Development of Active Neutron NDA Techniques for Nuclear Nonproliferation and Nuclear Security (1)Study on next generation DDA

摘要

Under the collaboration program with the EC Joint Research Centre, we are carrying out the R&D program "Development of active neutron NDA techniques for nuclear non-proliferation and nuclear security" with DDA (Differential Die-away Analysis), NRTA (Neutron Resonance Transmission Analysis), PGA (Prompt Gamma-ray Analysis) / NRCA (Neutron Resonance Capture Analysis) and DGS (Delayed Gamma-ray Spectroscopy). The purpose of this program is to update the NDA techniques for high radioactive nuclear materials such as spent fuel and next generation MA transmutation fuel. In this paper, we present the outline of the current activity and study on next generation DDA. The goal of this study is to establish the DDA technique for high radiation nuclear materials with small measurement uncertainty. The next generation DDA which is going to be developed in this program has mainly following features. (1) Fast neutron rich neutron field is generated in the cavity of the DDA system using a DT neutron generator and fast neutron reflector made of steel or stainless steel, (2) thermal neutrons in a target sample are produced using a neutron moderator made of HDPE etc. which surrounds the target sample, and (3) the amount of fissile materials is calculated by total fission neutron counts and dieaway time. In this manuscript, mainly the differences between generation Ⅰ, Ⅱ and Ⅲ of JAEA-type DDA is introduced, and simulation study on ideal and practical generation Ⅲ JAEA-type DDA systems is reported.