In this work, the isotopes 99Tc, 129I, 234U, and 237Np were identified as potential long term radiotoxic hazards. The Yucca Mountain Viability Assessment also targeted colloid formation, secondary phase formation, and waste form solubility as areas of research needs. The U fuel forms more 99Tc, 237Np, and 239Pu from the production of higher actinides. The long term radionuclide inventory for the two different fuels is assessed. In addition, the behavior of Th intrinsic and pseudocolloids is not well understood.
Work is presented on estimating the behavior of thorium in the repository near field.
A search for existing thermodynamic and speciation data has been initiated. Future research directions and needs are presented.