Nano-to-micro aerosol contaminants emissions from dismantling of nuclear reactor pressure vessel using mock-up experiments

The decommissioning of nuclear power plants presents significant challenges due to the release of radioactive aerosols from contaminated or activated metal cutting, posing risks of internal radiation exposure. To protect workers, it is crucial to characterize aerosol generation and verify the performance of air purification systems. Although previous studies relied on lab-scale experiments, full-scale mock-up testing is necessary to validate under field conditions. This study conducted remote oxy-fuel cutting experiments on a mock-up reactor pressure vessel (RPV) to evaluate aerosol characteristics and filtration efficiency. The mock-up, simulating the upper shell of the Kori Unit 1 RPV, was enclosed within a shielding tent connected to a ventilation system. During thermal cutting, we confirmed a bimodal size distribution, with nanoparticles (<100 nm) comprising a significant fraction. Chemical analysis identified that aerosol contained the key elements of RPV materials such as iron, chromium, nickel, and manganese. Filtration efficiency of mock-up system exceeded 99.87 % for particles under 10 μm. However, the dose conversion factors for inhalation calculated from experimental data were up to 4.71 times higher than the ICRP-recommended values. These findings emphasize the importance of precise aerosol monitoring and respiratory protective equipment to enhance safety protocols in nuclear decommissioning.