Radionuclide sorption kinetics and column sorption studies with Columbia River basalts

Technical Report · Thu Sep 01 00:00:00 EDT 1983

OSTI ID:5201088

Barney, G S ^[1]; Ames, L L; McGarrah, J E; Walker, B A ^[2]

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1. Rockwell International Corp., Richland, WA (USA). Rockwell Hanford Operations
2. Pacific Northwest Lab., Richland, WA (USA)

The kinetics of radionuclide sorption and desorption reactions in basalt-groundwater systems were evaluated at 60{degrees}C using a batch equilibration method. It was found that many sorption reactions on surfaces of fresh (unaltered) basalt from the Umtanum and Cohassett flows are slow. Some reactions require more than 50 days to reach a steady state. Sorption of neptunium and uranium in oxidizing (air saturated) groundwater appears to be controlled by slow reduction of these elements by the basalt surfaces. The resulting lower oxidation states are more strongly sorbed. Technetium and selenium, which are anionic under oxidizing conditions, are not measurably sorbed on fresh basalt surfaces, but are slightly sorbed on the altered surfaces of flow top basalt. Under reducing conditions, where the groundwater contains dilute hydrazine, sorption is faster for neptunium, uranium, technetium, selenium, and lead. Plutonium sorption rates were not affected by the groundwater Eh. It was shown that radium was precipitated rather than sorbed under the conditions of these experiments. Umtanum flow top material sorbed radionuclides much faster than fresh basalt surfaces due to its greater surface area and cation exchange capacity. Desorption rates for plutonium, uranium, neptunium, technetium, and selenium were generally much less than sorption rates (especially for reducing conditions). These radionuclides are irreversibly sorbed on the basalts. 25 refs., 20 figs., 19 tabs.

• Research Organization: Rockwell International Corp., Richland, WA (USA). Rockwell Hanford Operations; Pacific Northwest Lab., Richland, WA (USA)
• Sponsoring Organization: DOE/RW
• DOE Contract Number: AC06-77RL01030
• OSTI ID: 5201088
• Report Number(s): RHO-BWI-TI-168; ON: TI90005850
• Country of Publication: United States
• Language: English

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