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TitleSpatial deconvolution of aerial radiometric survey and its application to the fallout from a radiological dispersal device
AuthorSinclair, L EORCID logo; Fortin, RORCID logo
SourceJournal of Environmental Radioactivity vol. 197, 2018 p. 39-47, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20180112
PublisherElsevier BV
Mediapaper; on-line; digital
File formatpdf; html
SubjectsHealth and Safety; geophysics; Science and Technology; geophysical surveys; radiometric surveys, airborne; radioactivity; mapping techniques; radionuclides; Methodology; Emergency services
Illustrationsplots; 3-D models; geoscientific sketch maps; profiles
ProgramCanadian Hazard Information Service
Released2018 12 06
AbstractMapping radioactive contamination using aerial survey measurements is an area under active investigation today. The radiometric aerial survey technique has been extensively applied following reactor accidents and also would provide a key tool for response to a malicious radiological or nuclear incident. Methods exist to calibrate the aerial survey system for quantification of the concentration of natural radionuclides, which can provide guidance. However, these methods have anticipated a spatial distribution of the source which is large in comparison to the survey altitude. In rapid emergency-response aerial surveys of areas of safety concern, deposits of relatively small spatial extent may be expected. The activity of such spatially restricted hot spots is underestimated using the traditional methods. We present here a spatial deconvolution method which can recover some of the variation smoothed out by the averaging due to survey at altitude. We show that the method can recover the true spatial distribution of concentration of a synthetic source. We then apply the method to real aerial survey data collected following detonation of a radiological dispersal device. The findings and implications of the deconvolution are then discussed by reference to a groundbased truckborne survey over the same contamination.
Summary(Plain Language Summary, not published)
Radioactive contamination distributed on the ground can be mapped by aircraft equipped with radiation sensors flying a grid pattern overhead. Unfortunately, high contamination in a small area may appear as a much lower concentration in a map produced in this way. This article presents a method of "spatial deconvolution" to partially correct for this averaging effect. The method is applied on simulated data to prove that it works. Then the method is applied to real data. The spatially deconvolved map of real data is then compared to a map made from data collected by radiation detectors on a truck on the ground. Indeed, the spatially deconvolved map is much closer to the map produced by the ground survey than the non-deconvolved map. This is an important outcome for the health and safety of workers on the ground. This proves that hot spots seem to be less concentrated in aerial survey maps than they really are, and presents a way to deal with that.

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