ALTERNATIVE CONCEPTUAL MODELS FOR RADIONUCLIDE RELEASE

摘要

The U.S. Nuclear Regulatory Commission uses four alternative conceptual models of spent fuel dissolution and one for vitrified glass in its Total System Performance Assessment model for the proposed Yucca Mountain repository. The dissolution models are based on experimental observations under different water chemistries, natural analog observations, and theoretical considerations of secondary minerals for uranium. There are also alternative models for the fuel surface area and the wetting and mixing processes within waste packages. The commercial spent fuel waste form is expected to dominate releases from the engineered barrier. Dissolution rate of the waste form is likely to be the most important control on releases rather than solubility limits for the radionuclides of most concern. Fast release fractions of radionuclides are most important for the alternative models that show the lowest rate of dissolution.