Experimental Insights into Formation and Characterization of Iodine Oxide Aerosols

Mariam .^1,2*Manish Joshi¹Amruta Nakhwa¹Pallavi Khandare¹Samanta Soumen¹Arshad Khan¹Balwinder K Sapra^1,2

• ¹Bhabha Atomic Research Centre (BARC), Mumbai, Maharashtra, India
• ²Homi Bhabha National Institute, Mumbai, Maharashtra, India

Significant quantity of radioactive iodine is expected to release following nuclear reactor accidents. Recent researches have shown that among various species expected, Iodine oxides (IxOy) is less explored but play a crucial role in nuclear safety assessments due to their impact on source term evaluation. Therefore, study was designed to generate and characterize iodine oxide in laboratory scale set-up. Experiments were conducted at room temperature and ambient humidity using an iodine concentration of ~1 ppm and an ozone concentration of ~30 ppm inside a controlled chamber. The reaction kinetics were determined by continuously monitoring ozone concentration, and the results showed that ozone decay followed first-order kinetics with a high correlation (R² > 0.99). While many of the previous studies have relied on radioactive tracer iodine and gamma spectroscopy, this study uses an alternative methodology by analysing ozone decay as a proxy for iodine oxidation. The generated iodine oxide aerosols were characterized for their physical as well as chemical characterisation. Impactor and gross samplers were used to collect aerosols giving particle mass size distribution and total mass concentration respectively. Particle morphology and chemical composition was determined using SEM, EDX, and XPS. The particles were found to have I2O5 chemical species with varied shape from small porous cloud like structure to rod shape large particles. The findings provide valuable insights into iodine oxidation under environmentally relevant conditions, bridging knowledge gaps in source term estimation and contributing to the enhancement of modelling codes for nuclear safety applications.