Dependence of radionuclide sorption on sample grinding surface area, and water composition
- Los Alamos National Laboratory, NM (United States)
In its 1987 technical position paper, `Determination of Radionuclide Sorption for High-Level Nuclear Waste Repositories`, the Nuclear Regulatory Commission (NRC) review panel delineated several studies needed to show that experimental sorption coefficients could accurately model radionuclide sorption behavior along release pathways. In particular, they focused on the potential problems involved with the use of crushed rock samples, stating `If crushed solids are used, it is essential to show that laboratory experiments involving sorption on crushed solids are relevant to the repository site. The surfaces of crushed material may be significantly different from the surfaces of intact material, both porous and fractured. Grinding may expose the surfaces of solid phases different from those which groundwater would contact in a repository and/or may change the reactivity of the same mineral surfaces with dissolved radionuclides. The surface of crushed mineral scan be enriched in certain elements by factors of two and three relative to the bulk composition...`. The experiments reported here were performed in direct response to the NRC technical position paper. They were designed to quantify the dependence of sorption properties and surface area on the crushed-particle size of the rock samples used in batch sorption experiments. To this end, nine different size fractions of tuff samples, ranging from 2 to 4 mm down to less than 38 {mu}m, were prepared by grinding, sieving, and washing bulk samples. These were reacted with solutions containing three different radioactive sorbers, {sup 137}Cs, {sup 85}Sr, and {sup 237}Np, the solid and solution fractions were separated, and both fractions were gamma counted to determine partitioning of the radioactive sorber. Surface areas of each sample were determined by BET analysis. From this information, the sorption coefficient (Rd) of each tracer on each particle-size fraction, and its correlation with surface area, was calculated.
- Research Organization:
- American Nuclear Society (ANS), La Grange Park, IL (United States); American Society of Civil Engineers (ASCE), New York, NY (United States)
- OSTI ID:
- 145377
- Report Number(s):
- CONF-930408-Vol.2; TRN: 94:005593-0071
- Resource Relation:
- Conference: 10. international high-level radioactive waste management conference, Las Vegas, NV (United States), 25-29 Apr 1993; Other Information: PBD: 1993; Related Information: Is Part Of High Level Radioactive Waste Management: Proceedings; Volume 2; PB: 1090 p.
- Country of Publication:
- United States
- Language:
- English
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