(Invited) Understanding the Corrosion of SS316L in Molten LiCl-Li2O-Li Using 3D Transmission X-Ray Microscopy and 3D XANES

摘要

Pyrochemical reprocessing (pyroprocessing) of used nuclear fuel (UNF) is a promising pathway towards closing the nuclear fuel cycle and providing the means to generate durable wasteforms for portions of the UNF that are not able to be recycled. To incorporate commercial UNF (UO_2) into the pyroprocessing scheme, the ceramic UNF must be converted to a metallic form at the head end of the process, which can be accomplished via electrolytic reduction of the UNF in LiCl-Li_2O molten salt electrolyte. During the electrolytic reduction of UO_2 at the cathode, metallic Li is inevitably co-reduced from the electrolyte due to the proximity of the reduction potential of the U~(4+) in UO_2 and Li~+ in the electrolyte. Metallic Li disperses into the LiCl electrolyte and can then interact with the process vessel and other apparatus in contact with the electrolyte, altering the rate and mechanism of the degradation of those materials.