Application of a 14 MeV Neutron Source to the Detection of Special Nuclear Material Diversion

Some special nuclear material (SNM) is seriously vulnerable to diversion if currently used safeguards methods are applied to an unattended material/equipment pass-through. Without visual inspection, radiation shielding can be used to defeat direct detection of characteristic 235U radiation. Plutonium-239 is much less vulnerable to concealment by radiation shielding due to the prompt radiation from 240Pu which accompanies 239Pu in small amounts. An active neutron technique can be used to combine direct SNM detection and neutron shield detection to limit the amount of shielding to conceal SNM. While this technique is not presently adequate to meet the desired SNM detection threshold of 20g, an additional detection option of neutron capture gamma-ray spectroscopy is being studied.