Organic Iodide Formation During Severe Accidents in Light Water Nuclear Reactors

The description of containment iodine behavior in reactor accident sequences involves a combination of iodine volatility effects, deposition/revaporization processes, and mass transport of iodine species. The formation and retention of volatile organic iodides such as methyl iodide, CH₃I, are important factors in determining iodine source terms. Tests have shown that the formation of organic iodide was enhanced by radiation and iodine in the chemical form of I₂. Methyl iodide, the only organic iodide detected in measurable quantities, formed predominantly in aqueous solution even when the organic material was introduced to the gas phase.