Application of muon tomography to encapsulated nuclear waste

Muon tomography is a non-invasive imaging technique which can be used to visualize the internal structures of an object using the Coulomb scattering of cosmic-ray muons. Because of their high penetrative power of high energy muons, this technique can potentially be used to image large and dense objects. It has been demonstrated in our previous study that this technique is capable of identifying and characterising high-Z materials within an air matrix using a prototype scintillating-fibre tracker system. In the present work, we extended our study to image a more complex object where two high atomic number materials and a medium atomic number material are sealed in a concrete filled stainless steel container. The same tracking detector was used to collect the muon scattering data, and images were reconstructed by using dedicated statistical image reconstruction software. This work serves as a feasibility study to determine if it is possible to use this technology to characterise the potential high-atomic number contents of legacy nuclear waste containers for the UK Nuclear Industry. Our results showed clear discrimination between the steel barrel wall, the concrete matrix and the high atomic number materials in the container. The possible application of this technique for future industrial scenarios is discussed.