey processes and the physical limitations on the measurements taken during surveys were considered, was a comparison made of a set of airborne and ground-based measurements taken at a chosen survey site compared. These measurements compared uranium, thorium and potassium activity concentrations, which had been determined by the two survey techniques, and a correlation was found particularly when the uranium measurements were examined.