Elemental Mapping and Shape Measurement by Integrating LIBS and Ultrasonic Technologies for Nuclear Fuel Debris Detection

抄録

This study was aimed at integrating the microchip laser-induced breakdown spec-troscopy (LIBS) technology with air-coupled ultrasonic technology to construct a three-dimensional (3D) element mapping system that can rapidly determine the posi-tion, shape, and surface element composition of objects. First, the working principles of the microchip-LIBS system and air-coupled ultrasonic system for shape measure-ment and solid–liquid surface differentiation were examined. Subsequently, a 3D el-ement mapping system was developed by integrating the microchip LIBS and air-coupled ultrasonic systems. The primary application of this system is expected to be the assessment of nuclear fuel debris in nuclear reactors. Thus, experimental validation was performed using simulated nuclear fuel debris in a mist environment. The 3D element mapping system successfully established a 3D element map containing information regarding the location, shape, and surface element composition of the nuclear fuel debris samples. Moreover, ultrasonic measurement helped clarify the shape and position, while also predicting the solid and liquid surfaces of the simulated fuel fragments. This information helped enhance the efficiency of microchip-LIBS measurement. Furthermore, the microchip-LIBS system could effectively determine the elemental composition on the surfaces of the simulated nuclear fuel debris and optimize the shape measurement results of the ultrasonic system. Overall, the integration of these two systems enables more effective and accurate determination of the shape, position, and surface element composition of nuclear fuel debris.