Separation Characteristics of Manganese as a Surrogate for Americium during the Distillation Operations of Pyroprocessing

The loss of americium metal during the pyroprocessing of used nuclear fuel has long been a concern due to its high vapor pressure relative to the operating conditions of the process. Of the two high temperature vacuum operations (distillation and casting) performed during pyroprocessing, the distillation operation would incur significantly more americium losses by several orders of magnitude. The distillation operation is required for the removal of cadmium from the transuranic products. Thus, a series of tests were initiated to investigate the evaporative characteristics of manganese as a surrogate for americium during distillation operations. The results for the separation of manganese are presented from the test program and compared against modeled data. Based on the modeling of manganese, similar data were calculated for americium evaporation during a typical liquid cathode operation in the cathode processor. It is anticipated that less than 0.15 wt.% of the americium will be lost during the distillation operation of liquid cathodes during the pyroprocessing of used nuclear fuel.