In this paper, the chemical state of fast reactor $\left(\text{U},\text{Pu}\right){\text{O}}_2$ fuel at high burnup has been simulated using OpenCalphad software and the TAF-ID thermodynamic database. This has been done in order to evaluate the combination of software and database for further implementation into the Germinal fuel performance code of the Pleiades simulation platform. The results have been compared with post irradiation examinations (PIE) of fuel samples from the Phénix sodium-cooled fast reactor. The calculations performed from isotopic data compositions were able to predict all precipitates encountered in the PIE, as well as several other phases. When possible, the measured composition of the phases were compared with the simulations, and show a good similarity in this regard. Additionally, calculations based on measured composition in the fluorite (U,Pu) ${\text{O}}_2$ phase have been performed at different temperatures and oxygen-to-metal ratios. Here, the calculations predict that the formation of fission product oxide compounds occurs to a greater extent in the cooler fuel periphery, which is also what experiments have shown. Oxygen potential has been calculated and compared with experiments with similar composition. The calculations are considered fast and reliable enough for implementation of the thermodynamic software into the fuel performance code.

本文介绍了快堆的化学状态 $（\text{ü}，\text{普}）{\text{Ø}}_2$使用OpenCalphad软件和TAF-ID热力学数据库对高燃耗燃料进行了模拟。这是为了软件和数据库为进一步实施评估结合到已经完成生发的燃料性能的代码昴仿真平台。将结果与来自费尼克斯钠冷快堆的燃料样品的辐照后检查（PIE）进行了比较。根据同位素数据组成进行的计算能够预测PIE中遇到的所有沉淀以及其他几个阶段。在可能的情况下，将测得的相组成与模拟进行比较，并在这方面显示出良好的相似性。此外，根据萤石中的测量组成（U，Pu）进行计算${\text{Ø}}_2$在不同的温度和氧金属比下进行了气相反应。在此，计算预测裂变产物氧化物化合物的形成在较冷的燃料外围中更大程度地发生，这也是实验表明的。已计算出氧势，并将其与具有相似组成的实验进行比较。计算结果被认为足够快速和可靠，足以将热力学软件实施到燃料性能代码中。