Perth Laboratory – Public Seminar Series 2010

The impact of multi-rate mass-transfer and sorption processes on reactive transport of uranium at the Hanford 300A site, USA

Dr Janek Greskowiak
CSIRO Land and Water

Thursday 3 June 2010 at 3.30 pm, CSIRO Auditorium

Abstract
Prediction of the fate and attenuation of radionuclides in aquifers is a challenging task due to the complex and interacting physical and (bio)geochemical processes that control the mobility of these contaminants. The former US Department of Energy nuclear fuel production site Hanford300A, Washington State, USA shows, in contrast to earlier predictions, that 25 years after ending the disposal of U-bearing waste fluids U(VI) concentrations still remain very high. The Hanford Integrated Field Scale Research Challenge project (IFRC), led by the Pacific Northwest National Laboratory (PNNL), USA was therefore initiated and started in 2007. It is aimed at understanding and quantifying the mechanisms that affects the mobility of U(VI) in the Hanford 300A aquifer. The aquifer is a highly permeable, heterogeneous sand and gravel aquifer, and is strongly influenced by a very dynamic river water groundwater interaction with rapid changes in groundwater flow and hydrochemical conditions.

The major hypothesis investigated in this project is that the transport behaviour of U(VI) at this site is controlled by a combination of surface complexation reactions and non-equilibrium multi-scale mass transfer processes that occur between the bulk water phase and the intra-grain and intra-aggregate regions of the aquifer matrix. This presentation will give a brief project overview and discuss (i) the present, mainly laboratory derived conceptual model of U(VI) transport at the Hanford 300A site and (ii) how the conceptual model was implemented into a numerical reactive transport model. The talk will discuss the analysis of scenario models and its predictions under the much more complex field scale conditions. The presented work is a collaborative effort between CSIRO Land and Water, the University of Alabama, PNNL and USGS.

About the speaker
Janek Greskowiak is a CSIRO Office of the Chief Executive postdoctoral research fellow. His main research interests are reactive transport processes in groundwater and numerical modelling of these processes. Before joining CSIRO in 2008, Janek worked at the KompetenzZentrum Wasser GmbH Berlin, where he was involved in several projects investigating the viability of managed aquifer recharge systems. During his PhD at Leibniz-Institute for Freshwater Ecology and Inland Fisheries in Berlin he investigated and modelled redox-processes in managed aquifer recharge systems and their impact on micro pollutant fate.

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