Performance evaluation of differential die-away system in an integrated active neutron NDA system for nuclear non-proliferation and nuclear security

The detection performance of a Differential Die-away Analysis (DDA) system with a large measurement sample such as a MOX can container (2 liter) was evaluated through the Monte Carlo simulation studies and experimental tests. The system employing the fast neutron direct interrogation method was designed to effectively quantify fissile materials in samples which have different volume from a small container (vial size) to a large container (pail size). The simulation results show that the
²³⁹
Pu mass of around 10 mg even in the MOX can container can be detected. It has been demonstrated experimentally that the DDA system is capable of quantifying a nuclear fissile material (
²³⁹
Pu) of 100 mg in the MOX can container including a matrix of metal pipes. The simulation results are discussed and compared with those of the experimental tests.