Experimental and kinetic study of the iodine reactivity in low pressure H2/H2O/HI/O2/Ar premixed flames

To specify kinetic aspects of iodine chemistry in an environment of severe accident in a Pressurized Water Reactor (PWR), reproduced at the laboratory scale, an experimental reactor named 'flat flame burner' has been implemented. The work presented in this article focuses on the study at high temperature of low pressure flames of H2/O2/Ar premixed gas seeded with known amounts of steam and iodhydric acid. The quantification of chemical species and the evolution of temperature in such environment are measured by specific analytical techniques (Fourier Transform Infrared absorption spectrometry (FTIR) and Laser Induced Fluorescence (LIF) for the key chemical species, a Pt/Rh coated thermocouple for the temperature). A first measurement campaign to characterize three H2/ H2O/ HI/O2/ Ar premixed flames by using FTIR absorption spectrometry approach has been carried out and the first HI and H2O profiles has been drawn. The development of Laser Induced Fluorescence approach to measure OH radical and iodine species is in progress. This experimental database will be used as a support to develop and to valid a detailed kinetic mechanism for the (I, O, H) system devoted to be implemented in IRSN's severe accident simulation code ASTEC/SOPHAEROS. A first version of this kinetic mechanism has been established by analogy from data available on chlorine. The mechanism has to be optimized by taking into account the experimental results and thermo-kinetic parameters determined by using theoretical chemistry tools. (authors)