Hydrogen and oxygen production by radiolysis of iodide solution

In severe reactor accident scenarios, pressurization of the containment system is of vital concern. Hydrogen and oxygen gases produced by water radiolysis recombine through the reaction of hydrogen with OH radicals. If fission products, such as cesium iodide, are dissolved in water, this recombination of hydrogen and oxygen can be restricted, leading to increased amounts of these gases. The amounts of hydrogen and oxygen were measured during irradiation of an iodide solution with gas bubbling to simulate the boiling condition. The results were compared with numerical analysis results obtained using a model that considers chemical reactions and mass transfer between the gas and liquid phases. The predicted dependence of hydrogen and oxygen productions on iodine concentration agreed well with the experiments. The production of hydrogen and oxygen increased in the solutions with higher iodide ion concentration and approached a constant value with the iodide ion concentration over 10-5 mol/dm3. It was necessary, therefore, to consider the effect of iodide ions when evaluating hydrogen and oxygen production. The calculated hydrogen and oxygen concentrations were higher than those of the experiments. This may be caused by the error in the rate constants used in the model and elimination of the reactions that include iodine species of higher oxidation states. The reaction scheme most likely requires modification for greater reliability