Development of active neutron nondestructive assay system

アクティブ中性子非破壊測定装置の開発

藤 暢輔   ; 大図 章  ; 土屋 晴文 ; 古高 和禎  ; 北谷 文人  ; 米田 政夫   ; 前田 亮  ; 小泉 光生 

Toh, Yosuke; Ozu, Akira; Tsuchiya, Harufumi; Furutaka, Kazuyoshi; Kitatani, Fumito; Komeda, Masao; Maeda, Makoto; Koizumi, Mitsuo

There is no acceptable and practicable single nondestructive method for the assay of Special Nuclear Materials (SNM) and Minor Actinides (MA) in highly radioactive nuclear materials. The Japan Atomic Energy Agency (JAEA) and the Joint Research Centre (JRC) of the European Commission have been developing an active neutron nondestructive assay (NDA) system for nuclear non-proliferation and nuclear security. We utilize four different NDA techniques, namely Differential Die-Away Analysis (DDA), Prompt Gamma-ray Analysis (PGA), Neutron Resonance Transmission Analysis (NRTA) and Delayed Gamma-ray Analysis (DGA). The techniques give us different and useful analytical results, which could provide complementary information. We developed a combined NDA system, which enables the simultaneous measurements of DDA and PGA in the first phase of the collaboration. The improved DDA is possible to quantify a small amount of the fissile mass as low as 1mg (Pu-239). In the second phase, we developed an advanced NDA system which allows us to measure by NRTA as well as DDA and PGA. The third phase has started to study a compact NRTA system from 2022 for four years. NRTA would be the most promising method for highly radioactive nuclear materials. An overview of the projects and the recent results will be presented. This research was implemented under the subsidiary for nuclear promotion of MEXT (the Ministry of Education, Culture, Sports, Science and Technology of Japan).