Electrorefiner liquid cadmium cathode crucible thermal shock

A liquid cadmium cathode is used in an electrorefiner to remove plutonium and minor actinides from spent nuclear fuel by pyroprocessing. Liquid cadmium in a beryllia crucible, originally at 35°C, is lowered into 500°C salt electrolyte to begin reprocessing. Crucible cracking from thermal stress would release cadmium into the liquid salt causing electrorefiner failure. This study's purpose was to predict if the ceramic crucible would fail. A handbook method showed it would. An analytical model eliminating two large conservatisms predicted no failure. A beryllia crucible preheated to 321°C was successfully immersed in electrorefiner salt without failure. The conclusion is that handbook methods can be severely conservative in predicting thermal stress failures for immersion in low thermal conductivity fluids.