Efficient radioactive aerosol removal with the development of water mist pre-injection methods and advanced spray charging system for safe Fukushima Daiichi decommissioning: insights from recent experimental studies in UTARTS facility
Ruicong Xu, Avadhesh Kumar Sharma, Ravinder Kumar, Zeeshan Ahmed, Ryo Yokoyama, Shuichiro Miwa, Shunichi Suzuki, Koji Okamoto
Abstract
Decontaminating surfaces and retrieving fuel debris are critical tasks in mitigating elevated radiation levels at the damaged Fukushima Daiichi Nuclear Power Plants during their decommissioning. Laser technology is considered as a promising solution for cleaning contaminated surfaces and cutting large-scale fuel debris. However, significant proportion of submicron radioactive aerosol particles could generate, typically for those within 0.1 to 1 μm, which are challenging to remove using traditional containment water sprays. To address this challenge and optimize radioactive aerosol control, experimental studies at the UTARTS facility of the University of Tokyo focused on laser-generated aerosol characterization and innovative methods for efficient aerosol management. A novel agglomeration technique involving pre-injected water mist was proposed and validated under various experimental conditions, demonstrating improved aerosol scavenging performance. Further enhancements were achieved by integrating a mist charging system to boost aerosol-mist agglomeration. Besides, an electrical charging system for water spray was developed and improved through electrode configuration adjustments to accelerate aerosol removal. This paper analyzes the insights and outcomes from recent UTARTS experimental studies to develop practical and effective strategies for managing laser-generated radioactive aerosols. The findings contribute valuable knowledge for future development of safe and sustainable Fukushima Daiichi decommissioning strategies.