Radionuclide Release from Slag and Concrete Waste Materials, Part I: Conceptual Models of Leaching from Complex Materials and Laboratory Test Methods (NUREG/CR-7025)
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Manuscript Completed: March 2010
Date Published: December 2010
Argonne National Laboratory
9700 South Cass Avenue
Argonne, IL 60439
M. Fuhrmann, NRC Project Manager
NRC Job Code N6669
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington DC 20555-0001
The technical literature was surveyed to evaluate test methods and modeling approaches used to characterize the release of contaminants during the weathering of portland cement-based materials and slag wastes from metal processing and recycling operations. Data sets were selected to represent various approaches used to study contaminant leaching, mineral dissolution, and waste material corrosion, and both the testing methods and data interpretations were evaluated. Models were evaluated with regard to both interpreting the test results and predicting long-term behavior. This study concludes that test results can be misinterpreted if testing artifacts are not taken into account, such as the interval used in solution replacement tests, the flow rate used in dynamic tests, and failure to reach steady-state, or if an inappropriate process is modeled. Contaminant release may be controlled by a diffusion process (mass transport) or by the chemical reaction affinity, and oxidation reactions can affect the releases of multivalent contaminants, such as Tc. The mechanism controlling the release might not be identifiable by a single test method. While well-established models for each of these processes and standardized test methods are available, the challenge is to identify which process controls contaminant release under the conditions of interest and how the laboratory test results relate to the model and long-term material behavior.