Year
2018
Abstract
For the past three years the Japan Atomic Energy Agency (JAEA) and the Joint Research Centre (JRC) of the European Commission have been researching the delayed gamma-ray spectroscopy (DGS) technique for nuclear safeguards. DGS has great potential for high-radioactivity nuclear materials (HRNM), such as spent fuel solutions, since it determines fissile nuclide compositions by correlating the observed time-dependent gamma-ray energy spectrum to the unique fission product (FP) yield of the individual nuclides. Experiments were performed with low-radioactivity nuclear material using both the Pulsed Neutron Interrogation Test Assembly (PUNITA) of JRC and a californium shuffler designed at the JAEA and tested in the PERLA Laboratory of JRC. The data was analyzed using an inverse Monte Carlo method that both determines delayed gamma-ray peak intensity correlations and provides an evaluation of the uncertainty of the measurements. The results were used to verify delayed gamma-ray signatures for varying fissile compositions, total fissile content, and DGS interrogation timing patterns. Future development will focus on measuring HRNM and designing a compact active-interrogation system by evaluating different neutron sources, moderating materials, and detection capabilities. This presentation summarizes the JAEA/JRC DGS program to date and the future direction of this collaborative work. This research was performed under the Japanese MEXT subsidiary funding for nuclear security promotion.