Chemical stability of caesium iodide deposits in air/steam atmosphere

• Published in: Journal of hazardous materials Vol. 409; p. 124519
• Main Authors: Obada, D., Hijazi, H., Paul, J.-F., Gasnot, L., Grégoire, A.-C., Mamede, A.-S., Cantrel, L.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 05.05.2021; Elsevier
• Subjects: Chemical Sciences; DFT calculations; Fission products; Re-vaporization; Severe nuclear accident; Severe nuclear accident; Fission products; DFT calculations; Re-vaporization
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2020.124519

Iodine compounds that may be released in case of severe nuclear accident will have important radiotoxicity if they are disseminated in air. One of the most important iodine species is CsI that is deposited on the surfaces of the reactor coolant system. However, depending on the conditions, CsI can volatilize or react with oxidants to produce I2(g). Theoretical and experimental studies demonstrate that the oxidation of iodide depends on the temperature and in the presence of oxidants in the gas. It is also slightly influenced by the crystallinity of the CsI particles and the nature of the support. In case of a high temperature deposition, the iodine release started at temperature lower than 300 °C. For the CsI vapour and aerosol depositions, the iodine is detected only at temperature above 450 °C and become very important above 550 °C. [Display omitted] •I2 vaporisation form CsI particle is favoured by oxidant in the gas phase.•Oxidation occurs on surface defect.•Particle support nature play a minor role.