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Groundwater flow and heat transport for systems undergoing freeze-thaw: Intercomparison of numerical simulators for 2D test cases

Advances in Water Resources

Grenier, Christophe; Anbergen, Hauke; Bense, Victor; Chanzy, Quentin; Coon, Ethan; Collier, Nathaniel; Costard, François; Ferry, Michel; Frampton, Andrew; Frederick, Jennifer M.; Gonçalvès, Julio; Holmén, Johann; Jost, Anne; Kokh, Samuel; Kurylyk, Barret; McKenzie, Jeffrey; Molson, John; Mouche, Emmanuel; Orgogozo, Laurent; Pannetier, Romain; Rivière, Agnès; Roux, Nicolas; Rühaak, Wolfram; Scheidegger, Johanna; Selroos, Jan O.; Therrien, René; Vidstrand, Patrik; Voss, Clifford

In high-elevation, boreal and arctic regions, hydrological processes and associated water bodies can be strongly influenced by the distribution of permafrost. Recent field and modeling studies indicate that a fully-coupled multidimensional thermo-hydraulic approach is required to accurately model the evolution of these permafrost-impacted landscapes and groundwater systems. However, the relatively new and complex numerical codes being developed for coupled non-linear freeze-thaw systems require verification. This issue is addressed by means of an intercomparison of thirteen numerical codes for two-dimensional test cases with several performance metrics (PMs). These codes comprise a wide range of numerical approaches, spatial and temporal discretization strategies, and computational efficiencies. Results suggest that the codes provide robust results for the test cases considered and that minor discrepancies are explained by computational precision. However, larger discrepancies are observed for some PMs resulting from differences in the governing equations, discretization issues, or in the freezing curve used by some codes.

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TYPE Journal Article YEAR 2018
ScopusOSTIDOI

PFLOTRAN-RepoTREND Source Term Comparison Summary

Frederick, Jennifer M.

Code inter-comparison studies are useful exercises to verify and benchmark independently developed software to ensure proper function, especially when the software is used to model high-consequence systems which cannot be physically tested in a fully representative environment. This summary describes the results of the first portion of the code inter-comparison between PFLOTRAN and RepoTREND, which compares the radionuclide source term used in a typical performance assessment.

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TYPE SAND Report YEAR 2018
OSTIDOI

Advances in Geologic Disposal System Modeling and Shale Reference Cases

Mariner, Paul M.; Stein, Emily S.; Frederick, Jennifer M.; Sevougian, Stephen D.; Hammond, Glenn E.

The Spent Fuel and Waste Science and Technology (SFWST) Campaign of the U.S. Department of Energy (DOE) Office of Nuclear Energy (NE), Office of Fuel Cycle Technology (OFCT) is conducting research and development (R&D) on geologic disposal of spent nuclear fuel (SNF) and high level nuclear waste (HLW). Two high priorities for SFWST disposal R&D are design concept development and disposal system modeling (DOE 2011, Table 6). These priorities are directly addressed in the SFWST Generic Disposal Systems Analysis (GDSA) work package, which is charged with developing a disposal system modeling and analysis capability for evaluating disposal system performance for nuclear waste in geologic media (e.g., salt, granite, shale, and deep borehole disposal).

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TYPE Other Report YEAR 2017
OSTIDOI

Development of a waste form process model in PFLOTRAN

ANS IHLRWM 2017 - 16th International High-Level Radioactive Waste Management Conference: Creating a Safe and Secure Energy Future for Generations to Come - Driving Toward Long-Term Storage and Disposal

Frederick, Jennifer M.; Hammond, Glenn E.; Mariner, Paul M.; Stein, Emily S.; Sevougian, S.D.

