Gascoin Mathieu, Freyss Michel, Cheik Njifon Ibrahim
CEA, DES, IRESNE, DEC, Cadarache, F-13108 Saint-Paul-Lez-Durance, France.
Canadian Nuclear Laboratories, Chalk River Laboratories, Chalk River, ON K0J1J0, Canada.
Inorg Chem. 2024 Dec 23;63(51):24083-24095. doi: 10.1021/acs.inorgchem.4c03096. Epub 2024 Dec 11.
We investigate the trapping properties of iodine, cesium, and tellurium in uranium dioxide, using the Hubbard-corrected density functional theory (DFT+). In order to avoid the metastable states inherent to this method, we use the occupation matrix control (OMC) scheme, which also allows us to monitor the oxidation states of the different species. The most favorable trapping sites, oxidation states, and solubility of I, Cs, and Te are evaluated in stoichiometric UO. To that end, vacancy-like defects under various charge states, including uranium and oxygen vacancies, U-O divacancy and bound Schottky defects, as well as the interstitial position, are considered as potential trapping sites in UO. Te is found to exhibit a wide range of possible oxidation states, ranging from Te to Te, depending on the stable trapping site considered. For I and Cs, one predominant oxidation state for each fission product, namely, I and Cs, is found. This behavior is mainly accommodated by the charge of the defects. By providing accurate trapping sites and oxidation states of volatile fission products in UO, this study is expected to contribute in the development of larger scale simulation methods, enabling a better prediction and mitigation of corrosion issues in nuclear fuel cladding.
我们使用哈伯德修正密度泛函理论（DFT+）研究碘、铯和碲在二氧化铀中的俘获特性。为了避免该方法固有的亚稳态，我们采用占据矩阵控制（OMC）方案，该方案还使我们能够监测不同物种的氧化态。在化学计量比的UO₂中评估了I、Cs和Te最有利的俘获位点、氧化态和溶解度。为此，包括铀空位和氧空位、U-O双空位和束缚肖特基缺陷以及间隙位置等各种电荷状态下的类空位缺陷被视为UO₂中的潜在俘获位点。发现Te根据所考虑的稳定俘获位点呈现出从Te⁰到Te⁶的广泛可能氧化态。对于I和Cs，发现每种裂变产物有一个主要的氧化态，即I⁻和Cs⁺。这种行为主要由缺陷的电荷来调节。通过提供UO₂中挥发性裂变产物准确的俘获位点和氧化态，本研究有望为大规模模拟方法的发展做出贡献，从而更好地预测和缓解核燃料包壳中的腐蚀问题。
