Continuous deuterium extraction from falling lithium-lead droplets in a vacuum

Abstract

This study experimentally verifies continuous deuterium extraction efficiency from falling liquid lithium-lead (LiPb) droplets in a vacuum, as an alternative to tritium The obtained efficiencies, from five runs, were between 0.59 and 0.69. The corresponding dispersion coefficient of deuterium in LiPb droplets is (2.6 + 0.8 – 0.6) × 10–7 m2s–1. These results closely resemble those obtained in a proof-of-principle (POP) experiment conducted at Kyoto University in 2013. Consequently, the deuterium release from falling LiPb droplets in a vacuum can be considered a stable function. The experimental campaign was carried out using a dedicated setup constructed on the liquid metal test loop (Oroshhi-2) at the National Institute for Fusion Science. Tritium breeding in a liquid LiPb blanket is substituted by the deuterium dissolution in circulating LiPb. The extraction efficiency was determined by comparing the time-series deuterium flux, released from falling droplets, with simulation. An alternative method involving a before and after concentration comparison did not yield consistent results. This inconsistency can be attributed to issues with the concentration sensor, which experienced difficulties due to surface degradation. The experimental parameters, the LiPb flow rate, nozzle diameter, falling height, temperature, and duration period, were set to 0.1 to 0.3 l-min–1, 1.0 mm, 500 mm, 350 °C, and 9 h, respectively.