ex21 {phreeqc} | R Documentation

## Example 21–Modeling Diffusion of HTO, 36Cl-, 22Na+, and Cs+ in a Radial Diffusion Cell

### Description

This example illustrates how PHREEQC version 3 can simulate a diffusion experiment, as is now often performed for assessing the properties of a repository for nuclear waste in a clay formation. A sample is cut from a core of clay, enveloped in filters, and placed in a diffusion cell (see Van Loon and others, 2004, for details). Solutions with tracers are circulated at the surfaces of the filters, the tracers diffuse into and out of the clay, and the solutions are sampled and analyzed regularly in time. The concentration changes are interpreted with Fick's diffusion equations to obtain transport parameters for modeling the rates of migration of elements away from a waste repository. Transport in clays is mainly diffusive because of the low hydraulic conductivity, and solutes are further retarded by sorption (cations) and by exclusion from part of the pore space (anions). The example can be run using the `phrRunString` routine.

### Source

http://wwwbrr.cr.usgs.gov/projects/GWC_coupled/phreeqc

### References

http://pubs.usgs.gov/tm/06/a43/pdf/tm6-A43.pdf

### See Also

Other Examples: `ex10`, `ex11`, `ex12`, `ex13a`, `ex14`, `ex15`, `ex16`, `ex17`, `ex18`, `ex19`, `ex1`, `ex20a`, `ex22`, `ex2`, `ex3`, `ex4`, `ex5`, `ex6`, `ex7`, `ex8`, `ex9`

### Examples

    phrLoadDatabaseString(phreeqc.dat)
    # example 21 requires the selected_output file to be turned on
    phrSetSelectedOutputFileOn(1, TRUE)
    phrSetOutputStringsOn(TRUE)
    # this takes longer than 5 seconds
    ## Not run: phrRunString(ex21)
    phrGetOutputStrings()

[Package phreeqc version 3.4.10 Index]