Abstraction of Drift-Scale Coupled Processes

Francis, N. D. ; Sassani, D.

United States. Department of Energy. Yucca Mountain Project Office.

关键词: Radioactive Waste Facilities;    Hydrology;    Ground Water;    Radionuclide Migration;    Geochemistry;   

DOI  :  10.2172/859049
RP-ID  :  ANL-NBS-HS-000029 REV 00
RP-ID  :  NA
RP-ID  :  859049

美国|英语

来源: UNT Digital Library

【 摘 要 】

This Analysis/Model Report (AMR) describes an abstraction, for the performance assessment total system model, of the near-field host rock water chemistry and gas-phase composition. It also provides an abstracted process model analysis of potentially important differences in the thermal hydrologic (TH) variables used to describe the performance of a geologic repository obtained from models that include fully coupled reactive transport with thermal hydrology and those that include thermal hydrology alone. Specifically, the motivation of the process-level model comparison between fully coupled thermal-hydrologic-chemical (THC) and thermal-hydrologic-only (TH-only) is to provide the necessary justification as to why the in-drift thermodynamic environment and the near-field host rock percolation flux, the essential TH variables used to describe the performance of a geologic repository, can be obtained using a TH-only model and applied directly into a TSPA abstraction without recourse to a fully coupled reactive transport model. Abstraction as used in the context of this AMR refers to an extraction of essential data or information from the process-level model. The abstraction analysis reproduces and bounds the results of the underlying detailed process-level model. The primary purpose of this AMR is to abstract the results of the fully-coupled, THC model (CRWMS M&O 2000a) for effects on water and gas-phase composition adjacent to the drift wall (in the near-field host rock). It is assumed that drift wall fracture water and gas compositions may enter the emplacement drift before, during, and after the heating period. The heating period includes both the preclosure, in which the repository drifts are ventilated, and the postclosure periods, with backfill and drip shield emplacement at the time of repository closure. Although the preclosure period (50 years) is included in the process models, the postclosure performance assessment starts at the end of this initial period. The postclosure period will be analyzed until ambient thermal conditions of the mountain have returned. Subsequently, both THC and TH conditions will be analyzed for 100,000 years or longer.