| Magnetic levitation of plutonium metal at elevated temperatures was demonstrated to be valuable in separating impurities by both zone refining and vacuum distillation. The levitation force kept molten plutonium from touching crucible walls, enabling handling molten plutonium for extended periods without mutual dissolution.; Plutonium was heated by radio-frequency power in Crystalox{dollar}sp{lcub}circler{rcub}{dollar} gold-plated, conducting crucibles. The RF power induced electric currents flowing in opposite directions in the crucible and plutonium. Magnetic fields in crucible and plutonium opposed, causing repulsion and levitation of the plutonium a small distance from crucible walls. Separate systems were used to study zone refining and vacuum distillation of plutonium. Differing plutonium metal alloys containing known amounts of impurities were studied for the two systems.; Zone refining was done using plutonium rods. The presence of oxygen had a large negative effect on zone refining effectiveness. Decreasing travel speed of the molten zone improved separation as did increasing the number of passes on a given rod. In all cases, all plutonium impurity elements tracked, moved in accord with anticipated element movement based on the distribution coefficient determined from the binary phase diagram of each element, with plutonium.; Vacuum distillation used molten plutonium in a relatively spherical bolus. Concentrations of americium in plutonium dropped by approximately 50% after 2 h experiments.; In each system, room temperature plutonium separated readily from the crucible without evidence of corrosion or deposits on either crucible or plutonium. |
