X-ray computed tomography and thermal neutron radiography for detection of low dense compounds inside pyro elements used in space applications

Neutron radiography (NR) can be used for the detection and characterisation of explosives having different macroscopic attenuation cross sections. However, if the explosives have similar macroscopic cross sections to neutrons, characterising them is not possible. In this investigation, an attempt is made to distinguish various explosives based on the attenuation cross section of these compounds to neutrons. A correlation between the grey level achieved in neutron image of each explosive taken in a thin walled shell and their corresponding macroscopic attenuation cross section is carried out. An attempt is made to study the possibility of detection of some low dense compounds kept inside pyro metallic cases using cone beam X-ray 3D computed tomography. X-ray CT sliced images of samples filled with calcium carbonate and epoxy can be easily distinguished from empty samples. Samples were tested in NR and X-ray CT facility to compare the results. It is observed that low dense compounds of small volume positioned inside a bulk volume of SS metal of a pyro element used in this study are giving sufficient contrast that makes it detectable in CT cross-sectional image. The study points towards usage of X-ray CT as an alternative tool for detecting the presence of explosives in pyro devices wherever NR imaging cannot be carried out due to wall thickness constraints.