Corrosion of Spent Nuclear Fuel and High-Level Waste Glass in Anoxic Clay Disposal Environment – Technical Note

Many countries are pursuing deep geologic disposal of spent nuclear fuel (SNF) and/or high-level waste (HLW) glass in carbon steel containers in anoxic clay (and/or bentonite backfill) environments. If water contacts the nuclear material due to container failure by corrosion, corrosion (i.e., traditional dissolution) of SNF and/or HLW glass will occur potentially resulting in radionuclide release to the geosphere. Studies, generally independent of each other, have been conducted on corrosion of containers, corrosion of SNF and HLW glass, and radionuclide transport in the geological disposal setting. The output of these efforts is abstracted into integrated system performance assessments (PAs) in order to analyze the safety associated with generic deep geologic disposal systems of SNF and/or HLW glass (together also called HLW).
This technical note considers the application of laboratory experimental test results from multiple research programs in the United States, Canada, Japan, and the European community on corrosion of SNF and/or HLW glass and mass transport in the clay/bentonite medium of a repository system. These studies also include work by staff at the U.S. Nuclear Regulatory Commission (NRC) and the Center for Nuclear Waste Regulatory Analyses (CNWRA). These are available to the public separately. Important examples include Ahn and Gwo (2020); and Pan and Ahn (2020, and 2018).
In this additional paper-specific consideration is given to the corrosion of SNF and HLW glass controlled by aqueous transport of dissolved species in the aqueous media as the media is reaching solubility (or steady state) limits of the dissolved species.