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.多个国家正推进乏燃料（spent nuclear fuel, SNF）和/或高放废物（high-level waste, HLW）玻璃的深部地质处置工作，将其封装于碳钢容器中，置于缺氧黏土（及/或膨润土回填层）环境内。若因容器腐蚀失效导致水接触核材料，则乏燃料和/或高放废物玻璃将发生腐蚀（即传统溶解过程），进而可能引发放射性核素向地质圈释放。学界已针对地质处置场景下的容器腐蚀、乏燃料与高放废物玻璃腐蚀，以及放射性核素输运开展了诸多相对独立的研究。上述研究的成果被整合至一体化系统性能评价（system performance assessments, PAs）中，用于分析乏燃料和/或高放废物玻璃（二者亦可统称为高放废物）的通用深部地质处置系统的安全性。本技术简报针对美国、加拿大、日本及欧洲共同体多项研究计划中，关于乏燃料和/或高放废物玻璃腐蚀，以及处置库系统黏土/膨润土介质内质量输运的实验室实验测试结果的应用展开探讨。这些研究还涵盖了美国核管制委员会（U.S. Nuclear Regulatory Commission, NRC）与核废物监管分析中心（Center for Nuclear Waste Regulatory Analyses, CNWRA）工作人员的相关工作，且相关成果可单独面向公众开放获取。典型研究案例包括Ahn与Gwo（2020）以及Pan与Ahn（2020、2018）的成果。本文还针对当水相介质达到溶解组分的溶解度（或稳态）极限时，由溶解组分的水相输运所控制的乏燃料与高放废物玻璃腐蚀过程展开专项探讨。