Thermochemical analysis of nuclear waste for safety assessment

The US Department of Energy's Hanford Site has 177 large underground tanks containing highly radioactive chemical processing waste from its defense plutonium production mission. A number of these tanks contain reduced-carbon compounds, nitrates, and nitrites mixed together in wet sludges or slurries. If their contents get too hot, some of the tanks could pose an unreviewed safety question in the form of a thermal runaway. To provide a quantitative characterization of the thermochemical hazard potential, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and adiabatic calorimetry have been and will continue to be employed on tank waste samples and surrogates. The means by which measurements of radioactive waste are accomplished, the interpretation of actual analyses, and the derivation of parameters to be used in engineering safety assessments are described