A brief overview of an AWE survey of existing techniques to detect SNM will be presented. This survey has identified
two techniques that incorporate active gamma sources for further study. These are a photonuclear based technique and
the use of nuclear resonance fluorescence. The current status of work in the development of these techniques is
presented. Developments in physics modelling capabilities, active source technologies, detector technologies and data
fusion and analysis approaches are summarised. Particular attention will be given to the potential for high current, pulsed
power based, active interrogation sources for remote detection of SNM.
Active interrogation techniques using photons (<10 MeV) and low energy neutrons are currently being investigated at
AWE for the remote detection of special nuclear material (SNM). To identify the presence of SNM the induced fission
signatures are measured. AWE is investigating the combination of the photon and neutron techniques to provide robust
detection for shielded scenarios involving either hydrogenous or high Z materials. A brief description of the interrogation
sources is given with consideration to the extraction of high fidelity fission signatures in the presence of typical naturally
occurring radioactive material and other background signals generated by the interrogation process. Initial results are
presented from MCNPX simulations of prompt and delayed neutrons and γ-rays produced from the induced fission of
SNM. Photon and low energy neutron interrogation simulations are compared to identify requirements for an initial
common detection system.