Development of an in-situ mechanical property identification system for use in high radiation fields

An in-situ mechanical property identification system is required for easy-to-identify mechanical properties, such as fuel debris and rubble, in high-radiation fields. This is necessary for planning fuel debris removal, a central issue in the decommissioning work of the Fukushima Daiichi Nuclear Power Station. Because of the high-radiation field inside PCV and RPV, it is difficult to use high-performance analytical equipment with semiconductor circuits. This study is for the first step in a technical solution to realize the conceptual design of an in-situ mechanical property identification system. A simple in-situ mechanical property identification system that combined electrical and mechanical components with relatively high radiation resistance was developed. The exploration unit of the system placed in a high-radiation field was composed of a thin drill, drill motor, and hydraulic actuator. The remote-controlled unit of the system could identify material types from data obtained by the power load of the drill motor and the repulsive force of the drill using a machine-learning model. Preliminary experiments were conducted to investigate the effectiveness of the system for metal samples with different hardness values. This study presents technical ideas for the conceptual design of an in-situ mechanical property identification system for use in the high-radiation fields.