Development of active neutron NDA techniques for nonproliferation and nuclear security, 2; Study on a compact NRTA system

Tsuchiya, Harufumi ; Kitatani, Fumito  ; Maeda, Makoto  ; Kureta, Masatoshi   

From a viewpoint of nuclear safeguards and nuclear security, it has recently become important to develop a non-destructive assay (NDA) system that accurately determines the amount of special nuclear materials (SNMs) in various samples such as spent fuels, next generation MA-Pu fuels and fuel debris. One candidate of those NDA techniques is neutron resonance transmission analysis (NRTA). It relies on a neutron time-of-flight measurement and is a well-established method to apply for the accurate evaluations of nuclear data, including total cross sections and resonance parameters. The potential of NRTA to quantify SNM in complex materials has been already demonstrated by performing NRTA measurement at IRMM/GELINA under collaboration of JAEA and JRC. However, a present NRTA system usually has a large electron accelerator facility to generate intense neutrons, whereas this is very difficult to apply to various facilities that need to measure SNM. Therefore a compact NRTA system would be required for practical applications of quantifying SNM in a variety of samples. In order to realize a compact NRTA system, we are developing a prototype with a D-T neutron generator that has a pulse width of 10 s and an average maximum neutron yield ranging from n/s to n/s. Numerical calculations were used to optimize the system performance to quantify SNM and MA in spent and MA-Pu fuels. In this presentation, those numerical calculation results, together with a brief description of the prototype, are presented. In addition, we discuss a future prospect of a compact NRTA system equipped with a neutron source with a shorter pulse width (ex. 100 ns) and a more intense neutron yield.