Deep geologic disposal of multiple nuclear waste packages with various heat sources can induce nonuniform hydro-thermal behaviors in the near-field of the repository, consequently influencing the long-term radionuclide transport in the far-field once waste form breach initiates. This study looks into three cases with variation in the spatial order of six groups of heat sources (10th, 50th, 75th, 90th, 95th, and 99th percentiles of heat outputs generated from 1,981 as-loaded dual-purpose canisters in the field site) in a shale-hosted repository with respect to the uni-directional groundwater flow (from west to east): (1) cooler waste packages from west to east, (2) hotter waste packages from west to east, and (3) hottest waste packages in the middle of the repository. Our field-scale PFLOTRAN simulation represents heat-driven multiphysics coupled mechanisms, including multiphase flow, heat transfer, and chemical/radioactive transport, and also, calculates the onset of waste form breach based on temperature-dependent canister vitality. The results from this sensitivity study will quantify the short- (less than 1 × 10 years) and long-term (up to 1 × 10 years) impacts of sporadic heat pulses from waste package on the spatio-temporal perturbation in hydro-thermal flow quantities and the rate of radionuclide transport in both near- and far-field of the repository system.

中文翻译：

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页岩地层中发热放射性废物空间变化驱动的耦合热液流和放射性核素输运

对具有不同热源的多个核废料包进行深层地质处置可能会在处置库近场引起不均匀的水热行为，从而影响一旦废料形成缺口开始在远场的长期放射性核素输运。本研究研究了六组热源空间顺序变化的三种情况（现场 1,981 个已装载的两用罐产生的热量输出的第 10、50、75、90、95 和 99 个百分位数）在页岩储存库中，关于单向地下水流（从西到东）：（1）从西到东较冷的废物包，（2）从西到东较热的废物包，以及（3）最热的废物包位于存储库的中间。我们的现场规模 PFLOTRAN 模拟代表了热驱动的多物理场耦合机制，包括多相流、传热和化学/放射性传输，并且还根据温度相关的罐活力计算废物形式破裂的发生。这项敏感性研究的结果将量化废物包中的零星热脉冲对热液流时空扰动的短期（小于 1 × 10 年）和长期（长达 1 × 10 年）影响储存库系统近场和远场中放射性核素传输的数量和速率。