Fusion Science and Technology / Volume 56 / Number 1 / July 2009 / Pages 540-544
Experimental Facilities and Nonelectric Applications / Eighteenth Topical Meeting on the Technology of Fusion Energy (Part 1)
Special Nuclear Materials (SNM) detection efforts have largely been divided into two main groups: active and passive. Passive techniques are highly desirable in that a radiation source need not be employed in order to detect fissile materials which broadcast a clear radiative signature. However, disadvantages can be seen in HEU (Highly Enriched Uranium) detection, for example, where the system's efficacy is limited by its ability to detect a weak self-radiative signature from U. Active interrogation provides a catalyst for amplifying HEU's presence vis-a-vis fission event inducement, which in turn yields a starker signature which can be discerned through an understanding of fissile materials and neutron transport in various media. Ongoing work in the Fusion Technology Institute's Inertial Electrostatic Confinement (IEC) Experiment has focused on using the pulsed D-D neutrons from an IEC to interrogate the presence of HEU in an enclosed space. The paper begins with a brief description of the neutron-based detection schemes of Delayed Neutron Analysis (DNA) and Differential Die-Away (DDA). Experimental delayed neutron counts of ninety above the background at an interrogating neutron flux of 5.5x104 n/cm2-s are seen to confirm MCNP modeling results. MCNP is also utilized to probe future concepts in neutron-based active interrogating SNM detection systems using DDA analysis.