N.A. Johansen, III,
"An active system for the detection of special fissile material in small watercraft,"
M.S. Thesis, Texas A&M University, August 2006.
Due to increasing terrorist threats and illegal proliferation of
nuclear material and technology, there is a need for increased
research in the area of detection of smuggled fissile material,
some of which is designated by the International Atomic Energy
Agency as special fissile material. This thesis focuses on a
hypothetical scenario in which a terrorist organization has managed
to smuggle an amount of special fissile material onto a personal
recreational watercraft and sail it into a marina. If the boat
could be forced to go through a detector system, then the contents
could be interrogated and a determination made of whether any
special fissile material was aboard. This thesis examines the
hypothesis that active interrogation may be used successfully in
the detection of special fissile material in such an environment.
It shows that it is feasible to use an active neutron system to
detect a significant quantity of special fissile material onboard a
small boat via the differential dieaway technique. The MCNP Monte
Carlo transport code was used to simulate the use of a pulsed
neutron generator to induce fission in the fissile material and
then estimate the detector response. The detector modeled was based
on elastic scattering-induced recoil protons using pure hydrogen
gas. There was a significant difference between the system with and
without the presence of fissile material, and the estimated
detector response for the system with fissile material present was
shown to be sufficiently greater than the response due to
background radiation only. Additionally, dose was estimated and
found to be small enough that the system would not likely pose a
significant radiological health risk to passengers on the boat.