Comparative investigation of detector responses and measurement uncertainties in fast-neutron coincidence counting for nuclear material accountancy

Abstract

Abstract Fast-neutron measurement with organic scintillators has been considered one of the alternative techniques to thermal neutron measurement based on He-3 proportional counters, due to their economic and measurement-uncertainty potential for nuclear material accountancy. Nevertheless, highly suppressed neutron detection efficiencies and nuclide-dependent features indicated in the fast system as well as the utilization of pulse-shape discrimination which necessitates a significant energy threshold could lead to challenges in terms of characterizing nuclear material samples. This work confirmed a reasonable similarity of simulated results to experimental results concerning the non-linear light-output function of proton recoils. Consequently, nuclide-dependent detector responses and measurement uncertainty were investigated with varying diverse measurement parameters (the number of detectors, measurement time, and sample quantity). Also, comparative studies were conducted for the ACP Safeguards Neutron Counter, a developed thermal system, and the Fission Informative Neutron-based ACcounting, the proposed fast system currently under development by Korea Atomic Energy Research Institute, for passive non-destructive assay of special nuclear materials.