Clay Hydration, Drying, and Cracking in Nuclear Waste Repositories

高放废物（HLW）和乏核燃料（SNF）的地质储存库的设计仍然是核燃料循环中一个未完全解决的问题，尽管在过去的几十年里取得了重大进展。当前设计的一个关键主题是多屏障概念，即多层屏障材料，从罐到EBS再到低渗透率的宿主岩石，确保废物的隔离。工程屏障系统（EBS）扮演着重要的角色，它必须在数千年的时间里保持足够的密封能力（即低水力渗透性，机械完整性），同时暴露于(1)由废物释放的热量引起的大热梯度；（ii）由于罐体- ebs和ebs -寄主岩石界面的腐蚀和离子交换反应，地球化学梯度较大；（iii）由毛细管应力驱动的大地质力学梯度，这些应力与初始的EBS再水化、水蒸发以及随后的腐蚀和水解反应可能在罐-EBS界面产生的气体有关。本项目的目的是开发一种新的多尺度模拟方法来预测高通量和SNF地质储存库近场工程粘土屏障的热-水文-机械-化学（THMC）耦合演化。

The design of geologic repositories for high-level waste (HLW) and spent nuclear fuel (SNF) remains an incompletely resolved question in the nuclear fuel cycle despite significant advances over the last several decades. A key theme in current designs is the multibarrier concept, whereby several layers of barrier materials, from canisters to EBS to low-permeability host rock, ensure the isolation of the waste. An important role is played by the Engineered Barrier System (EBS), which must maintain adequate sealing capacity (i.e., low hydraulic permeability, mechanical integrity) around the waste canisters for durations of thousands of years while exposed to (i) large thermal gradients caused by heat released by the waste; (ii) large geochemical gradients due to corrosion and ion-exchange reactions at the canister-EBS and EBS-host rock interfaces; and (iii) large geomechanical gradients driven by capillary stresses associated with the initial EBS rehydration, water evaporation and, later, with the possible generation of gases at the canister-EBS interface through corrosion and hydrolysis reactions. The objective of this project is to develop a new multi-scale simulation approach to predict the coupled thermal-hydrologic-mechanical-chemical (THMC) evolution of an engineered clay barrier in the near field of a geological repository for HLW and SNF.