The Volatility of Iodine from Irradiated Iodide Solutions in the Presence or Absence of Painted Surfaces: Modeling Work on the IODE Code at IPSN

Extensive experimentation and modeling have been performed within the framework of studying iodine behavior in containments in the event of a nuclear reactor severe accident. The results from bench-scale experiments conducted at the French Nuclear Protection and Safety Institute, Cadarache; AEA Technology, Harwell; and Atomic Energy of Canada Limited, Whiteshell are used to update the French IODE code. The work focuses on the behavior of inorganic iodine species. The challenge of the semiempirical approach adopted in IODE is to represent by simple correlations the complex chemistry occurring in the containment sump. Difficulties in interpreting the bench-scale experiments are addressed and mainly concern uncertainties in the knowledge of volatile iodine mass transfers, pH drifts during the experiments, and the possibility of iodide (I^-) sorption on immersed painted surfaces. Improvements in the modeling are presented; the needs for additional experimental data and a more systematic experimental approach to the effects of the different parameters are emphasized.