Wash and Leach Factor Development Support

Company Performed Work:

AEM Consulting, LLC

Work Description:

The objective of this work scope was to provide an alternative method for estimating the equivalent of retrieval, wash and leach factors for components tracked in the Hanford Tank Waste Operations Simulator (HTWOS).  The existing approach used by HTWOS was based on wash and leach factors that were only intended to provide a first order approximation of waste component distributions between solid and liquid phases as waste is retrieved and stored within the tank farm system or caustic leached during processing by the Waste Treatment and Immobilization Plant (WTP).  The alternate method developed by this work was intended to provide a solubility based estimate of distributions between solid and liquid phases for either very soluble or very insoluble components.

The project developed algorithms to approximate equilibrium distribution of components between solid and liquid phases, independent of the process step being performed.  The study scope included 46 radionuclide, 51 inorganic, and 22 organic components that may be encountered in the tank waste inventory.  A major result of the study was to bin the components and identify analytes that are likely to be considered either very soluble or very insoluble.  A number of components were identified as being moderately soluble and these components will likely require more detailed modeling to provide a realistic approximation of distribution between solid and liquid phases.

A precise validation of the algorithms was not performed as part of the study scope due to the large number of components investigated.  Instead, the algorithm predictions were compared to the source data and plots used to compare the predicted liquid phase composition in double-shell tanks with existing inventory estimates.  The comparisons indicated that the algorithms approximate the source information with a factor of about 2 to 10.  In addition, comparisons with tank inventory information indicated that implementation within HTWOS would be expected to produce reasonable results for some components and not for others.  This comparison was interpreted to indicate that the solubility algorithms are likely suitable for use in planning studies, but should not be used for safety evaluations or detailed process design.

Start / End Date:

March 2010 through September 2010

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