740. 放射性ヨウ化メチルの光分解と元素状ヨウ素および他のヨウ素種の生成

抄録

In appropriate evaluation of the internal dose of a population due to radioiodine released from a nuclear power plant during normal operation, it is necessary to clarify behavior of radioiodine in the environment. Sunlight appears to be one of the major factors in the chemical form changes, particularly for radioactive methyl iodide.
In the present work, photodissociation of gaseous methyl iodide and production of elemental iodine and other iodine species under the sunlight-simulated white light from a xenon lamp in various atmospheric conditions were studied. Methyl iodide dissociated exponentially with the product of the intensity of light and the irradiation time. The dissociation of methyl iodide produced mainly elemental iodine, and other iodine species (e.g. particulate iodine) up to about 10% in relatively low concentration (less than 10^-9g/cm³) of methyl iodide. The effect of relative humidity on the reaction was not observed.