Natural Resources Canada is responsible for the provision of aerial radiometric surveys in the event of a radiological or nuclear emergency in Canada .
Manned aerial surveys are an essential element of the planned consequence management operation , as demonstrated by the recovery work following the 2011 Tohoku earthquake and tsunami , and their effects in Fukushima , Japan .
Flying lower and slower than manned aircraft , an unmanned aerial vehicle ( UAV ) can provide improved spatial resolution .
In particular , hot spot activity can be underestimated in manned survey results as the higher flight altitude and wider line spacing effectively average the hot spot over a larger area .
Moreover , a UAV can enter an area which is too hazardous for humans , due not only to the radiological threat which is its target , but also to other anticipated hazards such as explosives , airborne chemical hazards , or open water .
Natural Resources Canada has been investigating the inclusion of UAV-borne radiation survey spectrometers into its aerial survey response procedures .
The Advanced Radiation Detector for UAV Operations ( ARDUO ) was developed to exploit the flight and lift capabilities available in the under 25 kg class of UAVs .
The detector features eight 2.8 cm \times 2.8 cm \times 5.6 cm CsI ( Tl ) crystals arranged in a self-shielding configuration , read out with silicon photomultipliers .
The signal is digitized using miniaturized custom electronics .
The ARDUO is flown on a main- and tail-rotor UAV called Responder which has a 6 kg lift capacity and up to 40 minute endurance .
Experiments were conducted to characterize the performance of the ARDUO and Responder UAV system in both laboratory and outdoor trials .
Outdoor trials consisted of aerial surveys over sealed point sources and over a distributed source of 10 MBq/m ^ { 2 } of La/140 .
Results show how the directional response of the ARDUO can provide an indication in real time of source location to guide the UAV during flight .
As well , the results show how utilization of the directional information in post-acquisition processing can result in improved spatial resolution of radiation features for both point and distributed sources .