Ab initio calculations and iodine kinetic modeling in the reactor coolant system of a pressurized water reactor in case of severe nuclear accident

► Thermodynamic and kinetic parameters are calculated using ab initio molecular orbital methods. ► Calculated reaction enthalpies at 0 K are close to their literature counterparts. ► Rate constants are calculated from 300 to 2500 K and compared to the available literature data. ► Iodine kinetic model is developed. ► Simulations with the ASTEC software are performed in the framework of nuclear safety.