Development of high temperature and pressure Eh and pH sensing instruments

Accurate groundwater Eh and pH data are essential for the design of a deep geologic nuclear waste repository. The waste canister corrosion behavior; stability of packing (backfill); and radionuclide dissolution, migration, sorption, and precipitation will be affected by the Eh and pH conditions existing in and near the repository. This report discusses the research effort to develop sensors that can be incorporated into autoclaves to continuously monitor the Eh and pH conditions existing during nuclear waste/barrier material/host-rock hydrothermal interaction experiments. The sensors must be stable over the temperature and pressure range of 250 to 3000C and 0.1 to 30 MPa in the presence of complex hydrothermal solutions. 18 references, 2 figures, 2 tables