Laboratoire d'accueil : Laboratoire d'expérimentation environnement et chimie (L2EC)
Date de début de thèse : octobre 2017
Nom de la doctorante : Hanaa HOUJEIJ
Descriptif du sujet
The reactivity of I2 and CH3I in the atmosphere has gained much interest in the field of nuclear industry safety as they are key gaseous iodine compounds believed to be released into the troposphere if a severe nuclear power plant accident type Chernobyl (Ukraine) and the more recent Fukushima (Japan) disaster were to occur   .
Iodine-131 released into the environment is known to have a high radiological impact on human health resulting from different absorption processes that include inhalation and ingestion. However, current post-accident management plans used to protect the public and to minimize the radiological impact of airborne fission products are based only on primary product physical dispersion tools (crisis operational tools), which do not consider any iodine chemical reactivity in the atmosphere. This is worrisome because the atmospheric transport of fission products is modelled without any chemical and photochemical processes that drive different degradation processes within the Earth's atmosphere.
The ability of the nuclear safety field community to accurately characterize the nature and quantities of reactive products that are released into the environment has evolved to the point where detailed comparisons of experimental data with theoretical model studies are limited by the accuracy and availability of rate coefficients for key chemical reactions. For these reasons, new experimental studies of important chemical processes are needed. Such high accuracy data will help and orient the risk management community and government policy makers to take a better political action to better protect the public health if a severe nuclear power plant accident was to occur.
In this context, this work aims at investigating the influence of atmospheric aerosols on the transport of gaseous iodine. The experimental study is focused on the interaction between gaseous iodine (CH3I) and sea salt aerosol surrogates in various humidity conditions (RH =10-80% at ambient temperature) as a preliminary study. The nature of the interaction between gaseous CH3I and particles is determined in situ by Raman micro spectroscopy and Infrared Spectroscopy (DRIFT) techniques. The methodology as well as first experimental uptake coefficients in controlled conditions close to that encountered in the atmosphere and surface characterization of the particles will be presented.
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