Abstract
The adsorption velocities of molecular iodine onto chemically inactive and active aerosols estimated through the analysis of the tests in the THAI-2 project were inputted to a series of severe accident analysis for a boiling water reactor with Mark-I containment vessel by an integral severe accident analysis code, THALES2/KICHE. A severe accident initiated by long-term station blackout with drywell failure due to overpressure was selected as a reference sequence. The results of the analysis implied that the iodine source term as molecular iodine increased in cases that its adsorption onto aerosol was taken into account, which was lower than but comparable to the release fraction of iodine as cesium iodide. The fraction of the aerosol-adsorbed molecular iodine in these cases was predicted to be larger than that of the gaseous molecular iodine. The analysis also indicated that the ratio of the releases for cesium iodide, aerosol-adsorbed and gaseous molecular iodine depended on characteristics of molecular iodine such as the gas/liquid mass transfer and the adsorption onto aerosol and structure surface.
