Development of an S-Saltcake Simulant Using Crossflow Filtration as a Validation Technique

Abstract

In the past several years, cross-flow filtration has been studied extensively in a bench-scale system at Pacific Northwest National Laboratory (PNNL) using both actual tank waste from the Hanford site and waste simulants. One challenge when creating a waste simulant is duplicating the filtration behavior of real waste, in particular when the waste composition is not known with certainty. Using a systematic approach to filtration testing, it has been found that the solid components that dominate the filtration behavior can be identified. This approach was used to develop a waste simulant for S-Saltcake tank waste. The analysis of filtration data assists in screening solid components when the chemical composition and structure of a metal is not known. This is well-illustrated in this study during the search for the appropriate chromium phase. After the likely components were identified, the solids were combined with a supernate that is representative of the real waste and the filtration performance was verified against real waste data. A secondary benefit of this approach is the construction of a database of filtration performance for various solid species that can be used to quickly develop waste simulants in the future.

Keywords:

• crossflow filtration
• nuclear waste treatment
• simulant development

ACKNOWLEDGEMENTS

The authors gratefully acknowledge the contributions of PNNL staff members Amanda Johnson, Andrew Casella, Matthew Edwards, Don Rinehart, and Bill Buchmiller who assisted with the simulant preparation and testing. The work described in this article was performed by Pacific Northwest National Laboratory, which is operated by Battelle for the U.S. Department of Energy under Contract DE-AC05-76RL01830. This work was funded by the U.S. Department of Energy through the Office of Environmental Management.

Notes

*Contains an array of metals (major ones are Ca, Pb, Mg, Ni, ZrO, Fe) and some phosphate, oxalate, and carbonate.