Results of a spectroscopic and microstructural investigation of mineral grains extracted from lava-like fuel-containing materials – Chernobyl “lava” – are presented. Raman, photoluminescence and infrared spectra reveal the presence of abundant U4+, traces of Sm3+ and Cr3+ in grains of U-containing zircon and ZrO2. No oxidation of UO2 particles is observed. The ZrO2 grains consist predominantly of the monoclinic polymorph and are often twinned. Raman spectra indicate the presence of the tetragonal polymorph, which is likely stabilized by the presence of U. It is suggested that spontaneous transformation of partially stabilized tetragonal (Zr,U)O2 to the monoclinic phase, and a corresponding volume expansion, are important factors affecting the rate of mechanical degradation of the “lava”. Transmission electron microscopy of U-rich zircon suggests the absence of precipitation of any independent U-containing phases, implying that U is fully incorporated within the zircon lattice as an impurity. Grains of rutile, corundum, quartz and natural zircon originating from construction materials of the reactor are described. Results obtained here are important for the validation of computer codes describing severe nuclear accidents.

中文翻译：

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从切尔诺贝利“熔岩”中提取的矿物颗粒的研究

介绍了从含熔岩类燃料的材料 - 切尔诺贝利“熔岩”中提取的矿物颗粒的光谱和微观结构研究结果。拉曼光谱、光致发光光谱和红外光谱揭示了在含 U 锆石和 ZrO2 晶粒中存在大量的 U4+、痕量 Sm3+ 和 Cr3+。未观察到 UO2 颗粒的氧化。ZrO2 晶粒主要由单斜多晶型物组成，并且通常是孪晶的。拉曼光谱表明存在四方多晶型物，这可能因 U 的存在而稳定。这表明部分稳定的四方 (Zr, U) O2 自发转变为单斜相，以及相应的体积膨胀，是重要的因素影响“熔岩”的机械降解率。富 U 锆石的透射电子显微镜表明没有任何独立的含 U 相沉淀，这意味着 U 作为杂质完全结合在锆石晶格中。描述了源自反应堆建筑材料的金红石、刚玉、石英和天然锆石颗粒。此处获得的结果对于验证描述严重核事故的计算机代码很重要。