Validity of batch sorption data to describe selenium transport through unsaturated tuff
- Tri-Cities Univ. Center, Richland, WA (United States)
As part of project for characterizing Yucca Mt. as a potential site for high-level nuclear waste respository, we used UFA {trademark} technology (centifuge-induced flow) to directly measure selenite retardation coefficients and hydraulic conductivity under unsaturated conditions on two tuff samples from Yucca Mt. Retardation factor for the selenite species was 2.5 in both Yucca Mt. vitric tuff at 62.6% saturation and zeolitic nonwelded tuff from G-tunnel at 52.8% saturation. For these column experiments, we prepared a solution, using J-13 well water from NTS, with a Se conc. of 1.31 mg/L(ppM). The retardation factor of 2.5 measured for both tuffs translates into a sorption distribution coefficient K{sub d} of 0.9 mL/g for the vitric tuff and 0.8 mL/g for the zeolitic tuff. For batch sorption experiments, using the same zeolitic tuff as for the column experiments and solutions of J-13 well water with a Se conc. of 1.1 mg/L(ppM), the average K{sub d} was determined to be 0.1{+-}0.2 mL/g. Given the small K{sub d} values for Se sorption, general agreement between batch and column measurements (obtained under unsaturated conditions) was observed. Unsaturated hydraulic conductivities during the experiments were 2.5x10{sup -8} cm/s for the Yucca Mt. vitric tuff and 1.2x10{sup -8} cm/s for the zeolitic nonwelded tuff from G- tunnel.
- Research Organization:
- Los Alamos National Lab., NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 288434
- Report Number(s):
- LA--12957-MS; ON: DE96012650
- Country of Publication:
- United States
- Language:
- English
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