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Title: Implications of Grain-Scale Mineralogical Heterogeneity for Radionuclide Transport in Fractured Media

The geological disposal of nuclear waste is based on the multi-barrier concept, comprising various engineered and natural barriers, to confine the radioactive waste and isolate it from the biosphere. Some of the planned repositories for high-level nuclear waste will be hosted in fractured crystalline rock formations. The potential of these formations to act as natural transport barriers is related to two coupled processes: diffusion into the rock matrix and sorption onto the mineral surfaces available in the rock matrix. Different in situ and laboratory experiments have pointed out the ubiquitous heterogeneous nature of the rock matrix: mineral surfaces and pore space are distributed in complex microstructures and their distribution is far from being homogeneous (as typically assumed by Darcy-scale coarse reactive transport models). We use a synthetically generated fracture–matrix system to assess the implications of grain-scale physical and mineralogical heterogeneity on cesium transport and retention. The resulting grain-scale reactive transport model is solved using high-performance computing technologies, and the results are compared with those derived from two alternative models, denoted as upscaled models, where mineral abundance is averaged over the matrix volume. In the grain-scale model, the penetration of cesium into the matrix is faster and the penetration front ismore » uneven and finger-shaped. The analysis of the cesium breakthrough curves computed at two different points in the fracture shows that the upscaled models provide later first-arrival time estimates compared to the grain-scale model. The breakthrough curves computed with the three models converge at late times. These results suggest that spatially averaged upscaled parameters of sorption site distribution can be used to predict the late-time behavior of breakthrough curves but could be inadequate to simulate the early behavior.« less
Authors:
ORCiD logo [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [1] ;  [5] ;  [2] ;  [5]
  1. AMPHOS 21 Consulting S.L., Barcelona (Spain)
  2. Forschungszentrum Julich (Germany). Inst. for Energy and Climate Research. Nuclear Waste Management and Reactor Safety
  3. Computer-Aided Fluid Engineering AB, Lyckeby (Sweden)
  4. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Applied Systems Analysis and Research
  5. Swedish Nuclear Fuel and Waste Management Company, Stockholm (Sweden)
Publication Date:
Report Number(s):
SAND-2016-5312J
Journal ID: ISSN 0169-3913; 672254
Grant/Contract Number:
AC04-94AL85000
Type:
Accepted Manuscript
Journal Name:
Transport in Porous Media
Additional Journal Information:
Journal Volume: 116; Journal Issue: 1; Journal ID: ISSN 0169-3913
Publisher:
Springer
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); AMPHOS 21 Consulting S.L., Barcelona (Spain); Computer-Aided Fluid Engineering AB, Lyckeby (Sweden)
Sponsoring Org:
USDOE; Swedish Nuclear Fuel and Waste Management Company (SKB)
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; 97 MATHEMATICS AND COMPUTING; grain-scale mineralogical heterogeneity; radionuclide transport; microcontinuum model; high-performance computing (HPC)
OSTI Identifier:
1497639

Trinchero, Paolo, Molinero, Jorge, Deissmann, Guido, Svensson, Urban, Gylling, Björn, Ebrahimi, Hedieh, Hammond, Glenn, Bosbach, Dirk, and Puigdomenech, Ignasi. Implications of Grain-Scale Mineralogical Heterogeneity for Radionuclide Transport in Fractured Media. United States: N. p., Web. doi:10.1007/s11242-016-0765-0.
Trinchero, Paolo, Molinero, Jorge, Deissmann, Guido, Svensson, Urban, Gylling, Björn, Ebrahimi, Hedieh, Hammond, Glenn, Bosbach, Dirk, & Puigdomenech, Ignasi. Implications of Grain-Scale Mineralogical Heterogeneity for Radionuclide Transport in Fractured Media. United States. doi:10.1007/s11242-016-0765-0.
Trinchero, Paolo, Molinero, Jorge, Deissmann, Guido, Svensson, Urban, Gylling, Björn, Ebrahimi, Hedieh, Hammond, Glenn, Bosbach, Dirk, and Puigdomenech, Ignasi. 2016. "Implications of Grain-Scale Mineralogical Heterogeneity for Radionuclide Transport in Fractured Media". United States. doi:10.1007/s11242-016-0765-0. https://www.osti.gov/servlets/purl/1497639.
@article{osti_1497639,
title = {Implications of Grain-Scale Mineralogical Heterogeneity for Radionuclide Transport in Fractured Media},
author = {Trinchero, Paolo and Molinero, Jorge and Deissmann, Guido and Svensson, Urban and Gylling, Björn and Ebrahimi, Hedieh and Hammond, Glenn and Bosbach, Dirk and Puigdomenech, Ignasi},
abstractNote = {The geological disposal of nuclear waste is based on the multi-barrier concept, comprising various engineered and natural barriers, to confine the radioactive waste and isolate it from the biosphere. Some of the planned repositories for high-level nuclear waste will be hosted in fractured crystalline rock formations. The potential of these formations to act as natural transport barriers is related to two coupled processes: diffusion into the rock matrix and sorption onto the mineral surfaces available in the rock matrix. Different in situ and laboratory experiments have pointed out the ubiquitous heterogeneous nature of the rock matrix: mineral surfaces and pore space are distributed in complex microstructures and their distribution is far from being homogeneous (as typically assumed by Darcy-scale coarse reactive transport models). We use a synthetically generated fracture–matrix system to assess the implications of grain-scale physical and mineralogical heterogeneity on cesium transport and retention. The resulting grain-scale reactive transport model is solved using high-performance computing technologies, and the results are compared with those derived from two alternative models, denoted as upscaled models, where mineral abundance is averaged over the matrix volume. In the grain-scale model, the penetration of cesium into the matrix is faster and the penetration front is uneven and finger-shaped. The analysis of the cesium breakthrough curves computed at two different points in the fracture shows that the upscaled models provide later first-arrival time estimates compared to the grain-scale model. The breakthrough curves computed with the three models converge at late times. These results suggest that spatially averaged upscaled parameters of sorption site distribution can be used to predict the late-time behavior of breakthrough curves but could be inadequate to simulate the early behavior.},
doi = {10.1007/s11242-016-0765-0},
journal = {Transport in Porous Media},
number = 1,
volume = 116,
place = {United States},
year = {2016},
month = {9}
}