Design study for moderator in delayed gamma measurement system using 14 MeV D-T neutron source

Year
2015
Author(s)
Mitsuo Koizumi - Japan Atomic Energy Agency
Jun Takamine - Japan Atomic Energy Agency
M. Seya - Integrated Support Center for Nuclear Nonproliferation and Nuclear Security, Japan Atomic Energy Agency
Douglas Chase Rodriguez - Integrated Support Center for Nuclear Security and Nuclear Nonproliferation, Japan Atomic Energy Agency
Abstract
For the fields of nuclear nonproliferation and security, the JAEA is developing a nondestructive delayed-gamma measurement system to determine the ratio of fissile isotopes contained in nuclear materials. Since this system is using a compact 14-MeV D-T pulsed neutron generator, it is important to develop moderators suitable to decrease the energy of the neutrons into the thermal region for the purpose of increasing possibility of fission reactions in nuclear materials of interest (e.g U-235, Pu-239, and Pu-241). In this design study, considering this primary requirement, we have been investigating a moderator system utilizing tungsten, lead, and polyethylene. In this report, we will describe the study of the physics required to efficiently induce fission for improved measurement of delayed gamma rays from isotopes of interest.