An important feature required in all geological disposal system modeling is proper representation of waste package degradation and waste form dissolution. These processes are often treated as batch operations, meaning they are zero-dimensional. However, waste package canister degradation or waste form dissolution are affected by near-field conditions, and thus they must be coupled to the computational domain through the exchange of information on local conditions. Accurate waste package and waste form degradation behavior is essential because processes occurring at the batch level also affect far field conditions through heat and mass transport by advection or diffusion. Presented here is the development and performance of the Waste Form Process Model, an integrated module for waste package canister degradation and waste form dissolution developed by Sandia National Laboratories within PFLOTRAN. PFLOTRAN is an open source, massively parallel subsurface simulator for multiphase, multicomponent, and multiscale reactive flow and transport processes in porous media. PFLOTRAN is used to model geologic disposal systems for the Spent Fuel and Waste Science and Technology (SFWST) Campaign under the Spent Fuel and Waste Disposition Program of the U.S. Department of Energy (DOE) Office of Nuclear Energy.

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TYPE Conference Poster YEAR 2017
ScopusOSTI

Modeling coupled reactive flow processes in fractured crystalline rock

ANS IHLRWM 2017 - 16th International High-Level Radioactive Waste Management Conference: Creating a Safe and Secure Energy Future for Generations to Come - Driving Toward Long-Term Storage and Disposal

Stein, Emily S.; Frederick, Jennifer M.; Hammond, Glenn E.; Kuhlman, Kristopher L.; Mariner, Paul M.; Sevougian, S.D.

Numerical simulation of a repository for heatgenerating nuclear waste in fractured crystalline rock requires a method for simulating coupled heat and fluid flow and reactive radionuclide transport in both porous media (bentonite buffer, surface sediments) and fractured rock (the repository host rock). Discrete fracture networks (DFNs), networks of two-dimensional planes distributed in a three-dimensional domain, are commonly used to simulate isothermal fluid flow and particle transport in fractures, but unless coupled to a continuum, are incapable of simulating heat conduction through the rock matrix, and therefore incapable of capturing the effects of thermally driven fluid fluxes or of coupling chemical processes to thermal processes. We present a method for mapping a stochastically generated DFN to a porous medium domain that allows representation of porous and fractured media in the same domain, captures the behavior of radionuclide transport in fractured rock, and allows simulation of coupled heat and fluid flow including heat conduction through the matrix of the fractured rock. We apply the method within Sandia's Geologic Disposal Safety Assessment (GDSA) framework to conduct a post-closure performance assessment (PA) of a generic repository for commercial spent nuclear fuel in crystalline rock. The three-dimensional, kilometer-scale model domain contains approximately 4.5 million grid cells; grid refinement captures the detail of 3, 360 individual waste packages in 42 disposal drifts. Coupled heat and fluid flow and reactive transport are solved numerically with PFLOTRAN, a massively parallel multiphase flow and reactive transport code. Simulations of multiple fracture realizations were run to 1 million years, and indicate that, because of the channeled nature of fracture flow, thermally-driven fluid fluxes associated with peak repository temperatures may be a primary means of radionuclide transport out of the saturated repository. The channeled nature of fracture flow gives rise to unique challenges in uncertainty and sensitivity quantification, as radionuclide concentrations at any given location outside the repository depend heavily on the distribution of fractures in the domain.

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TYPE Conference Poster YEAR 2017
ScopusOSTI

Status of Progress Made Toward Safety Analysis and Technical Site Evaluations for DOE Managed HLW and SNF

Sevougian, Stephen D.; Stein, Emily S.; Gross, Michael B.; Hammond, Glenn E.; Frederick, Jennifer M.; Mariner, Paul M.

The Spent Fuel and Waste Science and Technology (SFWST) Campaign of the U.S. Department of Energy (DOE) Office of Nuclear Energy (NE) is conducting research and development (R&D) on generic deep geologic disposal systems (i.e., repositories). This report describes specific activities in FY 2016 associated with the development of a Defense Waste Repository (DWR)a for the permanent disposal of a portion of the HLW and SNF derived from national defense and research and development (R&D) activities of the DOE.

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TYPE Other Report YEAR 2016
OSTIDOI
Results 51–100 of 113
Results 51–100 of 113