Updated Kd Estimates for Modeling Sorption of Cs, Sr, and Pu Isotopes in Hydrostratigraphic Units of Rainier Mesa and Shoshone Mountain
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Linear sorption (Kd) coefficients in bulk porous (matrix) rock were estimated for modeling of radionuclide transport in groundwater at Rainier Mesa (RM) and Shoshone Mountain (SM). These Kd estimates were derived from a “component additivity approach” applied in other areas of the Nevada National Security Site. This approach utilizes two types of variables: 1. average mass percentages of sorbing minerals: smectite, mica/illite, hematite, calcite, and zeolite determined from X-ray diffraction (XRD); and 2. linear coefficients derived from reactive chemistry models of surface complexation/ion exchange processes in representative groundwater. This study estimates Kd for Cs, Pu, and Sr isotopes using the same coefficients for component additivity approach applied to RM and SM in the earlier report, but instead uses an updated XRD mineralogy database that expands on the original XRD database. As transport modeling scope for RM/SM evolved since 2011, new considerations have emerged: Transport modeling or sorbing radionuclides has expanded from RM proper to adjacent areas; Probabilistic modeling approaches require examination of transport parameter uncertainty; and, More XRD data will improve estimates of Kd with consideration of uncertainty in mineralogy. This report addresses the above considerations by expanding the analysis of XRD data from two boreholes on RM to over twenty boreholes on RM, SM, and adjacent areas. This analysis focuses on XRD data relevant to potential radionuclide transport pathways sourced from RM and SM.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA)
- DOE Contract Number:
- AC52-07NA27344
- OSTI ID:
- 1459145
- Report Number(s):
- LLNL-TR-751397; 936533; TRN: US1901625
- Country of Publication:
- United States
- Language:
- English
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