Thermodynamic evaluation of the Cu-Zr system and treatment of zirconium base alloy wastes by using molten copper

Molten copper dissolves a considerable amount of zirconium at medium temperatures around 1500K, providing a possibility to treat refractory zirconium base alloy wastes in nuclear reprocessing plants. In this study, based on the experimentally determined heat contents and liquidus or solidus temperatures along with some other published data, thermodynamic optimization was made for the Cu-Zr binary system to evaluate the thermodynamic properties and phase diagram of this system. Using the evaluated data, thermodynamic and heat balance calculations were made to look for the optimum conditions in the following three processes, which had been proposed by the authors to treat the zirconium base alloy wastes: (a) melting of the cladding hulls by alloying with the minimum quantity of molten copper, (b) recovery of zirconium from the wastes by selective chlorination of the molten Cu-Zr base alloy, and (c) elimination of radioactive elements in the zircalloy by selective oxidation of the molten Cu-Zr base alloy.