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MARFA V3.2.3 and V3.3.1

LANL CODE LA-CC-11-089

Simulation Images

The computer code MARFA (Migration Analysis for Radionuclides in the FAr field) uses an extremely efficient particle-based Monte Carlo method to simulate the transport of radionuclides beneath the surface of the Earth. 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. In contrast to the conventional random walk particle tracking algorithm, which use a specified time step and random spatial displacement, the MARFA algorithms use a fixed spatial displacement and a random transit time for the displacement. The use of a fixed spatial displacement makes the code extremely robust and computationally efficient.

The physical processes represented in MARFA include advection, longitudinal dispersion, Fickian diffusion into an infinite or finite rock matrix, equilibrium sorption, decay, and in-growth. Because the algorithm uses non-interacting particles, the transport and retention processes are limited to those that depend linearly on radionuclide concentration. Multiple non-branching decay chains of arbitrary length are supported, as is full heterogeneity in the transport and retention properties.

Two variants of the code are provided. These two versions differ in how particles are routed through the computational domain.
MARFA 3.2.3 transport is assumed to occur along a set of trajectories or pathways that originate at radionuclide source locations. The trajectories are intended to represent the movement of hypothetical, advectively transported groundwater tracers and are typically calculated by streamline tracing using a numerically computed flow field. The groundwater speed and retention properties along each pathway may change in time, but the pathway trajectories are fixed.
MARFA 3.3.1 allows the transport effects of changing flow directions to be represented by abandoning the fixed pathways and performing node routing within MARFA.

MARFA is designed to accept flow fields computed by discrete fracture network (DFN) generators. MARFA has been used this way to evaluate the performance of a potential geologic repository for spent nuclear fuel.

Please refer to MARFA User's Manual for more information.


Capabilities

  • robust and efficient algorithm using fixed spatial displacement
  • advection and longitudinal dispersion
  • wide range of matrix retention processes including single, multiple, and infinite matrix layers
  • full heterogeneity in transport and retention properties
  • decay chains of arbitrary length
  • piecewise steady flow fields
  • optional downscaling algorithm to recover transport effects of unrepresented subgrid velocity variability

MARFA Software


MARFA is open source with a BSD-3 license and available on bitbucket at:

     https://bitbucket.org/scottpainter/marfa-docs/src/default/

     Contact: Scott Painter (scottpainter@bitbucket.org)


Copyright 2011. Los Alamos National Security, LLC. This software was produced under U.S. Government contract DE-AC52-06NA25396 for Los Alamos National Laboratory (LANL), which is operated by Los Alamos National Security, LLC for the U.S. Department of Energy. The U.S. Government has rights to use, reproduce, and distribute this software. NEITHER THE GOVERNMENT NOR LOS ALAMOS NATIONAL SECURITY, LLC MAKES ANY WARRANTY, EXPRESS OR IMPLIED, OR ASSUMES ANY LIABILITY FOR THE USE OF THIS SOFTWARE. If software is modified to produce derivative works, such modified software should be clearly marked, so as not to confuse it with the version available from LANL.

Additionally, redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
Neither the name of Los Alamos National Security, LLC, Los Alamos National Laboratory, LANL, the U.S. Government, nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY LOS ALAMOS NATIONAL SECURITY, LLC AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL LOS ALAMOS NATIONAL SECURITY, LLC OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.


MARFA Transport Simulation Example

Simulation Image

Detail from a complex radionuclide transport simulation using MARFA. The red and green dots represent locations of waste packages in a potential geologic repository for spent nuclear fuel sited in granitic rock. The trajectories represent potential pathways for radionuclide migration and are color-coded by MARFA-calculated cumulative discharge. The transport pathways were created by a discrete fracture network code and have a high degree of within-pathway and pathway-to-pathway variability.

MARFA development was funded by the Swedish Nuclear Fuel and Waste Management Company (SKB) and Posiva (Finland).


MARFA References

Painter, S., J. Mancillas, V. Cvetkovic, and O. Pensado, "Time-Domain Particle Tracking Method for Simulating Transport with Retention and First-Order Transformation," Water Resources Research, 44, doi:10.1029/2007WR005944, 2008.

Painter, S. "Accommodating Transient Velocities in Time-Domain Particle Tracking Algorithms of Radionuclide Transport," Proceedings of the 12th International High-Level Radioactive Waste Management Conference (IHLRWM); 7–11 September 2008; Las Vegas, Nevada. LaGrange Park, IL: American Nuclear Society (CD ROM). 2008.

Painter, S. and V. Cvetkovic, "Upscaling Discrete Fracture Network Simulations: An Alternative to Continuum Transport Models," Water Resources Research 41, doi:10.1029/2004WR003682, 2005.

Selroos, J.-O. and S. L. Painter, "Effect of transport-pathway simplifications on projected releases of radionuclides from a nuclear waste repository" (Sweden), Hydrogeology Journal, 8, 2012

Svensk Kärnbränslehantering AB, "Radionuclide Transport Report for the Safety Assessment SR-Site," SKB Technical Report TR-10-50, 2010.

For further information or questions on MARFA, please contact Scott Painter (spainter-at-lanl.gov)


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