Concrete decontamination tools capable of removing the nuclear contaminated surface are necessary to minimize the amount of concrete waste generated in the process of decontamination and dismantling of nuclear power plants. Laser scabbling is a decontamination technique that removes the contaminated surface layers concrete surface by inducing internal explosion. The application principle of laser scabbling technology uses the porous nature of concrete including moisture. When high thermal energy is applied to the concrete surface, an explosion at pores is induced along with an increase in water vapor pressure. High-powered laser beam can be an effective induction source of local explosive spalling on concrete surface. In this study, the scabbling test using a 5 kW highpowered fiber laser was conducted on the concrete blocks to establish the optimal conditions for surface decontamination. It was also measured the volume peeled off the concrete surface under the conditions of two different laser head speeds. Furthermore, we tested the removal efficiency of radioactive concrete particles generated during high-power fiber laser scabbling process. A 5 kW laser beam was applied to the concrete surface at two different laser head speeds - 120 mm/min and 600 mm/min. The laser beam repeatedly moved 200 mm horizontally and 40 mm vertically within the concrete block. The amount of surface concrete removed from concrete block was calculated from the measurement of the volume and mean depth using a 3D scanner device (laser-probed Global Advantage 9.12.8(HEXAGON)) for the two different the laser head speeds. By increasing the laser head speed, less explosive spalling occurred due to shorter contact time of the laser beam with the concrete. The laser head speed of 600 mm/min reduced about 89% of the waste generated by shallow depth of scabbling as compared to the waste generated at the laser head speed of 120 mm/min. The fiber laser scabbling system was developed for surface decontamination of radioactive concrete in nuclear power plants. Tests were performed to find the optimum parameters to reduce the generation of particulate waste from the contaminated concrete surface by controlling the laser head speeds. It was confirmed that the wastes from surface decontamination was reduced up to 89% by increasing laser head speed from 120 mm/min to 600 mm/min. It was also observed that the cylindrical tube effectively vacuumed the debris generated by the explosive spalling into the collector. Removal efficiencies of concrete particles were measured greater than 99.9% with ring blower power of 650 air watt of the filter system.

• Byung-Seon Choi(Korea Atomic Energy Research Institute (KAERI)) Corresponding author
• Seong-Yong Oh(Korea Atomic Energy Research Institute (KAERI))
• Sang-Hun Lee(Korea Atomic Energy Research Institute (KAERI))