Time-resolved structural and chemical investigations of metal oxide - water systems under conditions of extreme temperature, pressure and radiation

原位X射线和拉曼光谱技术将用于在极端温度（300-700摄氏度）、压力和辐射条件下直接探测水热金刚石对顶砧单元中选定的金属氧化物-水系统的结构和组成。建议的实验将解决三个重要的问题，有关腐蚀和腐蚀产物的运输在超临界水冷反应堆。这些是：（1）什么是铬（III）氧化物（eskolaite）在过氧化氢轴承超临界水中的溶解度？(2)金属氧化物纳米颗粒如何参与腐蚀产物的传输？（3）超临界水中辐照对过渡金属配合物的结构和稳定性有何影响？ 时间分辨，能量色散X射线吸收光谱（ED-XAS）将在本研究中首次监测（微秒分辨率）同步辐射X射线诱导辐解的局部结构和价态的过渡金属离子在超临界水中的影响。X射线吸收光谱也将用于研究超临界水中Cr和Fe纳米颗粒与过渡金属水溶液离子之间的反应。 同步加速器X射线荧光光谱（SXRF）将被用来直接确定在高温和高压下的水热金刚石对顶砧单元的流体的组成。预期的结果将显着推进我们的理解与候选材料的水相流体的相互作用和运输的腐蚀产物在水相流体在第四代运行条件相关的条件。 该研究还将为定量预测和控制水化学所需的数据库提供新的热化学数据，以最大限度地减少高温下的材料降解和腐蚀产物传输。

In situ x-ray and Raman spectroscopic techniques will be used to directly probe the structure and composition of selected metal oxide-water systems in hydrothermal diamond anvil cells at conditions of extreme temperature (300-700 degrees C), pressure, and radiation. The proposed experiments will address three important questions pertaining to corrosion and corrosion product transport in supercritical water cooled reactors. These are: (1) What is the solubility of chromium(III) oxide (eskolaite) in hydrogen peroxide-bearing supercritical water? (2) How might metal oxide nanoparticles participate in corrosion product transport? And, (3) What is the effect of irradiation on the structure and stability of aqueous transition metal complexes in supercritical water? Time-resolved, energy-dispersive x-ray absorption spectroscopy (ED-XAS) will be used in this study for the first time to monitor (with microsecond resolution) the effects of synchrotron x-ray induced radiolysis on the local structure and valence state of transition metal ions in supercritical water. X-ray absorption spectroscopy will also be used to investigate the reaction between Cr and Fe nanoparticles and transition metal aqua ions in supercritical water. Synchrotron x-ray fluorescence spectroscopy (SXRF) will be used to directly determine the composition of fluids at elevated temperatures and pressures in the hydrothermal diamond anvil cell. The anticipated results will significantly advance our understanding of the interaction of aqueous fluids with candidate materials and the transport of corrosion products in aqueous fluids at conditions relevant to GEN IV operating conditions. The research will also provide new thermochemical data for a database that is needed to quantitatively predict and control water chemistry in order to minimize material degradation and corrosion product transport at high temperatures.