超临界二氧化碳清洗铀样品技术研究

针对铀样品在机械加工过程中残留的几种常见冷却液成分：水、机油和三乙醇胺，开展了超临界二氧化碳对铀样品的清洗实验，探讨了超临界二氧化碳对铀样品表面常见机械加工残留物的清洗效果，同时对经超临界二氧化碳浸泡的铀样品表面化学成分及相结构也进行了分析。清洗实验结果表明，超临界二氧化碳流体对水和机油有一定的溶解能力，具有较好的清洗效果，但对三乙醇胺的溶解能力较差，几乎不溶解。对三乙醇胺可通过向超临界二氧化碳引入超声波的方法来有效清除。铀表面分析结果显示，清洗后的铀表面只有U和UO2相；俄歇电子能谱显示，铀与超临界二氧化碳作用过程中，碳和氧进入到了铀表层的一定深度范围。腐蚀实验结果表明，铀在超临界二氧化碳中浸泡后，其抗大气腐蚀的能力不会减弱，相反还有一定程度的提高。

Study on Cleaning Technique of Uranium Specimen With Supercritical Carbon Dioxide

Cleaning effectiveness to uranium surface contaminants residual using supercritical carbon dioxide(SCCO_2) fluids has been studied. Cleaning experiments mainly focusing on the general and typical machining residual contaminants such as machine oil, water and triethanolamine are carried out. By X-ray diffraction (XRD) and Auger Electron Spectrometry (AES) methods, the SCCO_2 compatibility of uranium is investigated. Results of cleaning experiments show that both machine oil and water can be dissolved by SCCO_2 and cleaned up from uranium surface easily. Triethanolamin can't be dissolved by SCCO_2. XRD study reveals that there are only U and UO_2 at cleared uranium surface. AES result indicates that during cleaning, C and O can ingress into the surface layer of uranium sample. Air corrosion test shows the uranium specimen cleaned with SCCO_2 has a better corrosion resistance than speciemen without SCCO_2 cleaning.