Addition of Tomographic Capabilities to NMIS

Mullens, J. A.

Oak Ridge Y-12 Plant

关键词: Attenuation;    Neutrons;    Radiations;    Production;    Fissile Materials;   

DOI  :  10.2172/809868
RP-ID  :  Y/LB-16,160
RP-ID  :  AC05-00OR22800
RP-ID  :  809868

美国|英语

来源: UNT Digital Library

【 摘 要 】

This paper describes tomographic capabilities for the Nuclear Materials Identification System (NMIS). The tomographic capabilities add weapons component spatial and material properties information that result in a more detailed item signature (template) and provide more information for physical attributes analyses. The Nuclear Materials Identification System (NMIS) is used routinely to confirm the identity of HEU components in sealed containers. It does this through a radiation signature acquired by shining a {sup 252}Cf source through the container and measuring the radiation at four detectors stacked vertically on the other side. This measurement gives a gamma and neutron radiation transmission profile of the weapons component, mixed with the radiation production due to the induced fissions in the fissile materials. This information is sufficient to match an ''unknown'' weapons component signature to a template signature from a reference item when measuring under controlled conditions. Tomography measures the interior of an item by making transmission measurements from all angles around the item, whereas NMIS makes the measurements from a single angle. Figure 1 is a standard example of tomographic reconstruction, the Shepp-Logan human brain phantom. The measured quantity is attenuation so high values (white) are highly attenuating areas.