Unmanned Aircraft System-Based Radiological Mapping of Buildings

The article focuses on acquiring a 3D radiation map of a building via a two-phase survey performed with an unmanned aircraft system (UAS). First, a model of the stud-ied building is created by means of photogrammetry. Then, radiation data are collected using a 2-inch NaI(Tl) detector in a regular grid at a distance of 2 m from all accessible surfaces of the building (i.e., the walls and the roof). The data are then georeferenced, filtered, projected to the building model, and interpolated to yield the detailed radiation map. A method to estimate the parameters of the radiation sources located inside is introduced and successfully tested, providing a localization accuracy in the order of meters. This task is aimed to deliver the proof of concept for employing such a mapping technique within nuclear safeguards. The acquisition of the radiation data was performed via a manual flight to ensure an appropriate safety level; in this context, it should be noted that the autonomous flight mode still requires major improvements in terms of safety.