Polyphosphate Amendments for In-Situ Remediation of Uranium
Environmental contamination of surface and subsurface geologic media by uranium is a lasting legacy of past operations related to nuclear energy and weapons production. Operations conducted at United States Department of Energy (DOE) and Department of Defense (DOD) sites including research activities, nuclear fuel processing, weapons development and testing, construction of nuclear energy reactors, and waste management have resulted significant surface and subsurface contamination of geologic media by heavy metals and radionuclides. Despite several decades of studies, effective uranium remediation strategies remain elusive for contamination in deep subsurface settings that prevail in the western United States. Polyphosphate technology has been demonstrated to delay the precipitation of phosphate phases for controlled in situ precipitation of stabile phosphate phases to control the long-term fate of uranium. Precipitation of phosphate minerals occurs when phosphate compounds undergo hydrolysis to yield orthophosphate. Accordingly, a detailed understanding of polyphosphate degradation and reaction kinetics, in the context of site specific information, allows the technology to be tailored as a time-released source of phosphate for subsurface treatment. Results of 1) a labortory testing program, providing a detailed understanding of the fundamental underpinnings necessary to evaluate the efficacy and potential use of polyphosphate technology for implementation through a field-scale demonstration, 2) field-scale injection into the aquifer demonstrating a reduction in the concentration of aqueous uranium and presenting field-scale challenges to implementation, and 3) infiltration into the vadose zone and capillary fringe stabilizing the inventory of uranium and mitigating a portion of the persistent flux of uranium to the aquifer will be presented. The data from field-scale demonstrations provide valuable information for designing a full-scale remediation of uranium within the 300 Area of the Hanford Site. Moreover, this study presents the fundamental information necessary to evaluate the efficacy and potential utilization of polyphosphate technology at other sites with varying geochemical and hydrodynamic conditions.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1059633
- Report Number(s):
- PNNL-SA-65123; 5592; 830403000
- Resource Relation:
- Conference: Proceedings of the 12th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM '09/DECOM '09), October 11-15, 2009, Liverpool, United Kingdom, Paper No. 16026
- Country of Publication:
- United States
- Language:
- English
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