The Effect of High-Scatter Shielding Geometries in Validating the Dose Inferred by N-Visage™

The aim of this paper is to further validate the physical capability of N-Visage™ under more challenging shielding geometries, when the number of mean free paths is greater than one. N-Visage™ is a recently established technique developed at REACT Engineering Ltd. The software locates radionuclide sources and contours radiation magnitude. The N-Visage™ software uses a geometric computer model combined with measured spectra. The software is able to estimate source locations through shielding materials by using mass attenuation coefficients to calculate the number of unscattered gamma photons arriving at the detector, and build-up factors to estimate scatter contribution to dose rate. The experiments described in this paper were carried out in a high-scatter environment using cobalt-60 and caesium-137 sources, these two sources are the primary sources of radiological contamination found in the nuclear industry. It is hoped that this will further assist in the identification, characterisation and removal of buried radiologically contaminated waste.