Geological disposal of nuclear waste relies upon a multiple barrier approach in which canisters containing nuclear wasteforms are proposed to be stored in geological repositories. In the event of a failed container situation, the groundwater present near the repository may penetrate the waste containment system and eventually come in contact with the nuclear wasteform. Assessing the chemical durability of nuclear wasteforms is of utmost importance and in this study, leaching experiments were conducted on rare-earth phosphate materials adopting the monazite- (LaPO₄), xenotime- (YbPO₄), and rhabdophane- (GdPO₄.H₂O) type structures. Monazite and xenotime are abundant rare-earth minerals containing varying amounts of actinides incorporated within their crystal structure and are proposed as a potential host matrix for the immobilization of actinides. Rhabdophane is a hydrous rare-earth mineral that forms on the surface of chemically altered monazite mineral and is proposed to act as a protective barrier by preventing the release of actinides to the biosphere. The as-synthesized materials were exposed to deionized water for a total period of seven months and the concentration of the leached elements in the water solution were determined using inductively coupled plasma – mass spectrometry (ICP-MS). In this study, the normalized leach rates of LaPO₄, YbPO₄, and GdPO₄.H₂O materials were found to be low and indicate the chemical durability of these materials. Structural characterization of materials before and after leaching was performed using powder X-ray diffraction (XRD) and X-ray absorption near-edge spectroscopy (XANES). Analysis of the powder XRD diffractograms and XANES spectra has shown that the long-range and local structures of monazite-, xenotime-, and rhabdophane-type materials remain unaffected after exposure to water for seven months.

核废料的地质处置依赖于多重屏障方法，在该方法中，建议将包含核废料形式的罐子存储在地质处置库中。在发生容器故障的情况下，储存库附近的地下水可能会渗入废物储存系统，并最终与核废料形式接触。评估核废料的化学耐久性至关重要，在这项研究中，对采用独居石-（LaPO ₄），xenotime-（YbPO ₄）和大黄酮-（GdPO ₄ .H ）的稀土磷酸盐材料进行了浸出实验。_2个O）类型结构。独居石和xenotime是丰富的稀土矿物，在其晶体结构中包含不同数量的act系元素，被提议作为固定potential系元素的潜在基质。Rhabdophane是一种含水的稀土矿物，形成于化学改变后的独居石矿物的表面，并被提议通过防止preventing系元素释放到生物圈中来作为保护性屏障。合成后的材料在去离子水中暴露了七个月，使用电感耦合等离子体质谱法（ICP-MS）测定了水溶液中浸出元素的浓度。在本研究中，LaPO ₄，YbPO ₄和GdPO ₄ .H的归一化浸出率发现₂ O材料含量低，表明这些材料的化学耐久性。使用粉末X射线衍射（XRD）和X射线吸收近边缘光谱（XANES）对浸出前后的材料进行结构表征。粉末XRD衍射图和XANES光谱分析表明，独居石，异诺时间和横纹烷类材料在接触水七个月后，其长程和局部结构不受影响。