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.