Results 1 - 1 of 1
Results 1 - 1 of 1. Search took: 0.021 seconds
[en] The tritium needed to fuel a fusion power plant will be produced in the so-called Breeding Blanket (BB) by neutron bombardment of lithium. Liquid concepts of BB are composed of eutectic Pb-Li and rely on a Tritium Extraction and Removal System (TERS) to extract the generated tritium from the liquid metal. The Vacuum Sieve Tray (VST) technique is proposed as TERS for the European Demonstration power plant (DEMO), which requires a minimum extraction efficiency of 80%. This technique consists in extracting the tritium dissolved in Pb-Li by generating small oscillating droplets, which fall in a vacuum chamber. Within the present work, a VST experimental facility operated with deuterium has been assembled and qualified. Experiments consisting in dissolving deuterium into the liquid metal (in a stainless-steel upper chamber) and subsequently extracting it from the falling Pb-Li droplets (in a stainless-steel lower chamber under vacuum) have been carried out in order to evaluate the extraction efficiency. The experiments have been assisted with a developed fluid-dynamics simulation code and a high-speed camera to analyse the size and motion of the liquid-metal droplets. The measured amount of deuterium dissolved into the Pb-Li is (8.9±1.5)×10 and (4.4±1.4)×10 mol of D for dissolving pressures of 1000 and 500 mbar, respectively. These results have been determined with a careful evaluation of the deuterium lost into the structure and correspond to a Sieverts' constant of (8.5±1.9)×10 mol m Pa. The amount of D extracted from droplets of about 1.2±0.2 mm diameter within a falling height of ≈ 0.5 m is lower than 8×10 mol. This result implies an extraction efficiency of ≤ 1.2%, which is substantially lower than the expected value relying on diffusion of deuterium towards the surface of the droplets. The obtained results suggest either a mass transfer coefficient of about 5×10 m s or a surface-limited extraction process.