Separation and Recovery of Uranium Metal from Spent Light Water Reactor Fuel Via Electrolytic Reduction and Electrorefining

TLDR

The study demonstrates bench‑scale separation and recovery of uranium metal from spent LWR fuel. The process involved crushing spent fuel, separating it from cladding, converting the oxide to metal through six electrolytic reductions in molten LiCl‑Li₂O at 650 °C, then purifying the metal via six electrorefining steps in molten LiCl‑KCl‑UCl₃ at 500 °C, with subsequent analyses of the recovered metal. The experiments achieved a 99.7 % conversion of uranium oxide to metal, with fission products partitioning into the molten salt during both reduction and electrorefining, and the recovered metal exhibited quantified decontamination factors.

Abstract

A series of bench-scale experiments was performed in a hot cell at Idaho National Laboratory to demonstrate the separation and recovery of uranium metal from spent light water reactor (LWR) fuel. The experiments involved crushing spent LWR fuel to particulate and separating it from its cladding. Oxide fuel particulate was then converted to metal in a series of six electrolytic reduction runs performed in succession with a single salt loading of molten LiCl-1 wt% Li2O at 650°C. Analysis of salt samples following the series of electrolytic reduction runs identified the partitioning of select fission products from the spent fuel to the molten salt electrolyte. The extent of metal oxide conversion in the posttest fuel was also quantified, including a 99.7% conversion of uranium oxide to metal. Uranium metal was then separated from the reduced LWR fuel in a series of six electrorefining runs performed in succession with a single salt loading of molten LiCl-KCl-UCl3 at 500°C. Analysis of salt samples following the series of electrorefining runs identified additional partitioning of fission products into the molten salt electrolyte. Analyses of the separated uranium metal were performed, and its decontamination factors were determined.