Following a severe incident on a pressurized water reactor, fission products may reach the containment, and radiation in the presence of water and iodine-based aerosols then provoke the formation of radioactive gaseous iodine. Specifically, the iodine may adhere to the coats of paint covering the containment walls.

The iodine/paint interaction is of an irreversible chemical nature for which the kinetics depend on temperature, the humidity of the gaseous phase, and the hydrothermal treatment applied to the paint before the reaction with the iodine. With the hindsight of 20 analytical tests, a kinetic model based on an irreversible reaction between the absorbed iodine and the water fixed in the coat of paint (initial or adsorbed) permits a satisfactory representation of the influence of the studied parameters. Despite its simplicity, this model constitutes a satisfactory summary of all the tests. In the future, it should be included in the calculation codes developed for nuclear reactor safety.