Intense Pulsed Active Interrogation System for Detection of Special Nuclear Materials

DTRA’s detection system couples an active interrogation source of pulsed monoenergetic or bremsstrahlung spectrum gamma rays and low energy neutrons with a series of passive neutron and gamma ray sensors and sensor networks. The design enables the scanning of ships, trucks, airplanes and other cargo carriers at normal transit speeds. A variety of commercially available sensors are compatible with the system, including devices developed in cooperation with DTRA.

The single, intense pulse interrogation of the DTRA system elicits a prompt response from the Special Nuclear Material (SNM), making it possible to interrogate fast moving objects in a matter of seconds. The nature of the pulse also boosts the signal compared to the natural background, and pulse power active interrogation technology is capable of simultaneously producing both neutron and gamma ray probing radiations from a single source.

The detection of SNM, such as uranium-235 and plutonium, is an ongoing national security interest. Radiation portal monitors exceed $150,000 in cost but are susceptible to variations in background radiation and not selective against naturally occurring radioactive material common in commerce. Advanced spectroscopic portals have also been deployed, but they are costly and have a limited production capacity. The DTRA system holds potential to quickly and accurately detect SNM. The development of this technology reflects a DTRA partnership with the Naval Research Laboratory (NRL) and several radiation detector developers.

Additional background can be found in DTRA Active Interrogation System overview (also linked below), and conference proceedings with more details on the NRL interrogator system can be found at IEEE Xplore.