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

A Differential Die-away Analysis (DDA) system using a compact pulsed neutron (14 MeV) generator has been newly developed for nuclear non-proliferation and nuclear security in the Japan Atomic Energy Agency. The DDA system was designed to be able to detect a nuclear fissile material ( ²³⁹ Pu) of as low as 10 mg and to handle samples of a different volume: a vial bottle (20 mL), a pail container (20 L), through a Monte Carlo simulation. In the DDA system, the Fast Neutron Direct Interrogation technique, which utilizes fast neutrons for interrogation, was applied to measure the amount of fissile mass contained in the sample. The fundamental performance of the DDA system was investigated in the demonstration experiment. The results of the experiment are discussed comparing to those of the simulation study.