Imaging of Shielded Uranium Assemblies Under Active Neutron Interrogation Using Inverse Methods

The point kinetics model for the emission of neutrons relies on several assumptions including that all neutrons are emitted from a single location. With the advancement of active neutron imaging systems, methods for determining the amount of fissile material, enrichment, and multiplication are constrained by the exclusion of extended geometry in the point kinetics model. This work begins to bridge between point kinetics and image reconstruction methods so that estimates of enrichment and multiplication can be derived throughout a geometry of large and shielded fissile materials. A theory for building this image reconstruction method is developed and inverse problem methods are applied to reconstruct the total and fission neutron macroscopic neutron cross sections for simulated data.