A severe nuclear accident can lead to the release of radiotoxic iodine compounds in either aerosol form (e.g. metal iodides or iodine oxides) or gaseous form (e.g. organic iodide as CH₃I or inorganic as I₂) species. ¹³¹I is particularly dangerous because of its possible absorption by the human body especially by the thyroid. Gaseous iodine is mainly formed in the nuclear containment building, is dispersed in the case of outside releases and may contribute in short term to long-distance contamination. Metallic iodide species are mainly formed at high temperature and partly condensed on the walls of the reactor coolant system (RCS), the rest being either deposited on the RCS or transported to the containment building. In this paper, we study theoretically, in severe accidental conditions, the adsorption of the metallic iodides on the surface of the primary circuit which is composed of Fe or Cr oxides. At high coverage, AgI and CdI₂ form networks on the surfaces of the RCS whereas at low coverage the molecules are isolated. This study, setting out from the stable adsorbates, investigates the chemical mechanisms leading to the iodine re-vaporization. The formation of I_2(g) from adsorbed AgI or CdI₂ is thermodynamically and kinetically possible on over-oxidized chromium surfaces. On alternative surfaces, the co-adsorption of an oxidant, OH^● issued from the steam radiolysis, is necessary to form I_2(g). This study tends to show that delayed releases of gaseous iodine are likely to happen from the deposited iodide.

严重的核事故可能导致以气溶胶形式（例如金属碘化物或氧化碘）或气态形式（例如有机碘化物如 CH ₃ I 或无机物如 I ₂）释放出具有放射性的碘化合物。¹³¹I 特别危险，因为它可能被人体吸收，尤其是被甲状腺吸收。气态碘主要在核安全壳建筑物中形成，在外部释放的情况下会分散，并可能在短期内造成远距离污染。金属碘化物主要在高温下形成，部分凝结在反应堆冷却剂系统 (RCS) 的壁上，其余部分要么沉积在 RCS 上，要么被运送到安全壳建筑物。在本文中，我们从理论上研究了在严重的意外条件下，金属碘化物在由 Fe 或 Cr 氧化物组成的初级电路表面上的吸附。在高覆盖率，碘化银和CDI ₂形式的网络上表面小号RCS 而在低覆盖率下分子被隔离。这项研究从稳定的吸附物出发，研究导致碘再蒸发的化学机制。从吸附的 AgI 或 CdI ₂形成 I _2(g)在过氧化铬表面上在热力学和动力学上是可能的。在其他表面上，蒸汽辐射分解产生的氧化剂 OH ^●的共吸附是形成 I _2(g)所必需的。这项研究倾向于表明，沉积的碘化物可能会延迟释放气态碘。