Advances in the Biogeochemical Role of Microorganisms in High-Level Waste Repository

The deep geological repository of high-level radioactive waste (HLW) is widely recognized as a safe and effective long-term management strategy, which hinges on the stability of the repository. Among the various factors that affect the stability of the repository, microorganisms are recognized as key contributors, which can be indigenous to the bentonite and introduced during the repository construction or through groundwater intrusion in later stages. Active microorganisms are typically observed in low-density regions and at the interfaces within the repository. The biogeochemical processes induced by microbial metabolic activities lead to the corrosion of repository containers, degradation of the buffer barrier, and other detrimental effects, potentially compromising the long-term integrity of the repository. Therefore, a thorough understanding of microbial survival, activity, and their interactions with repository materials is crucial for ensuring the safe management of HLW. This review summarizes microbial survival conditions and sources in the repository, recent research advances on microbial interactions with repository structures, and the impact of microbial activity on the physical properties of bentonite, offering valuable insights for the development of HLW repositories in China.