This paper describes recent INEEL research directed to the development of a practical means of obtaining real or near-real time feedback on the redox state of simulated radioactive waste (radwaste) glasses. Three basic approaches were investigated. The first is a streamlined version of the conventional spectrophotometric method which determines the ratio of ferrous to total iron in aqueous solutions prepared from the glasses. The second approach involves potentiometric measurement of Fe~(++)/Fe~(+++) ratios in similar solutions. The third monitors the voltage between a platinum sensing surface exposed to the molten glass and another exposed to a redox-buffered reference glass.
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