Radioactive waste disposal generally entails vitrifying the waste into a glassy solid. Initial processing can involve spraying the waste into an industrial flame reactor, where the intense heat evaporates benign components such as water. Given the toxicity of the material, even 99.99 percent efficiency is insufficient for the task. Collaborators at the University of Illinois at Urbana-Champaign and the University of Arizona developed a CCD-based spectrometer to investigate the role of large "rogue" droplets that escape vaporization and detract from reactor efficiency.

The system shapes the beam of an excimer laser into a sheet of light across the path of drops inside the reactor. A CCD camera captures the scattered light for analysis. In the October issue of Applied Spectroscopy, the researchers described the instrument and its ability to track large drops and soot particles in a coal combustion laboratory.