Simplified Reference Electrode for Electrorefining of Spent Nuclear Fuel in High Temperature Molten Salt

摘要

Pyrochemical processing plays an important role in development of proliferation-resistant nuclear fuel cycles. Electrorefining in a high temperature molten salt is considered a signature or central technology in pyroprocessing fuel cycles. Reference electrodes provide information essential for monitoring the reactions occurring at the electrodes, investigating separation efficiency, controlling the process rate, and determining the process end-point. Vycor-glass design reference electrodes have provided good durability and signal stability, but are not easily fabricated. The design is a complex construction involving multiple small pieces, glass joints, ceramic to glass joints, and ceramic to metal joints all assembled in a high purity inert gas environment. A simpler design, based on an ionpermeable membrane of mullite has been completed. The new design maximizes the use of commercial components, reduces assembly piece count more than one-half, and can be fabricated with less specialized skills. This has resulted in a significant reduction of effort and cost to fabricate replacements. The new design has been tested in a lab scale electrorefiner and has also been successfully scaled up and installed in engineering scale electrorefiners.