ABSTRACT We measured and modeled near‐infrared extinction of nuclear waste glasses from 300°C to 1150°C to enable predictive radiation heat transfer and thermal conductivity estimates. A composition‐ and redox‐informed model resolved contributions from key chromophores (Fe +2 ‐O‐Fe +3 , V +4 , free and bonded ≡Si‐OH groups) and, when present, spinel particles that can cause strong scattering. The model reproduced measured absorption from room temperature up to 1150°C, with minor discrepancies near 1 µm (likely due to possible trace impurities) and 2.5 µm (linked to uncertainty in hydroxy groups). Spectra showed silicate melts were semitransparent mainly in the 0.5–4.0 µm window, responsible for radiation thermal conductivity that generally increases with increasing temperature. We quantified the dependence of effective thermal conductivity on dissolved water and provided distributions across >100 LAW/HLW/DFHLW melts at 1150°C, supporting improved melter heat transfer modeling.
Ferkl et al. (Sun,) studied this question.