Abstract: The chemical durability, and structure of iron phosphate glasses containing 70wt% of a simulated high level nuclear waste (HLW), doped with different amounts of Cr₂O₃ were investigated. All
of these iron phosphate glassy and crystallized wasteforms possess an outstanding chemical durability as measured by their small dissolution rate (10^-9g/(cm²·min)) in deionized water at 90℃
for 128 days, their low normalized mass release as determined by the Product Consistency Test (PCT) and a barely measurable corrosion rate of <0.1 g/(m²·d) after 7 days at 200℃ by the
Vapor Hydration Test (VHT) can meet all current DOE requirements for chemical durability. The PCT results show that the Cr₂O₃ doping into IP70W samples can suppress the element release from
both the glassy and crystallized samples and improve the chemical durability. The solubility limit for Cr₂O₃ in the iron phosphate melts estimated at 4.1 wt%, is at least 3 times larger than that
for borosilicate glasses. The results from FTIR and DTA show that the structure of IP glass wasteforms has no significant changes when Cr₂O₃ doped into IP70W samples. Mossbauer spectra show
that there is a redox reaction between Fe and Cr ions during the melting process and that the ratio of Fe²⁺/Fe³⁺ increases with the increase of Cr₂O₃ amount in the compositions. These
Cr⁶⁺ ions formed can improve the chemical durability of the glass wasteforms.

Key words: iron phosphate glass, chrome oxide, nuclear waste treatment, chemical durability measurement