Entrapment of impurities inside a cold trap: a purification process for removal of corrosion impurities from molten Pb-16Li

Abstract

As a part of the development and testing of a lead lithium eutectic (Pb-16Li) purification system at IPR, a wire mesh packing based prototype cold trap (CT) was designed, fabricated and installed in a purification loop to remove the impurities from ∼ 260 kg of the Pb-16Li. In the present work, the functionality of CT has been assessed continuously for a long duration of ∼3500 hour (∼5 months), in the molten Pb-16Li system. This long-duration operation of CT in the Pb-16Li system was imperative to test its reliability, since the recurrent replacement of the CT in the Pb-16Li system may not be feasible due to stringent operating conditions of fusion reactors. During the present experiment, the working of an impurity generator has been tested and the deposition of corrosion impurities has been achieved on the wire mesh packing of CT. The efficiency of CT has been estimated to assess the performance of the CT. Some oxide depositions were also found inside the CT. Different characterization techniques such as SEM-EDX, XRD, and ICP-AES were used for the characterization of the samples taken from the CT. The characterization results of needle shape deposition suggest the formation of iron–nickel intermetallic while the characterization of oxide deposition suggests the formation of Pb2O, Li2O, and PbO.

Design, fabrication and validation of an electrical conductivity principle based two-phase detection sensor array for molten lead (Pb) based heavy metal coolants up to 600°C

“…Further, the probe retrieval allows these oxides to suddenly cool and, therefore, deposit at the coated surface. Although the possibility of oxide impurities generation and build-up over time within a molten metal circuit cannot be completely discarded, it is, however, expected that significant and rapid technological advancements being made toward efficiency enhancements of online impurity removal systems [21][22][23] will enable an effective trapping of such impurities from molten metal circuits. Removal of oxides and other impurities from the melt surface is followed by regular argon gas purging to maintain an inert environment over the melt surface.…”