Abstract
The global challenge of on-site detection of highly enriched uranium (HEU), a substance with considerable potential for unauthorized use in nuclear security, is a critical concern. Traditional passive nondestructive assay (NDA) techniques, such as gamma-ray spectroscopy with high-purity germanium detectors, face significant challenges in detecting HEU when it is shielded by heavy metals. Addressing this critical security need, we introduce an on-site detection method for lead-shielded HEU employing a transportable NDA system that utilizes the (252)Cf rotation method with a water Cherenkov neutron detector. This cost-effective NDA system is capable of detecting 4.17 g of (235)U within a 12 min measurement period using a (252)Cf source of 3.7 MBq. Integrating this system into border control measures can enhance the prevention of HEU proliferation significantly and offer robust deterrence against nuclear terrorism.