Single-Pass Flow-Through Test Elucidation of Weathering Behavior and Evaluation of Contaminant Release Models for Hanford Tank Residual Radioactive Waste

Journal Article · Tue Jan 01 04:00:00 EST 2013 · Applied Geochemistry, 28:119-127

DOI:https://doi.org/10.1016/j.apgeochem.2012.09.004· OSTI ID:1064567

Cantrell, Kirk J; Carroll, Kenneth C; Buck, Edgar C; Neiner, Doinita; Geiszler, Keith N

Contaminant release models are required to evaluate and predict long-term environmental impacts of even residual amounts of high-level radioactive waste after cleanup and closure of radioactively contaminated sites such as the DOE’s Hanford Site. More realistic and representative models have been developed for release of uranium, technetium, and chromium from Hanford Site tanks C-202, C-203, and C-103 residual wastes using data collected with a single-pass flow-through test (SPFT) method. These revised models indicate that contaminant release concentrations from these residual wastes will be considerably lower than previous estimates based on batch experiments. For uranium, a thermodynamic solubility model provides an effective description of uranium release, which can account for differences in pore fluid chemistry contacting the waste that could occur through time and as a result of different closure scenarios. Under certain circumstances in the SPFT experiments various calcium rich precipitates (calcium phosphates and calcite) form on the surfaces of the waste particles, inhibiting dissolution of the underlying uranium phases in the waste. This behavior was not observed in previous batch experiments. For both technetium and chromium, empirical release models were developed. In the case of technetium, release from all three wastes was modeled using an equilibrium Kd model. For chromium release, a constant concentration model was applied for all three wastes.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1064567
• Report Number(s): PNNL-SA-88084
• Journal Information: Applied Geochemistry, 28:119-127, Journal Name: Applied Geochemistry, 28:119-127
• Country of Publication: United States
• Language: English

Related Subjects

Hanford Site
Uranium
chromium
tank residual waste
technetium
uranium solubility