The release of the radioisotope ¹³¹I represents a major health concern because of its absorption by the thyroid gland. Capture materials, such as activated carbon, provide a means to efficiently mitigate ¹³¹I emissions during nuclear facility operations. In this study we use ab initio molecular dynamic calculations to investigate the effects of ¹³¹I radioactive decay on the molecular stability of I₂, acid iodine (HI, HIO, HIO₂, and HIO₃), and methyl iodide species in both the gas phase and adsorbed on graphite. Gas phase calculations show that I₂ is the least resistant to radiolytic decomposition, followed by the HIO_x family of molecules, then HI and CH₃I which are the most resistant. However, the graphite surface is found to greatly enhance the fragmentation of adsorbed molecular species. While the identification of gas phase fragments can offer new pathways for chemical kinetics models, the fragmentation products formed at the graphite surface can react with surface carbon atoms. Over time, this could reduce the number of adsorption sites available for iodine capture and degrade the abatement capability.

中文翻译：

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气相放射性碘分子中¹³¹ I mut变并吸附在石墨表面的后果

放射性同位素¹³¹ I的释放代表主要的健康问题，因为它被甲状腺吸收。捕集材料（例如活性炭）提供了一种在核设施运行期间有效减少¹³¹ I排放的方法。在这项研究中，我们使用从头算分子动力学计算来研究¹³¹ I放射性衰变对两种气体中I ₂，酸碘（HI，HIO，HIO ₂和HIO ₃）以及甲基碘物种的分子稳定性的影响。相并吸附在石墨上。气相计算表明，I ₂对辐射分解的抵抗力最低，其次为HIO _x分子家族，然后HI和CH ₃ I，其是最有抗性。然而，发现石墨表面极大地增强了吸附分子种类的破碎。虽然气相碎片的鉴定可以为化学动力学模型提供新的途径，但在石墨表面形成的碎片产物却可以与表面碳原子反应。随着时间的流逝，这可能会减少可用于捕获碘的吸附位点的数量，并降低减排能力。