Purification of Zirconium Tetrachloride (ZrCl₄) from UNF Cladding - A Progress Report

Zirconium-based cladding materials that surround used nuclear fuel (UNF) rods represent a significant fraction of the total amount of high level waste that must be disposed of in long term geological repositories. The decontamination and/or recovery and reuse of these materials would significantly reduce the amount of high level waste associated with light water nuclear energy reactors and could provide a new source of hafnium free zirconium for the fabrication of new nuclear components. A step in a strategy to recycle zirconium from used cladding materials is the direct, high yield chlorination reaction that produces zirconium tetrachloride (ZrCl₄). The ZrCl₄ so obtained is contaminated with other metal chloride species (FeCl₃, NbCl₅, NbOCl₃, SnCl₄, CsCl, SbCl₅, etc.) that originate from the alloying metals present initially as well as contaminants from oxide layers on the cladding, trace fission products, fuel residues, activation byproducts, and tritium. The suggested strategy to remove the metal chloride impurities is based on sublimation at atmospheric pressure combined with chemical treatments influencing volatility of the impurities