Radionuclide transport through hydrothermally altered concrete:
Use of I- as a tracer

Sara Matzen
Hampshire College

Radionuclide transport through hydrothermally-altered concrete is being assessed to characterize the performance of the proposed Yucca Mountain radioactive waste repository. Tracers were pumped through an altered concrete core in a constant flow apparatus that allowed varied temperature and pore pressure conditions. Iodide, a tracer that is conservative (non-retarded) in most rocks and sediments, was used to assess the dispersive characteristics of the core sample. Iodide has been observed to sorb on fresh, unaltered concrete having a different composition than the sample used in this study. Iodide transport through the altered concrete was compared to conservative transport through a similar core of repository horizon tuff, and the retardation of iodide was assessed.