Characterization of Interrogated Highly Enriched Uranium Using an Organic Glass Handheld Dual-Particle Imaging System

The detection of highly enriched uranium (HEU) proves challenging in nuclear nonproliferation applications due to the ease of gamma shielding and low passive neutron emission rates. A common solution is the use of neutron interrogation to induce fission in HEU, which induces a more substantial neutron signature for detection. A detection system capable of characterizing varying masses of HEU by performing neutron spectroscopy and imaging would be a valuable asset. In this work, two AmLi sources were used to interrogate kg-scale quantities of HEU at the National Criticality Experiments Research Center on the Nevada National Security Site. Neutron responses were recorded using the Handheld Dual-Particle Imaging system developed at the University of Michigan. The imager is composed of both organic and inorganic scintillators, leading to imaging and spectroscopy capabilities. This work reports on successful neutron imaging of ~14-kg and ~10-kg configurations of highly enriched uranium. A comparison of the detected neutron singles response demonstrated a 45.1±2.1% increase in neutron counts for the larger HEU mass.