On-Line Measurement of Gaseous Iodine Species During a PWR Severe Accident

International audience; Iodine is a highly radio-toxic element, due to its affinity to the thyroid, and represents the major part of the radioactivity released during a nuclear accident. In the context of nuclear safety and radio-protection, we are interested in identifying the iodine gaseous species which are released, in the nuclear power plants, under molecular (I$_2$) and organic (CH$_3$I) forms. Therefore, we are working on providing a spectroscopic database for both species. While the infrared spectrum of the ν6 band of methyl iodide was previously studied, only 4000 lines were assigned. We present the rovibrational analysis of a high quality experimental spectrum, of this band, recorded at the AILES beamline of the sychrotron SOLEIL, (780-850 cm$^{−1}$) with the glowbar internal source.The analysis of this incomplete spectrum was accomplished in collaboration with the LISA and led to 5000 experimental frequencies accurately measured at a resolution of 10$^{−3}$ cm$^{−1}$. The analysis of the full spectral range is in progress. On the other hand, we tested the C3$v$TDS package of the XTDS$^2$ program developed in Dijon on the CH$_3$I prototype molecule. These results will be shown and discussed. In the case of the molecular iodine, we are developing, in collaboration with the university of Joseph Fourier in Grenoble, an IBB-CEAS (Incoherent Broad Band Cavity Enhanced Absorption Spectroscopy) to measure its absorption spectrum at 520 nm.