Reductants, such as sucrose (C12H22O11), are added to nuclear waste melter feeds containing high fractions of nitrates and nitrites to reduce excessive foaming during feed‐to‐glass conversion, decrease sulfate segregation, and increase technetium retention. The effect of sucrose on foaming and melting reactions during the conversion was examined using the feed volume expansion test, thermogravimetric analysis, evolved gas analysis, x‐ray diffraction, and scanning electron microscopy with energy dispersive x‐ray spectrometry. Different amounts of sucrose were added to vary the carbon to nitrogen (C/N) ratio in the melter feed. As the C/N ratio increased, the extent of foaming decreased, and the N2/NO ratio increased in the evolved gas. Significant foam suppression, rapid gas release at approximately 250°C, and reduction in transition metal oxides were observed at C/N > 1.1.