ATTILHA A novel experimental setup for thermodynamic and thermophysical properties measurements on nuclear materials
Résumé
In order to obtain experimental data on the complex corium pool involved during a severe accident in a nuclear reactor as a first approximation U-Zr-Fe-O experiments at very high temperatures have to be performed (T>2300 K). However, when samples are in direct contact with the instrumentation (e.g., thermocouples) or with a crucible, inevitable chemical interactions affect the experimental measurements. Furthermore, handling radioactive materials impose radioprotection restrictions.In this framework, a novel experimental setup called ATTILHA has been conceived and developed CEA Saclay. The setup has the final objective to study the high temperature thermodynamics and thermophysical properties of liquid nuclear materials. This apparatus is based on a laser heating technique coupled with contactless temperature monitoring and an aerodynamic levitation system. Spherical samples levitate within a controlled gas flux out of an Al levitation nozzle. Experimental gaseous conditions reducing or oxidizing are suited choosing the carrier levitation gas. The setup may be placed inside an and#945;-shield glove-box to comply with radioprotection limitations.In a first step, the setup has been used to investigate the liquid miscibility gap in the Fe-Zr-O ternary system a tie-line has been obtained between a metallic liquid enriched in Fe and an oxide liquid of composition close to ZrO2. The solubility of Fe in ZrO2 liquid has been therefore quantified. UO2 will be used to validate the setup with radioactive materials.To validate the setup for thermal-physical properties acquisition, experiments have been conducted first on non-radioactive materials, namely liquid Al2O3 and ZrO2. Forced oscillations were transmitted through the levitation gas by an acoustic system. Surface tension and density were obtained using an ultra-high speed camera coupled with a Python code, which allows to detect the resonant oscillations of the levitating liquid sample on the camera images.