Iodine chemical and transport behaviour within containment

Iodine dissolved in water will be present predominantly as the nonvolatile iodide ion, I under most conditions. Here, the interest is in the transformation of the iodide ion into a volatile chemical form, the partitioning of this volatile chemical form into the atmosphere, and the behaviour of the volatile chemical form in the atmosphere. It will be shown that the processes taking place in the contaimnent involving the volatile chemical forms of iodine result in re-trapping the iodine as iodide ion in water. A sort of dynamic equilibrium is established in the contaimnent involving  

Non-Volatile Iodine — Volatile Iodine Volatile Iodine — Non-Volatile Iodine 

This dynamic equihbrium results in a steady-state concentration of gaseous iodine in the containment atmosphere. The objective of iodine management following a reactor accident is to reduce this steady-state concentration. The mechanisms for reducing the concentration in the containment atmosphere require an appreciation of the aqueous chemistry of iodine and the reactions of iodine vapours in the containment atmosphere. These topics are the foci of discussions in this subsection. From these discussions arise a number of approaches for mitigating the atmospheric concentration of iodine that are discussed further in the subsequent subsections of this chapter. 

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VI.2 Iodine chemical and transport behaviour within containment... 

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