Evaluation of the Dose Distribution of Gamma Radiation by a Discrete Measuring Point Method Using Drones

Abstract

The primary objective of the development was to create a more compact, easily portable, and deployable system, but  one which, in contrast with the previous ones, is more  sensitive. Despite background radiation (typically 0.01 μSv/h in the testing areas), a difference of +0.009 μSv/h has reliably been detected in the experiments made so far. In  this present development, this value was successfully  reduced to +0.005 – +0.007 μS/h. The improvement in  sensitivity was achieved primarily by increasing the  measurement time per point, which was realised using special flight control software. This sensitivity increase  either allows higher scanning altitude (approximately +1–2  m) or, in case of an identical flight device at an identical  altitude, a larger survey area with one take-off. In our experiments, we used a natural uranium mineral (Autunite)  with activity far below that of artificially produced isotopes.  In this series of experiments, we also covered the identification of several sources, which models the  possibility of mapping active sources scattered around the site of a possible accident. The main advantage of the  system developed and introduced by us over the survey  procedures used in practice is that it is easy to mobilise, a  large area can be surveyed at low cost without putting an  operator at risk in the field. The purpose of the system is to  detect the presence of the source and to localise it to such  an extent that the localisation can subsequently be easily specified by manual or other ground procedures. Since we  do not strive for centimeter positioning accuracy, standard  GPS localisation is sufficient for measurements. During the  measurements, the geographical coordinates are  interpreted in the WGS’84 system. The circles of latitude  and longitude coordinates are also shown in this system in  the figures presented.