Nuclear terrorism resulting from the illicit trafficking of nuclear and radioactive materials consists of a serious threat against the security of countries. Hence, the transportation of hidden nuclear materials in large-scale cargos has emerged as an important public issue that requires immediate attention. The security architecture should merge the nuclear security systems and execute a procedure for the detection of nuclear and radioactive materials. In this regard, the detection of special nuclear materials (SNMs) in liquid-filled cargo containers is an essential matter of homeland security because of the difficulties imposed by liquids in performing efficient manual inspection. This paper presents a new artificial intelligence (AI) system implemented with fuzzy logic tools for detecting composite materials, including Pb-Th, Pb-U, and Pb-Co, in containers filled with water by utilizing optical signature information obtained with COMSOL. The developed AI system and its underlying method are validated for a scenario of detecting Pb-Th, Pb-U, and Pb-Co in water-filled containers.