Particulars of scanning an underlying surface using a pilotless dosimetric complex

Abstract

A method of determining the surface activity of radioactive aerosols along the track of a radioactive cloud, due to a radiological accident, with the aid of a pilotless dosimetric complex is examined. The optimal flight altitude and the effective scan area on the underlying surface are determined. To determine the flight altitude, the altitude distribution of the dose rate is calculated for different photon energy taking account of the reflection of γ rays from the underlying surface by means of the Monte Carlo method and an analytical relation which takes account of the accumulation factor in the form of Berger’s relation. The calculations showed a substantial difference between the distributions, which required the introduction of a corrective function ψ(E i ) that does not depend on the scan altitude and makes it possible to decrease the computational error by analytical methods to 10% (the Monte Carlo error). The scan altitude hD above the underlying surface at which it best to conduct radiation monitoring is 40–100 m. The radius for evaluating the effective scan area is found and is given by the relation rb ≈ 3hD.