Recycling of Uranium from Uranium-Aluminium alloys by Chlorination with HCl(g)

Much attention has been paid to the handling of metallic nuclear fuel, which can offer a safe and more secure fuel cycle. To ensure this, it is essential to gain a thorough understanding of the related fundamental processes to scientifically assess the safety aspects. To this aim, a pyrochemical process for the recycling of actinides is being investigated in ITU. It is consisting of anodic dissolution of all actinides to a molten salt bath and electrochemical reduction on solid aluminium cathodes forming actinide-aluminium alloys. For the recovery of the Actinides a chlorination route is proposed consisting of the distillation of the adhered salt, the chlorination of the actinide-aluminium alloys by HCl(g) or Cl2(g) and possibly the sublimation of remaining AlCl3. In this work the chlorination step was studied by chlorinating UAl3 alloys using HCl(g) under conditions providing a complete chlorination without volatilisation of uranium as UCl4(g), UCl5(g) or UCl6(g). The optimal reaction conditions were initially evaluated by thermodynamic calculations for various chlorination temperatures and HCl/UAl3 molar ratios using the software HSC-Chemistry 6.0. The calculations showed that to ensure no volatilisation of uranium chloride species, the temperature range to be tested experimentally has to be limited to around 300-400°C. The experiments were realised out in a glove box kept under nitrogen atmosphere. The box is equipped with an Argon / HCl-gas line and a vertical oven in which a quartz reactor with a volume of 1liter could be placed. Experiments were carried out at temperatures of 300, 350 and 400 °C using approximately 300 mg starting material, resulting in a constant HCl/UAl3 molar ratio of 25/1. In most experiments two chlorination runs with the same material of 20h each were realised. After each run pictures and a sample were taken. Already after 20h of reaction time at 300°C, high chlorination efficiency was achieved. As main products UCl3(s) and UCl4(s) were obtained as confirmed by XRD analysis.

MEIER Roland;  SOUCEK Pavel;  MALMBECK Rikard;  FANGHAENEL Thomas; 

2013-01-09

Elsevier

JRC76916

1876-6196,   

http://dx.doi.org/10.1016/j.proche.2012.10.119,    https://publications.jrc.ec.europa.eu/repository/handle/JRC76916,   

10.1016/j.proche.2012.10.119,