A better simulation of radioactive releases when a steam generator tube fails

In case of the failure of a steam generator tube, water from the primary circuit, likely to be contaminated with iodine, flows out into the secondary circuit in the form of steam jets or fine water droplets. The size of the droplets depends on 2 processes: the mechanical fragmentation of the droplets due to hydrodynamical instabilities at the level of the breach and thermal fragmentation due to the explosive growth of steam micro-bubbles contained in the droplets. A mathematical model taking into account these 2 processes combined with a chemical model describing iodine chemical forms in the primary circuit has allowed us to get a more accurate distribution of the iodine chemical forms just after the breach: IO₃^-: 43.5%, HOI: 37.5%, I^-: 12.6%, IO: 2.9%, IO₃: 2.3%, and I: 1.2%. (A.C.)