Novel Active Interrogation Techniques for the Detection of Special Nuclear Material

Active interrogation techniques for the detection of special nuclear material are being investigated for many applications in the areas of nuclear safeguards, nuclear nonproliferation, and homeland security. The performance assessment of existing techniques and the development of new, more advanced ones rely on accurate simulation of realistic threat scenarios. The analysis of non-threat scenarios is also crucial to correctly evaluate the detection probability and to minimize the occurrence of false-positive alarms. In active interrogation systems, an external neutron or gamma-ray source is used to induce fission in the nuclear material, and appropriate radiation detectors are used to measure prompt and delayed neutrons and gamma rays emitted from fission. The readings from these detectors are subsequently analyzed to identify unique features that can be used to detect, identify, and characterize the special nuclear material. Thus, the simulation systems used in this research must be able to (1) accurately model the physics of various particle interactions and (2) correctly evaluate the detector response. To address this problem, research and development efforts at the Oak Ridg