Evaluation of a neutron-based active interrogation system for detection of smuggled fissionable material in packages

Abstract

ABSTRACT Active interrogation techniques to detect and characterize special nuclear materials (SNMs) show much promise. Depending on the targeted application scenario, the techniques employ a variety of detection concepts. Neutrons or high-energy bremsstrahlung photons can be used as interrogation sources, detecting either fission gamma rays or neutrons emitted by the SNM. At Canadian Nuclear Laboratories, an active interrogation system is under development for detecting SNM smuggled in shielded packages. The system uses a deuterium – deuterium (D – D) neutron generator as the interrogation source and detects delayed neutrons using arrays of He-3 detectors. The design of the detection system was optimized using Monte Carlo simulations, and the constructed system was tested with various nuclear materials under different measurement conditions. Within a few minutes, the system is capable of detecting U-235 on the level of grams, with the possibility to distinguish between enriched and depleted uranium.