interface FASTREACT Marfa

The computer code Migration Analysis of Radionuclides in the Far Field (Painter and Mancillas, 2009) simulates radionuclide transport in a sparsely fractured geological medium. The numerical tool FASTREACT (FrAmework for STOchastic REActive Transport; Trinchero et al., 2013) relies on the theory of stochastic convective models (e.g. Shapiro and Cvetkovic 1988) and provides a tool for reactive transport simulations along a set of streamlines based on mechanistic geochemical processes. Given their similarity (both codes uses particle-based methods), their remarkable efficiency and their complementarity, the two tools have been integrated in an interface, denoted as iFM (interface FASTREACT-MARFA) whose aim is to increase the scientific soundness of the retention model used by MARFA by periodically updating the


About

With iFM we propose a novel approach that constitutes a significant improvement over the traditional constant Kd model, while at the same time allows simulations performed with MARFA to be carried out sufficiently quick to permit probabilistic analyses. The basic premise of this approach is that the “background” geochemistry (excluding radionuclides) will first be pre-calculated using a reactive transport code in order to generate a dataset of Kd values in space in time that are representative of the actual geochemical conditions throughout the model spatial and time domains. This information will then be fed to MARFA in order to calculate radionuclide transport and retardation based on these “intelligent” Kd values.

The “background” geochemistry (excluding radionuclides) is calculated using a mechanistic reactive transport code (i.e. including explicitly each relevant geochemical reaction). The link between this mechanistic reactive transport simulation and the MARFA trajectory segments is provided by the FASTREACT approach. By performing a number of batch simulations over this pre-calculated geochemical background, a dataset of Kd values is generated, which is representative of the actual geochemical conditions throughout the model spatial and time domain. This information will then be fed to MARFA in order to calculate radionuclide transport and retardation based on these “intelligent” Kd values.

If you would like to reference Marfa in your publications, please use the following reference: Painter, S., V. Cvetkovic, and O. Pensado. "Time-domain random walk methods for simulating radionuclide transport in fractured porous rock." Proceedings of the 11th International High-level Radioactive Waste Management Conference (IHLRWM 2006). Las Vegas, Nevada. Vol. 30. 2006.

Painter, S., Cvetkovic, V., Mancillas, J., and Pensado, O. (2008). Time domain particle tracking methods for simulating transport with retention and first-order transformation. Water resources research, 44(1), W01406.

Painter, S., and Cvetkovic, V. (2005). Upscaling discrete fracture network simulations: An alternative to continuum transport models. Water resources research, 41(2), W02002.

If you would like to reference FastReact in your publications, please use the following reference: Trinchero, P., Molinero, J., Román-Ross, G. (2012) A streamline-based approach for the solution of multicomponent reactive transport problems, SKB report R-10-45.

Trinchero, P., Molinero, J., Román-Ross, G. (2014) FASTREACT -an efficient methodology for the solution of reactive transport problems, submitted to Applied Geochemistry.

These are the different partners support one or more iMaGe projects:

SKB_logo Posiva_logo logo_amphos21
  • Scott Painter; LANL; USA

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FASTREACT

FASTREACT is a numerical framework for the efficient solution of large-scale reactive transport problems. The methodology, which is based on the theory of stochastic-convective or stochastic-advective(-reactive) models, consists in simulating the flux-averaged concentration at a given control location, or other quantities of interest, using one single reference simulation that incorporates explicitly all the relevant geochemical processes (e.g. mineral dissolution/precipitation, aluminosilicates weathering, cation exchange reactions, and aqueous redox reactions). FASTREACT has been developed with safety assessment calculations of radionuclide transport in fractured rock in mind and thus provides efficient handling of the coupling between advection, reactions and exchange processes (i.e. matrix diffusion) for large amounts of input and output data.
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Marfa

The computer code Migration Analysis of Radionuclides in the Far Field (MARFA) is used to simulate the transport of radionuclides in a sparsely fractured geological medium. MARFA uses the particle on random streamline segment algorithm /Painter et al. 2006/, a Monte Carlo algorithm combining time-domain random walk methods /Painter et al. 2008/ with pathway stochastic simulation /Painter and Cvetkovic 2005/. The algorithm uses non-interacting particles to represent packets of radionuclide mass. These particles are moved through the system according to rules that mimic the underlying physical transport and retention processes. The set of times required for particles to pass through the geological barrier are then used to reconstruct discharge rates (mass or activity basis). Because the algorithm uses non-interacting particles, the transport and retention processes are limited to those that depend linearly on radionuclide concentration. Nonlinear processes such as solubility-limited transport or aqueous speciation are not represented.
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Screenshots

Screenshots
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Licensing

A complete wiki is under construction. It will contain complete documentation, Q&A and will be the site where technical support will be centralized .

If you are interested in the iFM and Posiva technology please contact ifm@image-modelling.net

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