Radiolytic Organic Iodide Formation under Nuclear Reactor Accident Conditions

Abstract

The radiological and environmental impacts of serious nuclear reactor accidents are governed to a large extent by the release of airborne radioiodine to the environment. The post-accident volatilization of radioiodine can be significantly affected by organic impurities present in a reactor containment structure. In this research, the impact of organic compounds on iodine behavior was investigated under chemical conditions representative of those expected post-accident in a reactor containment structure. Gas chromatography, mass spectrometry, and UV spectrophotometry were used to analyze the gas and liquid phases of irradiated iodide solutions containing various alkyl halide, carbonyl, and aromatic compounds; the three classes of organic molecules most likely present in containment. Chloro-iodo organics and alkyl iodides were the major types of volatile iodo-organics formed in the presence of alkyl chlorides and carbonyls, respectively, while no volatile iodo-organics were formed in the presence of aromatics. The originally present I - formed small amounts of I 2 in the presence of ionizing radiation. The quasi-steady-state I 2 concentration increased in the presence of alkyl chlorides and decreased in the presence of carbonyls and aromatics. These results indicate that using materials, such as paints, containing aromatics as opposed to alkyl halides and carbonyl compounds will provide a passive means to reduce iodine releases following reactor accidents.