Chemistry of Technetium and Rhenium Species during Low-Level Radioactive Waste Vitrification

We reviewed the chemistry of radioactive technetium species and their nonradioactive rhenium surrogates in the context of Hanford Site low-level radioactive waste processing and vitrification. Information concerning the hydrolysis, precipitation, phase transformation, volatilization, and redox chemistries of these species during the drying, calcining, and vitrification of aqueous waste slurries is condensed and extrapolated from the literature. The similarities between the chemistry of technetium and rhenium species were highlighted to evaluate the performance of rhenium as a surrogate for technetium in laboratory and engineering-scale low-level radioactive waste vitrification experiments.