Application of the Airborne Radiometric Method in Radiation Protection Applications

The airborne radiometric method has been extensively applied to uranium exploration and geological mapping problems since the 1940s, taking advantage of the natural variations in radioelement concentrations in the upper part of the earth’s crust and the information which can be deduced from these regarding surface geology and potentially economic mineralisation. In the process, a number of conventional practices have been adopted, largely regarding calibration and its supporting assumptions. The science of radiation protection looks at the quantification of radiological exposure to human beings, the assessment of the health impacts of these exposures and the development of strategies to minimise these exposures. As a result, the underlying methodologies and supporting assumptions differ, in some cases greatly, from those made in geophysical surveying, potentially resulting in misunderstandings between experts in the two fields. Airborne surveying on its own cannot generally directly quantify the radiological dose to human beings on the ground, although it can be used, given certain assumptions, to estimate ground level exposure rates. It can, however, play a vital role in the location, identification and, to some extent the characterisation of ground sources of radioactivity which could lead to increased radiological doses to the public. The extensive aerial coverage provided by the airborne survey method also offers a unique opportunity for the mapping of potentially radiologically significant sources. While it has traditionally been applied to the mapping of naturally occurring radioactive materials, modern multi-channel airborne spectrometers may also be applied to the search for and mapping of sources containing artificial radionuclides.