Enhanced Nuclear Materials Control and Acountability by Imaging

Tomographic and radiographic imaging capabilities have been added to the Nuclear Materials Identification System1 (NMIS) at ORNL. These imaging capabilities supplement the system’s existing time correlation (coincidence) measurements and enhance the system’s ability to identify fissile material in containers. The time correlation between an active interrogation source and detectors placed on the opposite side of the container are the basis of the imaging capability. The interrogation source is a small, portable DT neutron generator system which time tags each emitted neutron; time tags are also received from an array of eight small plastic scintillation detectors which measure the source radiation transmission through the container, as well has any radiation produced within the container via induced fissions. This paper describes feasibility measurements2 of a depleted uranium metal annular casting and a configuration of iron pipes and polyethylene. The casting configuration illustrates how imaging can determine the configuration of uranium metal in storage cans. The iron pipe and polyethylene configuration illustrate imaging of a more complicated object in a container.